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This chapter explores the various factors that pose risks to human health, including physical factors like natural disasters and radiation, biological factors like infectious diseases, and chemical factors like arsenic and synthetic chemicals. It also discusses the impact of certain diseases, such as tuberculosis, malaria, and the bubonic plague, and highlights the emergence of new infectious diseases. Additionally, it delves into toxicology and the study of chemical risks, as well as the determinants of health effects and the importance of retrospective studies. The chapter concludes by discussing specific incidents, like the Bhopal gas tragedy and the Chernobyl nuclear accident, and how children are more susceptible to chemical exposure.
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Chapter 17Human Health and Environmental Risks
Human Health Risk Factors (1) Physical • Natural disasters, UV exposure, radiation (2) Biological • Infectious diseases (3) Chemical • Arsenic, PCB’s, synthetic chemicals & pesticides
Disease • Infectious Diseases: Caused by Pathogens • Pathogens=vectors; viruses, bacteria, fungi, protists • Tuberculosis, Influenza, Bubonic Plague, HIV • Non-infectious Diseases: Genetic, Environmental, Dietary or a Combination • Cancer, Cardiovascular Diseases, Respiratory, and Digestive Diseases
Six illnesses account for 94% of all infectious-disease-related deaths • Respiratory infections (pneumonia) • Auto Immune Deficiency Syndrome (AIDS) • Diarrhea • Tuberculosis • Malaria • Childhood diseases (measles/tetanus)
Infectious Diseases Have Killed Large Numbers of People • Epidemic: when a pathogen causes a rapid increase in disease. • Pandemic: when an epidemic occurs over a large geographic region such as a continent.
Plague • Bubonic plague/Black Death • Bacteria carried by fleas. • Swollen glands, black spots, and extreme pain. • Estimated to have killed hundreds of millions of people; 30-50% of the European population in the 1300s.
Malaria • Infection caused by an infection from one of the several species of the protist Plasmodium. • One stage of the life cycle in the human, the other in the mosquito. • Causes recurrent flulike symptoms. • Sub-Sahara Africa, Asia, the Middle East, and Central and South America are hit the hardest.
Tuberculosis: • Highly contagious disease caused by a bacterium that infects the lungs. • Spread when a person coughs and expels the bacteria into the air. • Weakness, night sweats, and coughing up blood. • Can be infected but not develop the disease. • 9 million develop the disease and 2 million die. • Treated with antibiotics.
Emergent Infectious Diseases • Infectious diseases that were previously not described or have not been common for at least the prior 20 years. • Many can pass from animals to humans. • Of particular concern because of the rapid movement of people and cargo.
Emergent Infectious Diseases • HIV/AIDS • Ebola • Mad Cow Disease • Bird Flu • West Nile Virus
Toxicology is the Study of Chemical Risks • Humans have developed many different chemicals. • Some are very helpful while others are often harmful by-products from industry. • Some of the chemicals we have developed seemed helpful but are found to be harmful
Determining the Health Effects of Pollutants • Acute toxicity- adverse effects of a substance that result either from a single exposure or from multiple exposures in a short period of time (usually less than 24 hours). • Chronic toxicity is the development of adverse effects as the result of long term exposure to a toxicant or other stressor.
Synergistic interactions- when two risks come together and cause more harm that one would. • For example, the health impact of a carcinogen such as asbestos can be much higher if an individual also smokes tobacco.
Retrospective Studies • Look backwards and examine exposures to suspected risk or protection factors in relation to an outcome that is established at the start of the study. • Done in response to an unexpected or random outcome to an event
In 1984, a chemical spill in Bhopal Indiarelease of methyl isocyanate gas killed and injured thousands of people. Retrospective study found the survivors had long term hearth effects. • Monitor people who have been exposed to a chemical at some point in the past
Agent Orange • A defoliant used to strip the trees of leaves in the jungles of Vietnam-contained Dioxin • Later proven to cause serious health issues -cancer, birth defects, severe psychological problems- among the Vietnamese people as well as returning U.S. servicemen and their families. • Caused mutations to DNA that led to neurological problems in successive generations
Children and Chemical Exposure • Children more susceptible to chemicals: • Weigh less than adults • Bodies are still developing • Play on floors and lawns • Exposed to cleaning products and pesticides • Put things into their mouths
Factors determining Concentrations in Organisms (1) Route of Exposure
(2) Solubility, Bioaccumulation, Biomagnification • Water-v-fat soluble • Oil soluble chemicals stored in fatty tissues • Ex: mercury, DDT, PCB’s • DDT in birds that eat fish is 8 million times that found in water
Risk Analysis: Assess, Accept and Manage Risk Environmental Hazard: anything in our environment that potentially causes harm. Examples: smoking, volcanoes, draining swamps, air pollution.
Risk Acceptance • The level of risk that can be tolerated. • Difficult part of management. • No amount of information on the extent of the risk will overcome the conflict between those who are willing to live with some amount of risk and those who are not!
Risk Management • Integrates the scientific data in addition to the analysis of acceptable levels of risk with economic, social, ethical, and political issues. • Worldwide Standards of Risk
United States European Union
