Heavy Metal

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A heavy metal is a member of a loosely-defined subset of elements that exhibit metallic properties. It mainly includes the transition metals, some metalloids, lanthanides, and actinides. Many different definitions have been proposedsome based on density, some on atomic number or atomic weight, and some on chemical properties or toxicity.[1] The term heavy metal has been called a "misinterpretation" in an IUPAC technical report due to the contradictory definitions and its lack of a "coherent scientific basis".[1] There is an alternative term toxic metal, for which no consensus of exact definition exists either. As discussed below, depending on context, heavy metal can include elements lighter than carbon and can exclude some of the heaviest metals. Heavy metals occur naturally in the ecosystem with large variations in concentration. In modern times, anthropogenic sources of heavy metals, i.e. pollution, have been introduced to the ecosystem. Waste-derived fuels are especially prone to contain heavy metals, so heavy metals are a concern in consideration of waste as fuel.Contents[hide]

1 Relationship to living organisms 2 Heavy metal pollution 3 Medicine 4 Hazardous materials 5 Nuclear technology 6 See also 7 References

[edit]Relationship

to living organisms

Living organisms require varying amounts of "heavy metals." Iron, cobalt, copper, manganese, molybdenum, and zinc are required by humans. Excessive levels can be damaging to the organism. Other heavy metals such as mercury, plutonium, and lead are toxic metals that have no known vital or beneficial effect on organisms[citation needed], and their accumulation over time in the bodies of animalscan cause serious illness. Certain elements that are normally toxic are, for certain organisms or under certain conditions, beneficial. Examples includevanadium, tungsten, and even cadmium.[2]


[edit]Heavy

metal pollution

Motivations for controlling heavy metal concentrations in gas streams are diverse. Some of them are dangerous to health or to the environment (e.g. mercury, cadmium, lead, chromium),[3] some may cause corrosion (e.g. zinc, lead), some are harmful in other ways (e.g. arsenic may pollute catalysts). Within the European community the eleven elements of highest concern are arsenic, cadmium, cobalt, chromium, copper, mercury, manganese, nickel, lead, tin, and thallium, the emissions of which are regulated in waste incinerators. Some of these elements are actually necessary for humans in minute amounts (cobalt, copper, chromium, manganese, nickel) while others are carcinogenic or toxic, affecting, among others, the central nervous system (manganese, mercury, lead, arsenic), the kidneys or liver (mercury, lead, cadmium, copper) or skin, bones, or teeth (nickel, cadmium, copper, chromium).[4] Heavy metal pollution can arise from many sources but most commonly arises from the purification of metals, e.g., the smelting of copper and the preparation of nuclear fuels. Electroplating is the primary source of chromium and cadmium. Through precipitation of their compounds or by ion exchange into soils and muds, heavy metal pollutants can localize and lay dormant. Unlike organic pollutants, heavy metals do not decay and thus pose a different kind of challenge for remediation. Currently, plants or microrganisms are tentatively used to remove some heavy metals such as mercury. Plants which exhibit hyper accumulation can be used to remove heavy metals from soils by concentrating them in their bio matter. Some treatment of mining tailings has occurred where the vegetation is then incinerated to recover the heavy metals. One of the largest problems associated with the persistence of heavy metals is the potential for bioaccumulation and biomagnification causing heavier exposure for some organisms than is present in the environment alone. Coastal fish (such as the smooth toadfish) and seabirds (such as the Atlantic Puffin) are often monitored for the presence of such contaminants.[edit]Medicine

In medical usage, heavy metals are loosely defined[1] and include all toxic metals irrespective of their atomic weight: "heavy metal poisoning" can possibly include excessive amounts of iron,manganese, aluminium, mercury, cadmium, or beryllium (the fourth lightest element) or such a semimetal as arsenic. This definition excludes bismuth, the densest of approximately stable elements, because of its low toxicity.


Minamata disease results from mercury poisoning, and itai-itai disease from cadmium poisoning.[edit]Hazardous

materials

Heavy metals in a hazardous materials (or "hazmat") setting are for the most part classified in "Misc." on the UN model hazard class, but they are sometimes labeled as a poison when being transported.[edit]Nuclear

technology

Burnup of nuclear fuel is expressed in gigawatt-days per metric ton of heavy metal, where heavy metal means actinides like thorium, uranium, plutonium, etc., including both fissile and fertile material. It does not include elements such as oxygen that may be bonded to the fuel metals, or cladding materials such as zirconium, which might be considered heavy metals by some other standards.[edit]

Definition Beneficial Heavy Metals Toxic Heavy Metals

There are 35 metals that concern us because of occupational or residential exposure; 23 of these are the heavy elements or "heavy metals": antimony, arsenic, bismuth, cadmium, cerium, chromium, cobalt, copper, gallium, gold, iron, lead, manganese, mercury, nickel, platinum, silver, tellurium, thallium, tin, uranium, vanadium, and zinc (Glanze 1996). Interestingly, small amounts of these elements are common in our environment and diet and are actually necessary for good health, but large amounts of any of them may cause acute or chronic toxicity (poisoning). Heavy metal toxi ity can result in damaged or c reduced mental and central nervous function, lower energy levels, and damage to blood composition, lungs, kidneys, liver, and other vitalorgans. Long-term exposure may result in slowly progressing physical, muscular, and neurological degenerative processes that mimic Alzheimer's disease, Parkinson's disease, muscular dystrophy, and multiple sclerosis. Allergies are not uncommon and repeated long-term contact with some metals or their compounds may even cause cancer (International Occupational Safety and Health Information Centre 1999).

For some heavy metals, toxic levels can be just above the background concentrations naturally found in nature. Therefore, itis important for us to inform ourselves about the heavy metals and to take protective measures against excessive exposure. In most parts of the United States, heavy metal toxicity is an uncommon medical condition; however, it is a clinically significant condition when it does occur. If unrecognized or inapprop riately treated, toxicity can result in significant illness and reduced quality of life (Ferner 2001). For persons who suspect that they or someone in their household might have heavy metal toxicity, testing is essential. Appropriate conventional and natural medical procedures may need to be pursued (Dupler 2001) .

The association of symptoms indicative of acute toxicity is not difficult to recognize because the symptoms are usually sever , rapid in onset, and associated e with a known exposure or ingestion (Ferner 2001): cramping, nausea, and vomiting; pain; sweating; headaches; difficulty breathing; impaired cognitive, motor, and language skills; mania; and convulsions. The symptoms of toxicity resulting from chronic exposure (impaired cognitve, motor, and language i skills; learning difficulties; nervousness and emotional instability; and insomnia, nausea, lethargy, and feeling ill) are also easily recognized; however, they are much more difficult to associate with their cause. Symptoms of chronic exposure are very similar to symptoms of other hea conditions and often lth develop slowly over months or even years. Sometimes the symptoms of chronic exposure actually abate from time to time, leadin the person to postpone g seeking treatment, thinking the symptoms are related to something else.

Definition of a Heavy Metal"Heavy metals" are chemical elements with a specific gravity that is at least 5 times the specific gravity of water. The spec gravity of water is 1 at 4C ific (39F). Simply stated, specific gravity is a measure of density of a given amount of a solid subs tance when it is compared to an equal amount of water. Some well-known toxic metallic elements with a specific gravity that is 5 or more times that of water are arsenic, 5.7; cadmium, 8.65; iron, 7.9; lead, 11.34; and mercury, 13.546 (Lide 1992).

Beneficial Heavy MetalsIn small quantities, certain heavy metals are nutritionally essential for a healthy life. Some of these are referred to as th trace elements (e.g., iron, copper, e manganese, and zinc). These elements, or some form of them, are commonly foun naturally in foodstuffs, in fruits and vegetables, and in commercially d available multivitamin products (International Occupational Safety and Health Information Centre 1999). Diagnostic medical ap plications include direct injection of gallium during radiological procedures, dosing with chromium in parenteral nutrition mixtures, and the use of lead as a radiation shield aroundx-


ray equipment (Roberts 1999). Heavy metals are also common in industrial applications such as in the manufacture of pesticide batteries, alloys, s, electroplated metal parts, textile dyes, steel, and so forth. (International Occupational Safety and Heath Information Centre 1999). Many of these products are in our homes and actually add to our quality of life when properly used.

Toxic Heavy MetalsHeavy metals become toxic when they are not metabolized by the body and accumulate in the soft tissues. Heavy metals may ente the human body through r food, water, air, or absorption through the skin when they come in contact with humans in a griculture and in manufacturing, pharmaceutical, industrial, or residential settings. Industrial exposure accounts for a common route of exposure for adults. Ingestion is the most common ro of exposure in children ute (Roberts 1999). Children may develop toxic levels from the normal hand-to-mouth activity of small children who come in contact with contaminated soil or by actually eating objects that are not food (dirt or paint chips) (Dupler 2001). Less common routes of exposure are during a radiological procedure, from inappropriate dosing or monitoring during intravenous (parenteral) nutrition, from a broken thermometer (Smith et al. 1997), or from a suicide or homicide attempt (Lupton et al. 1985).

As a rule, acute poisoning is more likely to result from nhalation or skin contact of dust, fumes or vapors, or materials in the workplace. However, lesser i levels of contamination may occur in residential settings, particularly in older homes with lead paint or old plumbing (Inter national Occupational Safety and Health Information Centre 1999). The Agency for Toxic Substances and Disease Registry (ATSDR) in Atlanta, Georgia, (a part ofthe U.S. Department of Health and Human Services) was established by congressional mandate to perform specific functions concerning adverse human health effects and diminished quality of life associated with exposure to hazardous substances. The ATSDR is responsible for assessment of wastesites and providing health information concerning hazardous substances, response to emergency release situations, and education and training concerning hazardous substances (ATSDR Mission Statement, November 7, 2001). In cooperation with the U.S. Environmental Protection Agency, the ATSDR has comp a Priority List for iled 2001 called the "Top 20 Hazardous Substances." The heavy metals arsenic (1), lead (2), mercury (3), and cadmium (7) appear on this list.

Note: The ATSDR provides comprehensive protocols called Medical Management Guidelines for Acute Chemical Exposures in Volume III ofthe Managing Hazardous Material Incidents Series. These protocols have a Chemical Abstracts Service (CAS) number and give a description of toxic substances; routes of exposure; health effects; prehospital, triage, and emergency medical department care; antidotes a treatment; nd disposition and follow-up; and reporting instructions. The series may be viewed or downloaded from the ATSDR web site at no cost.

COMMONLY ENCOUNTERED TOXIC HEAVY METALS

Arsenic Lead Mercury Cadmium Iron Aluminum

As noted earlier, there are 35 metals of concern, with 23 of them called the heavy metals. Toxicity can re sult from any of these metals. This protocol will address the metals that are most likely encountered in our daily environment. Briefly covered will be four metals that are in cluded in the ATSDR's "Top 20 Hazardous Substances" list. Iron and aluminum will also be discussed even though they do not appear on the ATSDR's list.

ArsenicArsenic is the most common cause of acute heavy metal poisoning in adults and is number 1 on the ATSDR's "Top 20 List." Arsen is released into the ic environment by the smelting process of copper, zinc, and lead, as well as by the manufacturing of chemicals and glasses. Arsine gas is a common byproduct produced by the manufacturing of pesticides that contain arsenic. Arsenic may be also be found in water supplies worldwide, eading to exposure of shellfish, l cod, and haddock. Other sources are paints, rat poisoning, fungicides, and wood preservatives. Target organs are the blood, kidneys, and central nervous, digestive, and skin systems (Roberts 1999; ATSDR ToxFAQs for Arsenic).

LeadLead is number 2 on the ATSDR's "Top 20 List." Lead accounts for most of the cases of pediatric heavy metal poisoning (Robert 1999). It is a very soft s metal and was used in pipes, drains, and soldering materials for many years. Millions of homes builtbefore 1940 still contain lead (e.g., in painted surfaces), leading to chronic exposure from weathering, flaking, chalking, and dust. Every year, industry produces about 2.5 million ton of lead throughout the world. s Most of this lead is used for batteries. The remainder is used for cable coverings, plumbing, ammunition, and fuel additives. Other uses are as paint pigments and in PVC plastics, x-ray shielding, crystal glass production, and pesticides. Target organs are the bones, brain, blood, kidneys, and thyroid gland (International Occupational Safety and Health Information Centre 1999; ATSDR ToxFAQs for Lead).

MercuryNumber 3 on ATSDR's "Top 20 List" is mercury. Mercury is generated naturally in the environment from the degassing of the ear h's crust, from volcanic t


emissions. It exists in three forms: elemental mercury and organic and inorganic mercury. Mining operations, chloralkali plan and paper industries are ts, significant producers of mercury (Goyer 1996). Atmospheric mercury is dispersed across the globe by winds and returns to the earth in rainfall, accumulating in aquatic food chains and fish in lakes (Clarkson 1990). Mercury compounds were added to paint as a fungicide until 1990. Th ese compounds are now banned; however, old paint supplies and surfaces painted with these old supplies still exist. Mercury continues to be used in thermometers, thermostats, and dental amalgam. (Many researchers suspect dental amalgam as being a possible source of mercury toxicity [Omura et al. 1996; O 'Brien 2001].) Medicines, such as mercurochrome and merthiolate, are still available. Algaecides and childhood vaccines are also potential sources. Inh alation is the most frequent cause of exposure to mercury. The organic form is readily absorbed in the gastrointestinal tract (90-100%); lesser but still significant amounts of inorganic mercury are absorbed in the gastrointestinal tract (7-15%). Target organs are the brain and kidneys (Roberts 1999; ATSDR ToxFAQs for Mercury).

CadmiumCadmium is a byproduct of the mining and smelting of lead and zinc and is number 7 on ATSDR's "Top 20 list." It is used in nickel -cadmium batteries, PVC plastics, and paint pigments. It can be found in soils because insecticides, fungicides, sludge, and commercial fertilizers hat use cadmium are used in t agriculture. Cadmium may be found in reservoirs containing shellfish. Cigarettes also contain cadmium. Lesser known sources of exposure are dental alloys, electroplating, motor oil, and exhaust. Inhalation accounts for 15 -50% of absorption through the respiratory system; 2-7% of ingested cadmium is absorbed in the gastrointestinal system. Target organs are the liver, placenta, kidneys, lungs, brain, and bones (Roberts 1999; ATSDR Tox FAQs for Cadmium).

IronDiscussion of iron toxicity in this protocol is limited to ingested or environmental exposure. Iron overload disease (hemochromatosis), an inherited disorder, is discussed in a separate protocol. Iron does not appear on the ATSDR's "Top 20 List," but it is a heavy metal of concern, partcularly because ingesting i dietary iron supplements may acutely poison young children (e.g., as few as five to nine 30 -mg iron tablets for a 30-lb child).

Ingestion accounts for most of the toxic effects of iron because iron is absorbed rapidly in the gastroint stinal tract. The corrosive nature of iron seems to e further increase the absorption. Most overdoses appear to be the result of children mistaking red-coated ferrous sulfate tablets or adult multivitamin preparations for candy. (Fatalities from overdoses have decreased significantly with the introduction of child-proof packaging. In recent years, blister packaging and the requirement that containers with 250 mg or more of iron have child-proof bottle caps have helped reduce accidental ingestion and overdose of iron tablets by children.) Other sources of iron are drinking water, iron pipes, and cookware. Target organs are the liver cardiovascular system, , and kidneys (Roberts 1999).

AluminumAlthough aluminum is not a heavy metal (specific gravity of 2.55 -2.80), it makes up about 8% of the surface of the earth and is the third most abundant element (ATSDR ToxFAQs for Aluminum). It is readily available for human ingestion through the use of food additives, antacids buffered aspirin, astringents, , nasal sprays, and antiperspirants; from drinking water; from automobile exhaust and tobacco smoke; and from using aluminum foil, aluminum c okware, o cans, ceramics, and fireworks (ATSDR ToxFAQs for Aluminum).

Studies began to emerge about 20 years ago suggesting that aluminum might have a possible connection with developing Alzheimer's disease when researchers found what they considered to be significant amounts of aluminum in the brain tissue of Alzheimer's patients. Alt hough aluminum was also found in the brain tissue of people who did not have Alzheimer's disease, recommendations to avoid sources of aluminum received widespread public atten tion. As a result, many organizations and individuals reached a level of concern that prompted them to dispose of all their aluminu cookware and storage containers m and to become wary of other possible sources of aluminum, such as soda cans, personal care products, and even their drinking water (Anon. 1993).

However, the W orld Health Organization (W HO 1998) concluded that, although there were studies that demonstrate a positive relationship between aluminum in drinking water and Alzheimer's disease, the W HO had reservations about a causal relationship because the studies did not account for total aluminum intake from all possible sources. Although there is no conclusive evidence for or against aluminum as a primary cause for Alzheimer's disease, most researchers agree that it is an important factor in the dementia component and most certainly deserves continuing resear h efforts. Therefore, at this c time, reducing exposure to aluminum is a personal decision. W orkers in the automobile manufacturing industry also have concer s about long-term exposure n to aluminum (contained in metal working fluids) in the workplace and the development of de generative muscular conditions and cancer (Brown 1998; Bardin et al. 2000). The ATSDR has compiled a ToxFAQs for Aluminum to answer the most frequently asked health questions about alumin m. Target organs for u aluminum are the central nervous system, kidney, and digestive system.

Heavy Metal Toxicity

SYMPTOMS OF EXPOSURE AND TOXICITY


Arsenic Lead Mercury Cadmium Aluminum

Exposure to toxic heavy metals is generally classified as acute, 14 days or less; intermediate, 15 -354 days; and chronic, more than 365 days (ATSDR). Additionally, acute toxicity is usually from a sudden or unexpected exposure to a high level of the heavy metal (e.g., from careless handling, inadequate safety precautions, or an accidental spill or release of toxic material often in a laboratory, industrial, or transportationsetting). Chronic toxicity results from repeated or continuous exposure, leading to an accumulation of the toxic substance in the body. Chronic exposure may result from contaminated food, a ir, water, or dust; living near a hazardous waste site; spending time in areas with deteriorating lead paint; maternal transfer n the womb; or from participating in i hobbies that use lead paint or solder. Chronic exposure may occur in either the home or workplace. Symptoms of chronic toxiciy are often similar to many t common conditions and may not be readily recognized. Routes of exposure include inhalation, skin or eye contact, and ingestion (ATSDR MMGs and ToxFAQs; Anon. 1993; W HO 1998; International Occupational Safety and Health Information Centre 1999; Roberts 1999; Dupler 200 Ferner 2001). 1;

ArsenicExposure to arsenic occurs mostly in the workplace, near hazardous waste sites, or in areas with high natural levels. Symptoms of acute arsenic poisoning are sore throat from breathing, red skin at contact point, or severe abdominal pain, vomiting, and diarrhea, often within 1 h after ingestion. Other our symptoms are anorexia, fever, mucosal irritation, and arrhythmia. Cardiovascular changes are often subtle in the early stages but can progress to cardiovascular collapse.

Chronic or lower levels of exposure can lead to progressive peripheral and central nervous changes, such as sensory changes, numbness and tingling, and muscle tenderness. A symptom typically described is a burning sensation ("needles and pins") in hands and feet. Neuropathy (inflammation and wasting of the nerves) is usually gradual and occurs over several years. There may also be excessive darkening of the skin (hyperpigmentation) in areas that are not exposed to sunlight, excessive formation of skin on the palms and soles (hyperkeratosis), or white bands of arsenic deposits across the bed of the fingernails (usually 4-6 weeks after exposure). Birth defects, liver injury, and malignancy are possible. (Arsenic has also been used in homicides a suicides.) nd

LeadAcute exposure to lead is also more likely to occur in the workplace, particularly in m anufacturing processes that include the use of lead (e.g., where batteries are manufactured or lead is recycled). Even printing ink, gasoline, and fertilizer contain lead. Symptoms include a bdominal pain, convulsions, hypertension, renal dysfunction, loss of appetite, fatigue, and sleeplessness. Other symptoms are hallucinations, headache, numbness, a rthritis, and vertigo.

Chronic exposure to lead may result in birth defects, mental retardation, autism, psychosis, allergies, dysl xia, hyperactivity, weight loss, shaky hands, e muscular weakness, and paralysis (beginning in the forearms). Children are particularly sensitive to lead (absorbing as much as 50% of the ingested dose) and are prone to ingesting lead because they chew on painted surfaces and eat products not intended for human consumption (e.g., hobby paints, cosmetics, hair colorings with lead-based pigments, and even playground dirt). In addition to the symptoms found in acute lead exposure, symptoms of chronic lead exposure could be allergies, arthritis, autism, colic, hyperactivity, mood swings, nausea, numbness, lack of concentration, seizure and weight s, loss.

MercuryAcute mercury exposure may occur in the mining industry and in the manufacturing of fungicides, thermo meters, and thermostats. Liquid mercury is particularly attractive to children because of its beautiful silver color and unique behavior when spilled. Children are morelikely to incur acute exposure in the home from ingesting mercury from a broken thermometer or drinking medicine that contains mercury. Because mercury vapors concentrate at floor level, crawling children are subject to a significant hazard when the mercury is sprinkled throughout the house during religious ceremonies or when there is an accidental spill (Zayas et al. 1996). Mercury spills are difficult to clean up, and mercury may remain undetected in carpeting or some time. Symptoms of f acute exposure are cough, sore throat, and shortness of breath; metallic taste in the mouth, abdominal pa nausea, vomiting and diarrhea; headaches, in, weakness, visual disturbances, tachycardia, and hypertension.

Chronic exposure to mercury may result in permanent damage to the central nervous system (Ewan et al. 1996) and kidneys. Mercury can also cross the placenta from the mother's body to the fetus (levels in the fetus are often double those in the mother) and accumulate, resul ting in mental retardation, brain damage, cerebral palsy, blindness, seizures, and inability to speak.

Dental amalgam is also suspected as being a possible source of mercury toxicity from chronic exposure. Some physicians suggest that amalgam fillings could be part of the explanation for the explosion of learning problems and autism in children since W orld War II, a time perod corresponding with the i introduction and widespread use of mercury amalgam (O'Brien 2001). Studies in both animals and humans have confirmed the pres ence of mercury from amalgam fillings in tissue specimens, blood, amniotic fluid, or urine (Vimy et al. 1990; W ill ershausen -Zonnchen et al. 1992; Gebel et al. 1996; Omura et al. 1996; Sallsten et al. 1996; Isacsson et al. 1997). However, according to Dr. Robert M. Anderton of the American Dental Associ ation, "There is no sound scientific evidence supporting a link between amalgam fillings and systemic diseases or chronic illness" (Anderton 2001).


The ADA does acknowledge that amalgam contains mercury and reacts with others substances. However, to date the ADA concludes that amalgam continues to be a safe material. Researchers reported finding "no significant association of Alzheimer's disease with the number, surface area, or history of having dental amalgam restoration" and "no statistical significant differences in brain mercury levels between subjects withAlzheimer's disease and control subjects" (Saxe et al. 1999).

Interestingly, the metallic mercury used by dentists to manufacture dental amalgam is shipped as a hazardous material to dent offices. Although the ADA al does not advise removing existing amalgam fillings from teeth, it does support ongoing research to develop new materials that will prove to be as safe as dental amalgam (Anderton 2001). Symptoms in adults and children could include tremors, anxiety, forgetfulness, emotional inst ability, insomnia, fatigue, weakness, anorexia, cognitive and motor dysfunction, and kidney damage. People who consume more than two fish meals a week ar showing very high e serum levels of mercury.

CadmiumAcute exposure to cadmium generally occurs in the workplace, particularly in the manufacturing processes of batteries and color pigments used in paint and plastics, as well as in electroplating and galvanizing processes. Symptoms of acute cadmium exposure are nausea, vomiting, ab dominal pain, and breathing difficulty.

Chronic exposure to cadmium can result in chronic obstructive lung disease, renal disease, and fragile bones. Protect children by carefully storing products containing cadmium, especially nickel-cadmium batteries. Symptoms of chronic exposure could include alopecia, anemia, arthritis, learning disorders, migraines, growth impairment, emphysema, osteoporosis, loss of taste and smell, poor appetite, and cardiovascular disease.

AluminumAlthough aluminum is not a heavy metal, environmental exposure is frequent, leading to concerns about accumulative effects and a possible connection with Alzheimer's disease (Anon. 1993). Acute exposure is more likely in the workplace (e.g., unintentional breathing of aluminum -laden dust from manufacturing or metal finishing processes).

Chronic exposure may occur in the workplace from accumulated exposures to low levels of airborne aluminum dust and handling aluminum parts during assembly processes over many years. In the home, we are in constant contact with aluminum in food and in water; from cookware and soft drink cans; from s consuming items with high levels of aluminum (e.g., antacids, buffered aspirin, or treated drinking water; or even by using n asal sprays, toothpaste, and antiperspirants) (Anon. 1993; ATSDR ToxFAQs for Aluminum). Citric acid (e.g., in orange juice) may increase aluminum levels by its leaching activity.

Interestingly, aluminum-based coagulants are used in the purification of water. However, the beneficial effects of using aluminum in water treatmenthave been balanced against the potential health concerns. W ater purification facilities follow a number of approaches to minimizethe level in "finished" water (W HO 1998). Symptoms of aluminum toxicity include memory loss, learning difficulty, loss of coordin ation, disorientation, mental confusion, colic, heartburn, flatulence, and headaches.

LABORATORY TESTING AND DIAGNOSIS FOR THE PRESENCE OF HEAVY METALS

Arsenic Lead Mercury Cadmium Aluminum

The diagnosis of heavy metal toxicity requires observation of presenting symptoms, obtaining a thorough history of potentialexposure, and the results of laboratory tests. Laboratory tests routinely used for seriously exposed persons include blood tests, liver and renal function tests, urinalysis, fecal tests, x rays, and hair and fingernail analysis. Many of these tests are not routinely performed in a doctor's office. However, your p hysician can take blood samples and send them to the appropriate testing laboratory. Chest x-rays are recommended for persons with respiratory symptoms, and abdominal x-rays can detect ingested metals (refer to the ATSDR ToxFAQs for specific information).

ArsenicArsenic levels can be measured in blood, urine, hair, and fingernails. Because arsenic clears fairly rapidly from the blood, blood tests are not always usefu l (Dupler 2001). Therefore, urine tests are the most reliable for arsenic exposure within the past few days; hair and fingernai testing are used to measure l exposure over the past several months (ATSDR ToxFAQs for Arsenic). Abdominal x-rays can reveal metallic fragments (Ferner 2001). Note: Hair treatments, including hair dyes, can contaminate hair samples. W hen testing for any heavy metal, the most accurate results are obtained from hair that has not been chemically treated for at least 2 months.


LeadWhen there are presenting symptoms of lead toxicity, blood testing is done. Blood lead levels in children higher than 10 mcg/ are considered to be of dL concern (Ferner 2001; ATSDR ToxFAQs for Lead). Symptoms in adults may not appear until blood lead levels exceed 80 mcg/dL (Du pler 2001). However, medical treatment is usually necessary in children who have levels of 45 mcg/dL. Significanty lower levels of 30 mcg/dL in children can cause mental l retardation or cognitive and behavioral problems (ATSDR ToxFAQs for Lead). A complete blood count (CBC) is also done to check for abnormalities on red blood cells (basophilic stippling). In children, long-bone x-rays may reveal bands called "lead lines" that indicate failure of the bone to rebuild. These bands are not actual lead concentrations, but are bone abnormalities. Adults do not have lead lines. X -rays of the abdomen can reveal swallowed objects, such as paint chips, fishing sinkers, curtain weights, or bullets (Ferner 2001). A less common test is measurement of lead in teeth A TSDR ToxFAQs for Lead). All ( children with brain-related symptoms should be considered for lead toxicity (Ferner 2001).

MercuryA 24-hour urine specimen is collected for measurement of mercury levels. Chest x-rays can reveal a collection of mercury from exposure to elemental mercury or a pulmonary embolism containing mercury (Ferner 2001). Abdominal x-rays can reveal swallowed mercury as it moves through the gastrointestinal tract. Blood and urine samples are used to determine recent exposure, as well as exposure to elemental mercu and inorganic forms of ry mercury. Scalp hair is used in testing for exposure to methylmercury. Liver and kidney function tests are also important in severely exposed persons. Blood mercury levels should not exceed 50 mcg/L (see the ATSDR Medical Management Guidelines).

CadmiumLaboratory testing procedures for cadmium toxicity include collection of a 24-hour urine specimen, CBC, and hair and fingernail clippings. Blood levels show recent exposure; urine levels show both recent and earlier exposure (ATSDR). Blood levels of cadmium above 5 mcg/dL and creatinine levels in urine above 10 mcg/dL suggest cadmium toxicity (Dupler 2001). Note: The ATSDR is unsure of the reliability of tests for cadmium levels.

AluminumTesting procedures measure aluminum levels in blood, urine, hair and fingernails, and feces (ATSDR ToxFAQs for Aluminum). Acc ording to a spokesperson at the ATSDR in spring 2002, levels of aluminum that are recognized as average are less than 0.01 mg/L. However, blood testin might underestimate the g total body level of aluminum; postmortem brain, lung, and bone measurements reveal much hig levels of aluminum than blood tests. her

SIGNIFICANCE OF INDIVIDUALIZED TREATMENT REGIMENSIt is very important to note that treatment regimens vary significantly and are tailored to each specific individual's medica condition and the circumstance of l their exposure. Providing a complete history of the person, including their occupation, hobbies, recreational activities, and en vironment, is critical in diagnosing heavy metal toxicity. A possible history of ingestion often facilitates a diagnosis, particula in children. Findings from physical examinations vary rly with the age of the person, health status of the person, amount or form of the substance, and time since exposure (absorptionrate) (Ferner 2001).

Allopathic (conventional) and alternative medicine practitioners (and naturopathic practitioners to a lesser extent) treat heavy metal toxicity. Once toxicity is confirmed, all cases (even suspected) of heavy metal toxicity should be brought to the attention of a professional who is exp erienced in diagnosing and treating poisoning. Often professionals consult with regional poison control centers or medical toxicologists for added exper ise. Emergency room personnel t and first responders are trained in recognizing symptoms and in proper handling, decontamination, and treatment techniques in acute exposure cases (see the ATSDR Medical Management Guidelines).

Conventional and alternative medical treatment includes chelation therapy, supportive care (intravenous fluids, cardiac stabiization, exchange transfusion, l dialysis), and decontamination (charcoal, cathartics, emesis, gastric lavage, surgery). These procedures typically require hospitalization or treatment in a health care or clinical setting (Dr. Joseph F. Smith Medical Library 2001). Follow-up is required with laboratory testing until reference levels are within and remain in the normal range, particularly when the exposure was acute or if the person continues to have symptoms after treatm ent (ATSDR Medical Management Guidelines; W entz 2000). Additionally, if there is a suspected homicidal or suicidal association, proper medical and legal resources should be involved (Ferner 2001). Medical personnel should report exposures to the appropriate agency to prevent additional public health risks either in the workplace or in the home (ATSDR Medical Management Guidelines; Anon. 1993; W HO 1998; International Occupational Safety and Health Infor mation Centre 1999; Roberts 1999; Dupler 2001; Ferner 2001; USNML/NIH 2001a; 2001b; 2001c; 2001d).

April 1996 1. INTRODUCTION Increasing industrialisation has been accompanied throughout the world by the


extraction and distribution of mineral substances from their natural deposits. Following concentration, many of these have undergone chemical changes through technical processes and finally pass, finely dispersed and in solutions, by way of effluent, sewage, dumps and dust, into the water, the earth and the air and thus into the food chain.These include metals and thus also the heavy metals relevant for this document. Together with essential nutrients, plants and animals also take up small amounts of contaminant heavy metal compounds and can concentrate them. As certain heavy metals such as lead, cadmium and mercury have been recognised to be potentially toxic within specific limiting values, a considerable potential hazard exists for human nutrition. Not all the traces of heavy metals in plants and animals are the results of human activity. Some arise through the absorption processes of naturally occurring soil components, as has been shown for cadmium in particular. Purely theoretically, every 1000 kg of "normal" soil contains 200 g chromium, 80 g nickel, 16 g lead, 0.5 g mercury and 0.2 g cadmium! Therefore it is not always easy to assign a definite cause for an increased heavy metal content. Even foodstuffs produced in completely unpolluted areas are not entirely free of heavy metals. The absorption of very small amounts is therefore unavoidable in principle and has always occurred. As a result, the Codex Alimentarius is busy with the preparation of standards for heavy metals in foodstuffs among others. Explanation of symbols and units of measurement:


Pb = Lead 1 g = 1 000 mg Ni = Nickel 1 mg = 1 000 g Cd =Cadmium 1 ppm = 1 mg/kg Hg =Mercury 1 ppb = 1 g/kg Cr = Chromium HEAVY METALSHeavy Metals/2 E-mail : [email protected] 2. Definition Those metals are described as "heavy metals" which, in their standard state, have a specific gravity (density) of more than about 5 g/cm 3 . Some of them, such as copper, nickel, chromium and iron, for example, are essential in very low concentrations for the survival of all forms of life. These are described as essential trace elements. Only when they are present in greater quantities, can these, like the heavy metals lead, cadmium and mercury which are already toxic in very low concentrations, cause metabolic anomalies (see chapter 4.4). Here, the boundary between the essential and the toxic effect is somewhat problematic. There are 60 heavy metals. These also include the precious metals platinum, silver and gold. For this report, however, only the smalller group of toxic heavy metals is of significance. 3. The context of the heavy metal problem


Essentially, the heavy metals have only become a focus of public interest since analytical techniques have made it possible to detect them even in very small traces. The relatively reckless handling of heavy metals and their compounds in former times can partly be explained by the fact that their effects were unknown. Today, analytical detection is possible down to a thousandth of a mg/kg for certain matrixes. This has made it possible for toxicologists, in animal experiments, to follow up the effects of individual substances down to the smallest concentrations. Their warnings, particularly with regard to the effects on health of chronic consumption and the accumulations to which this leads, have startled the public and, at times, mostly as a result of the activities of so-called pressure groups, have generated genuine hysteria. All this has taken place against the background of a steady increase in the processing of all types of heavy metals in industry and the household. Therefore, proper disposal, recycling and the regulation of the application of sewage to agricultural land, have assumed great importance. 4. The toxic heavy-metals 4.1 Lead 4.1.1 The origin of lead in foodstuffs and their surroundings Lead has been mined since ancient times and has been processed in many ways, e.g. for water pipes, containers and, as acetate, even for sweetening wine ("lead sugar"). World production amounts to millions of tons and is used in the manufacture of accumulators, solders, pigments, cables and anti-rust agents (red lead/lead


oxide) and, a considerable amount still, into anti-knock petrol. The main sources of lead pollution in the environment are: Industrial production processes and their emissions, road traffic with leaded petrol, the smoke and dust emissions of coal and gas-fired power stations, the laying of lead sheets by roofers as well as the use of paints and anti-rust agents.Heavy Metals/3 E-mail : [email protected] Problems for foodstuffs were caused for a long time, and are still caused today on occasion, by the soldered seams of cans and the soldered closures of condensed milk cans, the metal caps of wine bottles and, still, by lead pipes in drinking water systems. 4.1.2 Toxic effects Lead can trigger both acute and chronic symptoms of poisoning. Acute intoxications only occur through the consumption of relatively large single doses of soluble lead salts. Chronic intoxications can arise through the regular consumption of foodstuffs only slightly contaminated with lead. Lead is a typical cumulative poison. The danger of chronic intoxications is the greater problem. . Basically, as a result of their comparatively high affinity for proteins, the lead ions consumed bond with the haemoglobin (red blood pigment) and the plasma protein of the blood. This leads to inhibition of the synthesis of red blood cells and thus of the vital transport of oxygen. If the bonding capacity here is


exceeded, lead passes into the bone-marrow, liver and kidneys. Such an intoxication leads to: - Encephalopathies in the central nervous system (CNS); - Disturbances in kidney and liver functions progressing as far as necrosis; - Damage to the reproductive organs; - Anaemias and many metabolic deficiency symptoms. Some of the injurious processes are still not properly understood. Particularly dangerous to all forms of life are the organic lead compounds. They cause injuries to mental development such as reduction of intelligence, growth disturbances and spasticity. Children are particularly at risk from lead consumption, both before and after birth, as they absorb lead more rapidly than adults. Particularly affected are small children, with their habit of placing dirty fingers and objects of all kinds into their mouths or licking them (so-called mouth/hand activity) and, in this way, swallowing dust and soil particles containing heavy metals, for example from lead-based paints. In animal experiments, the consumption of domestic and surface dust leads to a measurably increased heavy metal content in the blood. Little is known about the excretion of lead, once it has been absorbed. The greatest part accumulates in the body. Lead is not considered to be a carcinogen or mutagen.Heavy Metals/4 E-mail : [email protected] 4.1.3 Present contamination of foodstuffs and acceptable maximum levels


In 1993, the joint FAO/WHO Expert Committee for Additives and Contaminants (JECFA) reduced the value it had provisionally specified for adults in 1972, for tolerable lead consumption per week (PTWI - provisional tolerable weekly intake), from 0.05 mg/kg body weight to 0.025 mg (or 25 g). This value represents the upper limit, for consumption quantities over prolonged periods, still to be regarded as tolerable. Short-term excess consumption is accepted if the average value for consumption over a long period is not exceeded. The reason for the reduction which has now taken place is, firstly, that research has revealed further harmful potentials in lead and, secondly, that lead contamination has decreased throughout the world. Originally this PTWI was intended only to apply in the case of children. The foodstuffs which contribute most to the consumption of lead are vegetables, fruit, drinking water, beverages and cereal products. Compliance with the PTWI values of the JECFA can best be established by a study of the so-called food shopping basket. This is composed, according to country, of the various foodstuffs normally purchased in one week. An average value for them all is determined analytically. For details of a monitoring system which has been introduced throughout the world see chapter 5. It is reported that in individual cases in some countries the PTWI value for lead in fruit and vegetables was exceeded, but not that for the "shopping basket". Fruit and vegetables mostly acquire their contamination through impurities in


the air. Accordingly, they can be decontaminated to a large extent by simple washing. Since lead has been eliminated from petrol, the lead content has fallen sharply in many cases. The lead content in drinking water presents a problem in many countries. Thus, the present WHO guideline of 50 g/l is exceeded in Great Britain, for example, in 34 % of households. 4.1.4 The situation with regard to raw materials for confectionery Cocoa, milk, fats, flour and especially sugar neither belong to the highly contaminated foodstuffs, nor are they consumed in large quantities. Therefore they make little contribution to the total contamination of the "shopping basket". In the draft Codex Paper "Standard for Lead in Foods", therefore, they are not considered, but a document does exist which includes some of these materials (CX/FAC 95/18).Heavy Metals/5 E-mail : [email protected] 4.2 Cadmium 4.2.1 Origin of cadmium in foodstuffs and their surroundings Cadmium (world production in 1972, 15 000 t) exists in low concentrations in all soils. It is actively extracted from its ores for commercial purposes and is also emitted in industrial processes such as metal melting and refining, coal and oilfired power stations, electroplating plants, etc. It is spread by air and water (sewage sludge) far over sea and land, but especially in the vicinity of heavy industrial plants. Cadmium is today regarded


as the most serious contaminant of the modern age. It is absorbed by many plants and seacreatures and, because of its toxicity, presents a major problem for foodstuffs. Contamination through fertilisers becomes an increasing problem. Unlike lead, cadmium contamination cannot be removed from plants by washing them; it is distributed throughout the organism. It is often difficult to be certain of the cause of a cadmium content found in fruit or vegetables, as the substance in its natural form exists everywhere in the soil and is absorbed by the roots. For Central American cocoa, however, it has been possible to show that the increased cadmium content was related to the specific local constituency of the soil. As opposed to African cocoa kernels which contain 0.08-0.14 mg/kg, values from 0.18-1.5 mg/kg are found in the fine cocoa varieties from Venezuela and Ecuador, for example. The new sources from the Far East are also higher in cadmium content (see 4.2.4). 4.2.2 Toxic effects Cadmium is concentrated particularly in the kidneys, the liver, the bloodforming organs and the lungs. It most frequently results in kidney damage (necrotic protein precipitation) and metabolic anomalies caused by enzyme inhibitions. It is now known that the ltai-itai sickness in Japan (with bone damage) is a result of the regular consumption of highly contaminated rice. Cadmium, like lead, is a cumulative poison, i.e. the danger lies primarily in the regular consumption of foodstuffs with low contamination. However, in contrast


to lead, the definition of an exact toxicity limit is not possible for cadmium. The decisive point is whether absorption of the existing cadmium actually takes place. This is, firstly, dependent upon the composition of the diet as a whole and, secondly, on the bio-availability of the cadmium compound present. No connection with cancerous disorders has been found. 4.2.3 Present contamination of foodstuffs and acceptable maximum values Among the foodstuffs which present a problem are offal, crustaceans and shellfish and some fungi. Here, values of several mg/kg are found! Overall, however, vegetables are of greater importance for human cadmium contamination. Rice and wheat contain 10-150 g/kg; meat, fish and fruit between 1 and 50 g/kg. The Cd content of milk products is very low. In most countries, there are legal regulations regarding permissible cadmium contamination levels. As a rule, these are based on the PTWI value last set by the JECFA of the FAO/WHO in 1989 of about 7 g/kg body weight,Heavy Metals/6 E-mail : [email protected] corresponding with a quantity of 0.4-0.5 mg per person (70 kg) per week. The typical quantities of cadmium consumed per person per day in the western industrialised societies are between 10 and 50 g, but these are considerably higher in some localities. 70 % of this comes from foodstuffs. One problem of a special kind is the smoking of tobacco. 20 cigarettes a day provide a cadmium input of 4 g! 4.2.4 The situation with regard to raw materials for confectionery


Only in the manufacture of plain chocolates with high proportions of fine cocoa could one come into a range where caution is demanded. Such chocolates are, in any way, not popular with children, which due to their low bodyweight exceed the PTWI more easily. No problems arise with other chocolates because sugar, milk powder, hazelnuts, etc. tend to have a diluting effect. Theoretical calculation : A child weighing 20 kg who, as an "intensive" consumer was theoretically assumed to eat 100 g of a chocolate with 10 % cocoa paste with 0.35 mg cadmium/kg every day, would have increased his weekly consumption of cadmium by 0.0012 mg per kg body weight. That is 16 % of the tolerable total quantity. If a cocoa paste with 1.83 mg/kg cadmium had been processed, the quantity consumed would have been 0.0063 mg/kg body weight. Even in this unlikely case, however, only 83 % of the weekly tolerable quantity of cadmium would have been consumed. 4.3 Mercury 4.3.1 The origin of mercury in foodstuffs and their surroundings "Quicksilver" was already being extracted in ancient times. In 1972, world production from cinnabar was 9 000 t for industrial use in electrical engineering, for catalysts, thermometers and pigments, for pharmaceutical preparations (skin salves) and silver amalgam for filling teeth. It passes into the environment through emissions from chemical plants (paints, paper, chlorine, plant pesticides) and power stations, mostly in effluents and sludges. The situation in


sea water is of particular significance. Mercury becomes concentrated in shellfish, crustaceans and fish and thus also passes, in the form of highly toxic mercury methylate, into the human food chain. In 1965, the consumption of fish from regions of the sea contaminated by effluent led to the appearance of the so-called Minamata sickness in Japan and, in 1972, bread cereals contaminated with fungicides containing mercury led to epidemic poisoning in Iraq. 4.3.2 Toxic effects Mercury in the form of its methyl compounds is specifically the most toxic of the heavy metals. When consumed orally, it first passes into the liver, the kidneys and the brain. Accumulation only takes place temporarily. A large part is excreted with the faeces. The salts of bivalent mercury, in the case of chronic consumption, first cause tiredness, loss of appetite and weight loss. In the endHeavy Metals/7 E-mail : [email protected] the kidneys fail. Muscular weakness and paralysis are typical. The methylmercury from animal foodstuffs also damages the central nervous system and the immune system. Teratogenic effects have also been observed. 4.3.3 Present contamination of foodstuffs and acceptable maximum values Vegetable foodstuffs are only very slightly contaminated with mercury, except when they are grown in the vicinity of emitting industrial plants. Among animal foodstuffs it is practically only seafood which exhibits relatively high contents of mercury. A special case are animals which are fattened on contaminated


fishmeal. The FAO/WHO Expert Committee (JECFA) has set a provisional maximum acceptable value for mercury consumption at 5 g per kg body weight per week. Of this, however, not more than 55 % may be present in the form of organically bonded mercury (so-called methylmercury). For a person weighing 70 kg this represents a quantity of 0.35 mg total Hg per week (of which not more than 0.19 mg may be organically bonded). The average consumption of mercury varies in uncontaminated parts of the world between 20 and 80 g per day, but in contaminated regions is often temporarily higher. At these consumptions, however, the PTWI values quoted above are only reached in exceptional cases. Up to 80 % of the quantities of mercury consumed, originate by way of the food chain, either directly or indirectly from seafood. 4.3.4 The situation with regard to raw materials for confectionery Practically no mercury contamination problem exists for confectionery and fine bakery wares. 4.4 Other heavy metals Some heavy metals (the so-called trace elements) are essential in very small concentrations for the survival of all life forms, for example, copper, iron, zinc, chromium, molybdenum and others. It is possible that not all are yet known. Despite this fact, it is often forgotten that in some circumstances, in higher concentrations, these can also be quite toxic, for example when they are present in an organic compound. Heavy Metals/8


E-mail : [email protected] Nickel has often been associated recently with allergies (contact with jewellery and jeans buttons containing nickel). There is no established knowledge of effects of this type when it is absorbed in the gastro-intestinal tract. Cocoa is one of the foodstuffs with higher than average natural nickel contents. The copper content of tomato dishes prepared in copper pots and having a copper content of 0.1-0.2 mg/kg body weight has already been found to cause digestive disturbances in sensitive consumers! This is in spite of the specified tolerable quantity for daily consumption of 0.5 mg/kg. Chromium, copper and zinc play major roles in modern industry and, in the vicinity of extraction or processing plants, the emissions arising are certainly capable of causing an undesirable contamination of agricultural products. Considerable quantities have been found in fruit and vegetables. However, no adverse effects on health are known. It is nevertheless recommended not to omit these metals a priori from scrutiny. 5. Worldwide report and control system GEMS The members of the United Nations have long been called upon to take part in the "Global Environment Monitoring System GEMS". In 1991 it was announced that, of 21 countries whose institutes had reported, there was only one case in which the PTWI value for cadmium was exceeded. In general, cereal products and tuber and root vegetables are said to be most severely contaminated with cadmium. Whether seafood is really the main source of mercury in foodstuffs has also already


been questioned. The consumption quantities for lead reach or exceed the PTWI values of the FAO/WHO in many countries. 6. The IOCCC position The total avoidance of the consumption of heavy metals through foodstuffs, including confectionery, is not possible because these are often already naturally present in many raw materials. There are no acute problems for the confectionery industry arising from the heavy metal contents of raw materials as long as the composition of the articles remains true to type. In the case of fine cocoa and some fruit concentrates, caution should be observed.Heavy Metals/9

Arsenic - AsChemical properties of arsenic - Health effects of arsenic - Environmental effects of arsenic


Atomic num ber Atomic mass Electronegativity according to Pauling Density Melting point Boiling point Vanderwaals radius Ionic radius Isotopes Electronic shell Energy of first ionisation Energy of second ionisation Energy of third ionisation Standard potential Discovered by

33 74.9216 g.mol -1 2.0 5.7 g.cm-3 at 14C 814 C (36 atm) 615 C (sublimation) 0.139 nm 0.222 nm (-2) 0,047 nm (+5) 0,058 (+3) 8 [ Ar ] 3d 10 4s2 4p3 947 kJ.mol -1 1798 kJ.mol -1 2736 kJ.mol -1 - 0.3 V (As 3+ / As ) The ancients

ArsenicArsenic appears in three allotropic forms: yellow, black and grey; the stable form is a silver -gray, brittle crystalline solid. It tarnishes rapidly in air, and at high temperatures burns forming a white cloud of arsenic trioxide. Arsenic is a m ember of group Va of the periodic table, which combines readily with many elements. The metallic form is brittle, tharnishes and when heated it rapidly oxidizes to arsenic trioxide, which has a garlic odor. The non metallic form is less reactive but will dissolve when heated with strong oxidizing acids and alkalis.

Applications

Arsenic compounds are used in making special types of glass, as a wood preservative and, lately, in the semiconduc tor gallium arsenade, which has the ability to convert electric current to laser light. Arsine gas AsH 3 , has become an important dopant gas in the microchip industry, although it requires strict guidelines regarding its use because it is extremely toxic. During the 18th, 19th, and 20th centuries, a number of arsenic compounds have been used as medicines; copper acetoarsenite was used as a green pigment known under many different names.

Arsenic in the environment

Arsenic can be found naturally on earth in small concentrations. It occurs in soil and minerals and it may enter air, water a nd land through wind blown dust and water run -off. Arsenic in the atmosphere comes from various sources: vulcanoes release about 3000 tonnes per year and microorganisms release volatile methylarsines to the extent of 20.000 tonnes per year, but human activity is responsible for much more: 80.000 tonnes of arsenic per year are released by the burning of fossil fuels.

Despite its notoriety as a deadly poison, arsenic is an essential trace element for some animals, and maybe even for humans, necessary intake may be as low as 0.01 mg/day.

although the

Arsenic is a component that is extremely hard to convert to water -soluble or volatile products. The fact that arsenic is naturally a fairly a mobile component, basically means that large concentrations are not likely to appear on one specific sit e. This is a good thing, but the negative site to it is that arsenic pollution becomes a wider issue because it easily spreads. Arsenic cannot be mobilized easily when it is immo bile. Due to human activities, mainly through mining and melting, naturally im mobile arsenics have also mobilized and can now be found on many more places than


where they existed naturally.

A little uncombined arsenic occurs naturally as microcrystalline masses, found in Siberia, Germany, France, Italy, Romania an d in the USA. Most arsenic is found in conjuction with sulfur in minerals such as arsenopyrite (AsFeS), realgar, orpiment and enargite. Non is m ined as such because it is produced as a by -product of refining the ores of other metals, such as copper and lead. World production of arsenic, in the form of its oxide, is around 50.000 tonnes per year, far in excess of that required by indus try. China is the chief exporting country, followed by Chile and Mexico. World resources of arsenic in copper and lead ores exceed 10 million tonnes.

Health effects of arsenicArsenic is one of the most toxic elements that can be found. Despite their toxic effect, inorganic arsenic bonds occur on earth naturally in small amounts. Humans may be exposed to arsenic through food, water and air. Exposure may also occur through skin contact with soil or water that contains arsenic. Levels of arsenic in food are f airly low, as it is not added due to its toxicity. But levels of arsenic in fish and seafood may be high, because fish absorb arsenic from the water they live in. Luckily this is mainly the fairly harmless organic form of arsenic, but fish that contain significant amounts of inorganic arsenic may be a danger to human health. Arsenic exposure may be higher for people that work with arsenic, for people that live in houses that contain conserved wood for those who live on farmlands where arsen ic-containing pesticides have been applied in the past. of any kind and

Exposure to inorganic arsenic can cause various health effects, such as irritation of the stomach and intestines, decreased p roduction of red and white blood cells, skin changes and lung irritation. It is suggested that the uptake of significant amounts of inorganic arsenic can intensify the chances of cancer development, especially the chances of development of skin cancer, lung cancer, liver cancer and lymphatic cancer. A very high exposure to inor ganic arsenic can cause infertility and miscarriages with women, and it can cause skin disturbances, declined resistance to infections, heart disruptions and brain damage with both men and women. Finally, inorganic arsenic can damage DNA.

A lethal dose of arsenic oxide is generally regarded as 100 mg. Organic arsenic can cause neither cancer, nor DNA damage. But exposure to high doses may cause certain effects to human healt h, such as nerve injury and stomachaches.

Environmental effects of arsenicThe arsenic cycle has broadened as a consequence of human interference and due to this, large amounts of arsenic end up in the en vironment and in living organisms. Arsenic is mainly emitted by the copper producing industries, but also during lead and zinc production and in agriculture. It cannot be destroyed once it has entered the environment, so that the amounts that we add can spread and cause health effec ts to humans and animals on many locations on earth.

Plants absorb arsenic fairly easily, so that high -ranking concentrations may be present in food. The concentrations of the dangerous inorganic arsenics that are currently present in surface waters enhance the chances of alteration of g enetic materials of fish. This is mainly caused by accumulation of arsenic in the bodies of plant -eating freshwater organisms. Birds eat the fish that already contain eminent amounts of arsenic and will die as a result of arsenic poisoning as the fish is d ecomposed in their bodies.

Cadmium - CdChemical properties of cadmium - Health effects of cadmium - Environmental effects of cadmium


Atomic number Atomic mass Electronegativity according to Pauling Density Melting point Boiling point Vanderwaals radius Ionic radius Isotopes Electronic shell Energy of first ionisation Energy of second ionisation Standard potential Discovered

48 112.4 g.mol -1 1.7 8.7 g.cm-3 at 20C 321 C 767 C 0.154 nm 0.097 nm (+2) 15 [ Kr ] 4d 10 5s2 866 kJ.mol -1 1622 kJ.mol -1 -0.402 V Fredrich Stromeyer in 1817

CadmiumCadmium is a lustrous, silver-white, ductile, very malleable metal. Its surface has a bluish tinge and the metal is soft enough to be cut with a knife, but it tarnishes in air. It is soluble in acids but not in alkalis. It is similar in many respects to zinc but it forms more complex compounds.

Applications

About three-fourths of cadmium is used in Ni -Cd batteries, most of the remaining one -fourth is used mainly for pigments, coatings and plating, and as stabilizers for plastics. Cadium has been used particularly to electroplate steel where a film of cadmium onl y 0.05 mm thick will provide complete protection against the sea. Cadmium has the ability to absorb neutrons, so it is used as a barrier to control nuclear fission.

Cadmium in the environment

Cadmium can mainly be found in the earth's crust. It always occu rs in combination with zinc. Cadmium also consists in the industries as an inevitable by -product of zinc, lead and copper extraction. After being applied it enters the environment mainly through the ground, because it is found in manures and pesti cides.

Naturally a very large amount of cadmium i s released into the environment, about 25,000 tons a year. About half of this cadmium is released into rivers through weather ing of rocks and some cadmium is released into air through forest fires and volcanoes. The rest of the cadmium is released throug h human activities, such as manufacturing.

No cadmium ore is mined for the metal, because more than enough is produced as a byproduct of the smelting of zinc from its o re, sphelerite (ZnS), in which CdS is a significant impurity, making up as much as 3%. Con sequently, the main mining areas are those associated with zinc. World production is around 14.000 tonnes per year, the main producing country is Canada, with the USA, Australia, Mexico, JApan and Peru also being the major suppliers.

Health effects of cadmiumHuman uptake of cadmium takes place mainly through food. Foodstuffs that are rich in cadmium can greatly increase the cadmium concentration in human bodies. Examples


are liver, mushrooms, shellfish, mussels, cocoa powder and dried seaweed. An exposure to significantly higher cadmium levels occurs when people smoke. Tobacco smoke transports cadmium into the lungs. Blood will transport it through the rest of the body where it can increase effects by potentiating cadmium that is already present from cadmi um-rich food. Other high exposures can occur with people who live near hazardous waste sites or factories that release cadmium into the air industry. When people breathe in cadmium it can severely damage the lung s. This may even cause death. and people that work in the metal refinery

Cadmium is first transported to the liver through the blood. There, it is bond to proteins to form complexes that are transpo rted to the kidneys. Cadmium accumulates in kidneys, where it damages filtering mechanisms. This cau ses the excretion of essential proteins and sugars from the body and further kidney damage. It takes a very long time before cadmium that has accumulated in kidneys is excreted from a human body. Other health effects that can be caused by cadmium are: Diarrhoea, stomach pains and severe vomiting Bone fracture Reproductive failure and possibly even infertility Damage to the central nervous system Damage to the immune system Psychological disorders Possibly DNA damage or cancer development

Environmental effects of cadmium

Cadmium waste streams from the industries mainly end up in soils. The causes of these waste streams are for instance zinc pro duction, phosphate ore implication and bio industrial manure. Cadmium waste streams may also enter the air through (household) waste combustion and burning of fossil fuels. Because of regulations only little cadmium now enters the water through disposal of wastewater from households or industries. Another important source of cadmium emission is the production of artificial phosphate fertilizers. Part of the cadmium ends up in the soil after the fertilizer is applied on farmland and the rest of the cadmium ends up in surface waters when waste from fe rtilizer productions is dumped by production companies. Cadmium can be transported over great distances when it is absorbed by sludge. This cadmium -rich sludge can pollute surface waters as well as soils. Cadmium strongly adsorbs to organic matter in soi ls. When cadmium is present in soils it can be extremely dangerous, as the uptake through food will increase. Soils that are acidified enhance the cadmium uptake by plants. This is a potential danger to the animals that are dependent upon the pla nts for su rvival. Cadmium can accumulate in their bodies, especially when they eat multiple plants. Cows may have large amounts of cadmium in their kidneys due to this. Earthworms and other essential soil organisms are extremely susceptive to cadmium poisoning. The y can die at very low concentrations and this has consequences for the soil structure. When cadmium concentrations in soils are high they can influence soil processes of microrganisms and threat t he whole soil ecosystem. In aquatic ecosystems cadmium can bio accumulate in mussels, oysters, shrimps, lobsters and fish. The susceptibility to cadmium can vary greatly between aquati c organisms. Salt-water organisms are known to be more resistant to cadmium poisoning than freshwater organisms. Animals eating or drinking cadmium sometimes get high blood-pressures, liver disease and nerve or brain damage.

Lead - PbChemical properties of lead - Health effects of lead - Environmental effects of lead


Atomic number Atomic mass Electronegativity according to Pauling Density Melting point Boiling point Vanderwaals radius Ionic radius Isotopes Electronic shell Energy of first ionisation Energy Energy Energy Energy of of of of second ionisation third ionisation fourth ionisation fifth ionisation

82 207.2 g.mol -1 1.8 11.34 g.cm -3 at 20C 327 C 1755 C 0.154 nm 0.132 nm (+2) ; 0.084 nm (+4) 13 [ Xe ] 4f 14 5d10 6s2 6p2 715.4 kJ.mol -1 1450.0 kJ.mol -1 3080.7 kJ.mol -1 4082.3 kJ.mol -1 6608 kJ.mol -1 The ancients

Discovered by

LeadLead is a bluish-white lustrous metal. It is very soft, highly malleable, ductile, and a relatively poor conductor of electricity. It is very resistant to corrosion but tarnishes upon exposure to air. Lead isotopes are the end products of each of the three series of naturally occurring radioactive elements.

Applications

Lead pipes bearing the insignia of Roman emperors, used as drains from the baths, are still in service. Alloys include pewter and solder. Tetraethyl lead (PbEt 4) is still used in some grades of petrol (gasoline) but is being phased out on environmental grounds. Lead is a major constituent of the lead -acid battery used extensively in car batteries. It is used as a colorin g element in ceramic glazes, as projectiles, in some candles to threat the wick. It is the traditional base metal for organ pipes, and it is used as electrod es in the process of electrolysis. One if its major uses is in the glass of computer and television screens, where it shields the viewer from radiation. Other uses are in sheeting, cables, solders, lead crystal glassware, ammunitions, bearings and as weight in sport equipment.

Lead in the environment

Native lead is rare in nature. Currently lead is usua lly found in ore with zinc, silver and copper and it is extracted together with these metals. The main lead mineral in Galena (PbS) and there are also deposits of cerrussite and anglesite which are mined. Galena is mined in Australia, which produces 19% of the world's new lead, followed by the USA, China, Peru' and Canada. Some is also mined in Mexico and West Germany. World production of new lead is 6 million tonnes a year, and workable reserves total are estimated 85 million t onnes, which is less than 15 year's supply.

Lead occurs naturally in the environment. However, most lead concentrations that are found in the environment are a result of

human


activities. Due to the application of lead in gasoline an unnatural lead -cycle has consisted. In car engines lead is burned, so that lead salts (chlorines, bromines, oxides) will originate. These lead salts enter the envi ronment through the exhausts of cars. The larger particles will drop to the ground immediately and pollute soils or surface waters, the smaller particles will travel long distances through air and remain in the atmosphere. Part of t his lead will fall back on earth when it is raining. This lead -cycle caused by human production is much more extended than the natural lead -cycle. It has caused lead pollution to be a worldwide issue.

Health effects of leadLead is a soft metal that has known many applications ov er the years. It has been used widely since 5000 BC for application in metal products, cables and pipelines, but also in paints and pesticides. Lead is one out of four metals that have the most damaging effects on human health. It can enter the human body through uptake of food (65%), water (20%) and air (15%). Foods such as fruit, vegetables, meats, grains, seafood, soft drinks and wine may contain significant amounts of lead. Cigare tte smoke also contains small amounts of lead. Lead can enter (drinking) water through corrosion of pipes. This is more likely to happen when the water is slightly acidic. That is why public water treatment systems are now required to carry out pH -adjustments in water that wi ll serve drinking purposes. For as far as we know, lead fulfils no essential function in the human body, it can merely do harm after uptake from food, ai r or water. Lead can cause several unwanted effects, such as: - Disruption of the biosynthesis of hae moglobin and anaemia - A rise in blood pressure - Kidney damage - Miscarriages and subtle abortions - Disruption of nervous systems - Brain damage - Declined fertility of men through sperm damage - Diminished learning abilities of children - Behavioural disruptions of children, such as aggression, impulsive behavior and hyperactivity Lead can enter a foetus through the placenta of the mother. Because of this it can cause serious damage to the nervous system brains of unborn children. and the

Environmental effects of lead

Not only leaded gasoline causes lead concentrations in the environment to rise. Other human activities, such as fuel combusti on, industrial processes and solid waste combustion, also contribute. Lead can end up in water and soils through corrosion of leaded pipelines in a water transporting system and through corrosion of leaded paints. It cannot be broken down; it can only converted to other forms. Lead accumulates in the bodies of water organisms and soil organisms. These will experience health effects from lead poisoning. Health effects on shellfish can take place even when only very small concentrations of lead are present. Body functions of phytoplan kton can be disturbed when lead interferes. Phytoplankton is an important source of oxygen production in seas and many larger sea -animals eat it. That is why we now begin to wonder whether lead pollution can influence global ba lances. Soil functions are disturbed by lead intervention, especially near highways and farmlands, where extreme concentrations may b e present. Soil organisms than suffer from lead poisoning, too. Lead is a particularly dangerous chemical, as it can accu mulate in individual organisms, but also in entire food chains.

For more effects on freshwater ecosystem take a look at lead in freshwater

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Mercury - Hg

Chemical properties of mercury - Health effects of mercury Environmental effects of mercuryAtomic number Atomic mass Electronegativity according to Pauling Density Melting point Boiling point Vanderwaals radius Ionic radius Isotopes Electronic shell Energy of first ionisation Energy of second ionisation Energy of third ionisation Standard potential Discovered by 80 200.59 g.mol -1 1.9 13.6 g.cm-3 at 20C - 38.9 C 356.6 C 0.157 nm 0.11 nm (+2) 12 [ Xe ] 4f14 5d10 6s2 1004.6 kJ.mol -1 1796 kJ.mol -1 3294 kJ.mol -1 + 0.854 V ( Hg2+/ Hg ) The ancients

MercuryMercury is the only common metal which is liquid at ordinary temperatures. Mercury is som quicksilver. It is a heavy, silvery-white liquid metal. It is a rather poor conductor of heat if c metals but it is a fair conductor of electricity. It alloys easily with many metals, such as gold alloys are called amalgams. The most important mercury salts are mercuric chloride HgCl2 (corrosive sublimate - a viole chloride Hg2Cl2 (calomel, still used in medicine occasionally), mercury fulminate (Hg(ONC)2, explosives) and mercuric sulphide (HgS, vermillion, a high-grade paint pigment).


Applications Mercury metal has many uses. Because of its high density it is used in barometers and manometers. It is extensively used in thermometers, thanks to its high rate of thermal expansion that is fairly constant over a wide temperature range. Its Its ease in amalgamating with gold is used in the recovery of gold from its ores. Industry uses mercury metal as a liquid electrode in the manufacture of chlorine and sodium hydroxide by electrolysis of brine. Mercury is still used in some electrical gear, such as switches and rectifiers, which need to be reliable, and for industrial catalysis. Much less mercury is now used in consumer batteries and fluorescent lighting, but it has not been entirely eliminated. Mercury compounds have many uses. Calomel (mercurous chloride, Hg Cl2) is used as a standard in 2 electrochemical measurements and in medicine as a purgative. Mercuric chloride (corrosive sublimate, HgCl2) is used as an insecticide, in rat poison, and as a disinfectant. Mercuric oxide is used in skin ointments. Mercuric sulphate is used as a catalyst in organic chemistry. Vermilion, a red pigment, is mercuric sulphide; another crystalline form of the sulphide (also used as a pigment) is black. Mercury fulminate, Hg(CNO)2, is used as a detonator. Mercury in the environment Mercury occurs uncombined in nature to a limited extent. It rarely occurs free in nature and is found mainly in cinnabar ore (HgS) in Spain, Russia, Italy, China and Slovenia. World production of mercury is around 8.000 tonnes per year. Mineable reserves are around 600.000 tonnes. Mercury is a compound that can be found naturally in the environment. It can be found in metal form, as mercury salts or as organic mercury compounds. Mercury enters the environment as a result of normal breakdown of minerals in rocks and soil through exposure to wind and water. Release of mercury from natural sources has remained fairly the same over the years. Still mercury concentrations in the environment are increasing; this is ascribed to human activity. Most of the mercury released from human activities is released into air, through fo ssil fuel combustion, mining, smelting and solid waste combustion. Some forms of human activity release mercury directly into soil or water, for instance the application of agricultural fertilizers and industrial wastewater disposal. All mercury that is released in the environment will eventually end up in soils or surface waters. Mercury is not naturally found in foodstuffs, but it may turn up in food as it can be spread within food chains by smaller organisms that are consumed by humans, for instance thro ugh fish. Mercury concentrations in fish usually greatly exceed the concentrations in the water they live in. Cattle breeding products can also contain eminent quantities of mercury. Mercury is not commonly found in plant products, but it can enter human b odies through vegetables and other crops, when sprays that contain mercury are applied in agriculture.

Health effects of mercury


Metallic mercury is used in a variety of household products, such as barometers, thermometers and fluorescent light bulbs. The mercury in these devices is trapped and usually does not cause any health problems. However, when a thermometer will break a significantly high exposure to mercury through breathing will occur for a short period of time while it vaporizes. This can cause harmful effects, such as nerve, brain and kidney damage, lung irritation, eye irritation, skin rashes, vomiting and diarrhoea. Mercury has a number of effects on humans, that can all of them be simplified into the following main effects: - Disruption of the nervous system - Damage to brain functions - DNA damage and chromosomal damage - Allergic reactions, resulting in skin rashes, tiredness and headaches - Negative reproductive effects, such as sperm damage, birth defects and miscarriages Damaged brain functions can cause degradation of learning abilities, personality changes, tremors, vision changes, deafness, muscle incoordination and memory loss. Chromosomal damage is known to cause mongolism.

Environmental effects of mercury

Mercury from soils can accumulate in mushrooms. Acidic surface waters can contain significant amounts of mercury. When the pH values are between five and seven, the mercury concentrations in the water will increase due to mobilisation of mercury in the ground. Once mercury has reached surface waters or soils microrganisms can convert it to methyl mercury, a substance that can be absorbed quickly by most organisms and is known to cause nerve damage. Fish are organisms that absorb great amounts of methyl mercury from surface waters every day. As a consequence, methyl mercury can accumulate in fish and in the food chains that they are part of. The effects that mercury has on animals are kidneys damage, stomach disruption, damage to intestines, reproductive failure and DNA alteration.

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Iron - Fe

Chemical properties of iron - Health effects of iron - Environmental effects of iron


Atomic number Atomic mass Electronegativity according to Pauling Density Melting point Boiling point Vanderwaalsradius Ionic radius Isotopes Electronic shell Energy of first ionisation Energy of second ionisation Energy of third ionisation Standard potential Discovered by

26 55.85 g.mol 1.8

-1

7.8 g.cm -3 at 20C 1536 C 2861 C 0.126 nm 0.076 nm (+2) ; 0.064 nm (+3) 8 [ Ar ] 3d 6 4s2 761 kJ.mol -1 1556.5 kJ.mol -1 2951 kJ.mol -1 - o.44 V (Fe 2+ / Fe ) ; 0.77 V ( Fe 3+/ Fe 2+ ) The ancients

IronIron is a lustrous, ductile, malleable, silver -gray metal (group VIII of the periodic table). It is known to exist in four distinct crystalline forms. Iron rusts in dump air, but not in dry air. It dissolves readily in dilute acids. Iron is chemically active and forms two major series of chemical compounds, the bivalent iron (II), or ferrous, compounds and the trivalent iron (III), or ferric, compounds.

Applications

Iron is the most used of all the metals, including 95 % of all the metal tonnage produced worldwide. Thanks to the combinatio n of low cost and high strength it is indispensable. Its applications go from food containers to family cars, from scredrivers to washing machines, from cargo ships to paper staples. Steel is the best known alloy of iron, and some of the forms that iron takes include: pig iron, cast iron, carbon steel, wrou ght iron, alloy steels, iron oxides.

Iron in the environment

Iron is believed to be the tenth most abundant element in the universe. Iron is also the most abundant (by mass, 34.6%) element making up the Earth; the concentration of iron in the various layers of the Earth ranges from high at the inner core to about 5% in the outer cr ust. Most of this iron is found in various iron oxides, such as the minerals hematite, magnetite, and taconite. The earth's core is believed to consist largely of a metallic iron -nickel alloy. Iron is essential to almost living things, from micro -organisms to humans. World production of new iron is over 500 million tonnes a year, and recycled iron add other 300 million tonnes. Economically workable reserves of iron ores exceed 100 billion tonnes. The main mining areas are China, Brazil, Australia, Russia a nd Ukraine, with sizeable amounts mined in the USA, Canada, Venezuela, Sweeden and India.

Health effects of ironIron can be found in meat, whole meal products, potatoes and vegetables. The human body absorbs iron in animal products faste r than iron in plant products. Iron is an essential part of hemoglobin; the red colouring agent of the blood that transports oxygen through our bodies. Iron may cause conjunctivitis, choroiditis, and retinitis if it contacts and remains in the tissues. Chronic inhalation of excessive concentrations of iron oxide fumes or dusts may result in development of a benign pneumoconiosis, called siderosis, which is observable as an x -ray change. No physical impairment of lung function has been associated with siderosis. Inhalation of excessive concentrations of iron oxide may enhance the risk of lung cancer development in workers exposed to pulmonary carcinogens. LD50 (oral, rat) =30 gm/kg. (LD50: Lethal dose 50. Single dose of a substance that causes the death of 50% of an animal population from exposure to the substance by any route other than inhalation. Usually expressed as milligrams or grams of material per kilogram of animal wei ght (mg/kg or g/kg).)

A more common problem for humans is iron deficency, which leads to anaemia. A man needs an average daily intake pf 7 mg of iron and a woman 11 mg; a normal diet will generally provided all that is needed.

Environmental effects of ironIron (III) -O-arsenite, pentahydrate may be hazardous to the environment; special attention should be given to plants, air and water. It is strongly advised not to let th


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Aluminum - Al

Properties - Health effects of aluminum -Environmental effects of aluminum

Atomic number Atomic mass Electronegativity according to Pauling Density Melting point Boiling point Vanderwaals radius Ionic radius Isotopes Artificial isotopes Electronic shell Energy of first ionization Energy of second ionization Energy of third ionization Standard potential Discovered by

13 26.98154 g.mol -1 1.5 2.7 g.cm -3 at 20 C 660.4 C 2467 C 0.143 nm 0.05 nm 3 16 1s2 2s2 2p6 3s 2 3p1 577.4 kJ.mol -1 1816.1 kJ.mol 2744.1 kJ.mol -1 - 1.67 V Hans Christian Oersted in 1825

AluminumThe name aluminum is derived from the ancient name for alum (potassium aluminum sulphate), which was alumen (Latin, meaning bitter salt). Aluminum was the original name given to the element by Humphry Davy but others called it aluminum and that became the accepted name in Europe. However, in the USA the preferred name was aluminum and when the American Chemical Society debated on the issue, in 1925, it decided to stick with aluminum. Aluminum is a soft and lightweight metal. It has a dull silvery appearance, because of a thin layer of oxidation that forms quickly when it is exposed to air.


Aluminum is nontoxic (as the metal) nonmagnetic and non-sparking.

Aluminum has only one naturally occurring isotope, aluminium-27, which is not radioactive.

Applications

A silvery and ductile member of the poor metal group of elements, aluminum is found primarily as the ore bauxite and is remarkable for its resistance to oxidation (aluminum is actually almost always already oxidized, but is usable in this form unlike most metals), its strength, and its light weight. Aluminum is used in many industries to make millions of different products and is very important to the world economy. Structural components made from aluminum are vital to the aerospace industry and very important in other areas of transportation and building in which light weight, durability, and strength are needed. The use of aluminum exceed that of any other metal except iron. Pure aluminum easily forms alloys with many elements such as copper, zinc, magnesium, manganese and silicon. N early all modern mirrors are made using a thin reflective coating of aluminum on the back surface of a sheet of float glass. Telescope mirrors are also coated with a thin layer of aluminum. Other applications are electrical transmission lines, and packaging (can s, foil, etc.). Because of its high conductivity

Heavy Metal

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