RELATION BETWEEN ENVIRONMENTAL POLLUTION AND MENTAL DISABILITY

By Dr. Shewikar El Bakry Lecturer of Neuropsychiatry Benha University.

The Developing Brain

Brain development begins very early in human gestation and continues well after birth through adolescence. It depends on a tightly orchestrated cascade of sequential and concurrent events.

The abnormalities observed after exposure to a single toxic agent may vary with the timing of the exposure.1 The nature of the neurotoxicant, the extent of exposure, and the timing of exposure are, therefore, each important determinants of outcome.

Although genetic inheritance plays a prominent role in fetal brain development, environmental factors also significantly contribute to final outcomes through their direct impact on developing tissues, by alteration of signaling chemicals that are essential mediators of brain development (neurotrophins), or by modifying gene expression

Environmental Influences

Physical Toxins Nutrition Sick buildings Noise pollution Second-hand

smoke Lead

Social Violence Substance

abuse Child rearing

practices Poverty

Environmental Factors Attributable to DD

25% of developmental and neurological deficits in children are due to the interplay between chemicals and genetic factors

3% of DD can be attributed to chemical exposure alone

Known Causes of Developmental Disabilities

Lead Alcohol Nicotine Mercury PCBs

MENTAL RETARDATIONDSM4 (Diagnostic and Statistical Manual for PsychiatricDisorders, American Psychiatric Association)

1. Score of 70 or below on a standard IQ (intelligencequotient) test

2. Adaptive functioning: how well the individual meetsage and culture specific standards

3. Age of onset before 18

Degrees of severity:Mild: 55-70Moderate: 35-55Severe: 20-35Profound: below 20

The cause of approximately 80 percent of developmental disorders of childhood is not known; and in the absence of knowledge about causal factors, environmental exposures should be considered prime suspects for causing such problems or interacting with other factors (e.g. physical, genetic or psychosocial factors) to cause or exacerbate these conditions.

Mercury Exposure: Major Sources

Seafood: larger fish have most mercury, due to eating smaller fish

Vaccines: many childhood vaccines used to contain 12.5-25 ug of thimerosal, so that a fully-vaccinated child could receive up to 237.5 ug of thimerosal injected into them

Dental amalgams: usually emit 1-10 ug/day; amount of mercury in brain strongly correlated with number of dental fillings; could release much more when first placed or removed

OFFICIAL STATEMENT: US Centers for Disease Control and Prevention (CDC) “Mercury occurs naturally and is found

everywhere in the environment.” “The level of mercury exposure from

vaccines is low.” “Evidence is accumulating of lack of

harm resulting from exposure to thimerosal in vaccines.”

Evidence of Harm 12

KNOW YOUR MERCURY (Hg)

TYPE SOURCE EXPOSURE

Elemental Hg Thermometers VaporAmalgamsLights/batteries

Inorganic Hg Coal power plants Air pollutants(hydrophilic) Volcanoes

Organic Methyl Hg Fish Ingestion(lypophilic)

Organic Ethyl Hg Thimerosal Vaccines(lypophilic) Fish(?) OTC Topicals

Evidence of Harm 13

The LDA is convinced that there is a direct relationship between human exposure to mercury pollution-especially for women of child-bearing years- and the rising incidence of cognitive disabilities.

Mercury ExposureLow Dose Prenatal Impairments of:

motor skills attention visual spatial skills language memory

Blood pressure, heart rate variability

Mercury Exposure Prenatal High-Dose Effects Mental retardation Seizures Cerebral palsy Disturbances of vision, hearing,

sensation Abnormal gait Abnormal speech Disturbances of swallowing

and sucking Abnormal reflexes

Mercury Toxicity

“Mercury is considered to be a developmental

toxicant. … The symptoms observed in offspring of exposed mothers are primarily neurological in origin and have ranged from delays in motor and verbal development to severe brain damage.”

“The infant may be born apparently normal, but later show effects that may range from the infant being slower to reach developmental milestones, such as the age of first walking and talking, to more severe effects including brain damage with mental retardation, incoordination, and inability to move.”

“Other severe effects observed in children whose mothers were exposed to very toxic levels of mercury during pregnancy include eventual blindness, involuntary muscle contractions and seizures, muscle weakness, and inability to speak.” “It is important to remember, however, that the severity of these effects depends upon the level of mercury exposure and the time of dose.”

Maximum Hg exposure in 1st year of life - US Childhood Schedule - 1992-200? AGE SHOTS HG CONTENT

BIRTH Hep B 12.5mcg

8lb infant (3.6kg)– EPA Hg limit: 0.36mcg = 35 times over4lb infant (1.8kg) – EPA Hg limit: 0.18mcg = 70 times over

2 MONTHS Hep B 12.5mcgHIb 25.0mcgDTaP 25.0mcg

(subtotal for visit):62.5mcg

Avg. weight: 10lbs/4.5kg EPA limit: 0.45mcg = 138 times over

4 MONTHS HIb 25.0mcgDTaP 25.0 mcg

(subtotal for visit): 50.0 mcgAvg weight: 14lbs/6.5kg EPA limit: 0.65mcg = 72 times over

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ETHYL VS METHYL Main chemical difference: Ethyl form contains extra carbon

compound on molecule, making it larger.

Some scientists contend extra carbon compound makes ethylmercury less likely to cross the blood-brain barrier.

Methylmercury shown to remain in blood longer than ethyl (1/2 life of 50 days vs. 7 days for ethyl); it accumulates more readily in the body. But ethyl converts more readily to inorganic Hg, which appears to remain in brain longer.

Despite these differences, FDA researchers assumed that the two forms of mercury were equal in toxicity.

Arsenic is “less toxic” than cyanide.

Evidence of Harm 20

Bolus vs. Chronic ExposureFDA’s “Interpretation”

FDA totaled 4 large “bolus” doses at birth, 2, 4, & 6 months (162.5mcg) and divided by 180 days.

162.5mcg divided by 180 = 0.9mcg per day.

This “average” daily exposure was just above the EPA limit, but below FDA and CDC limits.

Analogy: You can take 2 tylenol a day for 60 days and be fine. But 120 tylenol in one day is a lethal dose.

Evidence of Harm 21

Evidence of Harm 22

                                                                                                                                             

CHILD WITH ACRODYNIA CHILD WITH AUTISM(Mercury poisoning) (Will Redwood)

Impact of Pb on human health

Pb is a highly toxic, heavy metal and remain stable over time (entering into ecological systems, water supply, plants, …)

Pb accumulates in the body over time causing health problems.

Pb has been confirmed to hamper neurological and physical development (harmful for children below 6 years)

Low level of exposure to lead can result in physical retardationlow IQhyperactivityhearing lossbehavioural changesinsomnia

High level of exposure (blood contains > 25 mg Pb/dl) can causelead poisoningAnemia, hypertension, mental retardation, convulsions, coma

PCB ExposureDevelopmental EffectsInfant

Birth weight Head circumference Performance on Brazelton Neonatal Behavioral Assessment

(BNBA) - motor immaturity, inc. startleEarly Childhood

Memory, attention, verbal ability, information processing Delayed psychomotor development; changes in play

behavior Hyperactivity

Preteen Word and reading comprehension Full scale and verbal IQ Memory and attention

Nicotine

Reduced IQ Learning disabilities Attention deficits

non-auditory effects on health

Noise pollution:

auditory effects

Hearing Impairment

Hearing is essential for well-being and safety. Hearing impairment is typically defined as an increase in the threshold of hearing as clinically assessed by audiometry.

Studies suggest that children seem to be more vulnerable than adults to noise induced hearing impairment

non-auditory effects on health 1-Interference with the spoken

communication. 2- Sleep Disturbances. 3- Cardiovascular Diseases. 4- Disturbances in Mental Health. 5- Impaired Task Performance. 6- Negative social Behaviour and

Annoyance Reaction.

Missing the Dark: Health Effects of Light Pollution Electric lighting has become an integral

part of modern society. When such light is inefficient, annoying, or unnecessary, it is known as light pollution. Many environmentalists, naturalists, and medical researchers consider light pollution to be one of the fastest growing and most pervasive forms of environmental pollution. Moreover, a growing body of scientific research suggests light pollution can impair biologic functions in both