AP Environmental Science Risk, Toxicology and Human Health © Brooks/Cole Publishing Company / ITP.

AP Environmental ScienceAP Environmental Science

Risk, Toxicology andRisk, Toxicology and Human Health Human Health

© Brooks/Cole Publishing Company / ITP

OutlineOutline1. Risks and Hazards

definitions, major types

2. Toxicologybioaccumulation, toxicity, dose–response curves

3. Chemical Hazardsmutagens, teratogens, carcinogens, hormone disrupters

4. Physical Hazardsearthquakes, volcanoes, ionizing radiation, EM radiation

5. Biological Hazardsdiseases, controlling disease

6. Risk Analysishow to estimate risk, major risks, managing risks


1. Risks and Hazards1. Risks and Hazards


Risk is the possibility of suffering harm from a hazard that can cause injury, disease, economic loss or environmental damage.

•risk expressed as a probability;

•1 in 250

• risk assessment involves using data, hypotheses and models to estimate the probability of harm to human health, society, or the environment that may result from exposure to specific hazards;

• risk management involves deciding how or whether to reduce a possible risk to a certain level and at what cost.

Major HazardsMajor Hazards


There are four major types of hazards:

• cultural hazards, such as unsafe working conditions, smoking, poor diet, drugs, drinking, driving, criminal assault, unsafe sex and poverty;

• chemical hazards from harmful chemicals in air, water, soil and food;

• physical hazards, such as noise, fire, tornadoes, hurricanes, earthquakes, volcanic eruptions, floods and ionizing radiation;

• biological hazards from pathogens, pollen and other allergens and animals, such as bees and poisonous snakes.

Causes of DeathCauses of Death


Tobacco use is the leading cause of preventable death (data from 1993).

2. Toxicology2. Toxicology


Toxicology is the study of the adverse effects of chemicals on health.

• toxicity is a measure of how harmful a substance is. Toxicity depends on several factors;

• the amount of a potentially harmful substance that is ingested, inhaled, or absorbed through the skin is called the dose;

• frequency of exposure;• who is exposed (adult or child);• how well the body’s detoxification system (liver, lung,

kidneys, etc.) work

The resulting type and amount of damage to The resulting type and amount of damage to health are called the health are called the responseresponse

Two types of responses:Two types of responses:acute effectacute effect: immediate or rapid harmful reaction, : immediate or rapid harmful reaction, e.g., dizziness, rash, death;e.g., dizziness, rash, death;

chronic effectchronic effect: permanent or long–lasting : permanent or long–lasting consequence, e.g., asthma, kidney damage, heart consequence, e.g., asthma, kidney damage, heart disease;disease;

ToxicologyToxicology

Five major factors can determine the harm caused Five major factors can determine the harm caused by a substanceby a substance Solubility Solubility

water-soluble toxins move through the environment and get in water-soluble toxins move through the environment and get in the water supplythe water supply

fat-soluble toxins can penetrate cell membranes and fat-soluble toxins can penetrate cell membranes and accumulate in body tissueaccumulate in body tissue

PersistencePersistencesome chemicals are resistance to breakdown and have long-some chemicals are resistance to breakdown and have long-lasting harmful effects on people and wildlifelasting harmful effects on people and wildlife

Bioaccumulation and biomagnificationBioaccumulation and biomagnificationsee next slidesee next slide

Toxicology

Bioaccumulation and Bioaccumulation and BiomagnificationBiomagnification


• Bioaccumulation results when the concentration of a chemical in specific organs or tissues is higher than would normally be expected.

• Biomagnification involves magnification of concentrations as they pass through the food chains and webs.

The pesticide DDT becomes increasingly concentrated high in the food chain because it is stored in fatty tissue and not easily broken down or excreted.

Chemical InteractionsChemical Interactionsantagonistic interactions reduce harmful effectsantagonistic interactions reduce harmful effects

Vitamin A and E apparently reduces some cancer-Vitamin A and E apparently reduces some cancer-causing chemicalscausing chemicals

synergistic interactions multiplies harmful effectssynergistic interactions multiplies harmful effects asbestos workers have a 20-fold increased chance of asbestos workers have a 20-fold increased chance of

getting lung cancer, but if they smoke they have a 400-getting lung cancer, but if they smoke they have a 400-fold increased in lung cancer ratefold increased in lung cancer rate

ToxicologyToxicology

Determining ToxicityDetermining ToxicityToxin or poison is a chemical that adversely affects the health of a living human or animal by causing injury, illness, or death

Three methods of determining toxicity:

• case reports (usually to physicians) about health effects after exposure to a chemical;

• epidemiology, involving studies of populations exposed to certain chemicals or diseases

• laboratory investigations (usually with test animals);

- LD50 is the median lethal dose, the amount of a chemical received that kills 50% of animals (usually rats or mice) in a test population (usually 60–200 animals) within a 14–day period;

- a poison is legally defined as a chemical that has an LD50 of 50 milligrams or less per kilogram of body weight.

ToxicityToxicityToxicity LD50 Lethal Dose Examples

Super < 0.01 less than 1 drop dioxin, botulismmushrooms

Extreme <5 less than 7 drops heroin, nicotine

Very 5-50 7 drops to 1 tsp. morphine, codeine

Toxic 50-500 1 tsp. DDT, H2SO4, Caffeine

Moderate 500-5K 1 oz.-1 pt. aspirin, wood alcohol

Slightly 5K-15K 1 pt. ethyl alcohol, soaps

Non-Toxic >15K >1qt. water, table sugar***Higher LD50, less toxic the substance is

(LD50 measured in mg/kg of body weight)

Dose–Response CurvesDose–Response Curves


Dose–response curves show the adverse effects of various doses of a toxic agent on a test population by plotting harmful effect as a function of dose.

The left dose–response curve shows increasing harmful effects with dose, and no dose is considered safe. The right example has a threshold, such that low doses are considered safe.

Why so little is known of toxicityWhy so little is known of toxicity Only 10% of at least 75,000 commercial Only 10% of at least 75,000 commercial

chemicals have been screenedchemicals have been screened ~2% determined to be carcinogen, teratogen or ~2% determined to be carcinogen, teratogen or

mutagenmutagen >1000 new synthetic chemicals added per year>1000 new synthetic chemicals added per year >99.5% of US commercial chemicals are NOT >99.5% of US commercial chemicals are NOT

regulatedregulated

3. Chemical Hazards3. Chemical Hazards


What are toxic vs. hazardous chemicals?

• toxic chemicals are generally defined as substances that are fatal to over 50% of test animals (LD50) at given concentrations.

• hazardous chemicals cause harm by

- being flammable or explosive (e.g., gasoline);

- irritating or damaging the skin or lungs (e.g., strong acids or alkalines such as oven cleaners);

- interfering with or preventing oxygen uptake and distribution (e.g., carbon monoxide, CO);

- inducing allergic reactions of the immune system (allergens).

Hazardous chemicals


• mutagens are agents, chemicals and radiation that cause random mutations, or changes in the DNA;

• teratogens are agents (chemicals, radiation, or viruses) that cause birth defects;

e.g., PCBs, steroid hormones, heavy metals; rubella, mercury in water, fetal alcohol syndrome and crack babies

• carcinogens are agents (chemicals, radiation, or viruses) that cause cancer;- over 100 types of cancer (depending on cells involved);- e.g., cigarette smoke.

- hormone disrupters

Hormone DisruptersHormone Disrupters


Each type of hormone has a unique molecular shape that allows it to attach to special receptors of cells (upper left).

Hormone disrupters (mimics and blockers), attach to receptors and disrupt/alter development (upper right).

Hormone DisruptersHormone Disrupters


Hormones are molecules that act as messengers in the endocrine system to regulate reproduction, growth and development. Hormone disrupters interfere with hormone function.

• So far 51 chemicals, many widely used, have been shown to act as hormone disrupters on wildlife, laboratory animals and humans;

- e.g., dioxins, certain PCBs, various chemicals in plastics, some pesticides, lead and mercury;

• 1997 study shows that sperm count of men in U.S. and Europe has declined 50%.

Taking PrecautionsTaking PrecautionsPrecautionary Principle:Precautionary Principle: New chemicals and technologies would be assumed to New chemicals and technologies would be assumed to

be harmful until shown otherwisebe harmful until shown otherwise Existing chemicals and technologies should be removed Existing chemicals and technologies should be removed

from the market until their safety can be establishedfrom the market until their safety can be established

Strictly applied precautionary principle would not Strictly applied precautionary principle would not have given us automobiles, antibiotics, and have given us automobiles, antibiotics, and plastics.plastics.

No easy answer for knowing when to apply No easy answer for knowing when to apply precautionary principleprecautionary principle

4. Physical Hazards4. Physical Hazards


Earthquakes are among various types of natural physical hazards. Other physical hazards include volcanoes and ionizing radiation.

Physical HazardsPhysical Hazards


Map of expected damage from earthquakes.

Preventing loss:

• understand where risk is high;

• establish building codes to regulate placement and design of buildings in high risk areas;

• determine if prediction is feasible.



Ionizing radiation, a form of electromagnetic radiation, has enough energy to damage body tissues.Examples include X rays and ultraviolet radiation, and various types of radiation emitted by radioactive isotopes



Natural and human sources of the average annual dose of ionizing radiation received by the U.S. population. Most studies indicate that there is no safe dose of ionizing radiation.



Each year people are exposed to some radiation from natural or background sources, as well as from human–caused exposure.

• background sources include about 82% of the exposure

• human–caused exposure include medical X rays (10%), nuclear medicine (4%), and consumer products (3%)

• harmful effects include burns, miscarriages, eye cataracts and certain cancers

• serious accidents, such as at the Chernobyl reactor, can release large quantities of radiation, far above background levels.



Is non-ionizing electromagnetic radiation harmful?

• we don't know

• concern that electromagnetic fields (EMFs) from electrical appliances (e.g., microwave ovens, hair dryers, electric blankets, computer and TV monitors) may increase risk of some cancers, miscarriages, birth defects and Alzheimer's disease

• many respected scientists say that a statistical link has between established, but the evidence is still not conclusive.

5. Biological Hazards5. Biological Hazards


Biological hazards include both non-transmissible and transmissible diseases.

• non-transmissible diseases are not passed from one person to another, e.g., cardiovascular disorders, most cancers, diabetes, emphysema and malnutrition;

• transmissible diseases are caused by bacteria, viruses, protozoa, or parasites, and can be passed from one person to another, e.g., colds, flus, hepatitis, sexually- transmitted diseases, malaria;

• some transmissible diseases are spreading over broad geographic areas as the result of human activity;

- e.g., Lyme disease carried by ticks and spread by people is now widespread over North America.

Biological HazardsBiological Hazards


Worldwide distribution of malaria today (red) and its projected distribution in 2046 (orange). If the world becomes warmer, as projected by current climate models, by 2046 malaria could affect 60% of the world’s population.



The complex life cycle of Plasmodium, the organism that causes malaria, involves transmission between infected individuals by Anopheles mosquitoes .

Malaria Video

7 Deadliest Infectious Diseases 7 Deadliest Infectious Diseases

Case Study: Growing Germ Case Study: Growing Germ Resistance to AntibioticsResistance to Antibiotics1 bacteria can produce 16,777,216 offspring 1 bacteria can produce 16,777,216 offspring in 24 hoursin 24 hours

this allows them to become genetically resistant to antibiotics this allows them to become genetically resistant to antibiotics through natural selectionthrough natural selection

Other factors that play a role in the increase Other factors that play a role in the increase in serious infectious bacterial diseases;in serious infectious bacterial diseases;

bacteria is spread around the globe by human travel and trade bacteria is spread around the globe by human travel and trade goodsgoods

overuse of pesticidesoveruse of pesticides overuse of antibioticsoveruse of antibiotics

Case Study: Growing Germ Case Study: Growing Germ Resistance to AntibioticsResistance to Antibiotics

Overuse of antibioticsOveruse of antibiotics ½ of all antibiotics are prescribed unnecessarily½ of all antibiotics are prescribed unnecessarily antibiotics are available is some countries antibiotics are available is some countries

without a prescriptionwithout a prescription In the U.S., 75% of all antibiotics used are fed to In the U.S., 75% of all antibiotics used are fed to

livestock as feed additives to boost production.livestock as feed additives to boost production.resistant strains of infectious disease can spread to resistant strains of infectious disease can spread to humans through contact with infected animalshumans through contact with infected animals

Every major disease-causing bacterium now has Every major disease-causing bacterium now has strains that resist at least one of the roughly 160 strains that resist at least one of the roughly 160 antibiotics used to treat bacterial infections.antibiotics used to treat bacterial infections.

Case Study: The Global Case Study: The Global Tuberculosis ThreatTuberculosis Threat

TB kills about 1.7 million people a year TB kills about 1.7 million people a year and could kill 28 million by 2020and could kill 28 million by 2020

The bacterium causing TB moves from The bacterium causing TB moves from person to person in airborne droplets person to person in airborne droplets by sneezing, singing, or talking.by sneezing, singing, or talking. it has infected 1 in 3 people in the worldit has infected 1 in 3 people in the world

it in the body, whether you are sick or notit in the body, whether you are sick or not

over ½ the infected people do not know they over ½ the infected people do not know they are infected and do not feel sickare infected and do not feel sick

silent global epidemicsilent global epidemic

Case Study: The Global Case Study: The Global Tuberculosis ThreatTuberculosis Threat

Increase in TB caused byIncrease in TB caused by lack of screening and control programslack of screening and control programs resistance to almost all effective antibioticsresistance to almost all effective antibiotics population growth and urbanization causes increased contact population growth and urbanization causes increased contact

between people, especially among the poorbetween people, especially among the poor AIDS weakens immune system and allows TB to multiplyAIDS weakens immune system and allows TB to multiply

Can be cured by a combination of 4 Can be cured by a combination of 4 inexpensive drugsinexpensive drugs must be taken daily for 6-8 monthsmust be taken daily for 6-8 months symptoms disappear, people think they are cured and stop symptoms disappear, people think they are cured and stop

taking their medicinetaking their medicine this cause the disease to recur in a drug-resistant formthis cause the disease to recur in a drug-resistant form

TB Evolution MovieTB Evolution Movie

HIV, Flu, and Hepatitis BHIV, Flu, and Hepatitis BHIV (human immunodeficiency virus) HIV (human immunodeficiency virus) transmitted bytransmitted by unsafe sex, sharing of needles by drug users, infected mother to unsafe sex, sharing of needles by drug users, infected mother to

offspring before or after birth, and exposure to infected blood.offspring before or after birth, and exposure to infected blood.

Influenza (flu) is transmitted byInfluenza (flu) is transmitted by body fluids body fluids airborne emissions of infected personsairborne emissions of infected persons

1918 Swine Flu1918 Swine Flu Killed 500 million worldwideKilled 500 million worldwide 20 - 30 million in the U.S.20 - 30 million in the U.S.

Today flu kills Today flu kills 1 million per year worldwide1 million per year worldwide 20,000 in the U.S.20,000 in the U.S.

HIV, Flu, and Hepatitis BHIV, Flu, and Hepatitis BHepatitis B virus (HBV) damages the liver and Hepatitis B virus (HBV) damages the liver and is transmitted byis transmitted by unsafe sex, sharing of needles by drug users, infected mother unsafe sex, sharing of needles by drug users, infected mother

to offspring before or after birth, and exposure to infected blood,to offspring before or after birth, and exposure to infected blood,

Other viruses that have received widespread Other viruses that have received widespread coveragecoverage Ebola virus transmitted by blood or other body fluidsEbola virus transmitted by blood or other body fluids West Nile virus transmitted by mosquitoes that have been West Nile virus transmitted by mosquitoes that have been

feeding on infected birdsfeeding on infected birds Severe Acute Respiratory Syndrome virus (SARS) emerged in Severe Acute Respiratory Syndrome virus (SARS) emerged in

China in 2002 and is easily transmitted.China in 2002 and is easily transmitted. Uganda: Out of the WildUganda: Out of the Wild

HIV, Flu, and Hepatitis BHIV, Flu, and Hepatitis BViral infections are harder to fight than infections Viral infections are harder to fight than infections caused by bacteria and protozoa.caused by bacteria and protozoa. drugs that kill viruses also harm the cells of the hostdrugs that kill viruses also harm the cells of the host antibiotics are useless and increase genetic antibiotics are useless and increase genetic

resistance in bacteriaresistance in bacteria vaccines that stimulate the immune system to vaccines that stimulate the immune system to

produce antibodies to ward off viral infections and produce antibodies to ward off viral infections and help reduce the spread of viral diseaseshelp reduce the spread of viral diseases

polio, influenza, measles, smallpox, rabies, and hepatitis B.polio, influenza, measles, smallpox, rabies, and hepatitis B.many viral diseases do not have vaccinesmany viral diseases do not have vaccines

HIVHIV



Generalized model of the epidemiological transition that may take place as countries become more industrialized.

Biological HazardsBiological HazardsWhat are some ways we reduce infectious diseases?

• reduce overcrowding, unsafe drinking water, poor sanitation, inadequate health care systems, malnutrition and poverty;

• increase funding for disease monitoring;

• sharply reduce antibiotic use to prevent evolution of resistant organisms;

• protect biodiversity as a means of reducing disease spread;

• increase research.

• careful hand washing

6. Risk Analysis6. Risk Analysis


Risk analysis involves identifying hazards and evaluating associate risks (risk assessment), ranking risks (comparative risk analysis), determining options (risk management), and informing decision makers and the public (risk communication).

• risk assessment estimates probabilities associated with different types of hazards;

• comparative risk analysis summarizes the greatest ecological and health risks

Risk AnalysisRisk Analysis

AP Environmental Science Risk, Toxicology and Human Health © Brooks/Cole Publishing Company / ITP.

Documents

Transcript of AP Environmental Science Risk, Toxicology and Human Health © Brooks/Cole Publishing Company / ITP.