P-198 3,3’-Dichloro-4,4’-Diaminodiphenylmethane (Mboca) Exposure and Biological Monitoring in Japanese Workers

Abstract Introduction 3,3’-Dichloro-4,4’-diaminodiphenylmethane (MBOCA) (CAS: 101-14-4) is used as urethane resin hardener etc. in industries. Mean concentration of occupational exposure limit (OEL-M) is recommended at 0.005 mg/m3, and biological exposure index (OEL-B) is provisionally recommended at 10 µg/g·creatine of urinary MBOCA after shift work by Japanese Society of Occupational Health (JSOH). Carcinogenicity classification of MBOCA is proposed as Group 2A based on sufficient evidence from animal carcinogenicity. Methods Personal exposure concentrations and biological exposure index of MBOCA in urine were assessed in ten male workers exposed to MBOCA during 5 consecutive workdays and next beginning of the work-shift in Japan. The types of works were handling dissolved MBOCA (type 1, n=3), handling molded urethane (type 2, n=3), and demolding urethane product (type 3, n=4). Results, discussion and conclusion No MBOCA personal exposure and urinary MBOCA were detected in type 2 and 3 engaged workers. MBOCA personal exposure were between N.D. and 0.2 µg/m3, these were below OEL-M. Urinary MBOCA were between 2.5 and 15 µg/g·creatinine in there type 1 engaged workers, and were relatively higher in comparison with exposure concentrations. It might be due to dermal absorption in addition to respiratory absorption.