1. Environmental Hazards and Human Health, Part 1

2. CHEMICAL HAZARDS A hazardous chemical can harm humans or other animals because it may: –Be flammable –Be explosive –Be an irritant –Interferes with oxygen uptake

3. RISKS AND HAZARDS Risk is a measure of the likelihood that you will suffer harm from a hazard. We can suffer from: –Biological hazards –Chemical hazards –Physical hazards –Cultural hazards

4. CHEMICAL HAZARDS A toxic chemical can cause temporary or permanent harm or death. There are five categories: –Neurotoxins –Mutagens –Carcinogens –Teratogens –Endocrine disrupters

5. More on endocrine disrupters Figure 18-9

6. Persistent organic pollutants (POPs) PCBs DDT Atrazine Dioxins Hayes et al. 2002

7. Bioaccumulation & biomagnification

8. Chemicals in the environment: heavy metals (eg lead, arsenic, mercury, cadmium)

9. Chemicals in the home environment Phthalates Bisphenol A (BPA) Vinyl chloride

10. TOXICOLOGY: ASSESSING CHEMICAL HAZARDS Factors determining the harm caused by exposure to a chemical include: –The amount of exposure (dose). –The frequency of exposure. –The person who is exposed (genetic make- up, age, other illness). –The effectiveness of the body’s detoxification systems.

11. 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. –Brains are not fully developed until the early 20s

12. LD-50/LC-50…ED-50/EC-50

13. TOXICOLOGY: ASSESSING CHEMICAL HAZARDS Under existing US laws, most chemicals are considered innocent until proven guilty, and estimating their toxicity is difficult, uncertain, and expensive. The European Union exercises the Precautionary Principle, which means that chemicals go through rigorous testing before commercial release.

14. Legislation Federal Insecticide, Fungicide, and Rodenticide Act –Gives EPA the authority to regulate all stages of pesticide production, distribution, and disposal. –EPA can suspend the use of any pesticides found to pose unreasonable risks to humans or wildlife. Federal Food, Drug, and Cosmetic Act (1938, last amended in 2004) –Lets EPA set tolerance levels for pesticide residues in food and livestock feed. Food Quality Protection Act (1996) –Amended the above two laws –Further requirements for assessing tolerance levels for pesticides in food Clean Air Acts Safe Drinking Water Act

15. Hazardous waste Threatens human health or the environment in some way because it is –toxic –chemically active –corrosive –flammable –or some combination of the above The two largest classes of hazardous wastes are organic compounds (e.g. pesticides, PCBs, dioxins) and toxic heavy metals (e.g. lead, mercury, arsenic).

16. Conversion to Less Hazardous Substances Physical Methods Chemical Methods Incineration

17. Conversion to Less Hazardous Substances Biological Methods: –Bioremediation –Phytoremediation

18. Long-Term Storage of Hazardous Waste Hazardous waste can be disposed of on or underneath the earth’s surface. –Deep-well disposal –Surface impoundments Without proper design and care these can pollute the air and water.

19. Long-Term Storage of Hazardous Waste Long-Term Retrievable Storage

20. Hazardous Waste Regulations in the United States Two major federal laws regulate the management and disposal of hazardous waste in the U.S.: –Resource Conservation and Recovery Act (RCRA) Cradle-to-the-grave system to keep track of hazardous material and waste. –Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Commonly known as Superfund program.

21. Love Canal 21,000 tons of toxic waste was buried by Hooker Chemical Co. in the 1940s and 1950s in Love Canal, a neighborhood in Niagara Falls, NY. Love Canal sparked creation of the Superfund law, which forced polluters to pay for cleaning up abandoned toxic waste dumps. Video 1 Video 2

22. International agreements Basel Convention (1989) Persistent Organic Pollutants Treaty (2001)

23. Brownfields Abandoned industrial/commercial sites that are contaminated with hazardous waste –eg gas stations, factories, junkyards, old landfills Can be cleaned up and used for new purposes EPA Brownfields Program gives low interest loans to companies or groups that are willing to clean up an area and repurpose it.