2/16/2015 THIS LECTURE WILL HELP YOU UNDERSTAND: BISPHENOL A MIMICS ESTROGEN CENTRAL CASE STUDY: POISON IN THE BOTTLE: IS BISPHENOL A (BPA) SAFE?

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1 THIS LECTURE WILL HELP YOU UNDERSTAND: ENVIRONMENTAL HEALTH AND TOXICOLOGY Chapter 10 Environmental hazards and environmental health Toxic substances in the environment Movement of toxics and their effects Chemical hazards Risk assessment and risk management Philosophical approaches to risk CENTRAL CASE STUDY: POISON IN THE BOTTLE: IS BISPHENOL A (BPA) SAFE? It is in hundreds of products Cans, utensils, baby bottles, laptops, toys BPA causes cancer, nerve damage, and miscarriages In extremely low doses BPA leaches into food, air, and bodies 93% of Americans have it in their bodies BISPHENOL A MIMICS ESTROGEN BPA mimics estrogen, a female hormone Researchers, doctors, and consumer advocates want governmental regulation, yet the chemical industry insists it is safe Some countries and states have banned it Many companies are voluntarily removing it due to consumer pressure FOUR TYPES OF ENVIRONMENTAL HEALTH HAZARDS THE FOUR TYPES OF ENVIRONMENTAL HAZARDS Environmental health assesses environmental factors that influence human health and quality of life Physical hazards occur naturally in our environment UV radiation, earthquakes, volcanoes, fires, floods, landslides, hurricanes, droughts, etc. We increase our vulnerability by deforesting slopes (landslides), channelizing rivers (flooding), etc. 1

2 CULTURAL (LIFESTYLE) HAZARDS Cultural hazards result from where we live, our socioeconomic status, occupation, or behavioral choices We can minimize some, but not all, of these hazards Smoking, drug use, diet and nutrition, crime, mode of transportation Risks (e.g., living near toxic waste) are often correlated with poverty or those with little political clout DIET Strong correlation between cardiovascular disease and the amount of salt and fat in an individual s diet Highly-processed foods, fat, and smokecured, high-nitrate meats appear to be associated with cancer DIET Sixty-percent of all U.S. adults are now considered overweight Estimated 1 billion worldwide Second leading cause of death in the US U.S. Centers for Disease Control (CDC) warn one in three U.S. children are at risk of becoming diabetic CHEMICAL AND BIOLOGICAL HAZARDS Biological hazards result from ecological interactions Infectious disease: viruses, bacteria, and other pathogens parasitize humans (e.g., malaria, cholera) DISEASE IS A MAJOR FOCUS OF ENVIRONMENTAL HEALTH INFECTIOUS DISEASES KILL MILLIONS Infectious diseases kill 14 million people/year Infectious diseases account for 50% of deaths in poor nations 2

3 PATHOGENS PATHOGENS Malaria is one of the most prevalent remaining infectious diseases Spread by mosquitos in tropical areas Global warming 1 million die each year Simple treatment solutions Insecticide-treated bed nets Chloroquine pills Influenza epidemic of million died in less than 12 months Recently recreated this virus Recent concerns over bird and swine flu EMERGENT DISEASES An emergent disease is one never known before or has been absent for at least 20 years An important factor in the spread of many diseases is the speed and frequency of modern travel SARS (SEVERE ACUTE RESPIRATORY SYNDROME) First appeared in China Quickly spread to 31 countries 8,500 cases, 800 deaths Linked to consumption of wild game species CHEMICAL HAZARDS Chemical hazards are synthetic chemicals such as pharmaceuticals, disinfectants, pesticides, as well as harmful natural chemicals TOXICOLOGY STUDIES CHEMICAL HAZARDS Toxicology is the study of the effects of poisonous substances on humans and other organisms Toxicity is the degree of harm a chemical can inflict Toxicant is any toxic substance (poison) Toxicity depends on the combined effect of the chemical and its quantity Environmental toxicology deals with toxic substances that come from or are discharged into the environment 3

4 INDOOR ENVIRONMENTAL HEALTH HAZARDS Most Americans spend 90% of their time indoors Cigarette smoke and radon cause lung cancer Mold in homes and offices produce toxic compounds Asbestos used for insulation causes problems if inhaled Lead in pipes and gasoline damages organs and causes learning problems, hearing loss, and death PBDE Polybrominated diphenyl ethers (PBDEs) are used in computers, televisions, plastics, and furniture Act as hormone disruptors Now banned in Europe, but not in the U.S. Widely used flame retardant Accumulates in breast milk in humans Dust at Ground Zero heavily laden SYNTHETIC CHEMICALS TRAVEL THROUGH THE ENVIRONMENT People receive toxicants from many sources SILENT SPRING CHANGED ATTITUDES Rachel Carson s Silent Spring (1962) showed DDT s risk to people, wildlife, and ecosystems DDT was banned in the U.S. in 1973 TOXICANTS COME IN DIFFERENT TYPES Carcinogens cause cancer Hard to identify because of the long time between exposure and onset of cancer Mutagens cause DNA mutations Can cause cancer and harm sperm or egg cells Teratogens cause birth defects in embryos Neurotoxins affect the nervous system (lead, mercury) Allergens overactivate the immune system Pathway inhibitors interrupt biochemical processes Rat poison stops blood clotting IMMUNE SYSTEM AFFECTER Allergens Substances that activate the immune system Formaldehyde Immune system depressants Dead seals contain high levels of PCBs that make the seal susceptible to opportunistic infections 4

5 TOXICOLOGY ENDOCRINE DISRUPTERS Sick Building Syndrome Headaches, allergies, and chronic fatigue caused by poorly ventilated indoor air contaminated by molds, carbon monoxide, nitrogen oxides, and other toxic chemicals Worker absenteeism and reduced productivity EPA estimates $60 billion annual loss Disrupt normal hormone functions Examples of hormones include: Testosterone Estrogen Insulin Adrenalin Endorphins MANY PRODUCTS MIMIC FEMALE HORMONES Bisphenol A binds to estrogen receptors Phthalates also disrupt hormones Toys, perfumes, makeup Birth defects, cancer, reproductive effects A substance can have multiple effects It can be carcinogenic, mutagenic, and an endocrine disruptor ENDOCRINE DISRUPTERS Can cause feminization of males Alligators in Florida NEUROTOXINS MUTAGENS Poisons that specifically attack nerve cells Different types act in different ways Heavy metals kill nerve cells and cause permanent damage Anesthetics and chlorinated hydrocarbons disrupt nerve cell membranes Organophosphates and carbamates inhibit signal transmission between nerve cells Mutagens - agents that damage or alter genetic material (DNA) Radiation Chernobyl heart 5

6 TERATOGENS Teratogens - specifically cause abnormalities during embryonic growth and development Alcohol - Fetal Alcohol Syndrome Thalidomide CARCINOGENS Substances that cause cancer, which is invasive out-of-control cell growth Cigarette smoke Chromium-6 Cancer rates rose most in industrialized nations during 20 th century INDIVIDUAL RESPONSES TO HAZARDS VARY THE TYPE OF EXPOSURE AFFECTS THE RESPONSE Different individuals respond differently to hazards Genetics can affect responses People in poor health are more sensitive Sensitivity also varies with sex, age, and weight Fetuses, infants, and young children are more sensitive The Environmental Protection Agency (EPA) sets standards for responses based on adult responses Standards may not be low enough to protect the young Acute exposure is high exposure to a hazard for short periods of time Easy to recognize Stem from discrete events: ingestion, oil spills, nuclear accident, etc. Toxicity tests reflect effects of acute toxicity Chronic exposure is low exposure for a long time More common but harder to detect and diagnose Affects organs gradually: lung cancer, liver damage Cause and effect may not be easily apparent TOXIC SUBSTANCES CAN TRAVEL WIDELY Chemicals can travel by air Impact areas far from the site of use Synthetic chemicals are found globally In arctic polar bears, Antarctic penguins, and people in Greenland Pesticide drift is airborne transport of pesticides Move long distances in water PERSISTENCE Some chemical compounds are very unstable and degrade rapidly under most conditions, thus their concentrations decline quickly after release Others are more persistent Stability can cause problems as toxic effects may be stored for long period of time and spread to unintended victims (DDT) 6

7 TOXICANTS CAN ACCUMULATE AND BIOMAGNIFY In bioaccumulation, fat-soluble toxicants build up in animal tissues Can transfer toxins to others through the food chain In biomagnification, toxicant concentrations are magnified through trophic levels Near extinction of peregrine falcons and bald eagles TOXICANTS CAN THREATEN ECOSYSTEM SERVICES Toxicants can change the composition of ecosystems Affecting how organisms interact with each other and the environment Threatening ecosystem services Pesticides have killed bees Farmers must hire beekeepers to pollinate their crops Pesticides and antifungals kill decomposers and detritivores in the soil Nutrient cycling rates are changed Reduced nutrients slow plant growth HUMAN STUDIES An epidemiological study compares a group of people that was exposed to a hazard to a group that was not Studies can last for years If rates of death, cancer, etc., are higher in the exposed group, the hazard may be responsible Does not show that the hazard caused the effect Manipulative experiments show causation But are unethical in humans Mammals (rats, mice, etc.) are used because they elicit fewer ethical objections DOSE-RESPONSE ANALYSIS Dose-response analysis: quantifies a substance s toxicity Measures the strength of toxicant s effects or the number of animals affected at different doses Dose is amount of substance the test animal receives Response is the type or magnitude of negative effects Dose-response curve is the dose plotted against the response DOSE RESPONSE CURVES LD 50 /ED 50 (lethal dose/effective dose): the amount of toxicant required to kill/affect 50% of the subjects A high number indicates low toxicity Threshold dose is the level where a response occurs Estimating human effects requires extrapolation, so regulatory agencies set standards below minimum toxicity levels 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 Mixed toxicants can sum, cancel out, or multiply each other s effects Synergistic effects: interactive impacts that are greater than the sum of their constituent effects DDE may cause or inhibit sex reversal, depending on the presence of other chemicals Scientists cannot test all chemical combinations 7

8 CONFLICTING RESULTS WE EXPRESS RISK IN TERMS OF PROBABILITY Bisphenol A (BPA) is suspected of causing reproductive harm (reduced sperm counts and quality, etc.) The chemical industry s studies show no health effects of BPA 151 of 178 studies by independent academic scientists show harm from low doses of BPA Exposure to a threat doesn t automatically produce an effect Rather, it causes some probability (likelihood) of harm A substance s threat depends on its identity and strength Chance and frequency of an encounter An organism s exposure and sensitivity to the threat Probability describes the likelihood of a certain outcome Risk is the probability that some harm results from an action, event, or substance PERCEPTIONS OF RISK MAY NOT MATCH REALITY ANALYZING RISK QUANTITATIVELY We try to minimize risk But perception may not match reality Flying versus driving We feel more at risk when we do not control a situation We fear nuclear power and toxic waste But not smoking or overeating Risk assessment is the quantitative measurement of risk Compares risks involved in different activities or substances It identifies and outlines problems It helps determine which substances and activities pose health threats to people or wildlife Risk assessment has several steps: The scientific study of toxicity Assessing an individual or population s exposure to the substance (frequency, concentrations, length) RISK MANAGEMENT THE PROCESS OF RISK MANAGEMENT Risk management represents decisions and strategies to minimize risk Federal agencies manage risk The U.S. has the Centers for Disease Control and Prevention (CDC), the EPA, the Food and Drug Administration (FDA), Occupational Heath and Safety Administration (OSHA) Scientific assessments are considered with economic, social, and political needs and values 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 suffering and lots of people not The end result of risk management is a policy decision that minimizes the risk of an environmental hazard 8

9 TWO APPROACHES TO DETERMINING SAFETY Innocent-until-proven-guilty approach: assumes a substance is harmless until it is shown to be harmful Helps technological innovation and economic activity But allows dangerous substances to be used Precautionary principle: assumes a substance is harmful until it is shown to be harmless Identifies troublesome toxicants before they are released But may impede the pace of technology and economic advancement TWO APPROACHES FOR DETERMINING SAFETY Who should have to prove a product is safe: the manufacturers or government/citizens? EPA REGULATION IS ONLY PARTLY EFFECTIVE EUROPE S REACH PROGRAM The Toxic Substances Control Act (1976): the EPA monitors chemicals made in or imported into the U.S. The EPA can ban substances that pose excessive risk Many health advocates think the TSCA is too weak Industry screening is minimal To push for more testing, toxicity must already be proven, but testing is minimal Only 10% of chemicals have been tested for toxicity Fewer than 1% are regulated Almost none have been tested for endocrine, nervous, or immune system damage The EU s REACH program (Registration, Evaluation, Authorization, and Restriction of CHemicals) Shifts the burden of proof for safety to industry 30,000 chemicals will have to be registered with the European Chemicals Agency REACH will cost industry $3.8 7 billion over 11 years Health benefits will be $67 billion over 30 years THE STOCKHOLM CONVENTION ON PERSISTENT ORGANIC POLLUTANTS (POPS) Enacted in 2004 and ratified by over 150 nations POPs: toxic, persistent chemicals Bioaccumulate and biomagnify The dirty dozen : the 12 most dangerous POPs (aldrin, chlordane, dieldrin, dioxins, DDT, endrin, furans, heptachlor, hexachlorobenzene, mirex, polychlorinated biphenyls (PCBs), toxaphene) The Stockholm Convention sets guidelines for phasing out these chemicals Encourages transition to safer alternatives WHICH OF THE FOLLOWING ACTS AS A HORMONE DISRUPTOR, HAS BEEN RECENTLY RECOGNIZED, IS USED IN COMPUTERS, PLASTICS, FURNITURE, AND WAS BANNED BY THE EU IN 2003? 1. Radon 2. Asbestos 3. Lead 4. Polybrominated diphenyl ethers (PBDEs) 5. None of these hormone disruptors are extremely rare 9

10 WHICH OF THE FOLLOWING IS A BIOLOGICAL HAZARD? WHAT IS A TOXICANT? 1. An earthquake 2. Smoking 3. A virus 4. A pesticide 5. All are biological hazards 1. The study of the effects of poisonous substances 2. Any substance that can exert a negative impact when we are exposed to it 3. Any substance that causes environmental degradation 4. The degree of harm a substance can cause 5. Any indoor hazardous substance WHAT DOES A TERATOGEN CAUSE? BIOACCUMULATION DESCRIBES: 1. Cancer 2. Mutations 3. Birth defects 4. Problems in the hormonal system 5. Problems in the elderly 1. An epidemiological study 2. The accumulation of a toxicant in fatty tissues 3. The accumulation of a toxicant in a fetus 4. The probability of risk after exposure to a toxicant 5. The concentration of a toxicant as one goes up the food chain WHICH EXAMPLE ILLUSTRATES A SYNERGISTIC EFFECT? 1. A person who drinks and smokes can develop liver problems and lung cancer 2. Alcohol can reduce the effects of drinking antifreeze 3. Alcohol and barbiturates can kill a person more easily than either one alone 4. Endocrine disruptors mimic female hormones 5. Risk managers are subject to political pressure when deciding to ban a chemical SHOULD THE UNITED STATES BE ABLE TO MANUFACTURE AND EXPORT CHEMICALS EVEN IF THEY HAVE BEEN BANNED IN THE U.S.? 1. No; if we won t have it in the United States, we shouldn t be able to make and export it to others 2. Yes, because the money we get from selling it will help our economy 3. Yes; let people decide what they want to do 4. Yes; in fact, chemicals should not be banned in the United States, either 5. No; chemicals made in the U.S. should stay in the U.S. 10

11 2/16/2015 SOME MEMBERS OF THE U.S. CONGRESS WANT TO ELIMINATE THE EPA BECAUSE IT KILLS JOBS. SHOULD THE EPA BE ELIMINATED? 1. No; the government should regulate industries to protect citizens 2. Yes; at this critical time, we need all the jobs we can get 3. Yes; industry knows chemicals best, so decisions should be left up to the industry 4. Yes, as long as a product makes money and jobs for an industry, it should be allowed, even if some people get sick or die from it 5. No; the government should protect citizens and find another way to provide jobs OUR PERCEPTION OF RISK 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? 1. Smoking is dangerous, but we still do it 2. Smoking is not dangerous, but we are anxious about it 3. Fire is dangerous, and we are anxious about it 4. Because being overweight is dangerous, we are anxious about it 5. Airplane accidents are very likely, but we still do it 11