CHAPTER 14: Risk, Human Health, and Toxicology

1. CHAPTER 14: Risk, Human Health, and Toxicology Alyssa Dunne, Jake Hartman, Kenny Thompson

2. Case Study: The Big Killer • A cigarette kills about 13,700 people everyday, or one person every 6 seconds. (440,000 Americans per year, 1,205 premature deaths a day.) • Cigarette smoking is the world’s most preventable major cause of suffering and premature death among adults. • The WHO, World Health Organization, estimates tobacco use contributes to at least 5 million premature deaths . • 34 illnesses that result from the tobacco use is the cause in these deaths. (heart disease, lung cancer, other cancers, bronchitis, and stroke)

3. Case Study Continued… • Nicotine in tobacco is addictive • Only 1 in 10 people who try to quit smoking succeed and relapse rate is high. • Suggestions to fix issue: • Health experts urge a federal tax of $3-5 on cigarette packs • Banning all cigarette advertising • Prohibiting sale of cigarettes and other tobacco products to anyone under the age of 21. • Banning cigarette vending machines.

4. 14-1. Risks and Hazards • Risk is the possibility of suffering harm from a hazard that can cause injury, disease, death, economic loss, or environmental damage. (expressed in terms of probability, an estimate of likelihood an event will occur.) • Risk Assessment – the scientific process of estimating how much harm a particular hazard can cause to human health. • Risk Management – deciding how to reduce a particular risk to a certain level at what cost.

5. Types of Hazards • Cultural hazards – include smoking, unsafe working conditions, poor diet, drugs, drinking, driving, criminal assault, unsafe sex, and poverty. • Biological hazards – from pathogens ( bacteria, viruses, and parasites) that cause infectious disease. • Chemical hazards – from harmful chemicals in the air, water, soil and food. • Physical hazards – include fire, earthquake, volcanic eruption, flood, tornado, and hurricane.

6. 14-2. Biological Hazards: disease in Developed and Developing Countries • ** Transmissible Disease • Stems from an infection, a pathogen in the form of bacterium, virus, or parasite invades your body and multiplies in its cells and tissues. • Spread from person to person by air, water, food, and bodily fluids. **Nontransmissible disease • not cause by living organisms • Does not spread from person to person • Tend to develop slowly Ex. Cardiovascular disease, asthma

7. Case Study: Growing Germ Resistance to Antibiotics • Infectious bacteria have high reproductive rate • Allows for natural selection • Therefore become genetically resistant to an increasing number of antibiotics. Other factors that create Resistance- -spread of bacteria around the globe -overuse of pesticides -overuse of antibiotics by doctors

8. Case Study: The Growing Global Threat from Tuberculosis • Disease strikes 9 million people per year • Kills 1.7 million of them-about 84% of the deaths in developing countries Spread Increase is due to: -lack of TB screening -Tb bacterium have developed genetic resistance -pop. Growth and urbanization

9. Viral Diseases World’s 3 most widespread and dangerous viruses • HIV (human immunodeficiency virus) • Flu (influenza) • Hepatitis B Virus (HBV) *AIDS (acquired immune deficiency syndrome), caused by infections with HIV. One of the world’s most serious and rapidly growing health threats.

10. Malaria – kills about 3 million people per year -caused by a parasite that is spread by the bites of certain mosquito species

11. Solutions: Reducing the Incidence of Infectious Disease • Increase research • Reduce poverty • Decrease malnutrition • Improve quality of drinking water • Reduce unnecessary use of antibiotics • Educate • Careful hand washing by medical personnel • Immunize children • Global campaign to reduce HIV/AIDS

12. Bioterrorism • Bioterrorism involves releasing infectious organisms into the air, water supply, or food supply and is a growing threat • It is deliberate and it’s purpose is to harm a group of people through biological means • These technologies have been cultivated since the end of World War II

13. Chemical Hazards • A toxic chemical can cause temporary or permanent harm or death to living organisms • A hazardous chemical can harm organisms due to its flammability or explosive qualities or because it can interfere with regular bodily functions • Mutagens are chemicals or radiation that cause or increase frequency of mutations. • Teratogens are chemicals that can cause birth defects to a fetus or embryo • Carcinogens are chemicals or radiation that promote cancer • Cancerous tumors then spread through metastasis, where parts of the tumor break off and spread to other parts of the body

14. 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, nervous, and endocrine systems • Neurotoxins are chemicals that can harm the human nervous system • They will disrupt the messages being passed throughout the body and cause behavioral changes, paralysis, and death • The endocrine system is responsible for regulating hormones and these levels can be effected by harmful chemicals

15. Assessing Chemical Hazards • Toxicity is a measure of how harmful a substance is in causing injury, illness, or death to a living organism and depends on many factors: • Dose-the amount of a substance the person has taken in • Genetic makeup- determines sensitivity to the toxin • 5 major factors that can affect the harm of a substance: • 1. Solubility- water soluble toxins can move through the environment and get into aqueous solutions that surround the cells in our bodies • -fat soluble toxins can penetrate the membranes surrounding cells which means they can accumulate in body tissues and cells • 2. Persistence-some chemicals are longer lasting than others and will therefore cause more damage over the longer span that they can survive • 3. Bioaccumulation- when molecules are stored in organs or tissues at higher than normal levels, the levels build up until they are harmful • 4. Biomagnification-toxicity increases because the toxin’s presence is magnified as it goes through the food chain • 5. Chemical interactions-other chemicals in the body will interact with the harmful chemicals and will either deter or promote their negative effects • -antagonistic interaction will reduce harmful effects • -synergistic interaction multiplies harmful effects

16. Assessing Chemical Hazards • An acute effect is a rapid harmful reaction to an exposure • A chronic effect is a long lasting consequence to an exposure • A basic concept of toxicology is that any chemical can be harmful if taken in in a large enough quantity. • Bodies have 3 major mechanisms for reducing harmful effects of some chemicals • 1. Break down, dilute, or excrete toxins to keep them at suitable levels • 2. Cells have enzymes that can repair damage • 3. Some cells can reproduce fast enough to replace damaged cells

17. Estimating the Toxicity of a Chemical • One method for determining the relative toxicity is to measure their effects on test animals • The lethal dose (LD50) is the amount received that kills 50% of the animals receiving that dose • Chemicals vary widely in toxicity

18. Using Laboratory Experiments to Estimate Toxicity • To get data on toxicity, live organisms are experimented with and many experience death in the name of science • There are arguments as to whether this is ethical or not but when scientists are not allowed to go through with full experiments, they must extrapolate data which decreases the validity of the experiments

19. Protecting Children from Toxic Chemicals • Children are more at risk than adults • 1. They breathe more air, drink more water, and eat more food per unit of body weight than adults • 2. They can come into contact with toxins through touching or putting their mouths on things which kids often do without thinking • 3. Reactionary responses to the toxins are weaker in children than adults • It is assumed that the risk of harm from toxins for children is 100 times that of adults.

20. Why do we know so little about the harmful effects of chemicals? • It is hard to assess the toxicity of many chemicals especially because different people can have such varying experiences with them and due to the combination effect, it is even harder • It is also very hard to do research on things that cause harm because in doing so you must cause harm • There is much controversy over this which impedes the scientific process of discovering things about toxicity • Only 10% of 80,000+ chemicals in commercial use have been thoroughly screened for toxicity and only 2% have been adequately tested to determine whether they are carcinogens, teratogens, or mutagens, says the US National Academy of Sciences

21. Pollution Prevention&The Precautionary Principle • Pollution Prevention- Eliminates output of harmful pollutants • Harmless/less harmful substitutes or recycling within the production processes • Precautionary Principle-Taking action early to prevent or reduce risk • Don’t wait for sound or consensus science to take action

22. The Precautionary Principle Cont. • Guilty until proven innocent approach • Two changes in the way we evaluate risks: • New chemicals/technologies assumed harmful until scientific evidence proves otherwise • Existing chemicals/technologies appearing to have a strong chance of causing significant harm removed from the market until safety is established • 2000- Phase out dirty dozen (POPs)

23. Opponents/Proponents • Too expensive and almost impossible to introduce any new chemical/technology • No risk-free society • Encourages innovation in developing less harmful alternatives • Doesn’t rely directly on pollution control • Reducing, not eliminating risk

24. Risk Analysis • Risk Analysis includes: • Risk assessment • Identifying • Comparative risk analysis • Ranking • Risk management • Reduction/Elimination • Risk communication • Informing4

25. Poverty • Greatest risk in terms of the # of premature deaths per year and reduced life span • High death toll: Malnutrition and disease • “A sharp reduction in or elimination of poverty would do far more to improve longevity and human health than any other measure.” • After poverty, most premature deaths result from voluntary lifestyle choices (i.e. smoking)

26. Technology and Risks • Hard to assess System Reliability (%)= Technology Reliability x Human Reliability • Space shuttle incidents

27. Perceiving Risks • Most of us are not good at assessing the relative risks from the hazards that surround us • Many shrug off high-risk chances of death from voluntary activities they enjoy • Motorcycling --Guns • Smoking vs. --Lightning • Driving --Shark Attack

28. Distorted Perceptions • Four Factors: • Degree of control we have • Fear of the unknown • Whether we voluntarily take the risk • Whether a risk is catastrophic, not chronic

29. Being Better at Risk Analysis • Three Things: • Carefully evaluate news reports • Compare risks • Concentrate on the ones you can change, disregard the ones you can’t