CHM 377 Practice Exam November 6, 2006

1. CHM 377 Practice Exam November 6, 2006

2. 1. Chlorinated pesticides remain a problem today because • They contribute to acid rain effects • Of residual soil contamination • They contribute to global warming • They add to the ozone depletion (b) Of residual soil contamination

3. 2. (5 pts) When assessing the impact of an anthropogenic compound on the environment, • the half-life is a constant value and not site specific • the LC50 is a constant regardless of the species • the lipophilic nature is correlated with the KOW value • the ultimate fate is unimportant. (c) The lipophilic nature is corrected with the KOW value

4. 3. DDT, once considered the miracle pesticide, was banned from use in the US in 1973, in part because • more effective pesticides became available • production costs became prohibitive because of costly chemicals • high levels of DDT in mother’s milk considered unfit for human consumption • found to be too easily degraded for agriculture use (c ) high levels of DDT in mother’s mike considered unfit for human consumption

5. 4. A dioxin that can be formed from 2,3-dichlorophenol is: • 1,6-dichlorodibenzo-p-dioxin • 2,7-dichlorodibenzo-p-dioxin • 1,9 –dichlorodibenzo-p-dioxin • none of the above (a) 1,6-dichlorodibenzo-p-dioxin

6. One of the difficulties with toxicity measurements is • an individual organism may give a unique response • response may depend upon sex, age, and general health • the effects of the chemical insult may appear later in the life cycle of the organism than 96 hours • all of the above (d) All of the above

7. Sites of action Sites of storage Using the model below discuss the fate of DDT in bird (answer on next slide. Uptake Excretion Sites of metabolism

8. In the model given, one would expect the DDT to go into storage, slowly be converted to DDE which would then take it to the toxic site of action. Doubt that very much would be excreted because of the high Kow value of 106.

9. Draw the chemical structure for 1,3-dichlorodibenzofuran.

10. The difference between the effect of DDT and DDE on the calcification of eggshells is due to • (a) number of chlorine atoms (b) structure • (c) chemical reactivity (d) lipophilicity (b) structure • The octanol-water partition coefficient measures • (a) ease of reduction (b) half-life • (c) chlorine/hydrogen ratio (d) degree of lipophilicity • (d) degree of lipophilicity

11. Herbicides are • used to treat for insects • more persistent then chlorinated pesticides • linked with high cancer rates among farmers • insoluble in aqueous systems (c) Linked with high cancer rates among farmers

12. The general dose-response curve for essential and non-essential elements is shown on the left. Explain what would happen if a person were exposed to a daily dose of a non-essential element, e.g. Hg, that would continue to build-up in the body until the concentration was greater than c4 shown on the curve [Be specific and discuss what would happen at c2 and c3.] At c2 the person would begin to experience effects, such as “shakes,” that were reversible, at c3, the effects would be irreversible, and at C4 the person would have passed the acute concentration, thus resulting in death. C4 C3