B C Ulbrich

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Five laboratories collaborated in the evaluation of detection limits of different testing concepts in behavioral teratology. In one laboratory, rat dams were treated by gavage with five doses of methylmercury (0.0, 0.25, 0.05, 0.5, and 5.0 mg/kg/day). The treatment period was restricted to days 6 to 9 of gestation. The usual reproduction parameters were(More)
Male and female Wistar rats exposed to methylmercury chloride prenatally via drinking water (1.5 and 5.0 mg/l) were tested in a microcomputer-directed learning task (visual discrimination reversal) at the age of two months. Differences were observed between control and high dose group for several parameters, the most obvious being an increase in passiveness(More)
Three laboratories collaborated to evaluate and compare different test concepts to be used for routine testing in behavioral teratology. Rat dams were treated orally with methylmercury starting two weeks prior to pairing until weaning of their offspring. In the first laboratory, the usual reproduction parameters were assessed in the dams, and all offspring(More)
It is difficult to understand why culling (reduction of litter size) has become such a widely used procedure in reproductive toxicity studies since there appear to have been no prior investigations to ascertain that it would improve the efficiency of studies with respect to detecting adverse effects. Perhaps the only provable advantage of culling is with(More)
Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the development of rat offspring were studied after administration of a loading dose of 300 or 1000 ng TCDD/kg body wt on day 19 of pregnancy, followed by weekly maintenance doses of 120 or 400 ng TCDD/kg body wt. The dose regimens led to a fluctuation of average TCDD concentrations in the liver of(More)
Tests for detection of neurobehavioral changes in the offspring have been a regulatory requirement in developmental toxicity testing of drugs for almost 20 years. Keeping their purpose of hazard identification and risk assessment for humans in mind, investigators and agency reviewers have become deeply ingrained with some stereotyped behaviors with respect(More)
Behavioral end points for neurotoxicity risk assessment have been developed and examined over the past three decades. They are now ready to move from simple qualitative guidelines, such as exemplified by reference doses, to more quantitative models, such as benchmark doses, based on dose-response information. Risk assessors, confronted by a wider array of(More)
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