Occupational asthma in a steel coating plant.

Abstract

An outbreak of occupational asthma, of unknown cause and extent, was detected in a steel coating plant. In 1979 a cross-sectional study which defined occupational asthma in terms of respiratory symptoms detected 21 people with suggestive symptoms among the 221 studied. They all worked in the coating shop, but the plastic coatings used at the plant contained many potential sensitising agents that might have caused the asthma. All 21 developed their symptoms after 1971, and it was found that in this year a supplier had modified a coating allowing, at the temperatures used in the process, toluene di-isocyanate to be liberated. Two of the symptomatic subjects were tested by inhalation of the isocyanate and showed asthmatic reactions and other subjects were found to have asthma related to periods spent at work by records of peak expiratory flow rate. Over half the 21 had a symptom free latent period after first exposure of three years or less, a pattern not seen in other subjects with respiratory symptoms. After the isocyanate had been removed from the process 17 of these subjects became asymptomatic or improved, a greater proportion than in other subjects with respiratory symptoms.Two men working in a steel coating plant developed symptoms suggestive of occupational asthma. It was necessary to establish if others were affected and to identify the cause in order to recommend appropriate remedial action. An epidemiological investigation was undertaken and the firm was asked to obtain information from its suppliers. ProcessThe factory coated rolled steel sheets with coloured plastic by a continuous process on two lines. After rolling, cleaning, and brushing, the steel received a base or prime coat that was cured by passage through an oven, after which a main coat was applied and, again, oven cured. The coated steel, after embossing, was cut up in lengths. The coatings were known to contain epoxy resins, acrylics, phenol formaldehyde, chromates, and polyvinyl chloride. All these and other agents were considered as potential causes of the asthma. The ovens were ventilated during normal operation by an extraction system that discharged into the atmosphere through a

Guidelines for the management of work-related asthma

“…This is because they are far too weakly associated with the development of workrelated asthma, symptoms or other signs of work-related asthma (*) [143][144][145]. 9) Early detection of work-related respiratory symptoms, sensitisation and work-related asthma is possible using medical surveillance, which includes a questionnaire in combination with at least one of the following options: detection of specific sensitisation, NSBHR testing, SIC, diagnostic work up in a referral centre (**) [57,123,[147][148][149][150][151][152][153].…”

Occupational Asthma, Lung Function Decrement, and Toluene Diisocyanate (TDI) Exposure: A Critical Review of Exposure-Response Relationships

“…(64) A 10 percent OA prevalence rate was reported as well among employees assigned to a process in which steel was coated with a plastic nish that was later found to have included a TDIbased component (21 cases determined mostly based on questionnaire responses among 221 employees). (56) The coated steel was oven-cured, apparently releasing fumes containing TDI at concentrations (HPLC analysis) of up to 26 ppb. After excluding the TDI-based component in 1979, no new OA cases were identi ed in a subsequent survey about nine months later.…”

Frequency and Trends of Occupational Asthma Due to Toluene Diisocyanate: A Critical Review

“…During the past 15 years, measures of prevalences between zero and 10 percent have been observed (27) 1978 66 Foam production Clinical evidence Survivor population 3.0 White et al, (28) 1980 147 Sewing laminated MD opinion Frequent pre-existing 0.7 nylon respiratory symptoms Kido, (29) 1983 87 Lacquer varnishing Self-reported symptoms 16.0 Belin et al, (30) 1983 48 Foam production Clinical evidence Survivor population 0 Venables et al, (31) 1985 221 Foam coating of steel Mostly self-reported 9.5 symptoms Wang et al, (2) 1988 38 Adhesive tape Self-reported symptoms Small subgroups with 0 production mean exposures of 12, 38 21, and 47 ppb TDI 85 Huang et al, (13) …”