In response to questions raised earlier about why breast milk is
singled out for toxic investigation:

The main reason that human milk is commonly used for estimating
chemical exposures in an entire human population is its high fat
content.  Many toxic substances are fat soluble.  They are present
inside our bodies in vanishingly small concentrations (parts per
billion or even parts per trillion) and yet apparently are biological
active even at these these low levels.

Therefore, to make good measurements--even with highly sensitive
equipment--you need a lot of volume of a fatty tissue.

Breast milk has eight times more lipid content than human blood.  (4
percent fat, vs. less than half percent fat).  Consider that four
ounce of expressed breast milk is pretty easy to obtain; 32 ounces of
blood is pretty daunting.

My colleagues in the Body Burden Dialogue Group who did have their
toxic body burdens estimated through blood and urine samples all
remarked on the sheer amount of each fluid they were required to
collect and submit over a period of time.  It was invasive and
exhausting.

(I personally think that liposuction samples would be a great
resource for this kind of investigation, but there are obvious
privacy issues.)

In the last few years, the technology to identify and measure low
levels of toxic substances in human tissues has improved, and the
cost and time required to do these studies has fallen.

So, now that it's more practical, there is a bigger interest in doing
human biomonitoring of all kinds--and on tissues other than human
milk.

For example, a study published last spring measured levels of
organophospate (OP) pesticides in the urine of preschool children in
Seattle. OP pesticides are widely used in fruit and vegetable
farming; they are more water soluble than other kinds of pesticides,
which is why we can use urine to estimate exposures.

Children with conventional diets had, on average, nine times more OP
pesticides in their urine than children fed organic produce.
[source:  C.L. Curl et al., "Organophorous Pesticide Exposures of
Urban and Suburban Pre-school Children with Organic and Conventional
Diets," Environmental Health Perspectives 19(2003): 377-83]

The question remains why this study received less press attention
than the flame retardants in breast milk study.  I know we all have
divergent (and very thoughtful!) opinions on this topic.

Nevertheless, studies of toxic substances in blood and urine are also
making headlines.

Those who are interested might wish to check out today's installment
of an excellent 15-part series on environmental health in the Gulf
States (Florida, Alabama, Mississippi, Lousiana, Texas) entitled
"Deep Trouble: The Gulf in Peril."  The journalist reports on
pesticides, dioxins, PCBs, heavy metals in communities ringing the
Gulf Coast and in the tissues of the people who live there, as well
as excessive cancer rates, birth defects, stillbirths, etc.

Never once is breast milk mentioned.

http://www.naplesnews.com/03/10/naples/d992434a.htm





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Sandra Steingraber, Ph.D.
Distinguished Visiting Scholar
Division of Interdisciplinary Studies
307 Job Hall
Ithaca College
Ithaca,NY 14850-7012
[log in to unmask]
www.steingraber.com

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