ENV200 Chapter 8 Notes

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School of Environment
Romila Verma

CHAPTER 8 – ENVIRONMENTAL HEALTH AND TOXICOLOGY [8.1] ENVIRONMENTAL HEALTH ­ Health = a state of complete physical, mental, and social well-being, not merely the absence of disease ­ Disease = an abnormal change in the body's condition that impairs physical or psychological functions ­ Morbidity = illness ­ Mortality = death ­ Environmental health = concerned with all aspects of the natural, social, cultural, and technological environments that cause disease Global disease burden is changing ­ Health organizations used to focus on the leading causes of death as the best indicator of world health o Mortality data fail to capture the impacts of non-fatal outcomes of disease and injury on human well-being ­ Health agencies now calculate disability-adjusted life years (DALYs) as a measure of disease burden o Disability-adjusted life years (DALYs) = premature deaths and loss of a healthy life resulting from illness or disability  To evaluate the total cost of disease, not just the number of deaths ­ Chronic diseases (e.g., CVD, cancer) will become the leading causes of the global disease burden o No longer afflict only wealthy people o Rapidly becoming the leading causes of disability and premature death worldwide, especially in developing countries  People in poorer countries are adopting the lifestyles and diet of richer countries ­ Communicable diseases (e.g., smallpox, polio, malaria) are being progressively being eliminated ­ Mental health conditions (e.g., depression) could increase ­ Chronic obstructive lung diseases (e.g., emphysema, asthma, lung cancer) are expected to increase o Tobacco is expected to the biggest single cause of death worldwide o Tobacco epidemic = the rising use of tobacco in developing countries o Tobacco-control convention = countries are required to impose restrictions on tobacco advertising, establish clean indoor air controls, and clamp down on tobacco smuggling ­ Obesity epidemic is growing o Poor diet and lack of exercise are the second leading underlying cause of death in America Emergent and infectious diseases still kill millions of people ­ Communicable diseases (e.g., diarrhea, acute respiratory illnesses, malaria, measles, tetanus) are responsible for about one-third of all disease-related mortality o Better nutrition, clean water, improved sanitation, and inexpensive inoculations could eliminate deaths ­ Pathogens = disease-causing organisms (e.g., viruses, bacteria, protozoans, parasitic worms, flukes) o Influenza = a family of viruses that mutate rapidly and move from wild/domestic animals to humans  The influenza pandemic (1918) was the greatest loss of life from an individual disease in a single year o Bacteria and intestinal protozoa cause foodborne illnesses and spread from feces through food and water o Malaria is one of the most prevalent remaining infectious diseases  Global climate change allows mosquito vectors to move into new territory  Insecticide-treated bed nets anti-malarial pills would prevent millions of new cases ­ Emergent diseases = diseases that are not previously known or that have absent for at least 20 years  E.g., H1N1, Ebola fever, Marburg fever, cholera, new drug-resistant form of tuberculosis, dengue fever, new human lymphotropic virus (HTLV) o Growing human populations push people into remote areas where they encounter diseases that may have existed for a long time but only now are exposed to humans o Rapid international travel makes it possible for new diseases to spread around the world  West Nile virus = a family of mosquito-transmitted viruses that causes encephalitis th  HIV/AIDS = 5 greatest cause of contagious deaths Conservation medicine combines ecology and health care ­ Ecological diseases = domestic animals and wildlife that experience sudden and widespread epidemics ­ Conservation medicine = attempts to understand how our environmental changes threaten our own health as well as that of the natural communities on which we depend for ecological services ­ Climate change facilitates the expansion of parasites and diseases into new territories o Tropical diseases (e.g., malaria, cholera, yellow fever, dengue fever) are spreading as mosquitoes, rodents, and other vectors expand into new habitats o Global warming causes higher sea temperatures at higher latitudes Resistance to antibiotics and pesticides is increasing ­ Methicillin-resistant Staphylococcus aureus (MRSA) o Common cause of sore throats and skin infections o Resistant to penicillin and antibiotic treatment o Can cause deadly infections, especially in people with weak immune systems o Most frequent in hospitals, nursing homes, correctional facilities, and other places o Spread through direct skin contact ­ Why have vectors (e.g., mosquitoes) and pathogens (e.g., bacteria, malaria parasite) become resistant to pesticides and antibiotics? o Ability of many organisms to evolve rapidly by natural selection o Human tendency to use control measures carelessly o Raising huge numbers of cattle, hogs, and poultry in densely packed barns and feedlots  Confined animals are dosed constantly with antibiotics and steroid hormones to keep them disease-free and to make them gain weight faster  These antibiotics and hormones are excreted in urine and feces, which then spread on the land or discharge into surface water Who should pay for health care? ­ Poor people o Carry the heaviest burden of illness o Cannot afford a healthy environment nor adequate health care ­ 10/90 gap = 90% of all disease burden occurs in developing countries, but less than 10% of all health care dollars is spent in developing countries ­ Disease is a cause and a consequence of poverty and political unrest o More charities in wealthy countries need to help eradicate diseases in developing countries o Reducing disease burden in developing countries will:  Increase world economy  Reduce population growth  Enable wealthy countries to live in a world less endangered by mass social instability, the spread of pathogens, terrorism, and drug trafficking [8.2] TOXICOLOGY ­ Toxic = poisonous ­ Toxicology = th
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