Cytogenetic analysis of lymphocytes from rats following formaldehyde inhalation.

Male and female Fischer-344 rats were exposed to target concentrations of 0.5, 6, or 15 ppm formaldehyde by inhalation for 6 h/day for 5 days. Blood was removed by cardiac puncture within 1 h following termination of exposures and cultured in the presence of 5-bromodeoxyuridine (BrdU) (4 microM) for analyses of sister-chromatid exchange (SCE) and chromosome breakage. Formaldehyde did not cause a statistically significant increase in either SCE frequency or in the number of metaphases displaying chromosome aberrations.