Int Arch Occup Environ Health ( 1996) 68:219-223 S * * *~k·IR G Calabrese A Martini · G Sessa · M Cellini G B Bartolucci · G Marcuzzo E De Rosa Otoneurological study in workers exposed to styrene in the fiberglass industry Received: 26 April 1995/Accepted: 3 November 1995 Abstract Twenty workers exposed to styrene and acetone in small fiberglass factories were monitored for 8 h using passive dosimeters Urine samples were col- lected at the end of the workshift and before the start of work on the next morning The 8-h time-weighted average exposure values for styrene and acetone ranged from 14 to 416 mg/m 3 and from 70 to 277 mg/m 3 , respectively The sum of styrene metabolites, mandelic acid and phenylglyoxylic acid (MA + PGA), in the next-morning urine samples ranged from 81 to 943 mg/g creatinine Different test sensitivity was iden- tified in the otoneurological battery: it was low for audiometric tests and ABR, and relatively high for vestibular tests The vestibular system seems partially sensitive to the toxic effects of styrene in the absence of clinical signs and symptoms The actual exposure levels for styrene cannot be considered devoid of functional subclinical consequences. Keywords Styrene · Mandelic acid Phenylglyoxylic acid Vestibular tests Posturography · Auditory brainstem responses G Calabrese · A Martini Clinica Otorinolaringoiatrica, Universita degli Studi di Ferrara, Italy G Sessa M Cellini Servizio di Medicina Preventiva ed Igiene del Lavoro, Azienda USL di Ferrara, Distretto di Portomaggiore, Italy G B Bartolucci · G Marcuzzo Istituto di Medicina del Lavoro, Universita degli Studi di Padova, Italy E De Rosa () Cattedra di Medicina del Lavoro, Universita degli Studi di Ferrara, via Fossato di Mortara 64, 1-44100 Ferrara, Italy Introduction The most significant exposure to styrene occurs in the fiberglass industry, where workers are usually also ex- posed to acetone (De Rosa et al 1993) Styrene is one of the most toxicologically interesting solvents used in the industry because it causes chromosomal damage and toxic effects on the central and peripheral nervous system, in addition to other adverse effects, such as hematological changes, hepatotoxicity, and, at high levels of exposure, neuroendocrine effects (Mutti et al. 1984 b). A slight reduction in peripheral nerve conduction velocity due to styrene exposure has been reported (Seppalainen and Harkonen 1976 ; Lilis et al 1978) while no statistical differences in nerve conduction ve- locity were observed in another study (Triebig et al. 1985) Most studies on styrene neurotoxicity concern effects on the central nervous system. Abnormal psychological test results, neuropsychiat- ric symptoms, and organic mental disorders have been reported (Mutti et al 1984 a; Flodin et al 1989 ; Jegaden et al 1993) for styrene doses lower than the threshold limit value (TLV) adopted for 1994-1995 by the Ameri- can Conference of Governmental Industrial Hygienists (ACGIH 1994-1995) On the other hand no neurotoxic effects were shown for styrene exposure levels of 100 ppm (Edling and Ekberg 1985 ; Triebig et al 1989). Furthermore, in a large recent review on the neuro- epidemiology of styrene (Rebert and Hall 1994) it was reported that the results on styrene toxicity are false- positive findings, and there is consequently no scientific basis for a reduction of the current TLV It was re- ported by Moller et al ( 1990), however, that moderate or low levels of styrene cause central nervous system disturbances which cannot always be diagnosed with psychometric tests but can be revealed by otoneurological tests The components of the equilib- rium and the auditory system had also been studied ( O Springer-Verlag 1996