Benchmark dose calculations of methylmercury-associated neurobehavioural deficits.

Prenatal methylmercury exposure is associated with neuropsychological deficits in Faroese children at age 7 years. Lower confidence bounds of benchmark doses (BMDLs) have now been calculated. With the cord-blood mercury concentration as the dose parameter, a logarithmic dose-response model tended to show a better fit than a linear dose model for the attention, language and verbal memory tests. The lowest BMDLs averaged approximately 5 microgram/l cord blood, which corresponds to a maternal hair concentration of approximately 1 microgram/g. However, most BMDLs for hair mercury concentrations were higher. Thus, the results of the benchmark calculations depend on the assumed dose-response model.