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THE INDUCTION OF ABERRANT CRYPT FOCI IN THE COLONS OF MALE F344/N RATS EXPOSED TO THIHALOMETHANE MIXTURES IN THE DRINKING WATER
Citation:
Sistrunk, C. M., M H. George, T. Moore, S. Kilburn, AND A B. DeAngelo. THE INDUCTION OF ABERRANT CRYPT FOCI IN THE COLONS OF MALE F344/N RATS EXPOSED TO THIHALOMETHANE MIXTURES IN THE DRINKING WATER. Presented at American Water Works Association Microbial/Disinfection By-Products Effects Symposium, Lisle, IL, March 24-26, 2001.
Description:
THE INDUCTION OF ABERRANT CRYPT FOCI IN THE COLONS OF MALE F344/N
RATS EXPOSED TO TRIHALOMETHANE MIXTURES IN THE DRINKING WATER
The trihalomethanes (THM), bromoform (TBM) and bromodichloromethane (BDCM), administered by corn oil gavage were found to increase large bowel cancer in male and female rats (TBM, NTP Technical Report No 321, 1987; BDCM, NTP Technical Report No.350, 1989). Our recently completed 2-year bioassay for BDCM administered in the drinking water of male F344/N rats failed to demonstrate large bowel tumor induction (George etal., Proc. Amer. Assoc. CancerRes., 40,349,1999; manuscript in preparation). However, we have found that male rats exposed to individual THM in the drinking water induced aberrant crypt foci (ACF) which are considered to be the putative preneoplastic lesions in colons of male rats, but not mice (DeAngelo et al., Toxicol. Sci., 48, 343,1999; manuscript in progress). The incidence (percent of animals with ACF) and multiplicity (ACF/colon) was a direct function of the number of bromine atoms on the molecule (TCM
The study thus far demonstrates that a mixture of primarily brominated THM at 100X ambient
drinking water concentrations can induce putative preneoplastic lesions in the colon of male
rats. The study will be carried out for 104 weeks with the objective of determining if these
lesions develop into colon cancer.
This is an abstract of a proposed presentation and does not necessarily reflect the view of
the US EPA policy.