Risk, Toxicology, and Human Health G. Tyler Miller, Jr.’s Environmental Science 10 th Edition Chapter 10 G. Tyler Miller, Jr.’s Environmental Science 10 th Edition Chapter 10

Key Concepts  Types of hazards people face  Defining toxicology and measuring toxicity  Types and measurement of chemical hazards  Types of biological hazards (diseases)  Risk estimation, management, and reduction

The Big Killer  Tobacco  Health hazards  Nicotine Fig. 10-1, p. 203  Costs of smoking  Antismoking programs

Risk and Probability  Risk  Probability  Risk assessment  Risk management Fig. 10-2, p. 204

Major Types of Hazards  Cultural  Chemical  Physical  Biological Fig p. 409

Toxicology  Toxicity  Dosage  Bioaccumulation  Biomagnification  Synergism  Response  Acute effect  Chronic effect

© 2004 Brooks/Cole – Thomson Learning Very sensitive Majority of population Very insensitive Dose (hypothetical units) Number of individuals affected Fig. 10-3, p. 205 Variations in Sensitivity to a Toxin within a Population

Bioaccumulation and Biomagnification Fig. 10-4, p. 205

Concerns about Trace Levels of Toxic Chemicals  Concentration determines toxicity  “Dose makes the poison”  Tolerance varies with individuals  Natural isn’t always safe  Synthetic isn’t always bad  Analytical methods are improving

Poisons  Poison  Median lethal dose (LD 50 ) Also see Table 10-1, p. 207 Fig. 10-5, p. 206

Estimating Toxicity  Case reports  Epidemiological studies  Laboratory animals  Animal welfare controversies  Dose-response curves  Reliability of toxicity estimates

Dose-Response Curves  Dose-response  Nonthreshold  Threshold Fig p. 207

Chemical Hazards  Hazardous chemicals  Mutagens  Teratogens  Carcinogens  Metastasis  Effects on immune, nervous and endocrine systems  Hormonally active agents

Hormone Receptor Cell Normal Hormone ProcessHormone MimicHormone Blocker Estrogen-like chemicalAntiandrogen chemical Fig. 10-7, p. 209 Hormonally Active Agents

Biological Hazards: Diseases  Nontransmissible disease  Transmissible disease  Pathogens (bacteria and viruses)  Epidemiological transition  Tuberculosis  HIV/AIDS (viral)  Malaria

Viruses HIV (AIDS) Hepatitis B Smallpox Ebola On this scale, a human hair would be 6 meters (20 feet) wide 1 micrometer Bacteria Vibrio cholerae (cholera) Myobacterium tuberculosis (tuberculosis) Treponema pallidum (syphilis) 6 micrometers Protozoa Plasmodium (malaria) 10 micrometers Fig. 10-8, p. 210 Pathogens

Genetic material Surface proteins Fig. 10-9a, p. 211 Typical Virus

The viral genetic material uses the host cell's DNA to replicate again and again. Each new copy of the virus directs the cell to make it a protein shell. The new viruses emerge from the host cell capable of infecting other cells. This process often destroys the first cell. The virus attaches to the host cell. The entire virus may enter or it may inject its genetic material, or genome. Virus Cell membrane Host cell Fig. 10-9b, p. 211 How a Virus Reproduces

Measles (virus) Deaths per year Pneumonia and flu (bacteria and viruses) Disease (type of agent) HIV/AIDS (virus) Diarrheal diseases (bacteria and viruses) Tuberculosis (bacteria) Malaria (protozoa) Hepatitis B (virus) 3.2 million 3.0 million 1.9 million 1.7 million 1 million 800,000 Fig , p. 211 World’s Deadliest Infectious Diseases

Deaths per 100,000 people < Fig , p. 212 Current Tuberculosis Epidemic

Malaria-free areasMalaria largely eliminatedMalaria transmission areas Fig , p. 214 World Distribution of Malaria

Anopheles mosquito (vector) in aquatic breeding area 1. Female mosquito bites infected human, ingesting blood that contains Plasmodium gametocytes 4. Parasite invades blood cells, causing malaria and making infected person a new reservoir 3. Mosquito injects Plasmodium sporozoites into human host 2. Plasmodium develops in mosquito eggs larva pupa adult Fig , p. 214 Life Cycle of Malaria

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 Careful hand washing by all medical personnel Immunize children against major viral diseases Oral rehydration for diarrhea victims Global campaign to reduce HIV/AIDS Fig , p. 215 Ways to Prevent or Reduce Infectious Diseases

Risk Analysis  Risk analysis  Risk assessment  Comparative risk analysis  Risk management  Risk communication

Fig , p. 216 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 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 Comparative Risk Analysis

© 2004 Brooks/Cole – Thomson Learning Poverty/malnutrition/ disease cycle 10 million (68) Tobacco Pneumonia and flu Air pollution AIDS Diarrhea TB Malaria Work-related injury and disease Hepatitis B Automobile accidents Measles Airline crashes 4 million (27) 3.9 million (27) 3 million (21) 2.1 million (14) 1.6 million (11) 1.1 million (8) 1 million (7) 885,000 (6) 800,000 (5) 1,126 (0.008) Fig , p. 217 Greatest Risks to Humans

© 2004 Brooks/Cole – Thomson Learning Hazard Shortens average life span in the United States by 7-10 years Poverty Born male Smoking Overweight (35%) Unmarried Overweight (15%) Spouse smoking Driving Air pollution Alcohol Drug abuse AIDS Drowning Pesticides Fire Natural radiation Medical X rays Oral contraceptives Toxic waste Flying Hurricanes, tornadoes Living lifetime near nuclear plant 7.5 years 6 years 5 years 2 years 1 year 7 months 5 months 4 months 3 months 2 months 1 month 8 days 5 days 4 days 1 day 10 hours Flu Air Pollution 6 years 5 months 1 month Fig , p. 218 Risk Comparisons Expressed in Shorter Average Life Span

Estimating Risks with Technological Systems System reliability (%) = Technology reliability × Human reliability  Difficulties in estimating reliabilities  Possible to achieve high reliability  “To err is human”  Automated control systems

Perceiving Risks  Often poorly perceived by citizens  Distortions from the media and accidents  Distrust of the new  Underestimating risks with the familiar  Risks perceived as involuntary  Risks viewed as unnecessary  “Unfair” distribution of risks  Better education of public on risk needed