On Sushi, Mercury, and Women’s Health: Can’t See the Pollution for the Fish
Amidst the relentless recent coverage of mercury in tuna, sushi and fish in general, I’ve read and heard a lot of hand-wringing over what is and is not a safe level of mercury, and how it’s really the pregnant women, the breastfeeding women, the pre-pregnant women (get it? the women!) who need to worry, but I haven’t heard one account that actually addresses how all this mercury gets in the fish in the first place.
In case you thought mercury fairies were poisoning your sushi just to ruin your trips to big coastal cities, here’s what the EPA says:
Mercury is found in the environment as a result of natural and human activities. The amount of mercury that cycles in the environment has increased since the industrial age. The main source of mercury is air emissions from power generation and other industrial and waste disposal activities.
Or, more explicitly, from a 2001 EPA report:
Solid waste incineration and fossil fuel combustion facilities contribute approximately 87% of the emissions of mercury in the United States. Other sources of mercury releases to the air include mining and smelting, industrial processes involving the use of mercury such as chlor-alkali production facilities and production of cement.
Mercury is released to surface waters from naturally occurring mercury in rocks and soils and from industrial activities, including pulp and paper mills, leather tanning, electroplating, and chemical manufacturing. Wastewater treatment facilities may also release mercury to water. An indirect source of mercury to surface waters is mercury in the air; it is deposited from rain and other processes directly to water surfaces and to soils. Mercury also may be mobilized from sediments if disturbed (e.g., flooding, dredging).
Sources of mercury in soil include direct application of fertilizers and fungicides and disposal of solid waste, including batteries and thermometers, to landfills. The disposal of municipal incinerator ash in landfills and the application of sewage sludge to crop land result in increased levels of mercury in soil. Mercury in air may also be deposited in soil and sediments.
In other words, the vast majority of the mercury that ends up in your air, dirt, water, and fish ultimately has a human industrial cause. Rather than fretting endlessly about how many bits of sushi our womenfolk can consume safely, we could focus on the cause and how to remedy it. Did I hear that discussed in all of this media coverage? No, no I didn’t.