Therefore, I am convinced that such water pollution is irrelevant as a cause of human cancer. The main current fallacy in our approach to such pollution consists in believing that carcinogens are rare and that they are mostly man-made chemicals. Quite the contrary is the case. Every meal has many carcinogens and when one compares the level of carcinogens in contaminated water or pesticide residues in food to the level of natural carcinogens also present in the diet, it is clear that water pollution or pesticide residues represent a trivial exposure by comparison. By comparison, the carcinogens in a few common drinks are listed below.
Every common drink contains carcinogens.
Calculating a possible hazard to humans from information obtained from a cancer test on rats must take into account the potency of the carcinogen in rats as well as the human dose. We are just completing a study where we compare possible hazards for humans due to typical daily intake of carcinogens, adjusting for the potency of each carcinogen from the animal data. I give some comparisons below. This is because trichloroethylene is an extremely weak carcinogen. It is comparable to saccharin and only 10 times more potent than alcohol, which is present at about 50 million ppb in a beer.