Why do you measure these contaminants down to such low concentrations
when we don't know (or don't believe) that there are effects at these
low levels?
Low detection levels enable development of an understanding of the processes
that affect the transport and persistence of chemicals in the environment.
It would be very difficult to gain an understanding of the behavior
of these compounds if the methods of analysis did not measure their
concentrations well below the known-effect levels. Understanding gained
at these low levels is of great value in predicting the behavior of
these chemicals, and when and where they may occur at higher concentrations.
Measurement at low levels is also important for early warning and for
detecting trends.
