Acute and subacute cytogenetic effects of the trihalomethanes on rat bone marrow cells in vivo.

The mutagenic effects of the trihalomethanes (THMs: chloroform, CHCl3; dichlorobromomethane, CHCl2Br; dibromochloromethane, CHClBr2; bromoform, CHBr3), found in chlorinated drinking water have been studied for their ability to induce chromosome aberrations (CA) in vivo in rat bone marrow cells. THMs were administered intraperitoneally (i.p. acute) and orally (subacute). Using a maximal dose of 1 mmole/kg body weight, positive results were noted for CHCl3, CHCl2Br, CHClBr2 and CHBr3 with i.p. treatment, and for CHCl3 and CHBr3 with oral treatment. The time-dependent increase in CA showed a maximum level at 12 h after i.p. injection and at 18 h after the fifth and last day of oral treatment.