Announcements 12/2/10 Hand in homework EXAM 3 during finals –12:15 Lecture: Sun. Dec. 12, 3:15 pm –1:40 Lecture: Mon. Dec. 13, 1 pm Final project paper – all questions answered except #14 – bring written copy to lab on Wed. or Fri., hand it in electronically with #14 by midnight that day Next week: Upload ONE group powerpoint to CampusWeb BEFORE lab; bring one printed copy of the powerpoint as well

II. Principles of Toxicology A.There are different types of env. risks (chemical, biological, physical) B. Different substances had different effects (asphyxiant, allergen, neurotoxin,mutagen, carcinogen, teratogen) C. Toxicity is affected by many factors (stability, movement, biomagnification, amount/dose, duration of exposure, type of organism, etc.) D. Measuring toxicity is difficult E. Risk management: Weigh costs and benefits, minimize risks

A substance found at higher amounts in organisms higher in the food chain has 1.biomagnified 2.bioaccumulated 3.ecotoxified 4.ecovillified 5.re-gifted

Biomagnification =Amount of substance increases in each higher level of food chain 1.Water - small amount  2.Phytoplankton (=tiny floating plants)  3.Zooplankton (=tiny floating animals)  4.Small fish  5.Larger fish, birds, frogs  6.Top predators: largest amount

Persistent Organic Pollutants Large, complex organic chemicals Biomagnify and cause many problems for wildlife PCBs, Dioxins Many pesticides Plastics? (#7?) Drugs in water Last year, researchers with the U.S. Geological Survey found male fish with immature female eggs, right here in the Potomac River.

Quick History Lesson Theo Colborn, author Our Stolen Future (1995) Synthesized massive amounts of studies on the effects and sources of endocrine disruptors – really easy to read, interesting!

" DDT - Powerful Insecticide, Harmless to Humans"

4) Amount/Dosage “The dose makes the poison” What amount of the substance is harmful 5) Duration and frequency of exposure Acute exposure - single exposure to a toxin – immediate effects Chronic exposure - repeated exposure to a toxin - can’t see any immediate effects C. What affects toxicity of a substance?

Dose= amount of toxic Response=number killed or harmed LD50 - the dose of a toxin that is lethal to half the test population

Substances have diff. dose-response curves Threshold = amount of substance where you start to see a bad effect

6) Factors related to organism Species Age: Young and old – more sensitive because cells are vulnerable when dividing, or deteriorating Weight: Heavier, can take higher dose Health: More vulnerable when ill C. What affects toxicity of a substance?

D. Measuring toxicity is difficult 1. Cell studies Expose cells to suspected toxin Count dead or damaged cells Problems? Not available for all cell types Doesn’t look at the “whole organism”

Most commonly used and widely accepted Problems? Expensive Time consuming Often very inhumane Rats not the same as humans! Usually done at high doses, short exposures (acute) 2. Animal Testing

3. Epidemiological studies Compare existing groups, see if more toxic=more disease (correlation) Try to control for age, income, race, other factors Problems? Need lots of individuals (large sample size) Using people as “guinea pigs” “Correlation does not equal causation”!!!

Plastics – bisphenol A Additive in some plastics: #1, 7 Implicated in breast cancer, prostate cancer, etc. Most experts warn – avoid if possible vom Saal, Frederick and Hughes, Claude; "An Extensive New Literature Concerning Low-Dose Effects of Bisphenol A Shows the Need for a New Risk Assessment" Environmental Health Perspectives, Vol. 113, No. 8, August "An Extensive New Literature Concerning Low-Dose Effects of Bisphenol A Shows the Need for a New Risk Assessment" Not all studies agree Don’t heat liquids in plastic Polycarbonate #7 plastics are the worst Don’t re-use #1’s #2, 4, 5 ok

Mercury Naturally occurring in soil, rocks Gets into air from burning coal, trash In water, becomes methylmercury=toxic Builds up in food chain  high in fish Large amounts  neurological problems; cardiovascular disease; stroke Children of mothers who eat a lot of high-mercury fish show reduced IQ, delayed development Studies also show that children who eat some fish show higher IQ and better development – omega fatty acids in fish Avoid fish or not?

Mercury is a… 1.Carcinogen 2.Neurotoxin 3.Asphyxiant 4.Teratogen 5.Allergen

A study in Japan compared children, whose mothers happened to eat a lot of highly mercury-contaminated fish, with children whose mothers did not eat the fish. What type of study is this? 1.Animal testing 2.Controlled lab study 3.Cell culture study 4.Epidemiological study

Given this new information, what is your opinion about whether to eat fish or not? 1.I see no reason to avoid eating fish 2.Only pregnant women and little kids should avoid fish 3.Everyone should avoid eating any fish 4.Pregnant women and kids should eat fish, but only certain kinds 5.Everyone should eat limited amounts of some kinds of fish

Mercury exposure from fish?

II. Principles of Toxicology A.There are different types of env. risks (chemical, biological, physical) B. Different substances had different effects (asphyxiant, allergen, neurotoxin,mutagen, carcinogen, teratogen) C. Toxicity is affected by many factors (stability, movement, biomagnification, amount/dose, duration of exposure, type of organism, etc.) D. Identifying effects is difficult E. Risk management: Weigh costs and benefits, minimize risks