The USGS has released a report showing that pollution, primarily from coal and auto exhaust, is leading to harmful amounts of mercury in fish throughout the U.S. As the introduction explains (bolding added):
Mercury (Hg) is a global pollutant that ultimately makes its way into every aquatic ecosystem through the hydrologic cycle. Anthropogenic (human-related) sources are estimated to account for 50–75 percent of the annual input of Hg to the global atmosphere and, on average, 67 percent of the total Hg in atmospheric deposition to the United States (Meili, 1991; U.S. Environmental Protection Agency, 1997; Seigneur and others, 2004). Elevated Hg concentrations that are attributed to atmospheric deposition have been documented worldwide in aquatic ecosystems that are remote from industrial sources (Fitzgerald and others, 1998).
The mercury flowing through the water ends up flowing through our veins as well:
Accumulation of MeHg in fish tissue is considered a significant threat to the health of both wildlife and humans. Approximately 95 percent or more of the Hg found in most fish fillet/muscle tissue is MeHg (Huckabee and others, 1979; Grieb and others, 1990; Bloom 1992). Women of child-bearing age and infants are particularly vulnerable to effects from consumption of Hg-contaminated fish (U.S. Environmental Protection Agency, 2001).
The report found dangerously high amounts of mercury throughout the U.S., but particularly, on the East Coast:
Hg concentrations in fish at more than two-thirds of the sites exceeded the value of 0.1 μg/g Hg ww that is of concern for the protection of fish-eating mammals, including mink and otters. Fish-Hg concentrations equaling or exceeding the 0.3 μg/g ww USEPA criterion for the protection of human health were found at 27 percent of the sites. The highest concentrations among all sampled sites occurred in fish from blackwater coastal-plain streams draining forested land or wetland in the eastern and southeastern United States, as well as from streams draining gold- or Hg-mined basins in the western United States.
The presence of mercury from old gold mines is noteworthy. Quite often, the market-oriented lovers of capitalism deride concern for the environment. But many of the mines that are causing problems were created 50 or 100 years ago. They made a few people rich and a century later are still making people sick! And they will probably continue to leech poison into the water for thousands of years. Business entrepeneurs and the government representatives that they buy off simply can't be trusted to look forward for decades or centuries so as to factor in the ultimate costs of what they do. The appearance of mercury throughout a key part of the foodchain is deeply disturbing. It shows limits to this growth-at-all costs mentality that drives so much of our thinking about the economy.