Environmental Engineering Reference
In-Depth Information
The percentage of mothers and women of childbearing age in Canada and Greenland that exceed
guideline limits for mercury in blood
We did not know the answer, but some important clues were emerging. We have already
seen that in mammals, mercury can cross the placenta into the foetus. Extrapolating from
knowledge of acute exposure effects, it was thought that children may be particularly vul-
nerable to upsets in their neurological development while in the womb. In 1992, Philippe
Grandjean and Pál Weihe and their colleagues published a paper that woke us all up. It
was a study from the Faroe Islands of umbilical cord blood sampled from more than 1,000
placentas taken from mothers at the time when they gave birth. Surprisingly high levels of
mercury were found. Maternal dietary information included in the study clearly related the
levels to a diet dominated by fish and marine mammals. This was not good news and it fea-
tured significantly in the heavy metals information compiled by AMAP for the CLRTAP
1994 report. I remember the resounding impact it made on the Executive Body to the con-
vention when it considered what actions to take. Grandjean, Weihe and colleagues then
began a benchmark study of a cohort of Faroese children who had been exposed prenat-
ally to known concentrations of mercury through placental transfer from their mothers. The
lasting legacy of this work will be seen a little later.
Now that we have digested a brief outline of what was known in the mid-1990s about
POPs and heavy metals pollution in the Arctic, we can return to the history of international
controls on these substances. At the end of 1994, Lars Lindau and I presented the POPs
state of knowledge report to the Executive Body of the CLRTAP. At the same time, the
heavy metals task force presented its report. To our great relief, it was decided that a legally
binding POPs protocol should be developed under the convention. However, these things
usually take two or three years to complete and the convention's negotiating body (called
the Working Group on Strategies and Review) had only the calendar year of 1997 avail-
able. It was decided to disband the POPs and heavy metals task forces and replace them
with a POPs preparatory working group and a heavy metals preparatory working group.
The new working groupswere instructed to prepare draft protocols but were to refrain from
negotiating any intractable issues. When these arose, alternative text would be prepared
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