Recent reviews on solvent exposure and PD risk showed that
observed risk estimates of most previous studies were between 1.0
and 1.5, suggesting that a weak association might exist [3,4]. We
only observed statistically non-significant slightly elevated odds
ratios for the highest tertile of duration and cumulative exposure
for aromatic solvents. No increased risks were observed for cumulative
exposure to chlorinated solvents, which is in contrast to a
previous study that found strong positive associations for several
chlorinated solvents (trichloroethylene, perchloroethylene and
carbon tetrachloride) [5]. Because these solvents are among the
most commonly used chlorinated solvents, it is unlikely that differences
in risk estimates from their and our study are caused by
the fact that we grouped all chlorinated solvents together. As such
the difference between the studies remains unknown.