Transfer of 85Sr through the placenta and mother's milk. II. Changes in the specific radioactivity in suckling mice

Abstract

In suckling mice which were born from an "Sr-contaminated mother and nursedby her breast rnilk, the accumulation of "Sr increased rapidly after birth.Taking the growth process of suckling mice into consideration, the specific activitieswere expressed as per cent of dose per mg ash in order to provide more exact deserip-tions on the changes of "Sr concentration in the suckling mice.During the nursing period, suckling mice showed no significant decrease in specificactivities when they were born frorn an "Sr-contaminated mother and nursed by herbreast milk, or when they were born from an intact mother arnd nursed by an "Sr-corntaminated foster-mother. In sucklings which were born from an "Sr-contaminatedmother and nursed by an intact foster-mother soon after birth, a significant decreasein specific activities was observed, and the value at weaning was much less than 10%of the value at birth.It should be mentioned, therefore, that the contamination of sucklings with theradioactive strontium in mothers milk is one of the important problems, like the con-tamination of fetuses during gestation through the placenta.