In 1973 an environmental accident occurred in northern Michigan in which 1000-2000 pounds of the toxic fire retardant polybrominated biphenyl (PBB) was added to the livestock food supply of much of northern Michigan. PBB is highly lipophilic, poorly metabolized, and biocumulative. It subsequently entered the human food chain of the entire state of Michigan. Health effects were noted in contaminated animals and among exposed farmers some months after the contamination; these often included cutaneous problems. Three years later a multidisciplinary study of the farming population was undertaken. Detected cutaneous abnormalities included halogen acne, hair loss, skin redness, skin peeling, and scaling, itching, increased sweating, and increased growth of fingernails and toenails. The mechanisms underlying these effects are unknown. PBBs appear to be etiologically implicated for significant cutaneous toxicity.