Do human milk concentrations of persistent organic chemicals really decline during lactation? Chemical concentrations during lactation and milk/serum partitioning.
BACKGROUND
Conventional wisdom regarding exposures to persistent organic chemicals via breast-feeding assumes that concentrations decline over the course of lactation and that the mother's body burden reflects her cumulative lifetime exposure. Two important implications stemming from these lines of thought are, first, that assessments of early childhood exposures should incorporate decreasing breast milk concentrations over lactation; and, second, that there is little a breast-feeding mother can do to reduce her infant's exposures via breast-feeding because of the cumulative nature of these chemicals.


OBJECTIVE
We examined rates of elimination and milk/serum partition coefficients for several groups of persistent organic chemicals.


METHODS
We collected simultaneous milk and blood samples of 10 women at two times postpartum and additional milk samples without matching blood samples.


RESULTS
Contrary to earlier research, we found that lipid-adjusted concentrations of polybrominated diphenyl ethers, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and furans, and organochlorine pesticides in serum and milk do not consistently decrease during lactation and can increase for some women. Published research has also suggested an approximate 1:1 milk/serum relationship (lipid adjusted) on a population basis for 2,3,7,8-tetrachlorodibenzo-p-dioxin; however, our results suggest a more complex relationship for persistent, lipophilic chemicals with the milk/serum relationship dependent on chemical class.


CONCLUSIONS
Decreases in concentration of lipophilic chemicals on a lipid-adjusted basis during lactation should no longer be assumed. Thus, the concept of pumping and discarding early milk as means of reducing infant exposure is not supported. The hypothesis that persistent lipophilic chemicals, on a lipid-adjusted basis, have consistent concentrations across matrices is likely too simplistic.
LaKind
Judy S
JS
LaKind Associates, LLC, Catonsville, Maryland, USA. lakindassoc@comcast.net
Berlin
Cheston M
CM
Sjödin
Andreas
A
Turner
Wayman
W
Wang
Richard Y
RY
Needham
Larry L
LL
Paul
Ian M
IM
Stokes
Jennifer L
JL
Naiman
Daniel Q
DQ
Patterson
Donald G
DG
D001942:Breast Feeding; D004147:Dioxins; D004785:Environmental Pollutants / Q000097:blood* / Q000378:metabolism; D005260:Female; D055768:Halogenated Diphenyl Ethers / Q000097:blood / Q000378:metabolism; D006801:Humans; D006843:Hydrocarbons, Chlorinated / Q000097:blood / Q000378:metabolism; D007231:Infant, Newborn; D007774:Lactation / Q000097:blood* / Q000378:metabolism*; D008895:Milk, Human / Q000737:chemistry* / Q000378:metabolism*; D010573:Pesticide Residues / Q000097:blood / Q000378:metabolism; D011078:Polychlorinated Biphenyls / Q000097:blood / Q000378:metabolism; D011247:Pregnancy
D004147:Dioxins; D004785:Environmental Pollutants; D055768:Halogenated Diphenyl Ethers; D006843:Hydrocarbons, Chlorinated; D010573:Pesticide Residues; D011078:Polychlorinated Biphenyls