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Study links factories with mercury levels in fish

by Archives October 16, 2007

EDMONTON (CUP) – New research is suggesting a powerful link between atmospheric mercury, and increased mercury levels in fish. Now, the researchers are calling for increased regulations on mercury emissions from industry.
According to a new study by an international contingent of researchers, the mercury showing up in fish comes from factory emissions produced on dry land. The group of 24 North American researchers includes Vincent St Louis, a University of Alberta professor of watershed biogeochemistry; and Jennifer Graydon, a PhD candidate in biological sciences.
Vincent St Louis, a watershed biogeochemist from the University of Alberta, explained that until now there was no study definitively linking higher levels of mercury in the atmosphere to higher levels of mercury in fish.
Instead, he said, legislators pointed to other causes for the rise in mercury found in fish.
“For example, climate change. If a lake’s warming up, it increases the microbial activity that converts the [type of] mercury in rain to the [type found in fish],” St Louis said. “So [previously], legislators could have said, ‘Well, it’s climate change causing this mercury problem in fish, so we don’t really need to regulate how much mercury we’re putting out into the atmosphere.'”
The results of this new study finally link atmospheric mercury emissions to mercury in fish, he said.
“When you burn coal, coal has a lot of mercury in it. So, you burn coal to produce energy, for example, at Lake Wabamun. The mercury goes up in the atmosphere,” St Louis said.
This mercury in the atmosphere then turns into a form of ionic mercury captured in rainfall. Rain falling into lakes and streams then comes into contact with bacteria that convert the ionic mercury it into methyl-mercury.
From there, the methyl-mercury finds its way into algae, then into fish, and finally into humans that eat these fish.
To prove the complex cycle, the group of researchers went to the Experimental Lakes Area in northwestern Ontario. They chose a lake with low levels of mercury, and with special permission, poured in approximately one teaspoon of inorganic mercury.
To make sure that any rise in methyl-mercury levels in fish in this lake was due to this increase in inorganic mercury and not any other factors, they used an easily identified isotope.
“What we found was that the [inorganic] mercury that we put in the lake directly showed up in the fish rapidly [in an organic form],” St. Louis said.
And, as Graydon pointed out, mercury does quite a bit of harm in living organisms.
“[It mostly has] neurological effects: stumbling, slurred speech, blurred vision, [and], in the very worse scenarios, total neurological death,” she said.
As a result, Health Canada advises people to limit their consumption of fish known to have high mercury levels to no more than once per week.
However, according to St Louis, despite the fact that ingesting mercury has long been known to be harmful, mercury emissions have remained, until now, either unregulated or under voluntarily regulations.
He said that this is because there was previously little proof of mercury emissions from factories affecting mercury levels in the human diet.
St. Louis now hopes that, in light of these results, the lack of regulation will change on an international scale, noting that mercury emitted from one country often ends up in the lakes and streams of another.
“Politicians used to say, ‘We can’t enforce these regulations because there is no direct link,'” St. Louis said. “Now they can’t say that because there is a direct link. Now it becomes the argument of, ‘If we do remove mercury from the emissions, it will cost all this money and cost all these jobs.'”
“In the acid rain days, they actually said the exact same thing: ‘This is going to cause a loss of jobs.’ It didn’t. It really didn’t. It actually pays off for industry to lower their emissions.”
St. Louis suggested that one factory could benefit by selling their emission credits to another factory, and that capping mercury emissions might even pay off in other ways.
“If you start looking at health benefits and things like that, those are big payoffs that are never accounted for in statements of the cost associated with putting in regulations.”

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