1. Toxicology and Chemical Hazards 19.1

2. Toxicology The study of harmful ____________ of chemicals on human and environmental ______________ ______________________ may study: –_______________ toxicity –Chronic exposure –_____________________ potential Data made available via ______________ like: –(__________) National Toxicology Program –__________ National Institute of Environmental Health Sciences –_________ Integrated Risk Information System (EPA) –Environmental Defense also creates “_____________”

3. Dose Response Dose: level of exposure multiplied by the length of _________ that exposure occurs Response: how the organism __________ to the dose, acute, chronic, or tumors Ex: Phenolphthalein (common chemical lab reagent & was used in ____________) –LDL 0 (lowest dose at which ________ occurs in animal testing) 500 mg/kg. (Low toxicity) –Concern about chronic exposure or ____________________ issues

4. Exposure Getting accurate info about human exposure often most difficult part of ______ ____________________ Exposure can come through: –The ________________ –Food –____________________ –Surrounding environment

5. Threshold Level The level at which _______ _____ __________ are observed There may be no ______________________ Above threshold, effect depends on concentration and _____________________ Sometimes _______ levels are tolerated if for a ______________ time EPA takes _______ dose, ___________ response approach to carcinogens However, difficult to distinguish low level dose from ___________ level of cancers in population

6. The Nature of Chemical Hazards HAZMAT: ________________ material- a chemical that represents a certain hazard or risk Categories –Ignitability –____________________ –Reactivity (ex: will it __________ with water?) –Toxicity (injurious when inhaled or ingested) Radioactive materials treated as _________________ category

7. Sources of Chemicals Entering the Environment Most items we use daily (shampoo, the TV) are products of chemical __________ Total Product _______ ___________: all steps from obtaining raw materials to final disposal Multiply these steps by hundreds of thousands of products used by ___________ of people at home and work 80,000 chemicals _________________ for commercial use in United States

8. Categories of Product Life Cycles _______________ Introduction to Environment: pesticides, road salts Intended Use ________ ____________ in Environment: evaporation of solvents from paint Materials that are used ______________ to desired item: lubricants, solvents, cooling fluids ____________ consumed for energy: gasoline, coal Each has unavoidable waste and potential for _____________________

9. Toxics Release Inventory A __________ ______________ that releases a large amount of a chemical may make headlines The total amounts entering the environment from millions of homes and businesses is far ______________ and bigger risk EPCRA Emergency ______________ and Community Right-to-Know Act of 1986: –requires industries to report ______________ and quantities or toxic chemicals stored on each site –Report to ___________ and local gov’t –Must report _______________ of toxins to environment

10. TRI, continued Does not include ___________ business or household hazardous waste (HHW) Disseminated on _________- annual report 2001 –Total production related wastes 26,740 million lb. –Releases to _________: 1, 679 million lb –Releases to _________: 221 million lb. –Releases to _________ disposal sites & underground injection: 4,258 million lb.

11. The Threat from Toxic Chemicals Many toxic chemicals are gradually broken down and ________________ by natural processes Once they are ______________ sufficiently, no threat Two major classes of chemicals do not readily degrade –__________ _________ and their compounds –__________________ Organics –Most OK if diluted, but there are some ____________________

12. Heavy Metals Most dangerous: lead, ____________, arsenic, cadmium, tin, chromium, zinc, and copper Uses: metal working/plating, batteries, electronics, pesticides, medicines, paint _______________, glazes, inks, dyes Toxicity as __________ or certain compounds are soluble in water, –may be absorbed in body, and – ___________ function of certain enzymes

13. Organic Compounds ________________-derived and synthetic organic compounds are chemical basis for: plastics, synthetic fibers, synthetic rubber, ______________, pesticides, wood preservatives, etc. _______________ to biodegradation is what makes them useful

14. Toxicity Often ___________ absorbed into body Interact with particular ______________ Nonbiodegradability ______________ them from being broken down further High dose may cause ___________ poisoning & death Low dose over time may be mutagenic, carcinogenic, or ______________ (birth defects)

15. Halogenated Hydrocarbons A particularly troublesome _________of synthetic organic compounds One or more atoms of hydrogen have been replaced by atoms of _______________, bromine, fluorine, or iodine Chlorinated ________________ (aka organic chlorides) most common –Plastics (________________ chloride) –________________ (DDT, Kepone, Mirex) –Solvents & electrical ____________________

16. Dirty Dozen POPs: Persistent Organic Pollutants Most of dirty dozen POPs are halogenated hydrocarbons Stockholm Convention on Persistent Organic Pollutants (2001) have banned or highly restricted top 12 (Dirty Dozen) All are toxic, most are carcinogenic Many are suspected of being endocrine disrupters at low levels

17. PERC Tetrachloroethylene (aka ______________________) a halogenated hydrocarbon ___________________, nonflammable, Major substance in _________________ fluid, effective solvent, used in industrial cleaning operations, shoe polish Doesn’t ________ to soil, enter groundwater easily

18. Dangers of PERC Most common human exposure: _______________ or use of dry cleaned garments Enters body most readily through ________________ Short periods of inhalation: dizziness, fatigue, headaches, __________________________ Long periods: can cause liver & ______ damage __________________- esophagus & bladder

19. MTBE Methyl tertiary butyl ether: an ____________ now added to ¼ gasoline sold in U.S. Added to make gasoline burn ______________ Suspected ________________________ Found in increasing levels of wells and surface waters (via 2-stroke ________________ or leaky underground storage tanks_ Gives water a nasty ____________ at low concentrations

20. Bioaccumulation & Biomagnification Heavy metals tend to ________________ in organisms Ex: ____________ Japan, 1950s, fishing village –Cats began to show ________________ movements, paralysis, coma, then death –Began to occur in ________________ –People also had mental retardation, ____________, & birth defects –50 people died, 150 suffered serious bone & ____________ damage