PCBs may cause serious harm when exposure occurs over a long period of time. That is why EPA has recommended a goal of minimizing students' and teachers' exposure to PCBs. It should be recognized that exceeding EPA's levels for a school exposure does not mean that adverse effects will necessarily occur. Because PCBs accumulate over such long averaging times, short term exceedances of the levels will likely cause only small changes to human blood concentrations, and these can be offset by other periods of exposure to lower air levels. Comparing total exposure from all sources to the levels is a conservative, health protective estimate, as it assumes that most of the inhaled PCB is absorbed and none exhaled. Some past research suggests that not all inhaled PCB is absorbed in the body. Studies conducted in Europe where children and teachers were exposed to higher PCBs levels (more than 1,000 nanogram/m3) in schools have shown that these exposures contributed very little to the overall PCB blood levels.
Are my children in danger if my school or building has PCB-containing caulk?
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