Apes Ch 11 Risk, Toxicology, and Human Healthy Student Guide to Notes May 2007

Risk Risk is the possibility of suffering harm for a hazard Risk = exposure X harm 1 in 1M or 1 in 1B

Risk Assessment How is risk (probability) determined?

Risk Assessment Three components (229) Contrast biological, physical, and chemical hazards Contrast to risk management – why is this more difficult than risk assessment? Key components of risk management

Risk and Probability Fig. 11-2 p. 229

Toxicity What factors determine whether a chemical is harmful? Are all people at equal risk for a given dose and time of exposure? Explain your answer Should the regulatory levels be set for “average” sensitivity or most sensitive Discuss pros of cons of each approach

© 2004 Brooks/Cole – Thomson Learning Figure 11-3 Page 230 © 2004 Brooks/Cole – Thomson Learning Number of individuals affected Very sensitive Majority of population Very insensitive 20 40 60 80 Dose (hypothetical units)

How much is concerning? Chemical Concentration What has happened to our ability to determine concentration levels? Can all substances be harmful? Why are some different than others? Levels of detection – can now identify much lower amounts – how does this affect risk management?

Degree of a Substances Harm Solubility Persistence Bioaccumulation Biomagnification Chemical interactions Antagonistic interaction Synergistic interaction

Figure 11-4 Page 231 DDT in fish-eating birds (ospreys) 25 ppm DDT in large fish (needle fish) 2 ppm DDT in small fish (minnows) 0.5 ppm DDT in zooplankton 0.04 ppm DDT in water 0.000003 ppm, Or 3 ppt Figure 11-4 Page 231

Threshold Levels (231-232) Define Why do some chemicals have threshold and some do not? How does body deal with some toxins?

100 75 50 25 2 4 6 8 10 12 14 16 Percentage of population killed by a given dose Dose (hypothetical units) LD © 2004 Brooks/Cole – Thomson Learning Figure 11-5 Page 231

What is a Poison? Discuss LD50 Using animals to determine toxicity and LD50 Advantages Disadvantages Why use acute levels of exposure when humans generally exposed to chronic levels? Alternatives to animal testing

Toxicity Ratings and Average Lethal Doses Study and discuss Table 11-1 How is toxicity estimated (232)? Animal tests Alternatives: tissue and cel cultures Chick egg membranes

Dose-Response Curve Acute toxicity levels

© 2004 Brooks/Cole – Thomson Learning Nonlinear dose-response Nonlinear dose-response Linear dose-response Linear dose-response Effect Effect Threshold level Dose Dose Threshold – many carcinogens and teratogens No threshold Figure 11-6 Page 233

Hazardous Substances and Wastes Toxic or poisons Mutagenic Teratogenic Carcinogenic Harmful to immune, endocrine or nervous systems Examples of each of above

Other Hazardous Materials and Wastes (233 and 527) Flammable or explosive Reactive (with other substances) Corrosive To humans and materials

Regulation and testing of hazardous substances “Toxicologists know a great deal about a few chemicals, a little about many, and next to nothing about most.” Explain why this is the case Apply precautionary approach – relate directly to hazardous chemicals

Biological Hazards (236) Non-transmissible diseases Discuss those related to environmental issues Transmissible diseases Name pathogens Name vectors Relate several to environmental issues as discussed this year (241-242) Focus on malaria & relate to environmental issues

Risk Analysis Fig. 11-17 p. 247 Contrast to risk management – why is this more difficult than risk assessment?

© 2004 Brooks/Cole – Thomson Learning Risk probability Risk assessment Risk severity Acceptability of a Risk Is the risk acceptable? Expressed preferences Cost–benefit Acceptable if benefits outweigh costs Acceptable if people agree to accept the risks Natural standards Revealed preferences Acceptable if risk is not greater than those created by natural hazard Acceptable if risk is not greater than those currently tolerated Figure 11-16 Page 247

Figure 11-15 Page 246 Scientists (Not in rank order in each category) Citizens (In rank order) High-Risk Health Problems • Indoor air pollution • Outdoor air pollution • Worker exposure to industrial or farm chemicals • Pollutants in drinking water • Pesticide residues on food • Toxic chemicals in consumer products High-Risk Ecological Problems • Global climate change • Stratospheric ozone depletion • Wildlife habitat alteration and destruction • Species extinction and loss of biodiversity High-Risk Problems • Hazardous waste sites • Industrial water pollution • Occupational exposure to chemicals • Oil spills • Stratospheric ozone depletion • Nuclear power-plant accidents • Industrial accidents releasing pollutants • Radioactive wastes • Air pollution from factories • Leaking underground tanks Medium-Risk Problems • Coastal water contamination • Solid waste and litter • Pesticide risks to farm workers • Water pollution from sewage plants Medium-Risk Ecological Problems • Acid deposition • Pesticides • Airborne toxic chemicals • Toxic chemicals, nutrients, and sediment in surface waters Figure 11-15 Page 246 Low-Risk Ecological Problems • Oil spills • Groundwater pollution • Radioactive isotopes • Acid runoff to surface waters • Thermal pollution Low-Risk Problems • Air pollution from vehicles • Pesticide residues in foods • Global climate change • Drinking water contamination