An evaluation of the respiratory health status of automotive spray-painters exposed to paints containing hexamethylene di-isocyanates in the greater Durban area.

OBJECTIVE

A survey of automotive spray-painting establishments was undertaken to evaluate the respiratory health status of spray-painters exposed to paints containing hexamethylene di-isocyanates (HDIs).

DESIGN

This was a cross-sectional study.

SETTING

Spray-painting establishments in the Durban municipal area.

PARTICIPANTS

Spray-painters from a random sample of 40 (25%) of the registered spray-painting establishments were studied.

MAIN OUTCOME MEASURES

Responses to an Interviewer-administered standardised respiratory health questionnaire and a cross-shift spirometric lung function test were obtained for each spray-painter, questionnaires assessing the firm's compliance with the spray-painting safety requirements were also obtained.

RESULTS

The mean cross-shift decrease in forced expiratory volume in 1 second (FEV1) was 130.5 ml (SD 203.19) (P = 0.0002). The lung function data indicated that of the 40 spray-painters examined, 10 (25%) showed clinically significant cross-shift decreases in FEV1, viz, decreases > 250 ml. Only 2 subjects had a diagnosis of asthma. Chronic respiratory symptoms of cough, wheeze and wheeze with breathlessness were similar to those noted in community-based studies. A high proportion had eye irritation (55%) and dermatitis of the hand (32%). The potential determinants of FEV1 were examined in a multiple linear regression analysis and only the isocyanate concentration levels approached statistical significance (P = 0.082), suggesting that other factors such as duration of exposure, spray-paint 'bounce-back' phenomenon, and 'healthy worker' effect may be more important. ('Bounce back' refers to the phenomenon whereby some of the mist from the spray-gun, after striking the surface being painted, is deflected back into the operator's breathing zone in the form of fine droplets or aerosols.) Forty per cent of the 40 spray booths had ventilation standards substantially below that specified in current South African legislation. Only 21 (55%) spray-painters were provided with the regulation respiratory protective equipment, and in the cases where it was provided, 7 (33%) of these spray-painters used the positive pressure air-line respiratory recommended by the leading manufacturers of isocyanate-based paints.

CONCLUSIONS

The findings in this study confirm the risk of exposure to HDIs in the spray-painting industry and highlight the need for more stringent industrial hygiene controls.