Chapter 18 Environmental Hazards and Human Health

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 Figure 18-2

Core Case Study: The Global HIV/AIDS Epidemic  The virus itself is not deadly, but it cripples the immune system, leaving the body susceptible to infections such as Kaposi’s sarcoma (above). Figure 18-1

What is a(n)  Epidemic – disease in a small area, i.e. Georgia, Midwest, United States  Pandemic – disease that is spreading through many continents around the world;

RISKS AND HAZARDS  RISKS – POSSIBILITY OF SUFFERING HARM FROM A HAZARD THAT CAN CAUSE ILLNESS, INJURY, DISEASE DEATH, ECONOMIC LOSS OR ENVIRONMENTAL DAMAGE.  RISK ASSESSMENT – SCIENTIFIC PROCESS OF ESTIMATING HOW MUCH HARM A PARTICULAR HAZARD CAN CAUSE TO HUMAN HEALTH OR THE ENVIRONMENT.

RISKS AND HAZARDS Biological hazards: from more than 1,400 pathogens. Biological hazards: from more than 1,400 pathogens. Chemical hazards: in air, water, soil, and food. Chemical hazards: in air, water, soil, and food. Physical hazards: such as fire, earthquake, volcanic eruption. Physical hazards: such as fire, earthquake, volcanic eruption. Cultural hazards: such as smoking, poor diet, unsafe sex, drugs, unsafe working conditions, and poverty. Cultural hazards: such as smoking, poor diet, unsafe sex, drugs, unsafe working conditions, and poverty.

BIOLOGICAL HAZARDS: DISEASE IN DEVELOPED AND DEVELOPING COUNTRIES  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

Transmissible Disease  WHO estimates that each year the world’s seven deadliest infections kill 13.6 million people – most of them the poor in developing countries. Figure 18-5

Case Study: Growing Germ Resistance to Antibiotics  Infectious bacteria are becoming genetically resistant to widely used antibiotics due to: Genetic resistance: Spread of bacteria around the globe by humans, overuse of pesticides which produce pesticide resistant insects that carry bacteria. 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. Overuse of antibiotics: A 2000 study found that half of the antibiotics used to treat humans were prescribed unnecessarily.

Case Study: The Growing Global Threat from Tuberculosis  The highly infectious tuberculosis (TB) kills 1.7 million people per year and could kill 25 million people  Recent increases in TB are due to: Lack of TB screening and control programs especially in developing countries due to expenses. Lack of TB screening and control programs especially in developing countries due to expenses. Genetic resistance to the most effective antibiotics. Genetic resistance to the most effective antibiotics.

Solutions to Tuberculosis  Early identification & treatment with active TB  Treatment with 4 inexpensive drugs cure up to 90% of individuals with active TB  Must be taken everyday for 6-8 months  Symptoms disappear after a few weeks, people stop taking the drugs allowing the  Disease to recur in drug-resistant forms and  Spread

Viral Diseases  Flu, HIV, and hepatitis B viruses infect and kill many more people each year than highly publicized West Nile and SARS viruses. The influenza virus is the biggest killer virus worldwide. The influenza virus is the biggest killer virus worldwide. Pigs, chickens, ducks, and geese are the major reservoirs of flu. As they move from one species to another, they can mutate and exchange genetic material with other viruses.Pigs, chickens, ducks, and geese are the major reservoirs of flu. As they move from one species to another, they can mutate and exchange genetic material with other viruses.

Viral Diseases  HIV is the second biggest killer virus worldwide. Five major priorities to slow the spread of the disease are: Quickly reduce the number of new infections to prevent further spread. Quickly reduce the number of new infections to prevent further spread. Concentrate on groups in a society that are likely to spread the disease. Concentrate on groups in a society that are likely to spread the disease. Provide free HIV testing and pressure people to get tested. Provide free HIV testing and pressure people to get tested. Implement educational programs. Implement educational programs. Provide free or low-cost drugs to slow disease progress. Provide free or low-cost drugs to slow disease progress.

Case Study: Malaria – Death by Mosquito  Malaria kills about 2 million people per year and has probably killed more than all of the wars ever fought. Figure 18-7

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

 Spraying insides of homes with low concentrations of the pesticide DDT greatly reduces the number of malaria cases. Under international treaty enacted in 2002, DDT is being phased out in developing countries. Under international treaty enacted in 2002, DDT is being phased out in developing countries. Case Study: Malaria – Death by Mosquito

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. 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. 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. Carcinogens are chemicals or types of radiation that can cause or promote cancer.

TOXICOLOGY Bioaccumulation – molecules stored in the body Biomagnification – moves up through food chains & increases concentration Acute effects – sudden Chronic effects – long-term Synergism – = 3

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

TOXICOLOGY: ASSESSING CHEMICAL HAZARDS  Factors determining the harm caused by exposure to a chemical include: The amount of exposure (dose). The amount of exposure (dose). The frequency of exposure. The frequency of exposure. The person who is exposed. The person who is exposed. The effectiveness of the body’s detoxification systems. The effectiveness of the body’s detoxification systems. One’s genetic makeup. One’s genetic makeup.

TOXICOLOGY: ASSESSING CHEMICAL HAZARDS  Typical variations in sensitivity to a toxic chemical within a population, mostly because of genetic variation. Figure 18-10

TOXICOLOGY: ASSESSING CHEMICAL HAZARDS  Under existing laws, most chemicals are considered innocent until proven guilty, and estimating their toxicity is difficult, uncertain, and expensive. Federal and state governments do not regulate about 99.5% of the commercially used chemicals in the U.S. Federal and state governments do not regulate about 99.5% of the commercially used chemicals in the U.S.

TOXICOLOGY: ASSESSING CHEMICAL HAZARDS  Precautionary principle – 1 st do no harm  Poison – any substance with an LD-50 of 50 mg or less /kg of body weight  LD50 – amount of a chemical received in 1 dose that kills 50% of the animals in a test population within 14-day period

Toxicity RatingLD50 (mg per kg of body weight) Average Lethal Dose Examples SupertoxicLess than 0.01Less than 1 dropNerve gases, botulism, mushroom toxins, dioxin Extremely ToxicLess than 5Less than 7 dropsK cyanide, heroin, atropine, parathion, nicotine Very Toxic5 – 507 drops to 1 teaspoon Mercury salts, morphine, codeine Toxic50 – 5001 teaspoon to 1 ounce Lead salts, DDT, NaOH, H2SO4, caffeine, CCl4 Moderately Toxic500 – 5,0001 ounce to 1 pintMethyl alcohol, ether, amphetamines Slightly toxic5000 – 15,0001 pint to 1 quartEthanol, lysol, soaps

Dose-Response Curves  Show effects of various dosages of a toxic agent  Threshold dose – takes minimum amount before damage is seen  Non-threshold dose – any dosage causes harm that increases with dosage

PCB’s  Most widespread toxin – stable  Used as cooling liquid in transformers, capacitors, hydraulic fluids, adhesives, paints, dirt road surfaces  Causes liver problems, miscarriages, low birth weight, cancer, endocrine disruption  Often in fatty parts of fish (fat-soluble)

Dioxins  Formed as by-product of herbicides, germ- killer (hexachlorophene), burning compounds with chlorine, Agent Orange  Source for humans = meat, eggs  Interferes with immunity; is a carcinogen; causes hormonal disruption (thyroid), nervous system,  Causes muscle aches and pains

Asbestos  From brake linings, fire-retardants, siding, floors  Causes: asbestosis, asbestosis, mesothelioma, mesothelioma, GI cancer GI cancer

Lead  From paints, metals, soldering  Interferes with blood cell formation,  Causes kidney damage, sterility, miscarriages, birth defects, and CNS damage

Mercury  Sources: Elemental (naturally occurring) Elemental (naturally occurring) Coal burning power plants Coal burning power plants Mercury using industries Mercury using industries  Problems with speech, swallowing, walking, deafness, vision, destroys cells, convulsions

RISK ANALYSIS  Estimating risks from using many technologies is difficult due to unpredictability of human behavior, chance, and sabotage.  Reliability of a system is multiplicative: If a nuclear power plant is 95% reliable and human reliability is 75%, then the overall reliability is (0.95 X 0.75 = 0.71) 71%. If a nuclear power plant is 95% reliable and human reliability is 75%, then the overall reliability is (0.95 X 0.75 = 0.71) 71%.

RISK ANALYSIS  Annual deaths in the U.S. from tobacco use and other causes in Figure 18-A

RISK ANALYSIS  Number of deaths per year in the world from various causes. Parentheses show deaths in terms of the number of fully loaded 400-passenger jumbo jets crashing every day of the year with no survivors. Figure 18-13

RISK ANALYSIS  Comparisons of risks people face expressed in terms of shorter average life span. Figure 18-14