some bits from an online issue of Hazardous Substances Review

[Philip Fleischer <philip@coc.powell-river.bc.ca>]

The following item is copied from a sample electronic issue
of "Hazardous Substances Review" (which I got to via
http://www.ozemail.com.au/~paulr/hazlnk.html, not sure of the
actual page url now)

Be interesting to see the data they are so far holding back..
....................

Effects of PCBs and dioxins on growth and development

There are a possible 209 polychlorinated biphenyls, 75
polychlorinated dibenzodioxins, and 135 polychlorinated
dibenzofurans. While the toxicity evaluation of these
substances has, in the past, centred on carcinogenicity
and acute toxicity (for dioxins), the reproductive and
neurobehavioural toxicity of these related compounds has
received much warranted attention in recent times.

The Dutch Multicenter study attempts to answer some of
the questions concerning the risk of infants ingesting these
compounds from mothers milk. One question to be answered
is whether these compounds have a subtle adverse effect on
the growth and development of infants, perhaps in a similar,
but not biochemically identical, manner as the metal lead.
The epidemiology of such exposures is made difficult not
only by the subtlety of such effects but by the large number of
individual compounds involved and the variation in toxicity
of many individual congeners.

Nevertheless, existing studies by Taylor, Rogan and the
Jacobsens point to measurable adverse effects on childhood
development from PCB exposure.

In this study 400 mother-infant pairs were studied, half
being breast fed, while the other half received a formula devoid of
PCBs and dioxins. Growth and development were carefully
documented but definitive data were not available in this
report. However, a significant negative correlation was found
between some dioxin and PCB congeners in milk and
plasma thyroid hormones in pregnant women, while newborn
infants showed higher thyroid stimulating hormone (TSH)
at higher levels of dioxin exposure. This could have
implications for neurotoxicity.

Further results are expected from this study.

Sauer PJ, Huisman M, Koopman-Essenboom C, et al. Effects of
polychlorinated biphenyls (PCBs) and dioxins on growth and development.
Human and Experimental Toxicology 13, 900-906, 1994.

Taylor PR et al. The relation of polychlorinated biphenyls
to birth weight and gestational age in the offspring of
occupationally exposed mothers. American Journal of Epidemiology
129, 395-406, 1989.

Rogan WJ et al. Congenital poisoning by polychlorinated biphenyls
and their contaminants in Taiwan. Science 241,
334-366, 1988.

Jacobsen JL et al. Effects of in utero exposure to
polychlorinated biphenyls and related contaminants on cognitive
functioning in young children. Journal of Paediatrics 116,
38-45, 1990.





Philip Fleischer    Philip@coc.Powell-River.BC.CA    604/483-4701