ABSTRACT
This difficulty is compounded by the shifting populations
and changes in the source and quality of water over the long
periods of time involved.
Therefore, we must rely on toxicological tests to tell
us of the possible hazards in water, as in the other parts
of the environment. Once a hazard is indicated, particularly
a carcinogenic one, steps should be taken to reduce public
exposure to it. Any other response is contrary to the
philosophy of protection of the public health.
