Time may not fully attenuate solvent-associated cognitive deficits in highly exposed workers

OBJECTIVE: To test the effects of lifetime occupational solvent exposure, as measured by dose and timing, on performance on multiple cognitive tests among retired French utility workers.
METHODS: A total of 2,143 retirees in the GAZEL cohort underwent cognitive testing in 2010. Lifetime exposure to chlorinated solvents, petroleum solvents, and benzene was assessed using a job exposure matrix. We modeled effects of lifetime solvent dose, timing of last exposure, and a combination of these metrics on risk for cognitive impairment.
RESULTS: Thirty-three percent of participants were exposed to chlorinated solvents, 26% to benzene, and 25% to petroleum solvents. High exposure to solvents was significantly associated with poor cognition; for example, those highly exposed to chlorinated solvents were at risk of impairment on the Mini-Mental State Examination (risk ratio 1.18; 95% confidence interval 1.06, 1.31), the Digit Symbol Substitution Test (1.54; 1.31, 1.82), semantic fluency test (1.33; 1.14, 1.55), and the Trail Making Test B (1.49; 1.25, 1.77). Retirees at greatest risk for deficits had both high lifetime exposure to solvents and were last exposed 12 to 30 years before testing. Risk was somewhat elevated among those with high lifetime exposure who were last exposed 31 to 50 years before testing. Those with high, recent exposure exhibited impairment in almost all domains, including those not typically associated with solvent exposure.
CONCLUSIONS: While risk of cognitive impairment among moderately exposed workers may attenuate with time, this may not be fully true for those with higher exposure. This has implications for physicians working with formerly solvent-exposed patients as well as for workplace exposure limit policies.

Source: Sabbath EL, Gutierrez LA, Okechukwu CA, Singh-Manoux A, Amieva H, Goldberg M, Zins M, Berr C. Neurology. 2014 May 13;82(19):1716-23.
http://dx.doi.org/10.1212/WNL.0000000000000413

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