Persistent Organic Pollutants and Heavy Metals (Including Mercury) - The Changing Arctic Environment: The Arctic Messenger - page 148

We will delay a close examination of these potential health outcomes until the end of the
POPs story, when we can take a look at the most up-to-date information. However, the
following are examples of the types of human and wildlife outcomes that had been asso-
ciated with exposure to POPs in the laboratory and in wildlife and human populations at
the time of the 1994 CLRTAP reports: immune system dysfunction; reproductive impair-
ment caused by functional, physiological (including hormonal), anatomical and behavi-
oural changes; developmental abnormalities mainly appearing from the time of fertiliza-
tion to early infancy; carcinogenesis; and behavioural abnormalities ( Table 8.3 ). In 1986,
Rogan and colleagues published a prescient study involving more than 900 children in
NorthCarolina(UnitedStates)thatsuggestedthattransplacentaltransferofPCBsandDDT
from mother to unborn child depressed muscle reflexes in the newborn. This was really
the beginning of a new perspective on the toxicity of POPs that took a giant step forward
with the workofJoseph andSandra Jacobson andtheir colleagues. Beginning in1992,they
published a series of papers showing lasting neurological and behavioural effects in chil-
dren in Michigan (United States) whose blood was carrying high burdens of POPs at the
time of their mothers' pregnancy. The first publication was just in time for inclusion in the
CLRTAPstateofknowledgereport.Itwastohaveagreatimpactondecisionmakingunder
the CLRTAP and subsequent global negotiations for control of POPs. It was also at about
this time that Theo Colborn was bringing together all the diverse information that pointed
towards a number of POPs being able to disrupt the way in which hormones of the endo-
crine system coordinate the development of animals (including humans) from conception
to old age. Possibly many of the health effects listed here involve hormone disruption.
I want to pause again for another little digression - this time about biomagnification.
It is key to understanding the behaviour of POPs and mercury in the Arctic and it all de-
pends on the structure of the Arctic food web (trophic relationships). One of the neat tricks
that biologists keep in their “toolboxes” to investigate trophic relationships is stable iso-
tope analysis. This is how it works: As described in the introduction to radioactivity, the
atoms of any given element will always have the same number of protons in the nucle-
us, but there can be small differences in the number of neutrons. Of these different forms