This lecture will help you understand:

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 internationally

Central Case: Lake Apopka alligators
Alligators in Lake Apopka, Florida, had reproductive problems Louis Guillette The lake had high levels of agricultural runoff Chemical contaminants were disrupting the endocrine systems of alligators during egg development Because alligators and humans share the same hormones, chemicals can affect people, too

There are many types of environmental hazards
Environmental health = assesses environmental factors that influence human health and quality of life Natural and human-caused factors are both considered Physical hazards = occur naturally in our environment Earthquakes, volcanoes, fires, floods, droughts We can’t prevent them, but we can prepare for them We increase our vulnerability by deforesting slopes (landslides), channelizing rivers (flooding), etc. We can reduce risk by better environmental choices

Chemical and biological environmental hazards
Chemical = synthetic chemicals such as pesticides, disinfectants, pharmaceuticals Harmful natural chemicals also exist 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

Cultural environmental hazards
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

Many diseases are increasing
Tuberculosis, acquired immunodeficiency syndrome (AIDS), and the West Nile virus Our mobility spreads diseases Diseases are evolving resistance to antibiotics Climate change will expand the range of diseases To predict and prevent diseases, experts deal with complicated interrelationships

Infectious disease accounts for ________% of deaths globally.
26

Environmental health hazards exist indoors
Radon = a highly toxic, radioactive gas that is colorless and undetectable Can build up in basements Lead poisoning = from lead pipes Damages organs; causes learning problems, behavior abnormalities, and death Asbestos = insulates, muffles sounds, and resists fire Asbestosis = scarred lungs may cease to function

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 Analogous to pathogenicity or virulence = the degree of harm of biological hazards that spread disease Toxicant = any toxic agent

Paracelsus “All substances are poisons: there is none which is not a poison. The right dose differentiates a poison and a remedy.” Paracelsus ( ) Swiss German Renaissance physician, botanist, alchemist, astrologer, and general occultist. He founded the discipline of Toxicology.

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
100,000 chemicals are on the market today 72,000 industrial 8,700 food additives 2,000 new chemicals introduced per year We don’t know the effects, if any, they have

NY Times Article In its history, the E.P.A. has mandated safety testing for only a small percentage of the 85,000 industrial chemicals available for use today. And once chemicals are in use, the burden on the E.P.A. is so high that it has succeeded in banning or restricting only five substances, and often only in specific applications: polychlorinated biphenyls, dioxin, hexavalent chromium, asbestos and chlorofluorocarbons.

Silent Spring began public debate over chemicals
Rachel Carson published Silent Spring in 1962 Brought together studies to show DDT risks to people, wildlife, and ecosystems 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

Types of toxicants Carcinogens = cause cancer
Mutagens = cause DNA mutations Can lead to severe problems, including cancer Teratogens = cause birth defects Allergens = overactivate the immune system Neurotoxins = assault the nervous system Endocrine disruptors = interfere with the endocrine (hormone) system

What was the significance of the Yaqui Valley, Mexico, study?
Found that pesticides caused neurological effects in children that affected their learning abilities. Video (5 min):

The Heavy Metals Mercury/Methylmercury Lead Cadmium Arsenic Copper
Zinc

Heavy Metals Minamata Disease 3:12

A recently recognized hazard
Polybrominated diphenyl ethers (PBDEs) = has fire-retardent 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

Endocrine disruption may be widespread
Theo Colburn wrote Our Stolen Future in 1996 Synthetic 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 Our stolen future 14 min Look back 15 years ago

Evidence for hormone disruption
Frogs also have gonadal abnormalities Male frogs became feminized from atrazine concentrations well below EPA guidelines PCB-contaminated human babies were born weighing less, with smaller heads Tyrone Hayes Developmental Exposure in Children is different (17:48)

Why are aquatic animals such as fish and frogs especially good indicators of pollution?
Most chemicals are water soluble so they enter these organisms through drinking or skin absorption

Male sperm counts are dropping
Scientists attribute the shocking drop in men’s sperm counts to endocrine disruptors The number and motility of sperm has dropped 50% since 1938 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 Studies reporting harm are publicly funded, but those reporting no harm are industry funded

What has the European Union's experience with PBDE's shown?
If the toxin is removed from the environment, concentrations in human tissues fall

What caused penis abnormalities in Taiwanese boys whose mothers used contaminated cooking oil ?
PCB’s

PCB (Polychlorinated biphenyl)
History of PCB 28 min (first 10) 8 min PCB Harms in Environment Widely used as dielectric and coolant fluids, for example in electrical apparatus, cutting fluids for machining operations, carbon paper and in heat transfer fluids A Persistant Organic Pollutant Endocrine Disruptor, Carcinogen, neurotoxin, immune system disorders. Banned in U.S. in 1979 but still in the environment because of persistence—it doesn’t break down

What was the significance of the book Our Stolen Future?
It focused on the impacts of endocrine-disrupting chemicals on humans. It was first published in 1994.

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

The U. S. Geological Survey found that 80% of U. S
The U.S. Geological Survey found that 80% of U.S. streams contain at least trace amounts of over how many wastewater contaminants? 80

Which organism was impacted by infection from sewage run-off from cat litter boxes from urban areas
Sea Otters Toxoplasma gondii is best known for the threat it poses to the fetuses of pregnant women exposed to the protozoan's eggs, or oocysts, when cleaning their pets' litter boxes. Autopsies have revealed that some otters have died from brain infections caused by the parasite.

Routes of chemical transport

Describe these methods of Toxin Movement
leaching drift run-off

Airborne toxicants travel widely
Because 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

What kind of toxicant is known to have a short persistence time?
Bt (Bacillus thuringiensis) 1:45 Bt resistance 3:50

Toxicants can accumulate and biomagnify
Some toxicants can be excreted or metabolized 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 Mercury Bioaccumualtion 2 min

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 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

Why are some threats to human health unavoidable?
They are wholly natural and part of the natural environment.

How does Radon gas, a highly toxic radioactive gas, get introduced into homes?

Toxoplasma Toxoplasma in Cats and Mice

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

Why is examining case studies not the best way to assess risk of toxicants for human populations?
Don’t show the effects of toxicants that build up over time to cause problems Tell little about probability or risk such as how many deaths might be expected in a population due to a particular cause.

Case Studies Analysis and observation of individuals
Tell little about effects of rare hazards, new synthetic chemicals, low environmental exposure, minor long term effects Tell little about probability and risk

Epidemiological Study
Identifies statistical correlations found in large samples of people. (Like a Natural Experiment) Tells probability and risk Does not show actual cause and effect

Animal Testing (Animal Models)
Manipulated experiment that identifies LD 50 and ED 50 Shows cause and effect Assumes similar reactions between animals and humans (relies on evolutionary history) Ethical questions

What kind of study is this?
Baseline body mass index* Number of incident cases of colon cancer Person-years of follow up Crude incidence rate/100,000 PY <22 28 53,475 52.36 22 - <24 41 38,919 105.35 24 - <26 36 36,610 98.33 26 - <28 40 32,635 122.57 28 - <30 35 21,122 165.70 30+ 42 34,904 120.33

My grandpa has smoked a pack of cigarettes a day since he was a teenager and has been healthy all his life. There are no health risks associated with smoking long term.

Back problems in employees in Cell phone manufacturing Age Persons cases Rate 25-39 1000 2 .002 40-55 700 25 .037 55+ 50 15 .300 Total 1750 42 .024

What kind of a study is this?

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/ED50= the amount of toxicant required to kill (affect) 50% of the subjects Threshold = the dose level where certain responses occur Organs can metabolize or excrete low doses of a toxicant Some toxicants show a J-shaped, U-shaped, or inverted curve Scientists extrapolate downward from animal studies to estimate the effect on humans Regulatory agencies set allowable limits well below toxicity levels in lab studies

Caffeine The minimum lethal dose of caffeine ever reported is 3,200 mg, administered intravenously. The LD50 of caffeine is estimated between 13 and 19 grams for oral administration for an average adult. So a person would have to drink over 100 cups of coffee within a small time span to reach the LD50. (That reminds me of the Futurama episode "300 big boys". )

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

Exposure Pathways Ingestion Inhalation Direct or External (Absorption through skin or mucous membranes)

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 and frequency that an organism will encounter it Amount of exposure to the threat An organism’s sensitivity to the threat

Perceiving risks Everything we do involves some risk
We try to minimize risk, but we often misperceive it Flying versus 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

MSDS Material Safety Data Sheets Risk Assessment Risk Management

The process of risk management

One approach to determining safety
Innocent until proven guilty approach: the government, scientists, and the public are required to prove a product is dangerous Benefits: not 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: Assume substances are harmful until they are proven harmless. Product manufacturers must prove a product is safe 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

European Trends

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 FIFRA TSCA Occupational Safety and Health Administration (OSHA): workplace hazards CDC Centers for disease control sets policy for infectious diseases 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

What does the The Toxic Substances Control Act (TSCA) regulate?
Industrial chemicals Carried out by the EPA Not… Drugs, pesticides, food additives, cosmetics Catch 22 because the chemicals must be shown to be toxic before more extensive tests are done.

Of the 80,000 chemicals that fall under the TSCA ________% have been tested for toxicity and ________ have been tested for endocrine, nervous, or immune system damage. 10; almost none

Which chemicals used in the U.S. are not reviewed for safety?
Cosmetics The agency charged with oversight of cosmetics, the U.S. Food and Drug Administration (FDA), has no authority to require pre-market safety assessment as it does with drugs, so cosmetics are among the least-regulated products on the market. The FDA does not review – nor does it have the authority to regulate – what goes into cosmetics before they are marketed for salon use and consumer use. In fact, 89 percent of all ingredients in cosmetics have not been evaluated for safety by any publicly accountable institution. The truth is, no one's minding the store when it comes to shampoo, skin moisturizers, baby products, lipstick or any other personal care product.

Cosmetics The FDA’s own Web site explains its limitations: “FDA's legal authority over cosmetics is different from other products regulated by the agency .... Cosmetic products and ingredients are not subject to FDA premarket approval authority, with the exception of color additives.” Toxins in Cosmetics 4 min Toxic Cosmetics (Story of Stuff) 8 min

TSCA Info TSCA Introduction in 1975 Video 1:30
Weakness of TSCA Video 1:30 TSCA Reform video 2:21 Industry TSCA reform video 3min

What is FIFRA? The Federal Insecticide, Fungicide, and Rodenticide Act and its later amendments charge the EPA with registering new pesticides and regulating their sale, use, and labeling. This is not really designed to protect workers and consumers but a “truth in advertising” law that requires that the pesticide is actually effective. It does not require a pesticide to be safe. FIFRA 5:30 min (doesn’t tell about health effects. Only registration regarding use—not health effects)

Match the toxicant with the regulatory agency
Industrial chemicals TSCA Drugs FDA Pesticides FIFRA Food additives Infectious disease protocols CDC Cosmetics No Agency Job site safety OSHA Agricultural Practices (Meat and Nutriion) USDA FDA USDA FIFRA/EPA TSCA/EPA OSHA CDC

Food Color This review finds that all of the nine currently US-approved dyes raise health concerns of varying degrees. Red 3 causes cancer in animals, and there is evidence that several other dyes also are carcinogenic. Three dyes (Red 40, Yellow 5, and Yellow 6) have been found to be contaminated with benzidine or other carcinogens. At least four dyes (Blue 1, Red 40, Yellow 5, and Yellow 6) cause hypersensitivity reactions. Numerous microbiological and rodent studies of Yellow 5 were positive for genotoxicity. Toxicity tests on two dyes (Citrus Red 2 and Orange B) also suggest safety concerns, but Citrus Red 2 is used at low levels and only on some Florida oranges and Orange B has not been used for several years.

Food Color The inadequacy of much of the testing and the evidence for carcinogenicity, genotoxicity, and hypersensitivity, coupled with the fact that dyes do not improve the safety or nutritional quality of foods, indicates that all of the currently used dyes should be removed from the food supply and replaced, if at all, by safer colorings. It is recommended that regulatory authorities require better and independent toxicity testing, exercise greater caution regarding continued approval of these dyes, and in the future approve only well-tested, safe dyes. -National Institutes of Health

Hazards of Food Dyes Food Dyes 3:40

International regulation
WHO (World Health Organization) A United Nations organization that monitors and makes recommendations about infectious diseases world wide. 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 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

What is the goal of the Stockholm Convention?
Identified POP’s (persistant organic pollutants) that breakdown slowly in organisms and the environment and easily bioaccumulate in tissues causing greater damage than small exposure would indicate. Dirty Dozen: 12 of the worst POPs. Dioxin, Furans, PCBs Sets international guidelines for phasing out these chemicals. Best slide show of POP’s (4 min) Dirty Dozen /Stockholm Convention.

Organochlorines and Organophosphates

Dirty Dozen

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 hose 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

What did Louis Guillette find?
Hormone mimics from pesticide runnoff that affect alligator hatching rates and gonad abnormalities

What did Tyrone Hayes find?
Deformities and reproductive abnormalities in frogs due to atrazine, the active ingredient in the best selling herbicide, round-up.

What unusual place have synthetic pesticides been found in high concentrations?
uninhabited polar regions

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

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

What was the contribution of Rachel Carson?
Wrote books that increased the awareness of the effect of industrial chemicals on ecosystems and on humans. Documented the prevalence of synthetic chemicals in animal and human tissues.

Explain each of the Following with examples.
biomagnification bioaccumulation synergism

Explain each with an example
neurotoxins allergens teratogens hormones antibiotics Carcinogens Vectors radon Bisphenol-A Bt

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

Chemicals Atrazine PCB DDT BPA Lead Phthalates Mercury PFOA Asbestos
Thalidamide Organochlorides Organophosphates BPA Phthalates PFOA PBDE PCE- Glyphosate

“The problem with toxicology is not the practicing toxicologists, but chemists who can detect, precisely, toxicologically insignificant amounts of chemicals” Rene Truhaut, University of Paris ( )

Here is a final concept worth considering.
Current technology allows us to accurately measure trace quantities of chemicals. Yet, the biological significance of the presence of these extremely small amounts of these chemicals is sometimes not clear (e.g., carcinogens). Just because a drug or environmental contaminant is measurable, does that mean that it poses a threat?

Food for thought… Many environmental contaminants (and even foodstuffs) are considered differently by different scientific groups and agencies with regard to their safety. It is, therefore, up to the “consumer” in many cases to make a judgment call as to how much exposure is reasonable, based on available information. This concept is related to RISK ASSESSMENT.

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