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.
- Baker, E. L. 2008. Chronic toxic encephalopathy caused by occupational solvent exposure. Annals of Neurology 63(5):545–547.
- Benignus, V. A., P. J. Bushnell and W. K. Boyes. 2011. Estimated rate of fatal automobile accidents attributable to acute solvent exposure at low inhaled concentrations. Risk Analysis 31(12):1935–1948.
- Benignus, V. A., P. J. Bushnell, W. K. Boyes, C. Eklund and E. M. Kenyon. 2009. Neurobehavioral effects of acute exposure to four solvents: meta-analyses. Toxicological Sciences 109(2):296–305.
- Benignus, V. A., T. Coleman, C. Eklund and E. M. Kenyon. 2006. A general physiological and toxicokinetic (GPAT) model for simulating complex toluene exposure scenarios in humans. Toxicology Mechanisms and Methods 16:27–33.
- Bushnell, P. J., V. A. Benignus and M. W. Case. 2003. Signal detection behavior in humans and rats: A comparison with matched tasks. Behavioral Processes 64(1):121–129.
- Bushnell, P. J., and W. M. Oshiro. 2000. Behavioral components of tolerance to repeated inhalation of trichloroethylene (TCE) in rats. Neurotoxicology and Teratology 22(2):221–229.
- Bushnell, P. J., et al. 2007. A dosimetric analysis of the acute behavioral effects of inhaled toluene in rats. Toxicological Sciences 99(1):181–189.
- Cairney, S., P. Maruff, C. Burns and B. Currie. 2002. The neurobehavioural consequences of petrol (gasoline) sniffing. Neuroscience & Biobehavioral Reviews 26(1):81–89.
- Crump, K. S. 1996. Risk of benzene-induced leukemia predicted from the Pliofilm cohort. Environmental Health Perspectives 104 Suppl 6:1437–1441.
- Evans, E. B. and R. L. Balster. 1991. CNS depressant effects of volatile organic solvents. Neuroscience & Biobehavioral Reviews 15(2):233–241.
- Kenyon, E. M., et al. 2008. Modeling the toxicokinetics of inhaled toluene in rats: influence of physical activity and feeding status. Journal of Toxicology & Environmental Health, Part A 71(4):249–265.
- Mayfield, R. D., M. Grant, T. Schallert and W. W. Spirduso. 1992. Tolerance to the effects of ethanol on the speed and success of reaction time responding in the rat: Effects of age and intoxicated practice. Psychopharmacology (Berl) 107(1):78–82.
- Oshiro, W. M., et al. 2011. Extrapolating the acute behavioral effects of toluene from 1- to 24-h exposures in rats: roles of dose metric and metabolic and behavioral tolerance. Toxicological Sciences 123(1):180–192.
- Oshiro, W. M., Q. T. Krantz and P. J. Bushnell. 2007. Repeated inhalation of toluene by rats performing a signal detection task leads to behavioral tolerance on some performance measures. Neurotoxicology and Teratology 29(2):247–254.
- Ramsey, J. C., and M. E. Andersen. 1984. A physiologically based description of the inhalation pharmacokinetics of styrene in rats and humans. Toxicology and Applied Pharmacology 73(1):159–175.
- Yucel, M., M. Takagi, M. Walterfang and D. I. Lubman. 2008. Toluene misuse and long-term harms: A systematic review of the neuropsychological and neuroimaging literature. Neuroscience & Biobehavioral Reviews 32(5):910–926.
- Zador, P. L., S. A. Krawchuk and R. B. Voas. 2000. Alcohol-related relative risk of driver fatalities and driver involvement in fatal crashes in relation to driver age and gender: an update using 1996 data. Journal of Studies on Alcohol and Drugs 61(3):387–395.
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