PBT:  Bioaccumulative
		u Bioaccumulate ->  build up in a food chain u Greater concentrations  at higher trophic levels – Concentrations can be very low in air and water but much greater in fish or mammals; up to 1,000,000 times higher – Polar bears, tuna, children – Accumulate in fat (PCBs) or muscle (methylmercury) – Foods tend to be most significant sources for adults u Children may receive greatest exposures from their mothers – In utero and breastfeeding