Developmental neurobehavioral toxicity of butylated hydroxyanisole (BHA) in rats

Butylated hydroxyanisole (BHA) was fed to rats throughout development (from prior to conception through 90 days of postnatal age) in doses of 0, 0.125, 0.25 or 0.5 percent (w/w) of the diet. A fifth group was also prepared as a positive control by administering 50 mg/kg/day of the antimitotic agent hydroxyurea on days 2-10 of postnatal age. Offspring from all groups were reared by their natural dams and were evaluated blind with respect to treatment assignment in a battery of standardized behavioral tests between 3 and 90 days of age. BHA at 0.5% of the diet impaired offspring growth during the last week of preweaning development and increased preweaning mortality (13.5%). No changes in maternal weight, reproductive performance or mortality were observed. No reductions in offspring growth after weaning or changes in day 90 brain weights were found. BHA at 0.25 and 0.125% of the diet had no effect on growth, reproduction or mortality; although a marginal increase was seen in the 0.25% BHA offspring mortality up to 30 days of age (8.3%, p = 0.06). BHA at 0.5 and 0.25% of the diet delayed startle development and showed a marginal trend towards increased diurnal running wheel activity; no other behavioral effects were found. Comparison of the present results to a similar study using BHT clearly indicates that BHA at equivalent dietary doses is considerably less toxic than BHT. The present results also suggest that BHA is not a potent behavioral toxin, although it is developmentally toxic using non-behavioral measures.