A report on the potential health effects of environmental tobacco smoke (ETS) or second-hand smoke raises serious questions about the science behind the controversial risk assessment released by the Environmental Protection Agency (EPA) in January 1993.

The EPA report concluded that ETS is a known human carcinogen, responsible for about 3,000 lung cancer deaths per year among nonsmokers.

However, the Congressional Research Service (CRS) criticized the EPA in its November 1995 review, stating that "...even at the greatest (exposure) levels, the measured risks are still subject to uncertainty" and "it is possible that very few or even no deaths can be attributed to ETS."

• The EPA based its risk assessment on analysis of 30 epidemiological studies of lung cancer among adult nonsmoking women which assumed that if their spouse smoked, they were exposed.

• EPA then carried out a rarely used statistical exercise known as meta-analysis to conclude that ETS increased the overall risk of lung cancer in nonsmoking women by 1.19 to 1.

• The CRS points out that the studies used depended on the recall of participants and that many of the women may have been misclassified in the wrong risk categories, resulting in potentially dramatic overstatements of risk.

• Additionally, the CRS points out that EPA's risk assessment did not account for the substantial dilution and aging of such sidestream smoke compared to even low levels of active smoking.

The CRS and the Department of Energy (DOE) previously released critical reviews of proposed workplace standards for ETS from the Occupational Safety and Health Administration (OSHA). The DOE stated that "OSHA did not provide an explicit rationale for the science policy decision that chronic exposure to ETS increases lung cancer risk by 20 to 50 percent."

Source: "Congressional Report Faults EPA on ETS Risk Assessment," EPA Watch, Vol. 4, No. 21, November 30, 1995.