I hope no one throws a tizzy-fit, but I'm pasting my Breastfeeding
Abstracts commentary on contaminants directly into LN. I believe it was
published in last winter's BA.

ABSTRACT OF: Milestone Development in Infants Exposed to Methylmercury from
Human Milk.  by P. Grandjean, P. Weihe, and RF. White.  Neuro Toxicology
1995; 16(1):27-34.
ABSTRACTER: Chris Hafner-Eaton, PhD, MPH, CHES
Purpose: Although human milk has been repeatedly demonstrated to enhance
mental and psychomotor development in children, the neurotoxic effects of
environmental pollutants transferred via breastfeeding were unclear and
undocumented.  Previous research focused on prenatal exposures and failed
to control for breastfeeding status or duration; although studies of
polychlorinated biphenyls (PCBs) have included breastfeeding with the
results being protective in spite of PCB transfer through the breastmilk.
This study investigated the significance of methylmercury exposure, a known
neurotoxicant, from human milk in Faroese infants.
Method:  Granjean, Weihe, and White followed a birth cohort from
consecutive deliveries during a 21 month period in 1986-1987 at three
hospitals in the Faoroe Islands where high consumption of contaminated
seafood was prevalent.  Questionnaire data, and samples of umbilical cord
blood and maternal hair for mercury analysis were obtained from 1022
singleton births (75.1% of all deliveries).  Midwives collected
questionnaire data regarding pregnancy course, dietary habits (frequency of
fish and pilot whale), and the use of alcohol and tobacco.  Additional
information obtained from hospital charts and midwife recordings included
parity, course of the parturition, birth weight and length and other
relevant information.   Following the birth, home visits by nurses provided
data for the month (5-12 months) that developmental milestones were
achieved for sitting without support, creeping, and getting to a standing
position with support.  The duration of nursing without supplements and age
at weaning were also scored in months.  Nonparametric statistical methods
were used because the data did not fit a normal Gaussian distribution
necessary.  Correlations were deemed significant using Spearman's
correlation coefficient, and differences between groups by the Mann-Whitney
U-test.
Results:  Only 15 infants were not nursed at all, with 97.4% breastfeeding
for at least 1 month.  One hundred (17.2%) were breastfeed for 2 months or
less, and 143 (24.5%) were breastfed for 3 months or less.  Human milk was
the sole source of nutrition for a median of 4 months, and weaning followed
at a median age of 7 months.  The age at which the child reached a
developmental milestone was not associated with indices of prenatal mercury
exposure, i.e., the  mercury concentrations in umbilical cord blood and in
maternal hair (p> 0.4 by Spearman's).  The same lack of correlation existed
for infants who were not breastfed at all or only briefly.  However,
milestone development was associated with the child's mercury burden at 12
months of age.  The results show a paradoxical relationship where the
longer a child was breastfed, the higher the child's hair mercury
concentration, and the earlier the child reached the developmental
milestones, i.e., indicating an advantage associated with breastfeeding.
Even among those breastfed for at least 3 or 4 months, early milestone
development was clearly associated with the child's hair-mercury
concentration.  These correlations were in an unexpected direction for all
three milestones.  Other potential confounders exhibited statistically
significant correlations with breastfeeding duration: smoking (median of 8
months for non-smokers vs. 5 months for smokers); increasing maternal age;
marital status (6 months for unmarried vs. 8 months for married mothers);
and low birthweigth.  These parameters were not associated with maternal
mercury exposure.   Major predictors of maternal mercury exposure included
seafood consumption, parity and alcohol intake, but these were not related
to the duration of breastfeeding. Only low birth weight was both a
significant predictor of length of breastfeeding (briefer) and delayed
milestone development.
Implications: This study suggests that breastfeeding is associated with an
advantage with regard to developmental milestone attainment in infants,
despite documented neurotoxic methylmercury transfer via breastmilk.  While
the study cohort was not a representative sample, selection factors (e.g.,
lack of a district health nurse or reluctance to accept nurse's visits) did
not appear to affect  the tendencies observed.  There appears to be
beneficial effects associated with breastfeeding such that the neurotoxic
effects on milestone attainment are overruled or compensated.  Had exposure
to mercury through milk caused neurotoxic effects in this study, the
duration of breastfeeding would have acted as a predictor for
neurobehavioral delays.   Clearly, three milestone measurements are limited
in their predictive power of subtle forms of neurotoxicity and time of
neurobehavioral assessment is also important.  Thus, we should not assume
that methylmercury from seafood is not a neurotoxicant.

: )Chris Hafner-Eaton, PhD, MPH, CHES, IBCLC  email: [log in to unmask]   : )
: )HSR & Health Educational Consultant        voice/fax: 541 753 7340    : )
: )LLLLLLLLLLLLL**CHANGE THE WORLD, NURTURE A CHILD!**LLLLLLLLLLLLLLLLLL : )