PBDE's are bioaccumlative meaning that they tend to increase in concentration as you move up the food chain. This is common for many of the nasty pollutants that have been reported in the media. PBDE's are organic compounds and behave similarly to other organic compounds like PCB's, Dioxons and many pesticides and herbicides that have made there way into the environment. What is very concerning to scientists is the fact that these bioaccumlative compounds are at extremely low levels in the environment, far below what can be detected in the lab. But because once these compounds enter the food chain they are greatly concentrated as they work there way up. These compounds have an affinity for the fatty tissues and once they are consumed by an organism they remain with it for its lifetime. This is why generally older organism's will have greater concentrations of these compounds than younger organism's because the older one's have had a chance to eat more.

Currently the only sewage treatment technology that will remove these compounds is reverse osmosis (RO). RO treatment systems are unpratically expensive when used for the volumes of sewage generated by municipalities. The sewage treatment technology used by King county and all other treatment plants in the area do not use RO systems, so the PBDE's in the sewage waste streams will not be removed.

I hope I am not boring people to sleep by being too technical. The bottom line is the way these compounds behave by moving up the food chain is very concerning. This is an unfortunate trend that will continue to rear its ugly head with a number of nasty compounds.

Steve