Letters.

Hot topic

In the space of a single paragraph ("Global warming debate gets hotter," SN: 6/16/01, p. 372), you report that the National Academy of Sciences and the United Nations conclude that human activity "very likely" has caused global warming and that "uncertainties remain about the role of human-generated gas emissions." One can't have it both ways. Given the uncertainties involved, President Bush is following the prudent course of action.

Mark Strobach
Seattle, Wash.

Risk vs. effect

I am writing to correct a significant inaccuracy in your recent article "Landfills make mercury more toxic" (SN: 7/7/01, p. 4). As a member of the National Research Council's committee that produced the report you cite, I feel obligated to correct your statement, attributed to that report: "Some 60,000 U.S. children are born with developmental impairments triggered by fetal exposure to methyl mercury, usually as a result of their moms having eaten tainted fish."

The report actually states that "over 60,000 newborns annually might be at risk for adverse neurodevelopmental effects from in utero exposure to MeHg (methyl mercury)."

The intent of that statement was to convey that 60,000 children are born each year with in utero exposures that exceed the committee's estimate of a safe level of exposure. This does not, however, mean that these children will necessarily have impairments.

I do not, of course, intend this clarification to imply that methylmercury exposure is not a serious concern or that governments should not take steps to reduce mercury emissions to the environment. They should.

However, the distinction between being at risk for an adverse effect and actually having the adverse effect is critical to current notions of risk assessment and risk management.

Alan H. Stern
University of Medicine and
Dentistry of New Jersey-Robert
Wood Johnson Medical School
New Brunswick, N.J.