This lecture will help you understand:

This lecture will help you understand:
Environmental health hazards Toxicants in the environment Hazards and their effects Philosophical approaches to risk Policy and regulation in the U.S. and world Alligator hatchling from Lake Apopka Florida (Start, 11/04/2008)

This lecture will help you understand:
Environmental health hazards Toxicants in the environment Hazards and their effects Risk assessment and risk management Philosophical approaches to risk Policy and regulation in the U.S. and world Alligator hatchling from Lake Apopka Florida (Start, 11/04/2008)

Central Case: Lake Apopka alligators, 1985
Alligators in Lake Apopka, Florida, had reproductive problems: unhealthy eggs, abnormal sex hormone level The lake had high levels of agricultural runoff Chemical contaminants were disrupting the endocrine systems of alligators during egg development - Pesticides, fertilizer(Nitrate) runoff to the lake (Guillette, 2003).

There are many types of environmental hazards (Four Types)
Environmental health : assesses environmental factors that influence human health and quality of life Natural and human-caused factors are both considered 1. Physical hazards : occur naturally in our environment Earthquakes, volcanoes, fires, floods, droughts we can prepare for some of them We increase our vulnerability by deforesting slopes (landslides), channelizing rivers (flooding), etc. We can reduce risk by better environmental choices

Chemical & biological environmental hazards
2. Chemical: synthetic chemicals such as pesticides, disinfectants, pharmaceuticals Harmful natural chemicals also exist Urushiol (an oil in poison ivy, etc.) 3. Biological : result from ecological interactions Viruses, bacteria, and other pathogens Infectious (communicable, or transmissible) disease other species parasitize humans, fulfilling their ecological roles We can’t avoid risk, but we can reduce the likelihood of infection Urushiol:

Cultural environmental hazards
4. Cultural: result from the place we live, our socioeconomic status, our occupation, our behavioral choices Smoking, drug use, diet and nutrition, crime, mode of transportation

Four types of environmental hazards

Disease is a major focus of environmental health
Despite our technology, disease kills most of us Disease has a genetic and environmental basis Cancer, heart disease, respiratory disorders Poverty and poor hygiene can foster illnesses

Infectious diseases kill millions
Infectious diseases kill 15 million people per year Half of all deaths in developing countries Developed countries have better hygiene, access to medicine, and money Vector : an organism that transfers pathogens to a host Mosquito, Malaria Plasmodium apicomplexan Lice, Typhus, Rickettsia prowazekii Ticks, Lime Disease, Borrelia Malaria is a mosquito-borne infectious disease caused by a eukaryotic protist of the genus Plasmodium.

Many diseases are increasing
Tuberculosis (TB) - mycobacteria Acquired immunodeficiency syndrome (AIDS), & the West Nile virus - virus (ss-RNA) Our mobility spreads diseases - Globalization Diseases are evolving resistance to antibiotics To predict and prevent diseases, experts deal with complicated interrelationships

Bacteria: Mycobacteria(Tuberculosis) Single Stranded-RNA:
Many old diseases are gone (w/ antibiotics), but new ones emerging Pathogens: bacteria, viruses, viroids, prions Bacteria: Mycobacteria(Tuberculosis) Single Stranded-RNA: Tobacco Mosaic Virus Human ImmunoDeficiency Virus (HIV): Acquired ImmunoDeficiency Syndrome (AIDS) West Nile Virus : Meningitis, Encephalitis Viroids (circilar RNA): Cadang cadang (coconut palm disease) Prions (Proteins): mad cow disease, kuru - long incubation period Diseases are evolving resistance to antibiotics

Bacteria: Mycobacteria(Tuberculosis) Virus: Single Stranded-RNA:
Many old diseases are gone (w/ antibiotics), but new ones emerging Pathogens: bacteria, viruses, viroids, prions Bacteria: Mycobacteria(Tuberculosis) Virus: Single Stranded-RNA: Tobacco Mosaic Virus Human ImmunoDeficiency Virus (HIV): Acquired ImmunoDeficiency Syndrome (AIDS) West Nile Virus : Meningitis, Encephalitis Viroids (circilar RNA): Cadang cadang (coconut palm disease) Prion (Protein + Infection): Mis-folded Protein, neuro-degerative Mad Cow Disease (bovine spongiform encephalopathy, BSE), 1986, UK, ~ 4.5 M cows slaughtered/burned Kuru (Fore Tribe in Papua) Diseases are evolving resistance to antibiotics

Bacteria: Mycobacteria(Tuberculosis)
Many old diseases are gone (w/ antibiotics), but new ones emerging Pathogens: Bacteria, Viruses, Viroids, Prions Bacteria: Mycobacteria(Tuberculosis) Virus: RNS/DNA + Protein Coat (+ Lipid Envelope) Tobacco Mosaic Virus: Single Stranded-RNA: Human ImmunoDeficiency Virus (HIV): Acquired ImmunoDeficiency Syndrome (AIDS) West Nile Virus : Meningitis, Encephalitis Viroids (circilar RNA): Plant pathogen Cadang cadang (coconut palm disease) Prion (Protein + Infection): Mis-folded Protein, neuro-degerative Bovine Spongiform Encephalopathy(BSE, Mad Cow Disease), 1986, UK, ~ 4.5 M cows slaughtered/burned Creutzfeldt–Jakob Disease (CJD), Kuru (Fore Tribe in Papua) claimed ~200 people in late 2000s in UK Diseases are evolving resistance to antibiotics

AIDS Acquired immune deficiency syndrome or acquired immunodeficiency syndrome (AIDS or Aids) is a set of symptoms and infections resulting from the damage to the human immune system caused by the human immunodeficiency virus (HIV).[1] This condition progressively reduces the effectiveness of the immune system and leaves individuals susceptible to opportunistic infections and tumors. HIV is transmitted through direct contact of a mucous membrane or the bloodstream with a bodily fluid containing HIV, such as blood, semen, vaginal fluid, preseminal fluid, and breast milk.[2][3] This transmission can involve anal, vaginal or oral sex, blood transfusion, contaminated hypodermic needles, exchange between mother and baby during pregnancy, childbirth, or breastfeeding, or other exposure to one of the above bodily fluids. AIDS is now a pandemic.[4] In 2007, an estimated 33.2 million people lived with the disease worldwide, and it killed an estimated 2.1 million people, including 330,000 children.[5] Over three-quarters of these deaths occurred in sub-Saharan Africa,[5] retarding economic growth and destroying human capital.[6] Most researchers believe that HIV originated in sub-Saharan Africa during the twentieth century.[7] AIDS was first recognized by the U.S. Centers for Disease Control and Prevention in 1981 and its cause, HIV, identified by American and French scientists in the early 1980s.[8] Although treatments for AIDS and HIV can slow the course of the disease, there is currently no vaccine or cure. Antiretroviral treatment reduces both the mortality and the morbidity of HIV infection, but these drugs are expensive and routine access to antiretroviral medication is not available in all countries.[9] Due to the difficulty in treating HIV infection, preventing infection is a key aim in controlling the AIDS epidemic, with health organizations promoting safe sex and needle-exchange programmes in attempts to slow the spread of the virus.

Immune System An immune system is a collection of mechanisms within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own healthy cells and tissues in order to function properly. Detection is complicated as pathogens can evolve rapidly, producing adaptations that avoid the immune system and allow the pathogens to successfully infect their hosts. To survive this challenge, multiple mechanisms evolved that recognize and neutralize pathogens. Even simple unicellular organisms such as bacteria possess enzyme systems that protect against viral infections. Other basic immune mechanisms evolved in ancient eukaryotes and remain in their modern descendants, such as plants, fish, reptiles, and insects. These mechanisms include antimicrobial peptides called defensins, phagocytosis, and the complement system. Vertebrates such as humans have even more sophisticated defense mechanisms.[1] The immune systems of vertebrates consist of many types of proteins, cells, organs, and tissues, which interact in an elaborate and dynamic network. As part of this more complex immune response, the human immune system adapts over time to recognise specific pathogens more efficiently. This adaptation process is referred to as "adaptive immunity" or "acquired immunity" and creates immunological memory. Immunological memory created from a primary response to a specific pathogen, provides an enhanced response to secondary encounters with that same, specific pathogen. This process of acquired immunity is the basis of vaccination. Disorders in the immune system can result in disease. Immunodeficiency diseases occur when the immune system is less active than normal, resulting in recurring and life-threatening infections. Immunodeficiency can either be the result of a genetic disease, such as severe combined immunodeficiency, or be produced by pharmaceuticals or an infection, such as the acquired immune deficiency syndrome (AIDS) that is caused by the retrovirus HIV. In contrast, autoimmune diseases result from a hyperactive immune system attacking normal tissues as if they were foreign organisms. Common autoimmune diseases include rheumatoid arthritis, diabetes mellitus type 1 and lupus erythematosus. Immunology covers the study of all aspects of the immune system which has significant relevance to human health and diseases. Further investigation in this field is expected to play a serious role in promotion of health and treatment of diseases.

Environmental health hazards exist indoors
Radon: Can build up in basements 86Rn-222 → 84Pb α-ray (24He) a highly toxic, radioactive gas colorless & undetectable. Carbon Monoxide (CO): Lead (Pb2+) poisoning: from lead pipes by mimicking Ca2+, Fe2+, & Zn2+ ions Damages organs (Brain, Liver, Kidney, etc); causes learning problems, behavior abnormalities, & death Asbestos: Mg3[Si2O5](OH)4 (white) insulates heats, muffles sounds, & resists fire (retardant): - does not degrade Asbestosis: scarred lungs may cease to function , & Lung Cancer Removing Asbestos

40K → 40Ar(g) (1.28 Gy) Source of atmospheric Ar
Natural Disintegrations of Radiosotpopes The major source of geothermal energy (γ-ray) Occurs in Earth Crust, Mantle, &Core 40K → 40Ar(g) (1.28 Gy) Source of atmospheric Ar 238U → → → 226Ra → 222Rn(g) → → → 206Pb (4.47G y) 235U → → → 223Ra → 219Rn(g) → → → 207Pb (0.704 Gy) 232Th → → → 224Ra → 220Rn(g) → → → 208Pb (14 Gy) Artificial Disintegrations (“forced”) Atomic Bomb & Nuclear Power Plant : 235U + n → 91Kr Kr +3n Add(9/12/2013) 7th Mtg starts (9/9/08)

A recently recognized hazard
Polybrominated diphenyl ethers (PBDEs): has fire-retardant properties Used in computers, televisions, plastics, and furniture Persist and accumulate in living tissue Endocrine disruptors: compounds that mimic hormones and interfere with the functioning of animals’ endocrine (hormone) systems Affect brain and nervous system development, and may cause cancer

Toxicology is the study of poisonous substances
Toxicology: the study of the effects of poisonous substances on humans and other organisms Toxicity : the degree of harm a toxicant can cause “The dose makes the poison” : Paracelsus( ) toxicity depends on the combined effect of the chemical and its quantity Analogous to pathogenicity or virulence : the degree of harm of biological hazards that spread disease Toxicant : any toxic agent

Toxicology is the study of poisonous substances
Toxicology: the study of the effects of poisonous substances on humans and other organisms Toxicity : the degree of harm a toxicant can cause “The dose makes the poison” : toxicity depends on the combined effect of the chemical and its quantity Toxicant : any toxic agent

Environmental toxicology
Deals with toxic substances that come from or are discharged into the environment Studies the health effects on humans, other animals, and ecosystems Focus mainly on humans, using other animals as test subjects Can serve as indicators of health threats Don’t forget, chemicals have given us our high standard of living

Toxic agents in the environment
The environment contains countless natural chemicals that may pose health risks But, synthetic chemicals are also in our environment Every human carries traces of industrial chemicals 80% of U.S. streams contain at least trace amounts of 83 wastewater contaminants

Very few chemicals have been thoroughly tested
10 M chemical substances (Natural & Artificial) Known Table 14.2 100,000 chemicals (1% of the 10 M) are on the market today 72,000 Industrial 8,700 Food additives 2,000 New chemicals introduced per year 600 Pesticides 7,500 Cosmetic ingredients 3,300 Pharmaceuticals We don’t know the effects, if any, they have

Silent Spring began public debate over chemicals
Dichloro-Diphenyl-Trichloroethane (DDT): a neurotoxin inhibit normal function of neuron → spasm, death Rachel Carson published Silent Spring in 1962 Brought together studies to show DDT risks to people, wildlife, and ecosystems (banned in US in 1972) In the 1960s, pesticides were mostly untested and were sprayed over public areas, assuming they would do no harm The book generated significant social change: (cf. p 68) triggering enactment of Many Environmental Protection Laws since 1963 (→ saved bald eagles) Mechanism of insecticide action In insects it opens sodium ion channels in neurons, causing them to fire spontaneously, which leads to spasms and eventual death. Insects with certain mutations in their sodium channel gene are resistant to DDT and other similar insecticides. DDT resistance is also conferred by up-regulation of genes expressing cytochrome P450 in some insect species.[15] In humans, however, it may affect health through genotoxicity or endocrine disruption. See Effects on human health.

Carcinogens: cause cancer Mutagens: cause DNA mutations
Types of toxicants: Carcinogens: cause cancer Mutagens: cause DNA mutations Can lead to severe problems, including cancer Teratogens: cause birth defects Allergens: induce unnecessary immune responses Neurotoxins: assault the nervous system Endocrine disruptors: interfere with the normal hormonal function Thalidomide, sedative, late 50s, 60s A hormone (from Greek ὁρμή "impetus") is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one cell to another. All multicellular organisms produce hormones; plant hormones are also called phytohormones. Hormones in animals are often transported in the blood. Cells respond to a hormone when they express a specific receptor for that hormone. The hormone binds to the receptor protein, resulting in the activation of a signal transduction mechanism that ultimately leads to cell type-specific responses. Endocrine hormone molecules are secreted (released) directly into the bloodstream, whereas exocrine hormones (or ectohormones) are secreted directly into a duct, and, from the duct, they flow either into the bloodstream or from cell to cell by diffusion in a process known as paracrine signalling. Recently it has been found that a variety of exogenous modern chemical compounds have hormone-like effects on both humans and wildlife. Their interference with the synthesis, secretion, transport, binding, action, or elimination of natural hormones in the body are responsible of homeostasis, reproduction, development, and/or behavioural changes sameway as the endogenous produced hormones."

Endocrine disruption may be widespread
Theo Colburn, et al. (World Wildlife Fund) wrote Our Stolen Future in 1996 Synthetic industrial chemicals may be altering the hormones of animals This book integrated scientific work from various fields Shocked many readers and brought criticism from the chemical industry 1996: Our Stolen Future (Theo Colborn, Dianne Dumanoski, John Peterson Myers of World Wildlife Fund) – some synthetic chemicals disrupt hormonal systems to cause of abnormalities in animals. Epinephrine (also known as adrenaline) is a hormone and a neurotransmitter.[1] It increases heart rate, constricts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system.[2] Chemically, epinephrine is a catecholamine, a monoamine produced only by the adrenal glands from the amino acids phenylalanine and tyrosine. The term adrenaline is derived from the Latin roots ad- and renes and literally means "on the kidney", in reference to the adrenal gland's anatomic location on the kidney. The Greek roots epi and nephros have similar meanings, and give rise to "epinephrine". The term epinephrine is often shortened to epi in medical jargon.[3] Adrenal extracts containing adrenaline were first obtained by Polish physiologist Napoleon Cybulski in These extracts, which he called nadnerczyna, contained epinephrine and other catecholamines.[4] Japanese chemist Jokichi Takamine and his assistant Keizo Uenaka independently discovered adrenaline in 1900.[5][6] In 1901, Takamine successfully isolated and purified the hormone from the adrenal glands of sheep and oxen.[7] Adrenaline was first synthesized in the laboratory by Friedrich Stolz and Henry Drysdale Dakin, independently, in 1904.[6] Insulin is a hormone central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle.

Evidence for hormone disruption
Frogs also have gonadal abnormalities Male frogs became feminized from atrazine (herbicide) concentrations well below EPA → inhibit photosynthesis PCB (PolyChlorinated Biphenyls): Coolants, Insulating fluids in transformer, additives in plastics contaminated human babies were born weighing less, with smaller heads. → Banned in 1970 Atrazine, 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine, an organic compound consisting of an s-triazine-ring is a widely used herbicide. Its use is controversial due to widespread contamination in drinking water and its associations with birth defects, menstrual problems, and cancer when consumed by humans at concentrations below government standards.[1] Although it has been excluded from a re-registration process in the European Union,[2] it is still one of the most widely used herbicides in the world. Atrazine is prepared from cyanuric chloride, which is treated sequentially with ethylamine and isopropyl amine. Like other triazine herbicides, atrazine functions by binding to the plastoquinone-binding protein in photosystem II, which animals lack. Plant death results from starvation and oxidative damage caused by breakdown in the electron transport process. Oxidative damage is accelerated at high light intensity.[5] Photosystem II (or water-plastoquinone oxidoreductase) is the first protein complex in the Light-dependent reactions. It is located in the thylakoid membrane of plants, algae, and cyanobacteria. The enzyme uses photons of light to energize electrons that are then transferred through a variety of coenzymes and cofactors to reduce plastoquinone to plastoquinol. The energized electrons are replaced by oxidizing water to form hydrogen ions and molecular oxygen. By obtaining these electrons from water, photosystem II provides the electrons for all of photosynthesis to occur. The hydrogen ions (protons) generated by the oxidation of water help to create a proton gradient that is used by ATP synthase to generate ATP. The energized electrons transferred to plastoquinone are ultimately used to reduce NADP+ to NADPH or are used in Cyclic Photophosphorylation. Research Scientist (Academia) vs. Industry-backed Scientist

Male sperm counts are dropping
Drop in men’s sperm counts may be caused by endocrine disruptors The number and motility of sperm has dropped 50% since 1938, in more industrialized country in particular Testicular cancer, undescended testicles, and genital birth defects are also increasing

Endocrine disruption research is controversial
Research results are uncertain, which is inherent in any young field Negative findings pose economic threats to chemical manufacturers Banning a top-selling chemical could cost a company millions of dollars Bisphenol-A, found in plastics, can cause birth defects, but the plastics industry protests that the chemical is safe epoxy resins & other plastics (bottles, CD/DVD, etc.) Studies reporting harm are publicly funded, but those reporting no harm are industry funded is used to make a variety of common products including baby and water bottles, sports equipment, medical and dental devices, dental fillings and sealants, eyeglass lenses, CDs and DVDs, and household electronics.[10] BPA is also used in the synthesis of polysulfones and polyether ketones, as an antioxidant in some plasticizers, and as a polymerization inhibitor in PVC. Epoxy resins containing bisphenol A are used as coatings on the inside of almost all food and beverage cans,[11] however, due to BPA health concerns, in Japan epoxy coating was mostly replaced by PET film.[12]

Toxins may concentrate in water
Runoff carries toxins from large land areas to small volumes of surface water Chemicals can leach into the soil Chemicals enter organisms through drinking or absorption Aquatic organisms are effective pollution indicators → Oyster

Routes of chemical transport

Airborne toxicants travel widely, globally
Chemicals can travel by air, their effects can occur far from the site of chemical use Pesticide drift = airborne transport of pesticides Synthetic chemical contaminants are found globally They appear in arctic polar bears, Antarctic penguins, and people living in Greenland

Some toxicants persist for a long time
Toxins can degrade quickly and become harmless Or, they may remain unaltered and persist for decades Rates of degradation depends on temperature, moisture, and sun exposure Persistent chemicals have the greatest potential for harm Breakdown products = toxicants degrade into simpler products May be more or less harmful than the original substance DDT degrades into DDE, which is also highly persistent

Some toxicants can be excreted or metabolized
Toxicants can accumulate and biomagnify DDT (from Zooplankton to Fish to Falcon) Some toxicants can be excreted or metabolized However, many Fat-soluble toxicants are stored in fatty tissues Bioaccumulation = toxicants build up in animal tissues Biomagnification = toxicants concentrate in top predators Near extinction of peregrine falcons and brown pelicans Note: ppm = 10,000 x %

Not all toxicants are synthetic
Chemical toxicants also exist naturally and in our food Don’t assume natural chemicals are all healthy and synthetic ones are all harmful Snake venom (mixture of various proteins) urushiol(poison ivy), tetrodotoxin (puff fish) Some scientists feel that natural toxicants dwarf our intake of synthetic chemicals Natural defenses against toxins are effective against synthetic ones, too Critics say natural toxins are more readily metabolized and excreted, and synthetic chemicals persist and accumulate Snake venom consists of proteins, enzymes, substances with a cytotoxic effect, neurotoxins and coagulants. Phosphodiesterases are used to interfere with the prey's cardiac system, mainly to lower the blood pressure. Phospholipase A2 causes hemolysis through esterolysis of red cell membranes and promotes muscle necrosis.[1] Snake venom inhibits cholinesterase to make the prey lose muscle control. Hyaluronidase increases tissue permeability to increase the rate that other enzymes are absorbed into the prey's tissues. Amino acid oxidases and proteases are used for digestion. Amino acid oxidase also triggers some other enzymes and is responsible for the yellow color of the venom of some species. Snake venom often contains ATPases which are used for breaking down ATP to disrupt the prey's energy fuel use.

Wildlife studies Museum collections provide data from times before synthetic chemicals were used Measurements from animals in the wild can be compared to controlled experiments in the lab Scientists can first measure effects in the lab, then look for correlations in the wild Conspicuous mortality events can trigger research Many sea otters died and washed ashore Research showed they died from parasites carried in sewage runoff containing cat litter

Human studies Case histories = studying sickened individuals directly
Autopsies Don’t tell about future risks Epidemiology = large-scale comparisons between groups of people Studies between exposed and unexposed people last for years Yield accurate predictions about risk Animals are used as test subjects Some people object to animal research New techniques (human cell cultures, bacteria, etc.) may replace some live-animal testing

Dose-response analysis
Dose-response analysis: measuring how much effect a toxicant produces at different doses Animal testing Dose: the amount of toxicant the test animal receives Response: the type or magnitude of negative effects of the animal Dose-response curve: the plot of dose given against response

Dose response curves LD50: the amount of toxicant required to kill 50% of the subjects The smaller this value, the more toxic Threshold: the dose level where certain responses occur Scientists extrapolate downward from animal studies to estimate the effect on humans Regulatory agencies set allowable limits well below toxicity levels in lab studies

LD50 for some chemicals (mostly, for rats, oral route)
mg/kg Table Sugar 29,700 Vitamin C 11,900 EtOH ,060 NaCl ,000 FeSO ,500 Caffeine NaNO Heroin mg/kg Pb Cocaine NaCN Nicotine Tetrodotoxin Snake Venom ~0.025 Dioxin Polonium

Individuals vary in their responses to hazards
Different people respond differently to hazards Affected by genetics, surroundings, etc. People in poor health are more sensitive Sensitivity also varies with sex, age, and weight Fetuses, infants, and young children are more sensitive Standards for responses are set by the Environmental Protection Agency (EPA) Often, standards are not low enough to protect babies

The type of exposure affects the response
Acute exposure: high exposure for short periods of time to a hazard Easy to recognize Stem from discrete events: ingestion, oil spills, nuclear accident Chronic exposure: low exposure for long periods of time to a hazard Hard to detect and diagnose Affects organs gradually: lung cancer, liver damage Cause and effect may not be easily apparent

Mixes may be more than the sum of their parts
We can’t determine the impact of mixed hazards They may act in ways that cannot be predicted from the effects of each in isolation Synergistic effects = interactive impacts that are more than or different from the simple sum of their constituent effects Mixed toxicants can sum, cancel out, or multiply each other’s effects New impacts may arise from mixing toxicants

Risk assessment Risk: the probability that some harmful outcome will result from a given action Exposure to environmental health threats doesn’t automatically produce an effect Rather, it causes some probability (likelihood) of harm Probability entails Identity and strength of threat Chance & frequency that an organism will encounter it Amount of exposure to the threat An organism’s sensitivity to the threat

Risk assessment Risk: the probability that some harmful outcome will result from a given action Exposure to environmental health threats doesn’t automatically produce an effect Rather, it causes some probability (likelihood) of harm Probability involves Identity and strength of threat Chance/frequency that an organism will encounter it Amount of exposure to the threat An organism’s sensitivity to the threat

Perception of Risk vs. Reality of Risk
Everything we do involves some risk We try to minimize risk, but we often misperceive it - Flying poses 50 x less risk than Driving We feel more at risk when we cannot control a situation We fear nuclear power and toxic waste, but not smoking or overeating

Analyzing risk quantitatively
Risk assessment: the quantitative measurement of risk and the comparison of risks involved in different activities or substances It is a way of identifying and outlining problems Several steps: Scientific study of toxicity Assessing an individual or population’s likely extent of exposure to the substance, including frequency, concentrations, and length of exposure Studies are often performed by industry-associated scientists, which may undermine the study’s objectivity

Risk management Combines decisions and strategies to minimize risk
Scientific assessments are considered with economic, social, and political needs and values Developed nations have federal agencies to manage risk The U.S. has the Centers for Disease Control (CDC), the EPA, and the Food and Drug Administration (FDA) Comparing costs and benefits is hard Benefits are economic and easy to calculate Health risks (costs) are hard-to-measure probabilities of a few people being affected

The process of risk management

One approach to determining safety
Innocent until proven guilty approach: product manufacturers must prove a product is safe Benefits: now slowing down technological innovation and economic advancement Disadvantage: putting into wide use some substances that may later on turn out to be dangerous

Another approach to determining safety
Precautionary principle approach: (~ Guilty until proven innocent approach) the government, scientists, and the public are required to prove a product is dangerous Assume substances are harmful until they are proven harmless Identifies troublesome toxicants before they are released But, this may impede the pace of technology and economic advance

Two approaches to determining safety
Innocent until proven guilty approach: Guilty until proven innocent approach: (Precautionary principle approach) the government, scientists, and the public are required to prove a product is dangerous Assume substances are harmful until they are proven harmless Identifies troublesome toxicants before they are released But, this may impede the pace of technology and economic advance

Two approaches for determining safety

Philosophy affects policy
Different nations use different policies; most use a mix between the “innocent until proven guilty” principle and the precautionary principle Europe is shifting more towards the precautionary principle Industries like the “innocent until proven guilty” approach because it allows them to produce more and make more money

The EPA regulates many substances
Federal agencies apportion responsibility for tracking and regulating synthetic chemicals FDA: food, food additives, cosmetics, drugs, and medical devices EPA: pesticides Occupational Safety and Health Administration (OSHA): workplace hazards Many public health and environmental advocates fear it isn’t enough Many synthetic chemicals are not actually tested Only 10% have been tested for toxicity Fewer than 1% are government regulated

International regulation
Nations address chemical pollution with international treaties Stockholm Convention on Persistent Organic Pollutants (POPs) was ratified by 140 nations in 2004 Ends the release of the 12 most dangerous POPs “ The Dirty Dozen” (Table 14.3, p407) 8 pesticides and others EU’s Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) Program Aims to evaluate and restrict dangerous chemicals while giving industries a streamlined regulatory system It will cost the chemical industry 2.8 – 5.2 billion euros (U.S. $3.8 – 7.0 billion), but will save more than 10 times that in health benefits (End, 11/04/2008)

Conclusion International agreements represent a hopeful sign that governments are working to protect society, wildlife, and ecosystems from toxic chemicals and environmental hazards Once all the scientific results are in, society’s philosophical approach to risk management will determine what policies are enacted A safe and happy future depends on knowing the risks that some hazards pose and on replacing those substances with safer ones

QUESTION: Review Which of the following is a biological hazard?
Earthquake Smoking Virus A pesticide All are biological hazards Answer: c

QUESTION: Review A “vector” is defined as …
A highly toxic, radioactive compound An organism that transfers pathogens to a host A compound with fire-retardant properties A compound that mimics natural substances Answer: b

QUESTION: Review Toxicity is …
The study of the effects of poisonous substances Any toxic agent Any substance that causes environmental degradation The degree of harm a substance can cause Answer: d

QUESTION: Review A “teratogen” causes…? Cancer Mutations Birth defects
Problems in the hormonal system Answer: c

QUESTION: Review Why is research into endocrine disrupters controversial? Negative findings threaten the industry’s economics Research is still only beginning Much research is funded by industry All of these are reasons why research is controversial Answer: d

QUESTION: Review A human-based study that compares a group of smokers to non-smokers to determine the effects of smoking is … An epidemiological study A case study Not likely to be funded Not going to tell about future risks Answer: a

QUESTION: Interpreting Graphs and Data
Our perception, and the reality, of risk often do not match. Given this graph (reality), and your knowledge of sources of anxiety (perception), which statement is correct? Smoking is very dangerous and we are very anxious about it Smoking is not dangerous, but we are very anxious about it Airplane accidents are dangerous, and we are very anxious about it Airplane accidents are not dangerous, but we are very anxious about it Answer: d

Smoking is very dangerous and we are very anxious about it
Our perception, and the reality, of risk often do not match. Given this graph (reality), and your knowledge of sources of anxiety (perception), which statement is correct? Smoking is very dangerous and we are very anxious about it Smoking is not dangerous, but we are very anxious about it Airplane accidents are dangerous, and we are very anxious about it Airplane accidents are not dangerous, but we are very anxious about it Answer: d

QUESTION: Interpreting Graphs and Data
If the “low” dose = 5 units of a chemical, the “medium” dose = 10 units, and the “high” dose = 15 units, how much of the chemical is required to kill 50% of the study population? About 5 units About 10 units About 15 units You can’t tell from the graph Answer: b From The Science behind the Stories

QUESTION: Viewpoints Is it unethical for a country that has banned a chemical to manufacture and export it to other countries? Yes; if we won’t have it in the U.S., we shouldn’t make it Yes, but the money we get from selling it will help our economy No; let people decide what they want to do No; in fact, chemicals should not be banned in the U.S. either Answer: any

QUESTION: Viewpoints Should the government follow the precautionary principle and force industries to prove their products are safe? Absolutely; it is up to industry to prove its chemicals are safe Maybe, if it is not too expensive No; let the government and scientists prove a chemical is dangerous before it is taken off the market No, as long as the product makes money and jobs for the industry, it should be allowed Answer: any

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