The Government Over Regulates Mercury

See Energy Fact of the Week: Mercury Rules and Public Health By Steven F. Hayward of AEI.

"Last week the Environmental Protection Agency finally re-issued its new mercury rules under the Clean Air Act, calling for a 91 percent reduction in mercury emissions from coal-fired power plants. Strangely, the EPA cannot estimate any health benefits from the mercury rules, and rests its entire case on the co-benefit of lower particulate emissions (17,000 premature deaths a year will be prevented by lower particulate levels).

Maybe one reason the EPA can’t estimate any health benefits from lower mercury emissions is that there aren’t any. Figure 1 below shows that mercury emissions have fallen 58 percent between 1990 and 2005 (the most recent year for which the EPA reports mercury data). Most of this reduction came from shutting down municipal incinerators and other industrial processes; mercury emissions from coal-fired power plants are down only 11 percent."

"But it is also the case that there may not be anyone with dangerously elevated levels of mercury, whether airborne or from fish. Figure 2 shows trends in blood lead levels in women of childbearing age from ten years’ worth of data from the Centers for Disease Control’s Human Exposure to Environmental Chemicals study. Average mercury levels in blood among all people the CDC screened are extremely low, about one-thousandth the level of the threshold of health risk. Women of childbearing age (16–49), however, have reason for concern. In the CDC’s 2000 screening, a small proportion of them (about 8 percent of the sample) recorded levels of mercury in blood samples above the government’s very strict “reference dose level.” The reference dose level of 5.8 micrograms per liter of blood is set to allow for the most extreme uncertainty about the effects of low-level exposure, and to serve as a tripwire for determining which populations are potentially at risk and whether exposure is increasing. (The government’s threshold of actual harm from mercury is 58 micrograms—ten times the reference dose, which is used as regulatory tripwire.) There is reason to doubt that any women or their unborn children face significant risk at this low level, but abundant concern warrants planting a caution flag. The good news is that subsequent CDC screenings have found almost no cases of women recording blood-mercury levels above the reference dose."