Exposure to 4,4'-methylene bis (2-chloroaniline) (MbOCA) in New South Wales, Australia

This study was conducted to determine the level of exposure of 4,4'-methylene bis (2-chloroaniline) (MbOCA) in New South Wales (NSW), Australia.

An integrated occupational hygiene and biological monitoring program were used to assess the workers' exposure to MbOCA via inhalation, ingestion and dermal contact. This was conducted by personal air monitoring, static air monitoring and surface contamination monitoring of the work environment and biological monitoring of the workers' exposure to MbOCA at nine workplaces in NSW.

The air monitoring results for MbOCA gave a geometric mean (GM) of 0.06 μg/m³ and a geometric standard deviation (GSD) of 2.70 and a 95% confidence interval of 0.29 μg/m³. The surface contamination in the main work area showed the highest contamination with a GM of 74 ng/cm² and a GSD of 17 and a 95% confidence interval of 7,751 ng/cm². Biological monitoring showed a GM of 0.89 μmol/mol cr and a GSD of 11.9 and a 95% confidence interval of 52 μmol/mol cr. This indicated that 13% of the workers were over the SafeWork NSW Biological Occupational Exposure Limit of 15 μmol/mol cr.

Workers' exposure through inhalation was minimal; however, evidence from biological monitoring of MbOCA suggested that the main contributing factor to exposure was skin absorption. This was attributed to poor housekeeping and inadequate personal protection. Improvements in these areas were recommended, and it was also recommended to improve the awareness of the workers to the adverse effects to their health of exposure to this carcinogen.