1. To assess risk, many scientific studies have involved feeding rats high doses of a chemical. In this sense, high doses are a model of low doses, and rats become a model for humans. What impediments to scientific progress to these two models help overcome? Explain your answer. Answer with reference to the impediments discussed in class: rare events, time lags, complexity, ethics, and conflict. (one or two paragraph answer)

2. Cite an example of each of the following impediments to scientific progress, drawing on the Grandjean et al. (1998) or the Dose-Response chapter of the methylmercury risk assessment. For each impediment, describe a model that scientists use to overcome it.

First impediment: Rare events are difficult to quantify.




Model used to overcome first impediment:

Second impediment: Time lags slow scientific progress




Model used to overcome second impediment:

Third impediment: Pitfalls of complexity




Model used to overcome third impediment:

Fourth impediment: Ethical constraints inherent in human studies




Model used to overcome fourth impediment: