Unit 9: Environmental Health and Toxicology Section 1: Risks and Hazards

Central Case Study: Poison in the Bottle Bisphenol A (BPA) – Used to make hard plastic found in utensils, baby bottles, laptops, toys, etc. Leaches into food, water, air, and human bodies 93% of Americans currently have it in their body Only a low dose required to have negative effects Linked to Cancer, nerve damage, and miscarriages Mimics the hormone estrogen Conflicting information regarding health risk Many countries banned use in baby bottles U.S. FDA rejected a ban on its use in 2012

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: (lifestyle choices) such as smoking, poor diet, unsafe sex, drugs, unsafe working conditions, and poverty.

BIOLOGICAL HAZARDS 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) Bacteria: single-celled, prokaryotic organisms Notable bacterial diseases: cholera, Tuberculosis, bubonic plague, anthrax, food poisoning, gonorrhea, strep throat, etc. Viruses: small, infectious agent that replicates itself using the living cells of other organisms Notable viral diseases: common cold, small pox, Ebola, influenza, rabies, measles, HIV, herpes

BIOLOGICAL HAZARDS Antibiotics used against bacteria (antivirals CAN work against viruses, but usually do not) Bacteria are developing genetic resistance to antibiotics We are starting to see “superbugs” in different bacterial species

Transmissible Disease Pathway for infectious disease in humans.

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.

The Growing Global Threat from Tuberculosis The highly infectious tuberculosis (TB) kills 1.7 million people per year and could kill 25 million people 2020. Recent increases in TB are due to: Lack of TB screening and control programs especially in developing countries due to expenses. Genetic resistance to the most effective antibiotics.

VIRAL DISEASES Flu, HIV, and hepatitis B viruses infect and kill many more people each year then highly publicized West Nile, SARS, and Ebola viruses. 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.

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. Concentrate on groups in a society that are likely to spread the disease. Provide free HIV testing and pressure people to get tested. Implement educational programs. Provide free or low-cost drugs to slow disease progress.

Malaria – Death by Mosquito Malaria kills about 2 million people per year Caused by parasitic protozoans Get into blood stream and cause cells to burst Major problem in tropical regions

Preparation for LD50 Lab – Friday Practice in performing a serial dilution

Pre Lab Definitions: (Fill these in on your lab paper) Serial: In a series, order or interval. Measured steps. Dilution: Water down Pipette: “Little pipe” for moving and measuring liquids. Serial dilutions reduce the concentration of a sample in small steps or fractions.

Lab: Fill in the instructions as we go along. Read each step carefully. 1. Label test tubes 1, 2, 3, 4.

Lab: Fill in the instructions as we go along. Read each step carefully. 1. Add 10 mL of water to test tube 1. 2. Add 3 drops of methylene blue to test tube 1. (mix) – use paper towel over mouth of tube as methylene blue WILL dye your skin 3. Transfer 1 mL of water from test tube 1 to test tube 2.

Lab: Fill in the instructions as we go along. Read each step carefully. 4. Add 9 mL of water 5. Pipette 1 mL of water from test tube 2 to test tube 3. 6. Add 9 mL of water 7. Pipette 1 mL of water from test tube 3 to test tube 4. 8. Add 9 mL of water

The Basics of Toxicology Toxicology – the science that examines effects of poisonous substances Toxicity – the degree of harm a substance can inflict Toxicant – poison; toxic substance Environmental toxicology – deals with toxic substances that come from or are discharged into the environment

CHEMICAL HAZARDS A hazardous chemical can harm humans or other animals because it: Is flammable Is explosive An irritant Interferes with oxygen uptake Induce allergic reactions.

Effects of Chemicals on the Immune, Nervous, and Endocrine Systems Long-term exposure to some chemicals at low doses may disrupt the body’s: Immune system: specialized cells and tissues that protect the body against disease and harmful substances. Nervous system: brain, spinal cord, and peripheral nerves. Endocrine system: complex network of glands that release hormones into the bloodstream; help regulate the body.

Dose-Response Studies LD50- lethal dose that kills 50% of the individuals ED50- effective dose that causes 50% of the animals to display the nonlethal effect

Synergistic Interactions Sometimes, when a person is exposed to more that one risk at a time, the risk can compound and become worse Ex: the health impact of a carcinogen such as asbestos can be much higher if an individual also smokes tobacco.

Case Study: A Black Day in Bhopal, India The world’s worst industrial accident occurred in 1984 at a pesticide plant in Bhopal, India. An explosion at Union Carbide pesticide plant in an underground storage tank released a large quantity of highly toxic methyl isocyanate (MIC) gas. 15,000-22,000 people died Indian officials claim that simple upgrades could have prevented the tragedy.

Stockholm Convention In 2001, a group of 127 nations gathered in Stockholm, Sweden, to reach an agreement on restricting the global use of some chemicals 12 chemicals were to be banned, phased out, or reduced These include DDT, PCBs, and certain chemicals that are by-products of manufacturing processes.

TOXICOLOGY: ASSESSING CHEMICAL HAZARDS Children are more susceptible to the effects of toxic substances because: Children breathe more air, drink more water, and eat more food per unit of body weight than adults. They are exposed to toxins when they put their fingers or other objects in their mouths. Children usually have less well-developed immune systems and detoxification processes than adults.

Cause of death Annual deaths 11 million (75) 5 million (34) Poverty/malnutrition/ disease cycle Tobacco 5 million (34) Pneumonia and flu 3.2 million (22) Air pollution 3 million (21) HIV/AIDS 3 million (21) Malaria 2 million (14) Diarrhea 1.9 million (13) Tuberculosis 1.7 million (12) Figure 18.13 Global outlook: number of deaths per year in the world from various causes. Numbers in parentheses give these deaths in terms of the number of fully loaded 400-passenger jumbo jets crashing every day of the year with no survivors. Because of sensational media coverage, most people have a distorted view of the largest annual causes of death. QUESTION: Which three of these items are most likely to shorten your life span? (Data from World Health Organization) Car accidents 1.2 million (8) Work-related injury & disease 1.1 million (8) Hepatitis B 1 million (7) Measles 800,000 (5)

Shortens average life span in the U.S. by 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 Figure 18.14 Global outlook: comparison of risks people face, expressed in terms of shorter average life span. After poverty and gender, the greatest risks people face come mostly from the lifestyle choices they make. These are merely generalized relative estimates. Individual responses to these risks can differ because of factors such as genetic variation, family medical history, emotional makeup, stress, and social ties and support. QUESTION: Which three of these items are most likely to shorten your life span? (Data from Bernard L. Cohen) 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 Lifetime near nuclear plant 10 hours