Epidemiological studies indicate an association between exposure to chlorinated
drinking water and risk of
intestinal cancer. In order to study this experimentally, we have examined the effects of 3,4-dichloro-5-hydroxy-2[5H]-furanone (
mucochloric acid, MCA) and 3-chloro-4-(dichloromethyl)-5-hydroxy-2[5H]-furanone (MX), mutagenic and genotoxic compounds in
drinking water, on
aberrant crypt foci and tumours in the intestines of male F344 rats and Balb/cA mice, and C57BL/6J-Min (multiple intestinal
neoplasia)/+ mice of both sexes, in six independent experiments. In some experiments the effects of MCA and MX on
aberrant crypt foci induced by the colon
carcinogens 1,2-dimethylhydrazine or its metabolite
azoxymethane were also studied. Neither MCA nor MX alone induced
aberrant crypt foci or intestinal tumours when given in
drinking water. With this route of exposure neither MCA nor MX, when given in combination with
1,2-dimethylhydrazine or
azoxymethane, had any effect on the induction or growth of the
aberrant crypt foci.
Drinking water exposure of MX did not affect the number or growth of
aberrant crypt foci or intestinal tumours in the Minl+ mice. When administered intrarectally MCA had a weak inducing effect on
aberrant crypt foci in the colons of Balb/cA mice. Exposure to MCA and MX intrarectally apparently promoted the growth of
aberrant crypt foci both in rats and mice, increasing the crypt multiplicity, aberrant crypts/
aberrant crypt foci. Based on an overall evaluation of these experiments, the intestinal tract, at least in rats and mice, seems not to be a main target organ for effects of MCA or MX on preneoplastic or neoplastic development.