I work in the environmental chemistry field and have some comments about this article. I have written before about how some of these toxins persist for long periods of time in the environment and have the tendency to bioaccumulate. The three toxins mentioned in this article - mercury, DDT and PCB's tend to both persist and bioaccumulate.

As far as sources go PCB's are man made compounds used mainly as electrical insulators. There are no natural sources of PCB's. Same goes for DDT and all other organo pesticides and herbicides. DDT have not been used in this country for many years, yet DDT contamination is still showing up.

There are two pieces of the puzzel to the mercury contamination in LK WA. Piece #1 -Mercury is a naturally occuring element. No new mercury has ever been created by man. A portion of the mercury contamination in LK WA is geologic mercury. Man has not played any role in this geologic mercury enetring the environment. Piece #2 - Man has played a role in nongeologic mercury entering the environment. There are a varity of sources of this mercury (industrial, residental waste, etc). The question that scientists are trying to answer is what portion of the mercury is nongeologic and what can be done to reduce this source of mercury.

We are coming to the conclusion that many water bodies around the country are not as pristine as previously thought. Ecspecially when it comes to mercury. If you look low enough mercury will be found in every water body that is studied. Organic contaminants have popped up in many surprizing as well.

This will continue to come up in the news media as breaking stories. Keep in mind that this contamination is not necessarily new, but has only recently been found.

In the 50's metro was formed to clean up LK WA and LK Samm. LK WA was so contaiminated that swimming in many parts of the lake was forbidden. LK WA still has some environmental problems (probably steming from its urban setting), but consider how far we have come in fifty years.

DOE and DOH set max consumption limits for the weakest groups in our society. Pregnant women and young childern are the most suseptable to contaminants in the environment. Healthy adults can hadle much higher amounts of contaminants with no ill effects.

This was kind of a rambling collection of my thoughts on the article. Mores I'm sure have other thoughts, I would like to hear them.