Dermal sensitization potential and inhalation toxicological evaluation of 4-phenylcyclohexene

4-Phenylcyclohexene (4-PCH) is a by-product formed in trace amounts during the production of styrene-butadiene latexes, which are used in carpet manufacturing. The dermal sensitization potential of 4-PCH was evaluated by using a modification of the Buehler method. The condition of the test site was evaluated 24 and 48 hr after the challenge application with no response observed in any of the guinea pigs. For the acute inhalation study, groups of five Fischer 344 rats/sex were exposed to 16 or 60 ppm 4-PCH for a single 6-hr exposure. Subsequently, groups of 10 Fischer 344 rats/sex were exposed to time-weighted average concentrations of 0, 1, 10, or 50 ppm (0, 6.6, 65, or 320 mg/m3) 4-PCH for 6 hr/day, 5 days/week for nine exposures. The highest vapor concentration, 50 ppm, was the maximum attainable during the course of the 2-week study. It was only achieved by acclimating the chamber with saturated vapor prior to each animal exposure. The following parameters were evaluated for the 2-week study: clinical signs, body weights, selected organ weights, hematology, clinical chemistry, urinalysis, and histopathology. All rats survived to the termination of the study and had no clinical or pathologic evidence of eye, skin, nasal, or respiratory tract irritation. There were no exposure-related effects identified in any of the parameters monitored. Thus, 4-PCH produced no toxicity at the highest concentration that could be generated and did not produce delayed contact hypersensitivity in guinea pigs.