Environmental Hazards and Human Health Chapter 19 (see Bozeman video- Health Impacts of Pollution)

Risks and Hazards Risk is the possibility of suffering harm from a hazard that can cause injury, disease, economic loss or environmental damage. Risk is expressed as a probability (Insurance actuary) 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 © Brooks/Cole Publishing Company / ITP

Risk and Probability Fig. 19-2 p. 410

Major Hazards There are 4 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. © Brooks/Cole Publishing Company / ITP

Toxicology the study of the adverse effects of chemicals on health. Toxicity - a measurement of how harmful a substance is; dependent on: Dose - the amount of a potentially harmful substance that is ingested, inhaled, or absorbed through the skin Age/ Body mass Genetic makeup Multiple chemical sensitivity (MCS) Solubility and persistence of the chemical Biomagnification © Brooks/Cole Publishing Company / ITP

Responses Dose Response- the resulting type and amount of damage to health; TWO types of responses: acute effect: immediate or rapid harmful reaction, e.g., dizziness, rash, death; chronic effect: permanent or long–lasting consequence, e.g., asthma, kidney damage, heart disease

Determining Toxicity 3 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/ Analysis of umbilical cord blood) © Brooks/Cole Publishing Company / ITP

Water pollutant levels Scientific measurements and modeling Air pollutant levels Soil/dust levels Food pesticide levels Nutritional health Overall health Scientific measurements and modeling Lifestyle Figure 17.13 Science: Estimating human exposure to chemicals and measuring their effects are very difficult because of the many and often poorly understood variables involved. Question: What three of these factors might make you more vulnerable to the harmful effects of chemicals? Predicted level of toxicant in people Personal habits Metabolism Genetic predisposition Accumulation Excretion Lung, intestine, and skin absorption rates Fig. 17-13, p. 454

Scientists Use Live Lab Animals and Nonanimal Tests to Estimate Toxicity LD50 is the median lethal dose = the kills 50% of animals amount of a chemical received that (usually rats or mice) in a test population (usually 60–200 animals) within a 14–day period. Poison - legally defined as a chemical that has an LD50 of 50 milligrams or less per kilogram of body weight.

Hypothetical Dose-Response Curve Showing Determination of the LD50

Some Toxicity Ratings Table 9–1 p.414 © Brooks/Cole Publishing Company / ITP

Dose–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. Fig.19–6 © Brooks/Cole Publishing Company / ITP

Two Types of Dose- Response Curves

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). © Brooks/Cole Publishing Company / ITP

Potential Pathways on Which Toxic Chemicals Move Through the Environment

Biomagnification in a Food Chain

Mercury’s Toxic Effects Hg: teratogen and potent neurotoxin Once airborne, persistent and not degradable 1/3 from natural sources 2/3 from human activities Enters the food chain: biomagnification

Photo-chemical oxidation WINDS PRECIPITATION WINDS PRECIPITATION Hg and SO2 Hg2+ and acids Hg2+ and acids Photo-chemical oxidation Human sources Elemental mercury vapor (Hg) Inorganic mercury and acids (Hg2+) Inorganic mercury and acids (Hg2+) Coal-burning plant Incinerator Deposition Runoff of Hg2+ and acids Deposition Deposition Large fish Vaporization Small fish BIOMAGNIFICATION IN FOOD CHAIN Zooplankton Phytoplankton Figure 17.A Science: cycling of mercury in aquatic environments, in which mercury is converted from one form to another. The most toxic form to humans is methylmercury (CH3Hg+), which can be biologically magnified in aquatic food chains and webs. Some mercury is also released back into the atmosphere as mercury vapor. Bacteria and acids Elemental mercury liquid (Hg) Oxidation Inorganic mercury (Hg2+) Organic mercury (CH3Hg+) Bacteria Settles out Settles out Settles out SEDIMENT Fig. 17-A, p. 450

SOLUTIONS Mercury Pollution Prevention Control Phase out waste incineration Sharply reduce mercury emissions from coal-burning plants and incinerators Remove mercury from coal before it is burned Switch from coal to natural gas and renewable energy resources such as wind, solar cells, and hydrogen Tax each unit of mercury emitted by coal-burning plants and incinerators Convert coal to liquid or gaseous fuel Figure 17.B Ways to prevent or control inputs of mercury into the environment from human sources—mostly coal-burning power plants and incinerators. Question: Which four of these solutions do you think are the most important? Require labels on all products containing mercury Phase out use of mercury in batteries, TVs, compact fluorescent lightbulbs, and all other products unless they are recycled Collect and recycle mercury-containing electric switches, relays, and dry-cell batteries Fig. 17-B, p. 451

Mutagens, Teratogens, and Carcinogens Mutagens are agents, chemicals and radiation, that cause random mutations, or changes in the DNA - e.g., UV radiation; x-rays Teratogens are agents (chemicals, radiation, or viruses) that affect embryo and cause birth defects; e.g., PCBs, steroid hormones, heavy metals Carcinogens are agents (chemicals, radiation, or viruses) that cause cancer; over 100 types of cancer (depending on cells involved) e.g., cigarette smoke. © Brooks/Cole Publishing Company / ITP

Mutagens

Teratogens – affect embryos

Hormonally active agents (HAAs) Gender benders (hormone mimickers, or disruptors) Thyroid disrupters Phthlates “THAL-ates,”- group of chemicals used to soften and increase the flexibility of plastic and vinyl flexible plastic and vinyl toys, shower curtains, food packaging, plastic wrap, detergents, plastic plumbing pipes, lubricants, medical tubing and fluid bags, vinyl flooring) *Prior to1999, U.S. manufacturers have used phthalates in baby pacifiers, soft rattles, and teething toys! Disrupt endocrine system signaling pathways Cancer

Hormone Disrupters DDT; Bisphenol A Fig.19-7 (Endocrine Disrupting Chemicals “EDC’s”) DDT; Bisphenol A Fig.19-7 © Brooks/Cole Publishing Company / ITP

Bisphenol A Estrogen mimic Found in many common products (baby bottles; hard, clear plastic products- reusable, water bottles) Laboratory findings Effects on human health TED Talk – Toxic Baby Should it be banned?

PCBs: Legacy from the Past Class of chlorine-containing compounds (PCB = Polychlorinated Biphenyl ) Oily liquids or solids that can enter the air as vapor Were widely used as lubricants, hydraulic fluids, electrical insulators in transformers Were used in paints, pesticides, fire retardants in fabrics, preservatives, adhesives. Highly persistent. Banned in 1979 in the U.S. Fat soluble – Biomagnification Banned, but found everywhere

Perfluorochemicals to add shine Shampoo Teddy bear Clothing Baby bottle Perfluorochemicals to add shine Some stuffed animals made overseas contain flame retardants and/or pesticides Can contain perfluorochemicals Can contain bisphenol-A Nail polish Perfluorochemicals and phthalates Mattress Flame retardants in stuffing Perfume Phthalates Carpet Padding and carpet fibers contain flame retardants, perfluorochemicals, and pesticides Hairspray Phthalates Food Some food contains bisphenol-A TV Wiring and plastic casing contain flame retardants Milk Fat contains dioxins and flame retardants Sofa Figure 17.16 Some potentially harmful chemicals found in most homes. Most people have traces of these chemicals in their blood and body tissues. We do not know the long-term effects of exposure to low levels of such chemicals. (Data from U.S. Environmental Protection Agency, Centers for Disease Control and Prevention, and New York State Department of Health) Question: Does the fact that we do not know much about long-term harmful effects of these chemicals make you more likely or less likely to minimize your exposure to them? Why? Frying pan Foam padding contains flame retardants and perfluorochemicals Nonstick coating contains perfluorochemicals Fruit Water bottle Computer Toys Tennis shoes Tile floor Imported fruit may contain pesticides banned in the U.S. Can contain bisphenol-A Flame retardant coatings of plastic casing and wiring Vinyl toys contain phthalates Can contain phthalates Contains perfluorochemicals, phthalates, and pesticides Fig. 17-16, p. 458

Pollution Prevention and the Precautionary Principle Those introducing a new chemical or new technology would have to follow new strategies A new product is considered harmful until it can be proved to be safe Existing chemicals and technologies that appear to cause significant harm must be removed 2000: Stockholm Convention- global treaty to ban or phase out the “Dirty Dozen” of toxic chemicals (Persistant Organic Pollutants “POPs”)

Physical Hazards (not in this chapter!) Earthquakes are among various types of natural physical hazards. Other physical hazards include volcanoes and ionizing radiation. © Brooks/Cole Publishing Company / ITP

Preventing loss: understand where risk is high 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. © Brooks/Cole Publishing Company / ITP

Cultural / Biological Hazards: The Global HIV/AIDS Epidemic Acquired immune deficiency syndrome (AIDS) caused by human immunodeficiency virus (HIV); many secondary infections No vaccine to prevent or cure AIDS Expensive drugs—live longer 25 Million deaths, so far; alter country’s age structure

AIDS Is the Leading Cause of Death for Ages 15–49 Worldwide

Some Diseases Can Spread from One Person to Another Nontransmissible disease – not capable of being passed to another Infectious disease - transmitted via microorganisms in the air or water (Cholera, Malaria, TB) Transmissible disease (contagious or communicable disease) – physical contact needed

The World’s Seven Deadliest Infectious Diseases Kill 12 The World’s Seven Deadliest Infectious Diseases Kill 12.5 Million People

SOLUTIONS Infectious Diseases Increase research on tropical diseases and vaccines Reduce poverty Decrease malnutrition Improve drinking water quality Reduce unnecessary use of antibiotics Educate people to take all of an antibiotic prescription Reduce antibiotic use to promote livestock growth Figure 17.10 Solutions: ways to prevent or reduce the incidence of infectious diseases, especially in developing countries. Question: Which three of these approaches do you think are the most important? Require careful hand washing by all medical personnel Immunize children against major viral diseases Provide oral rehydration for diarrhea victims Conduct global campaign to reduce HIV/AIDS Fig. 17-10, p. 447

Case Study: The Growing Global Threat from Tuberculosis Why is tuberculosis on the rise? Not enough screening and control programs Genetic resistance to a majority of effective antibiotics Person-to-person contact has increased AIDS individuals are very susceptible to TB

Tracking the Spread of Infectious Diseases to Humans from Other Animals Ecological medicine Human practices that encourage the spread of diseases from animals to humans Emerging infections HIV SARS West Nile virus Lyme virus

Malaria—Death by Parasite-Carrying Mosquitoes Caused by Plasmodium (PROTIST!) specifically carried by Anopheles mosquitoes Spread Symptoms Malarial cycle

Case Study: Malaria—Death by Parasite-Carrying Mosquitoes (2) Malaria on the rise since 1970 Drug resistant Plasmodium Insecticide resistant mosquitoes Effect of global warming AIDS patients particularly vulnerable Prevention of spread and current research

Global Outlook: Distribution of Malaria

A Boy in Brazil’s Amazon Sleeps Under an Insecticide-Treated Mosquito Net

Animation: HIV replication

Animation: Life cycle of plasmodium

ABC Video: Bird flu

ABC Video: Polio scare

ABC Video: The problem with pork

Comparative Risk Analysis: Most Serious Ecological and Health Problems