dr. winetrop to come um to answer questions, that would be great. >> an i am sure we have quite a few public comments, but i do one question in terms of the cumulative effects of the contaminants. >> hi. good morning. i'm jean winetrop and the senior epidemiologist and the manager of the water regulatory programs at the san francisco department of public health, and specifically the environmental health branch. so i have more than 30 years in background and water supply and wifb i have been with the city for 17 years. that is my background for you. specifically to the question about what is called bio accumulations and whether what happened, for example, with mercury and fish, if you have a fish swimming around and it eats up plankton that has some mercury in it and a bigger fish eats that fish and it has eats three of those fish and now it has three times as much mercury. and then so it accumulates and never goes away and when i eat the fish, i get a lot of mercury. that doesn't happen with the come tam nants that we are talking -- that doesn't happen with the contaminants. they all get met