Tuesday, April 27, 2010

The Hidden Danger in Our Waterways

Here in Nova Scotia, fishing season is well underway. Just yesterday I saw a number of folks out enjoying the sunshine with their hooks in the water, and chances are, at least some of them got lucky and took their prize home for supper that night.

But if they knew what was in that fish, they make have thought twice about making a meal out of it. Chances are extremely high that their meal was heavily contaminated with methylmercury. In fact, 80% of all “Fish Advisories” are due to mercury contamination.

What is Methylmercury, you might ask? Methylmercury is a substance that is produced when mercury, produced mainly by coal burning power plants, waste incinerators and other industries, falls from the sky and ends up in our lakes and rivers. It is also produced naturally by volcanoes and forest fires, and some leaches naturally from rock.

The mercury is converted to the more dangerous form, methylmercury, very easily and very naturally by anaerobic organisms in the water. This new form of mercury is easily absorbed in our digestive tract, and it accumulates in the body over time. (It can linger in our bodies for fifteen to twenty years.) It also readily crosses the blood-brain barrier and can also cross the placental barrier, making the developing fetus particularly vulnerable.

Long term exposure to tiny amounts in our food can cause neurodevelopmental problems, especially in children due to their smaller body mass. It can lead to permanent brain damage, heart disease, kidney failure, liver damage, loss of vision, and tremors. It is also an “endocrine disruptor” meaning that is can damage the reproductive and hormonal development of unborn children and infants.

As methylmercury accumulates in the flesh of fish, the larger and older the fish, the more methylmercury there will be in the flesh. Shark, tuna, and other large predatory fish contain the most, small fish like herring contain the least.

Mercury levels in Canadian lakes and rivers increase as you move from West to East, following the paths of prevailing winds. This is of great concern for us here in the Maritimes, as we are often referred to as “Canada’s Tailpipe”, referring to the pollution that seems to funnel through this area.

Scientists have concluded that there is no level of Mercury that is “safe” for us to consume. Unfortunately, governmental agencies, while issuing increasingly stern warnings every few years about the possible dangers of fish consumption, stop short at advising us to not eat any fish at all. Doing so would put a lot of hard-working fishermen out of business, not to mention anger an awful lot of recreational fishers.

However, based on the evidence we have today about the contamination of our waterways, I would suggest that you eat very little fish, if any, and avoid it altogether if you are pregnant, may become pregnant or are nursing. If you do eat fish, eat smaller, deep ocean fish and avoid those caught in inland waters.

Nova Scotia’s own 2010 Angling Guide advises the following:
“Traces of mercury have been detected in certain species of freshwater sportfish. The Nova Scotia departments of Health, Environment and Fisheries and Aquaculture advise people to limit consumption of these freshwater sportfish.

Rainbow trout have levels of contaminants below the Health Canada Guidelines and are safe to eat. Brook trout and white perch under 25 cm (11 in.) in length are also safe to eat. Consumption of brook trout and white perch larger than 25 cm should be limited to one meal once every week. Consumption of other freshwater sports fish should be limited to one meal every two weeks. Children under eight, pregnant women, and nursing mothers should consume only rainbow trout, white perch, and brook trout less than 25 cm (11 in.) in length.”

If there is no safe level of mercury, and our sportfish clearly are contaminated with mercury, as the government seems to acknowledge, then they should be advising us to avoid these contaminated fish altogether. To do otherwise, in the interest of politics, is doing us all a disservice.

Source: Slow Death by Rubber Duck, by Rick Smith and Bruce Lourie

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