Is the Coefficient of Detection Useful? A Critical Comment on the Summary Report of the Collaborative Behavioral Teratology Study

Behavioral teratogenic effect of methylmercury and d-amphetamine: meta-analysis and power analysis of data from the Collaborative Behavioral Teratology Study of National Center for Toxicological Research

The data of the Collaborative Behavioral Teratology Study (CBTS) were analyzed. Population-effect sizes were estimated, in terms of confidence intervals, by meta-analysis. A treatment effect of methylmercury was clearly observed and a dose-response effect was also observed. On the other hand, no clear treatment effect was observed in the d-amphetamine study. The effect of auditory startle habituation was very large, although it was limited to the high-dose group in the methylmercury study. The effects observed for physical landmarks were, as a whole, somewhat larger than those for behavioral measures. There is no clear evidence for sex-related differences except for activity measures. A curious treatment effect that was not referred to in the CBTS report was observed: eye-opening day and incisor-eruption day were hastened by the treatment of methylmercury. Power analysis results showed that obtaining a statistically significant effect for these compounds is very difficult, suggesting that even though published papers reported the significant effect of these compounds there might have been many unpublished experiments that obtained nonsignificant effects. If one uses these compounds as positive controls, a very large sample size will be needed. No highly sensitive test that is reproducible across compounds or dose-levels was observed among tests employed in the CBTS.

Behavioral teratogenic insult of methylmercury assessed by using sets of measures: reanalysis of data from the Collaborative Behavioral Teratology Study of National Center for Toxicological Research

The data of the Collaborative Behavioral Teratology Study were analyzed by using sets of measures simultaneously. A set of preweaning measures offered far more information as to treatment effects than a set of postweaning measures. The treatment effect observed in behavioral measures was also explained considerably by physical measures. However, the effect explained by uniquely behavioral measures (i.e., magnitude of semipartial R2) was also observed in some degree. A sex-related difference was observed in auditory startle response habituation appearing only later or earlier in life. The usefulness of using a set of measures and assessing the relationship among sets in behavioral teratology, in addition to conventional single measure analysis, was discussed.