Apes Ch 11 Risk Toxicology and Human Healthy

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

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

Risk Assessment n How is risk (probability) determined?

Risk Assessment n Three components (229) n Contrast biological, physical, and chemical hazards n 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 n What factors determine whether a chemical is harmful? n Are all people at equal risk for a given dose and time of exposure? – Explain your answer n Should the regulatory levels be set for “average” sensitivity or most sensitive – Discuss pros of cons of each approach

Figure 11 -3 Page 230 Number of individuals affected © 2004 Brooks/Cole – Thomson Learning Very sensitive 0 Majority of population 20 40 Dose (hypothetical units) Very insensitive 60 80

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

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

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) n Define n Why do some chemicals have threshold and some do not? n How does body deal with some toxins?

© 2004 Brooks/Cole – Thomson Learning Percentage of population killed by a given dose 100 75 50 25 LD 0 2 4 6 8 50 10 12 Dose (hypothetical units) 14 16 Figure 11 -5 Page 231

What is a Poison? n Discuss LD 50 n Using animals to determine toxicity and LD 50 – 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 n Study and discuss Table 11 -1 n How is toxicity estimated (232)? – Animal tests – Alternatives: tissue and cel cultures – Chick egg membranes

Dose-Response Curve n Acute toxicity levels

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

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

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

Regulation and testing of hazardous substances n “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 n Apply precautionary approach – relate directly to hazardous chemicals

Biological Hazards (236) n Non-transmissible diseases – Discuss those related to environmental issues n 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 n. Contrast to risk management – why is this more difficult than risk assessment? Fig. 11 -17 p. 247

Risk probability Acceptability of a Risk assessment 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 Figure 11 -16 Page 247 © 2004 Brooks/Cole – Thomson Learning Risk severity Acceptable if risk is not greater than those currently tolerated

Scientists (Not in rank order in each category) 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 Citizens (In rank order) 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 Ecological Problems • Acid deposition • Pesticides • Airborne toxic chemicals • Toxic chemicals, nutrients, and sediment in surface waters Medium-Risk Problems • Coastal water contamination • Solid waste and litter • Pesticide risks to farm workers • Water pollution from sewage plants 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 Figure 11 -15 Page 246