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Explore the different types of hazards and diseases that people face, including biological and chemical hazards. Learn how risks are estimated and recognized, and the effects of chemicals on human health. Discover the importance of toxicology in assessing chemical hazards and understanding the impacts of exposure.
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Chapter 11 Risk, Toxicology, and Human Health
Chapter Overview Questions • What types of hazards do people face? • What types of disease (biological hazards) threaten people in developing countries and developed countries? • What chemical hazards do people face? • How can risks be estimated and recognized?
RISKS AND HAZARDS • Risk is a measure of the likelihood that you will suffer harm from a hazard. • We can suffer from: • Biological hazards: from more than 1,400 pathogens. • Chemical hazards: in air, water, soil, and food. • Physical hazards: such as fire, earthquake, volcanic eruption… • Cultural hazards: such as smoking, poor diet, unsafe sex, drugs, unsafe working conditions, and poverty.
Effects of Chemicals on the Immune, Nervous, and Endocrine Systems • Molecules of certain synthetic chemicals have shapes similar to those of natural hormones and can adversely affect the endocrine system. Figure 18-9
CHEMICAL HAZARDS • A toxic chemical can cause temporary or permanent harm or death. • Mutagens are chemicals or forms of radiation that cause or increase the frequency of mutations in DNA. • Teratogens are chemicals that cause harm or birth defects to a fetus or embryo. • Carcinogens are chemicals or types of radiation that can cause or promote cancer.
TOXICOLOGY: ASSESSING CHEMICAL HAZARDS • Under existing laws, most chemicals are considered innocent until proven guilty. • Federal and state governments do not regulate about 99.5% of the commercially used chemicals in the U.S.
TOXICOLOGY: ASSESSING CHEMICAL HAZARDS • Some scientists abide by the Precautionary Principle • Manufacturers contend that following the Precautionary Principle is too expensive.
BIOLOGICAL HAZARD: DISEASE • Diseases not caused by living organisms cannot spread from one person to another (nontransmissible disease), while those caused by living organisms such as bacteria and viruses can spread from person to person (transmissible or infectious)
Transmissible Disease • Pathway for infectious disease in humans. Figure 18-4
Lyme Disease Risk Chapter 20 Section 2 Biological Hazards
Disease (type of agent) Deaths per year Pneumonia and flu (bacteria and viruses) 3.2 million HIV/AIDS (virus) 3.0 million Malaria (protozoa) 2.0 million Diarrheal diseases (bacteria and viruses) 1.9 million Tuberculosis (bacteria) 1.7 million Hepatitis B (virus) 1 million Measles (virus) 800,000 Fig. 18-5, p. 420
Case Study: Malaria – Death by Mosquito • Economists estimate that spending $2-3 billion on malaria treatment may save more than 1 million lives per year. Figure 18-6
A Model of Increase in Malaria Risk Due to Climate Change Chapter 20 Section 2 Biological Hazards
Core Case Study: The Global HIV/AIDS Epidemic • AIDS has reduced the life expectancy of sub-Saharan Africa from 62 to 47 years – 40 years in the seven countries most severely affected by AIDS. Projected age structure of Botswana's population in 2020. Figure 18-2
Water pollutant levels Air pollutant levels Soil/dust levels Food pesticide levels Nutritional health ? Mathematical measurements & modeling Overall health Lifestyle Predicted level of toxicant in people Personal habits Metabolism Genetic predisposition Accumulation Excretion Lung, intestine & skin absorption rates Fig. 18-11, p. 431
An increasing dose has a greater effect Dose-Response Curve
Number of individuals affected Majority of population Very sensitive Very insensitive Dose (hypothetical units) Fig. 18-10, p. 430
RISK ANALYSIS • Annual deaths in the U.S. from tobacco use and other causes in 2003. Figure 18-A
Hazard Shortens average life span in the U.S. by Poverty 7–10 years Born male 7.5 years Smoking 6–10 years Overweight (35%) 6 years Unmarried 5 years Overweight (15%) 2 years Spouse smoking 1 year Driving 7 months Air pollution 5 months Alcohol 5 months Drug abuse 4 months Flu 4 months AIDS 3 months Drowning 1 month Pesticides 1 month Fire 1 month Natural radiation 8 days Medical X rays 5 days Oral contraceptives 5 days Toxic waste 4 days Flying 1 day Hurricanes, tornadoes 1 day 10 hours Lifetime near nuclear plant Fig. 18-14, p. 436
Epidemiology: • Is the scientific study of the geography of disease. For example, mercury poisoning in Virginia.
Bioaccumulation – the increasing concentration of a toxin in an organisms body over its lifetime.
Perceiving Risk • Most individuals evaluate the relative risk they face based on: • Degree of control. • Fear of unknown. • Whether we voluntarily take the risk. • Whether risk is catastrophic. • Unfair distribution of risk.
TOXICOLOGY: ASSESSING CHEMICAL HAZARDS • Factors determining the harm caused by exposure to a chemical include: • The amount of exposure (dose). • The frequency of exposure. • The person who is exposed. • The effectiveness of the body’s detoxification systems. • One’s genetic makeup.
Toxicity: How Dangerous Is It? • Almost any chemical be harmful if taken in, or ingested, in large enough amounts. • A dose is the amount of a harmful substance to which a person is exposed. • The damage to health from exposure to a given dose is the response.
