Exposure to mutagenic airborne particulate in a rubber manufacturing plant

Epidemiological studies conducted in the 1980s revealed that people working in the rubber manufacturing industry had an increased risk of cancer. Even now, workers employed in rubber processing are still at risk despite the m easures adopted to improve their working conditions. The aim of the study w as to evaluate the presence of a genotoxic risk in a rubber industry and to verify whether or not it was possible to locate the most dangerous positio n among the different rubber-working processes. The mutagenic activity of a irborne particulate was evaluated in samples collected in the mixing depart ment of a rubber manufacturing plant. Ambient air samples were taken over 3 -h period in two stable positions near the mixing (Banbury mixer) and calen dering areas. Personal air samples were taken over 2-h period during a norm al workday from five workers employed in different rubber processing operat ions (mixing, weighing, calendering, compounding and extruding). The mutage nic activity of the air samples was determined by plate incorporation assay using Salmonella typhimurium strains (TA 98, TA 98NR, TA 100, YG 1021) wit h and without metabolic activation. Polycyclic aromatic hydrocarbon (PAH) c oncentrations were determined by high-performance liquid chromatography (HP LC); the presence of other presumable contaminants were carried out by gas chromatography-mass spectrometry (GC-MS). The results showed substantial di rect and indirect frameshift mutagenicity in both ambient and personal samp les. No mutagenic activity was present in S. typhimurium TA 100, except in the personal sample from a worker employed on the Banbury mixer. HPLC analy sis revealed very low concentrations of PAHs. GC-MS analysis showed the pre sence of compounds such as azulene derivative, 1,2-dihydro-2,2,4-trimethylq uinoline, N-methyl N-phenylbenzenamine, diphenylamine, bis(2-ethylhexyl)pht halate and bis(methyl-propyl)phthalate. We conclude that the high levels of mutagenic activity in ambiental and personal samples indicate the presence of substances with high genotoxic potency; no substantial differences were seen among the several rubber processing operations. PAHs were not involve d in indoor pollution. GC-MS analysis revealed the presence of compounds wh ich may be produced by high temperatures to which the raw materials are sub jected during rubber manufacturing processes. These substances are potentia l carcinogen though their mutagen properties have not been clearly determin ed. (C) 1999 Elsevier Science B.V. All rights reserved.