CHAPTER 18 Environmental Hazards and Human Health By Brittney Jones
What types of hazards do people face? • We can suffer from -biological hazards: from more than 1,400 pathogens than can infect people (bacteria, viruses, parasites, protozoa and fungi) -chemical hazards: from chemicals in air, water, soil, and food -physical hazards: fires, earthquakes, volcanic eruption, flood, tornado, and hurricane -cultural hazards: smoking, unsafe working conditions, poor diet, drugs, drinking etc.
What types of disease (biological hazards) threaten people in developing and developed countries? • Rapid producing infectious bacteria are becoming genetically resistant to widely used antibiotics • Tuberculosis kills 1.7 million people per year and could kill 25 million more people by 2020 • The worlds three most widespread and dangerous viruses are influenza (biggest killer), HIV, and hepatitis B • Malaria kills about 2 million people a year
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
infectious bacteria are becoming genetically resistant to widely used antibiotics • Genetic resistance: Spread of bacteria around the globe by humans, overuse of pesticides which produce pesticide resistant insects that carry bacteria. • Overuse of antibiotics: A 2000 study found that half of the antibiotics used to treat humans were prescribed unnecessarily.
What chemical hazards do people face? • Toxic chemicalcan cause temporary or permanent harm or death to humans or animals • Hazardous chemicalharms human or animals because its flammable or explosive so it can irritate or damage skin and lungs • mutagens are chemicals or forms of radiation that cause harm or birth defects to fetus or embryo (ethyl alcohol, chlorine, PCB’s, tobacco smoke, etc.) • Carcinogens are chemicals that cause cancer(chromium, PCB’s, benzene, etc) • Long term exposure to some chemicals at low doses may disrupt the body’s immune, nervous and endocrine systems.
How can risks be estimated ad recognized? • Scientists have developed ways to evaluate and compare risks, decide how much risk and acceptable and find affordable ways to reduce it • Risk assessment: involves deciding whether or how to reduce a particular risk to a certain level and at what cost • Risk analysis: involves identifying hazards and evaluate their associating risks, ranking risks, determining options and making decisions about reducing or eliminating risks and informing decision makers and public about the risks. • Estimating risks from using many technologies is difficult because of the unpredictability of human behavior, chance and sabotage.
EXTRA VOCAB • Risk: the possibility of suffering harm from a hazard that can cause injury, disease, death, economic loss or environmental damage. • Non-transmissible disease: not caused by living organisms and does not spread from one person to another • Transmissible disease: an infection, pathogen, virus, or parasite invades the body and multiplies in its cells and tissues • Toxicology: the science that examines the effects of harmful chemicals on humans, wildlife, and ecosystems • Toxicity: a measure of how harmful a substance is in causing injury, illness, or death to a living organism