Reading

Clarkson, T.W. et al. 2003. The toxicology of mercury---Current exposures and clinical manifestations. New England Journal of Medicine 349: 1731-1737. (Provides a broad overview of mercury.)

Rice, D.G. 2003. Testimony before Senate Environment and Public Works Committee. July 29, 2003. (Provides a broad overview of the science in the methylmercury risk assessment.)

National Research Council. 2000. Toxicological effects of methylmercury. Read only pages 1-6 of the Executive Summary. (This is the methylmercury risk assessment. This is not an easy read. But I want you to take a look at just a few pages.)

Questions for class discussion

Mercury: What is it?

1. In class, I will provide a very basic overview of mercury chemistry. What are the different forms of mercury (see Clarkson article)? What are the major sources of human exposure to mercury? (Hint, dental amalgams, methylmercury in fish, and vaccines). What form is the mercury in each of these?

2. What is bioaccumulation? (Hint: See the figure in the Clarkson et al. article). Why are the highest methylmercury concentrations found in large, long-lived, predatory fish?

3. There are 3 major studies that have looked at effects of methymercury on young children (Faroe Islands, New Zealand, and Seychelles). Do these studies agree? Does the National Research Council believe that any of these studies were seriously flawed? Do you believe that one or more were seriously flawed?

Reference dose, benchmark dose, and more tiny numbers

4. How much canned tuna can an adult human eat in a day, according to current government guidelines? Also, just how much tuna is 0.04 kg? Would you get a stomach ache if you ate this much? Would this amount of tuna make a decent sandwich?

5. What is a reference dose (RfD)? What is a benchmark dose (BMD)? How does the methylmercury risk assessment use a benchmark dose to calculate a reference dose?

Models

6. The methylmercury risk assessment essentially uses Faroe Island residents as a model of US residents. What assumptions are inherent in the use of this model? How would you test these assumptions?