TY - JOUR
T1 - Changes in blood lead after cessation of breastfeeding
AU - Gulson, Brian L.
AU - Mizon, Karen J.
AU - Patison, Nicole
AU - Korsch, Michael J.
PY - 2000/10
Y1 - 2000/10
N2 - We have monitored seven subjects postpartum for periods ranging from 9 to 22 months to observe the changes in blood lead (PbB) isotope ratios and lead concentrations as a function of length of breastfeeding. The length of breastfeeding varied from 1 day to 14 months. These subjects were part of a larger cohort who had been monitored pre-pregnancy, during pregnancy and for 6 months postpartum to establish the validity of the mechanism of mobilization of lead from the maternal skeleton. These are the first published PbB data, to our knowledge, of a longitudinal investigation for an extended period postpartum. We had hypothesised that after cessation of breastfeeding there would be a rapid return to pre-pregnancy isotopic levels as we had observed in one subject. In three cases, there was no significant decrease in isotopic composition, in two cases there was a rapid decrease but not until up to about 200 days after cessation of breastfeeding, and in the other two subjects there was a slow decrease in isotopic ratios. After reaching a minimum, half the subjects exhibited increases in isotope ratios and, in all cases, there appeared to be an equilibrium reached with estimated skeletal/tissue contributions to PbB of about 60% to 80%. In contrast, there was a decrease in PbB concentrations to about half the earlier levels almost immediately after cessation of breastfeeding. However, in four of the seven cases there was a rebound of PbB, which in three cases exceeded the earlier levels. We interpret these results to indicate that there is ongoing mobilization of lead from maternal tissues for a much longer period than predicted. This sustained mobilization does not appear to be related to length of breast feeding, resumption of menses, and is inconsistent with conclusions from other lactation studies using bone mineral density and calciotropic hormones. Quarterly monitoring of air, house dust, drinking water and a 6-day duplicate diet indicates that the environmental exposures contribute only a small amount to the PbB of the subject.
AB - We have monitored seven subjects postpartum for periods ranging from 9 to 22 months to observe the changes in blood lead (PbB) isotope ratios and lead concentrations as a function of length of breastfeeding. The length of breastfeeding varied from 1 day to 14 months. These subjects were part of a larger cohort who had been monitored pre-pregnancy, during pregnancy and for 6 months postpartum to establish the validity of the mechanism of mobilization of lead from the maternal skeleton. These are the first published PbB data, to our knowledge, of a longitudinal investigation for an extended period postpartum. We had hypothesised that after cessation of breastfeeding there would be a rapid return to pre-pregnancy isotopic levels as we had observed in one subject. In three cases, there was no significant decrease in isotopic composition, in two cases there was a rapid decrease but not until up to about 200 days after cessation of breastfeeding, and in the other two subjects there was a slow decrease in isotopic ratios. After reaching a minimum, half the subjects exhibited increases in isotope ratios and, in all cases, there appeared to be an equilibrium reached with estimated skeletal/tissue contributions to PbB of about 60% to 80%. In contrast, there was a decrease in PbB concentrations to about half the earlier levels almost immediately after cessation of breastfeeding. However, in four of the seven cases there was a rebound of PbB, which in three cases exceeded the earlier levels. We interpret these results to indicate that there is ongoing mobilization of lead from maternal tissues for a much longer period than predicted. This sustained mobilization does not appear to be related to length of breast feeding, resumption of menses, and is inconsistent with conclusions from other lactation studies using bone mineral density and calciotropic hormones. Quarterly monitoring of air, house dust, drinking water and a 6-day duplicate diet indicates that the environmental exposures contribute only a small amount to the PbB of the subject.
UR - http://www.scopus.com/inward/record.url?scp=0034473430&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:0034473430
SN - 1522-7987
VL - 2
SP - 235
EP - 240
JO - Environmental Epidemiology and Toxicology
JF - Environmental Epidemiology and Toxicology
IS - 4
ER -