Solvents, Ethanol, Car Crashes & Tolerance
How risky is inhalation of organic solvents?
Other Considerations and Implications
These simulations necessarily simplify complex real-life situations, which involve many variables that are not considered here. For example, single-car crash fatalities are not the only effect of ethanol, just one that has been linked quantitatively to intoxication. Many other costs are associated with driving errors, including injury, hospitalization, property damage and insurance claims; abuse of ethanol exerts other societal costs as well. In addition, 16–20 year-old drivers—those most likely to be involved in fatal car crashes—were excluded from this analysis. Thus we have probably underestimated both the risk of a car crash from acute solvent intoxication and its costs.
Our simulations were all based on exposure to a single volatile chemical, and it is unlikely that there would be only one solvent in the air. Other solvents have the same effects on behavior, and their effects are probably additive, as would be the combined effect of inhaling a solvent and drinking alcohol.
This analysis does not consider the size of the risk pool, that is, the number of people who are exposed to airborne solvents at concentrations around 0.5 ppm. The EPA’s National Air Toxics Assessment from 2002 (http://www.epa.gov/ttn/atw/nata2002/tables.html) showed that statewide average ambient concentrations of toluene are no greater than 0.0015 ppm, but individual “hot spots” near industrial locations can be much greater. The public health risk of these exposures must include information about the number of people exposed.
From a regulatory perspective, this analysis suggests that setting standards on the basis of chronic exposure protects public health from the long-term hazards of continuous exposure to chemicals but does not consider the potential consequences of acute, episodic exposure to chemicals. Efforts at the EPA are underway to address this concern, and time and support are needed to develop and implement appropriate procedures to do so. The approach of linking effects of toxicants to familiar, well-documented chemicals like ethanol may prove valuable in addressing this problem more generally.
Finally, these considerations illustrate that, in the end, management of risk is not a scientific problem. Decisions about acceptable exposure will ultimately be made balancing tradeoffs among benefits and costs of the chemical to society, including lifestyle, economics, environmental justice, and public and environmental health, as guided by the legislation governing that chemical. Few people are apparently willing to stop driving due to the risk of car crashes, and it is unlikely that awareness of possible effects of airborne solvents will alter this choice. In the end, we all manage our risks for ourselves, assiduously avoiding carcinogens like benzene while ignoring the acute risks inherent in driving. Put simply, nobody wants leukemia, but everyone wants to drive.
The research described in this article has been reviewed by the National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, and approved for publication. Approval does not signify that the contents reflect the views and policies of the agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.
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