CFR 138 - Occupational Exposure to 4,4'-Methylenedianiline (MDA)

On August 10, 1992, Federal OSHA promulgated new occupational safety and health standards for general industry and the construction industry which regulate employee exposure to 4,4'-Methylenedianiline (Federal Register). These new standards - 29 CFR 1910.1050 and 29 CFR 1926.60, respectively - are based on human and animal data that have shown this substance to be a hepatotoxic agent and a suspect human carcinogen, and set forth an eight-hour time-weighted average (TWA) exposure limit of 10 parts per billion (10 ppb) and a 15-minute short-term exposure limit (STEL) of 100 ppb. In addition, the standard includes requirements for medical surveillance, exposure monitoring, engineering controls and work practices, proper respirator use, and recordkeeping. An action level (AL) of 5 ppb has also been established to exempt employers from certain requirements, such as periodic employee exposure monitoring, where the employer can demonstrate that employee exposures are at or below these levels.

These new federal final rules at 29 CFR 1910 Subpart Z and 29 CFR 1926 Subpart D were adopted verbatim in North Carolina by the Commissioner of Labor with an effective date of February 8, 1993.