Persistent Organic Pollutants and Heavy Metals (Including Mercury) - The Changing Arctic Environment: The Arctic Messenger - page 159

ing lower levels. A study published in 2012 showed that mercury levels in Svalbard polar
bear teeth have dropped over the last 40 years but with no changes over the same period
in the stable isotope ratios of nitrogen ( δ 15 N) and carbon ( δ 13 C). You will remember from
our digression on food web dynamics that this suggests that it is unlikely that the trend to
lower mercury concentrations reflects changes in their diet. Most probably, it represents
decreasing atmospheric deposition to eastern North Atlantic seawater and to lower regional
emissions from Europe.
The basic question that matters to most of us is whether these levels are likely to have
animpactonArcticwildlifeandthepeoplelivingintheArctic.Mercuryhasbeenknownto
have toxic properties for many years. The English term mad as a hatter shows that even in
the eighteenth and nineteenth centuries, it was understood that long-term chronic exposure
could lead to serious neurological and behavioural abnormalities. This colloquial phrase
comes from the dementia suffered by the hatmakers at the time, who used mercury to treat
the felt used in hat production. In more modern times, these properties gained notoriety
in Minamata, Japan, where from 1932 to 1968, industrial wastewater was discharged into
Minamata Bay and the Shiranui Sea. Aggressive biomagnification of methylmercury took
place, leading to very high concentrations in local shellfish and fish. People who consumed
these species began to suffer from a wide range of neurological and muscle problems, in-
cluding difficulties with vision, hearing, speech, numbness, muscle weakness and, in more
severe cases, insanity, coma and death. The syndrome became known as Minamata disease
and it was eventually realized that these outcomes were caused by exposure to methylmer-
cury through diet. What was especially disconcerting was the realization that children were
particularly vulnerable and could acquire a dose leading to significant effects while still in
the womb.
In the 1970s, Canadians in Ontario also became tragically familiar with methylmer-
cury through very similar circumstances. In 1962, a chloralkali industrial plant began to
discharge wastes into the Wabigoon and English rivers, but it was not until 1970 that com-
mercial fishing was closed due to the discovery of widespread mercury contamination.
Meanwhile, identical symptoms to those found in Minamata with the same sad conse-