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From:
Sandra Steingraber <[log in to unmask]>
Reply To:
Lactation Information and Discussion <[log in to unmask]>
Date:
Sun, 10 Jun 2001 11:22:20 -0400
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Dear Lactnet colleagues,

I've been a subscriber to Lactnet for a couple of months now, but
have been traveling so wanted to wait and send this introduction once
I was home again.  In the meantime, I learned that someone on the
list made reference to an essay I wrote ("A Mother's Lament") and
also posted an excerpt from a lecture I gave in Toronto a few years
ago. This evidently prompted vigorous discussion on the issue of
dioxins in breast milk (during the last week of April). Now that I'm
back in town, I've had a chance to read the archives and can respond
briefly.  My apologies for joining the conversation belatedly.

But first, my introduction.  I'm a biologist at Cornell University
and am associated with a project here called the Program on Breast
Cancer and Environmental Risk Factors. Our primary objective is to
examine the role that environmental contaminants play in contributing
to breast cancer.  In the capacity, we are very interested in how
lactational history modifies breast cancer risk (i.e., is
protective). My recent research specifically focuses on a number of
questions related to lacation:  1) the life history of the breast
from embryonic development through pregnancy, breastfeeding, weaning,
and menopause; 2) the presence of chemical contaminants in breast
tissue and breast milk and their possible relevance to a) breast
cancer in the mother and b) developmental problems in the nurslings;
3) how the presence of breast milk contaminants changes through the
period of lactation;  4) how the functioning of various constiuents
of breast milk (e.g. immunoglobulins) may be compromised by the
presence of chemical contaminants (e.g. immunosuppressive chemicals,
such as PCBS and dioxins); and 5) how the presence of certain
contaminants might interfere with milk production (possibly through
endocrine disruption, e.g. prolactin and oxytocin pathways).

I know that the chemical contamination of breast milk is a hot button
topic, but I do feel that public health is never served by keeping
secrets or failing to ask certain questions.  I should add here that
I'm a breastfeeding mother of a 2.5 year old and am now, at age 41,
seven month pregnant with my second child, whom I hope to breastfeed
at least as long (probably in tandem with my first born).  Whenever I
speak to the public--or to my colleagues in the sciences--on these
issues, I always begin by stating that breast milk, however
chemically contaminated, is still a far better food for babies than
its inferior pretender, infant formula.  Nevertheless, breast milk
could be better still if we got the chemicals out of it--meaning out
of women's bodies, which are the first environment for all of us,
meaning out of the larger environment in which women's bodies
co-exist.  I usually conclude by saying that the goodness of breast
milk has been compromised by the presence of chemical contaminants,
and even though, thus compromised, it still does not injure babies as
severely as formula does, we shouldn't wait until breast milk is as
dangerous to infants as formula before taking action.  Hopefully, my
always acknowledged identity as a breastfeeding mother makes this
message clear.  In 1999, when I testified at the United Nations in
Geneva on the issue of breast milk contamination, for example, I
passed around a jar of my own breast milk so all the delegates could
see that I was talking about a sacrament of motherhood, not toxic
waste.

I won't try to respond to all the issues and questions brought up on
this list six weeks ago, but here are a few salient findings I've
uncovered in the literature that may address some of them:

--on average, breast milk is 10-20 times more contaminated with
persistent fat-soluble chemicals (dioxins, PCBs, chlorinated
pesticides) than cow's milk.  This is because breast exists higher on
the food chain, and these chemicals biomagnify with every link
ascended.  Infant formula is actually even less contaminated than
cow's milk because its fats (oils) are derived from plants rather
than animals. (This does not include pesticides that might be found
in tap water, with which formula is often mixed.)

--The U.S. does not have a breast milk monitoring program, so it's
really impossible to know what's going on in this country.  However,
German and Dutch studies show that breastfed babies have
significantly higher levels of persistent organic pollutants in their
blood serum than bottle-fed babies.  These differences persist
through childhood, so that 3.5 year old children breastfed as infants
still have 4 times more pcbs in their blood serum than children who
had been formula fed.  The longer the duration of breastfeeding, the
higher the levels.

--You can't get rid of dioxins by dieting.  They have a half life of
about 8 years in the human body.  When you burn body fat, you don't
metabolize the contaminants it contains; you simply release the
dioxins stored there into your bloodstream.  They then resettle in
your remaining fat reserves, which you always have, even if you burn
all your subcutaneous fat.  (You have large reserves of fat in your
liver, brain, adrenal glands, and in the lipid fraction of blood, for
example.)  That's the problem with dioxins and other fat-soluble
persistent contaminants:  you can't easily metabolize and pee them
out.   Lactation, which does remove fat from a woman's body, is the
only effective way to "purge" dioxin from the body.  (There are a
couple of exceptions regarding  bile duct excretion and the effect of
chronic diarrhea, which I can explain in more detail if anyone is
interested.)

--The fat found in breast milk is mostly drawn from fat reserves laid
down over a lifetime, not fat in the current diet.  The best
estimates that I've been able to find indicate that 60 percent of the
fat in breast milk fat globules comes from body fat reserves, with
only 30 percent from current diet, and 10 manufactured de novo in the
breast itself.  This is why breast milk contains such high levels of
chemicals, like PCBs and DDT, which were banned for use years ago.
The fat in the breast itself is normally  not metabolized during
lacation.


--In spite of all this, as a group, breastfed babies still outperform
their formula-fed counterparts on tests of intelligence, immunity,
and psychomotor skills.   However, the real test of whether breast
milk contamination is harming babies would be to compare breastfed
babies drinking contaminated milk with breastfed babies drinking
contaminant-free milk.  This study cannot be carried out because all
women on the planet have contaminated breast milk.  (DDT is the most
widespread contaminant worldwide; PCBs are the most commonly found
contaminant in the breast milk of mothers living in industrialized
countries.)  Therefore, the best we can do is to compare babies who
receive breast milk that less contaminated than average with babies
that receive breast milk that is more contaminated than average.  The
Dutch have done this.  Their findings show subtle but measurable
differences:  babies whose mothers have less contaminated milk
perform better on certain tests of infant development that babies
whose mothers' milk is in the higher percentiles of contamination.

--prental exposures to dioxins are actually less, not more, than
breast milk exposures (10-20 times lower), but these smaller, earlier
exposures still seem to be more significant in creating developmental
problems later on.

--levels of contaminants in breast milk drop rapidly with
breastfeeding duraction.  After six months, levels of organochlorines
are 20 percent lower than those at birth.  One U.S. mother of twins
who nursed for three years dropped her body burden of dioxins by 69
percent.

--first-born children receive more chemical contaminants than their
later-born siblings, and older first-time mothers have higher levels
of contaminants in their milk than younger first-time mothers.

--the good news:  the Swedish breast milk monitoring program, which
is the gold standard and has been operating for 30 years, shows
significant drops in dioxin and ddt levels since the 1980s.  These
drops reflect stricter European laws in the use and manufacture of
these chemicals, incinerator closings, etc.  That is to say,
political action does work to clean up breast milk.

Hope this is helpful.  There is a wonderful new website, "Healthy
Milk, Healthy Baby," about breast milk contamination, created by Dr.
Gina Solomon at the National Resources Defense Council, if you want
more details.  It has a very pro-breastfeeding focus.  The url is
http://www.nrdc.org/breastmilk/

warmly,

Sandra Steingraber
--
--

Sandra Steingraber, Ph.D.
Visiting Assistant Professor
Program on Breast Cancer and Environmental Risk Factors
110 Rice Hall
Cornell University
Ithaca, NY  14853
[log in to unmask]
www.steingraber.com

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