| Human Neurobehavioral Effects Of Long-Term Exposure To Styrene:
A Meta-Analyses Vernon A. Benignus,1,2 Andrew M. Geller,3 William
K Boyes,3 and Philip J. Bushnell3 1Human Studies Division, National Health and Environmental Effects
Research Laboratory, Office of Research and Development, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina, USA; 2Department
of Psychology, University of North Carolina at Chapel Hill, Chapel Hill, North
Carolina, USA; 3Neurotoxicology Division, National Health and Environmental
Effects Research Laboratory, Office of Research and Development, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina, USA Abstract
Many reports in the literature suggest that long-term exposure to styrene may exert a variety of effects on the nervous system, including increased choice reaction time and decreased performance of color discrimination and color arrangement tasks. Sufficient information exists to perform a meta-analysis of these observations quantifying the relationships between exposure (estimated from biomarkers) and effects on two measures of central nervous system function: reaction time and color vision. To perform the meta-analysis, we pooled data into a single database for each end point. End-point data were transformed to a common metric of effect magnitude (percentage of baseline) . We estimated styrene concentration from biomarkers of exposure and fitted linear least-squares equations to the pooled data to produce dose-effect relationships. Statistically significant relationships were demonstrated between cumulative styrene exposure and increased choice reaction time as well as increased color confusion index. Eight work-years of exposure to 20 ppm styrene was estimated to produce a 6.5% increase in choice reaction time, which has been shown to significantly increase the probability of automobile accidents. The same exposure history was predicted to increase the color confusion index as much as 1.7 additional years of age in men. Key words: choice reaction time, chronic, color perception, long-term, meta-analyses, neurobehavioral, review, styrene, workplace. Environ Health Perspect 113:532-538 (2005) . doi:10.1289/ehp.7518 available via http://dx.doi.org/ [Online 27 January 2005]
Address correspondence to V.A. Benignus, Neurotoxicology Division, Mail Code B105-06, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 USA. Telephone: (919) 541-1522. Fax: (919) 541-4849. E-mail: benignus.vernon@epa.govThis manuscript has been reviewed by the National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency (EPA) , and approved for publication. Approval does not signify that the contents necessarily reflect the policies of the U.S. EPA, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. This work was performed at the U.S. EPA, Office of Research and Development, National Health Environmental Effects Research Laboratory, Human Studies Division and Neurotoxicology Division, with internal funding. The authors declare they have no competing financial interests. Received 23 August 2004 ; accepted 27 January 2005. The full version of this article is available for free in HTML or PDF formats. |
