Yellow staining caused by 4,4'-methylenedianiline exposure. Occurrence among molded plastics workers

Workers engaged in a molded plastics operation were studied to determine the etiology of yellow staining reactions involving the skin, nails, and hair. A walk-through survey of the facility, medical interviews, physical examinations, and blood and urine tests were performed. 4,4'-Methylenedianiline (MDA), a component chemical of the manufacturing process, produced intense yellow discoloration of nitrocellulose paper in the laboratory and appeared to volatilize readily under ambient conditions. Thirty-five (65%) of 54 process workers showed varying degrees of staining while 11 workers employed in other parts of the factory showed no staining. Yellow staining was restricted to areas of the body where direct contact with MDA appeared likely. Laboratory studies did not provide evidence of systemic toxic effect. Because MDA is a known hepatotoxin for man, with carcinogenic properties in animal test systems, it is important to recognize yellow staining as a cutaneous marker of exposure to this chemical.