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Probucol (4,4′-(isopropylidenedithio)bis(2,6-di- t -butylphenol)), a cholesterollowering drug, was evaluated for cytogenetic toxicity in the bone-marrow cells of Sprague-Dawley rats. Male and female rats were fed diets containing 0, 200, 400, or 800 mg/kg body weight/day for 8 consecutive days. Animals treated with trimethylphosphate served as positive controls. Femoral bone-marrow specimens were aspirated from all animals for cytogenetic evaluation. Analysis of the data generated by this study indicated that the incidence of cytogenetic aberrations in the bone marrow of rats was not affected by administration of probucol within the present treatment regimen.

This report presents the cytogenetic findings in bone marrow cells of rats exposed to styrene vapor. Male and female Sprague-Dawley rats were exposed to 0, 600 and 1000 ppm of styrene vapor by inhalation 6 hr per day, 5 days a week, for a period of one yr. Blind scoring of metaphase spreads prepared from bone marrow cells collected at the end of the last exposure revealed that neither the 600 ppm nor the 1000 ppm exposures to styrene vapor produced an incidence of chromosomal anomalies higher than those occurring spontaneously. It is interpreted that styrene is non-clastogenic within the present exposure regimen.

High doses of a test chemical sometimes affect the food consumption of the treated animals even to the point of starvation. The effect of such a non-specific toxicological stress on the bone marrow micronucleus test was investigated in male and female Sprague-Dawley rats. A 42-h starvation had a noticeable effect on the ratio of polychromatic to normochromatic erythrocytes (PCE and NCE); the values in the starved animals were approx. 77% of the negative controls. An effect of starvation on the frequency of micronucleated erythrocytes (MN-E) was not discernable from the results of the present experiment.