4-PHENYLCYCLOHEXENE - 2-WEEK INHALATION TOXICITY AND NEUROTOXICITY STUDIES IN SWISS-WEBSTER MICE

4-Phenylcyclohexene (4-PCH) is a by-product formed during the polymeri zation of styrene-butadiene latex used in carpet backing. Limited repo rts suggest that exposure to very low levels of 4-PCH or other emissio n products following new carpet installation may result in health comp laints. Significantly, it has been claimed that Swiss-Webster mice hel d in neck restraints and exposed head-only to approximately 0.4 ppm 4- PCH for a few hours suffered severe toxicity including death. A 2-wk i nhalation and neurotoxicity study was therefore conducted in Swiss-Web ster mice using standard methods of toxicity testing. Groups of 40 mic e were exposed to 0, 7, 18 or 71 ppm (near-saturated atmosphere) 4-PCH vapour, 6 hr/day for 9 consecutive days. Data were collected on a wid e variety of clinical, neurological and histopathological parameters i ncluding extensive neurohistopathology. All animals survived the expos ures, and there were no treatment-related effects. Because of the occu rrence of spontaneous lesions in two high-dose group mice, 40 addition al marks were exposed to 0 ppm or a near-saturated atmosphere of 4-PCH under the same exposure regimen. No treatment-related lesions were ob served in the follow-up study, confirming the conclusions of the origi nal study. These findings, consistent with the reported lack of toxici ty of inhaled 4-PCH in rats, do not suggest a direct, organic, associa tion between low-level 4-PCH exposure and human complaints. Further, t he results of this study suggest that positive findings in mice may ha ve been due to methodological problems and not to exposure to 4-PCH. C opyright (C) 1996 Elsevier Science Ltd