A COMPARISON OF THE LACTATIONAL AND TRANSPLACENTAL DEPOSITION OF MERCURY IN OFFSPRING FROM METHYLMERCURY-EXPOSED MICE - EFFECT OF SELENO-L-METHIONINE

Females exposed to methylmercury expose their offspring to mercury acr oss the placenta as well as through milk. The relative importance of t hese two routes of exposure has hitherto been unresolved. Using a cros s-fostering model with female mice, the transplacental and lactational exposures to mercury were evaluated separately. In female mice expose d to low, non-toxic levels of methylmercury in the drinking water the deposition of mercury in offspring before birth was quantitatively mor e important than later transfer of mercury from milk to offspring. Sel eno-L-methionine supplementation of the dams increased the whole-body deposition in offspring. As methylmercury is anticipated to be absorbe d completely and the young mice are unable to excrete mercury, these d ata indicate that seleno-L-methionine affects the kinetics of the inor ganic mercury pool, which, due to demethylating processes, is present in both blood and milk of methylmercury-exposed females.