Long-term effects of repeated exposure to 3-methylfuran in hamsters and mice.

Male and female Syrian golden hamsters were exposed for 2 h once a week for 10 consecutive weeks to 344 mumol/l of 3-methylfuran (3MF), an agent known to produce acute Clara-cell necrosis. Ten months later their respiratory function was evaluated. No functional differences were found between control and treated animals, and histopathologic evaluation of the lungs did not reveal any major treatment-related alterations. Male and female BALB/c mice were exposed for 1 h to 26.8 mumol/l of 3MF once weekly for 10 wk. After 2 yr the tumor incidence in exposed animals was not increased when compared to controls. It is concluded that the acute Clara-cell necrosis produced by 3MF at the doses used is of little long-term consequence.