New Term Paper Due Dates

1. New Term Paper Due Dates November 18 – final version of paper for peer editing. December 2 – return edited papers to classmates. December 9 – Final edited paper due.

2. Persistent Organics in the Environment • Some common persistent organics: • DDT • PCBs • Dioxins • PBDE • MTBE

3. Persistent Organics in the Environment • Why are we concerned? • Bioaccumulation • Stability • Toxicity

4. Persistent Organics in the Environment 1. Bioaccumulation Due to their low solubility, persistent organics tend to partition to soils and animal fats. This partitioning can be modeled to within about a factor of 10 using octanol (C8H17OH).

5. Persistent Organics in the Environment 1. Bioaccumulation

6. Persistent Organics in the Environment 1. Bioaccumulation This is usually reported as the logKow because the values for molecules of interest can be quite large. Online database: http://logkow.cisti.nrc.ca/logkow/index.jsp

7. Persistent Organics in the Environment 1. Bioaccumulation Do to the stability and partitioning of organics in fatty tissue, the concentration of organics may magnify many orders of magnitude through several trophic levels. From: www.absc.usgs.gov

8. Persistent Organics in the Environment 2. Stability: Low volatility – no gas phase sink. Low solubility – not very mobile. Usually consist of chlorine or bromine bonded to an aromatic ring – not very reactive. Long lifetime – can be transported long distances over time.

9. Persistent Organics in the Environment 2. Stability From: Thomann, Environmental Health Perspectives Volume 103, Supplement 5, June 1995

10. Persistent Organics in the Environment • 3. Toxicity • exposure • acute versus chronic toxicity • mode of toxicity • mutagen • carcinogen • teratogen • dose-response relationship

11. Persistent Organics in the Environment • 3. Toxicity • Exposure depends on Kow. From: Thomann, Environmental Health Perspectives Volume 103, Supplement 5, June 1995

12. Persistent Organics in the Environment 3. Toxicity Dose is usually expressed as a mass of chemical per mass of organism. Response is usually expressed as the % of the population that has a specific response (or dies) after exposure to the corresponding dose. From: www.rstp.uwaterloo.ca

13. Persistent Organics in the Environment • 3. Toxicity • Major health concerns: • Chronic • hormone disruption • cancer development • birth defects • Acute • all of the above • allergic reaction • respiratory issues

14. para-dichlorodiphenyltrichloroethane (DDT) • Used to control typhus and malaria during WWII. • Used as an agricultural pesticide since WWII. • 1.8 million metric tonnes released to the environment worldwide. • Banned in the US in 1972 and subsequently worldwide. • Still used today in the tropics to control mosquitoes that carry malaria. DDT log Kow = 6.2

15. para-dichlorodiphenyltrichloroethane (DDT) DDT DDE • DDE (dichlorodiphenyldichloroethane) is a major derivative of DDT and is responsible for much of both the effectiveness of DDT and its harmfulness.

16. para-dichlorodiphenyltrichloroethane (DDT) • Kills bugs by interfering with their neurological activity. • Causes thinning of shells in predatory birds. • Low acute toxicity for humans (LD 50 ≈ 113mg/kg) DDT

17. para-dichlorodiphenyltrichloroethane (DDT) log Kow = 6.91 From: www.geo.arizona.edu

18. para-dichlorodiphenyltrichloroethane (DDT) From: National Resources Defense Council

19. Polychlorinated biphenyl (PCBs) 209 individual compounds, about 130 were commonly used.

20. Polychlorinated biphenyl (PCB) • Industrial production began in 1929 • Approximately 1.5 million metric tonnes have been produced globally. • Production peaked in the 1960s. • Mostly banned in the 1970s for ‘open’ uses. • No new production today, however, some PCBs are still in use. • insulating fluid for transformers and capacitors • plasticizer • fire retardant

21. Polychlorinated biphenyl (PCB) • Properties: • Low water solubility • High organic solubility • Generally low vapor pressures • Chemically stable • log Kow = 5.2 (4,4’-dichlorobiphenol) • Acute toxicity for humans: • grams/kg • For fish: • µg/kg

22. Polychlorinated biphenyl (PCB) • Removal from the environment involves: • dispersion – slow due to bioaccumulation • chemical breakdown – slow due to stability • removal of contaminated soils or sediments – must then store the contaminated material • incineration – potential to create other hazardous materials – furans and dioxins • microbial – conversion to Cl2 and biphenyl

23. Polychlorinated biphenyl (PCB) • Hudson River PCBs • General Electric dumped up to 1.3 million lbs of PCB into the Hudson river between 1947 and 1977. • Dredging to remove contaminated sediments began earlier this year (2009). From: www.riverkeeper.org

24. Polychlorinated biphenyl (PCB) From: New York State Dept of Environmental Conservation

25. Polychlorinated biphenyl (PCB) USEPA suggests a maximum safe level for consumption is 3 ppm in dairy, meat, and seafood. From: National Resources Defense Council

26. Dioxin • Sources: • Natural – is created anytime organic material is burned in the presence of chlorine. • Industrial – is created anytime organic material is burned in the presence of chlorine. • incineration • pulp and paper bleaching • Mostly a by-product of other processes, however has been used directly. • defoliant – Agent Orange • poison

27. Dioxin chloracne Viktor Yushchenko, president of Ukraine, was allegedly poisoned with dioxin and had dioxin levels thousands of times greater than found in average blood.

28. Dioxin Toxicity: LD50 = 100s of µg/kg for the most toxic form. 2,3,7,8-Tetrachlorodibenzodioxin (TCDD)

29. Dioxin From: Natural Resources Defense Council

30. Dioxin log Kow = 6.8 (TCDD) From: Natural Resources Defense Council

31. Polybrominated diphenyl ethers(PBDE) • Flame retardant • Integrated into many consumer products including plastics and fabrics. • Still produced in the US, recently banned in California, Washington, and Maine. Banned in the European Union. • LD50 is grams/kg • log Kow = 5.8

32. Polybrominated diphenyl ethers(PBDE) From: Natural Resources Defense Council

33. Polybrominated diphenyl ethers(PBDE) From: Natural Resources Defense Council

34. Methyl tert-butyl ether (MTBE) • Fuel additive • Increases octane number. • Reduces engine knocking – replaced lead • Reduces VOC emissions from gasoline. • LD50 = 4g/kg (comparable to pure ethanol) • log Kow = 0.94

35. Methyl tert-butyl ether (MTBE) Seeps into groundwater from underground fuel storage tanks. -gives water an unpleasant taste at 5µg/L Has been measured in well water around Santa Monica and Lake Tahoe -California now has regulations for MTBE (5µg/L)

36. Next Week’s Exam • The exam is on Wednesday, November 4 during the first 50 minutes of regular class time. • You are allowed to use a calculator (no PDAs or cell phone calculators). • You may not use your calculator to look at pre-recorded notes – this is considered cheating. • Don’t forget your calculator, there will be no extras to hand out.

37. Next Week’s Exam • No aids in addition to a calculator are allowed. • Do everything possible to avoid even the suggestion of cheating: • no hats, sunglasses, wandering eyes, etc. • Partial credit can be given only if your work is well organized and easily readable. • All calculations need to be worked out on the exam to receive credit, even if you have the correct answer.

38. Next Week’s Exam • The form of the exam: • Multiple choice: • 20-30% • Short answer • 30-40% • Worked out calculations • 30-40% • This exam is worth 22% of your grade.

39. Next Week’s Exam • Priority of material on the exam: • Topics covered in lecture • Topics covered by the assigned reading • You are responsible for material in the readings, even if it was not explicitly covered in lecture. • Preparing for the exam: • Do the suggested problems • Study the lecture notes • Study text