PROPOSAL FOR THE ASSESSMENT OF QUANTITATIVE DERMAL EXPOSURE LIMITS INOCCUPATIONAL ENVIRONMENTS - PART 2 - FEASIBILITY STUDY FOR APPLICATION IN AN EXPOSURE SCENARIO FOR MDA BY 2 DIFFERENT DERMAL EXPOSURE SAMPLING METHODS

Objective-To evaluate two different techniques for assessing dermal ex posure to 4,4'-methylene dianiline (MDA) in a field study. The results were used to test the applicability of a recently proposed quantitati ve dermal occupational exposure Limit (DOEL) for MDA in a workplace sc enario. Methods-For two consecutive weeks six workers were monitored f or exposure to MDA in a factory that made glass fibre reinforced resin pipes. Dermal exposure of the hands and forearms was assessed during week 1 by a surrogate skin technique (cotton monitoring gloves) and du ring week 2 by a removal technique (hand wash). As well as the dermal exposure sampling, biological monitoring, measurement of MDA excretion in urine over 24 hours, occurred during week 2. Surface contamination of the workplace and equipment was monitored qualitatively by colorim etric wipe samples. Results and conclusions-Geometric means of daily e xposure ranged from 81-1762 mu g MDA for glove monitoring and from 84- 1783 mu g MDA for hand washes. No significant differences, except for one worker, were found between exposure of the hands in weeks 1 and 2. Significant differences between the mean daily exposure Of the hands (for both weeks and sampling methods) were found for all workers. The results of the colorimetric wipe samples indicated a general contamina tion of the workplace and equipment. Excretion of MDA in 24 hour urine samples ranged from 8 to 249 mu g MDA, whereas cumulative MDA excreti on over a week ranged from 82 to 717 mu g MDA. Cumulative hand wash an d MDA excretion results over a week showed a high correlation (R-2=0.9 4). The highest actual daily dermal exposure found seemed to be about 4 mg (hand wash worker A on day 4), about 25% of the external DOEL. Te sting of compliance by means of a biological limit value (BLV) led to similar results for the same worker. It is concluded that both dermal exposure monitoring methods were applicable and showed a compatible pe rformance in the present exposure scenario, where the exposure relevan t to dermal absorption is considered mainly restricted to hands. The c oncept for a DOEL seemed to be relevant and applicable for compliance testing and health surveillance in the situation under investigation.