Mary S. Wolff

Asbestos exposure during brake lining maintenance and repair

Abstract Data obtained on asbestos exposure of garage mechanics during brake lining maintenance and repair work show that fiber concentrations frequently in excess of regulated limits are common. The presence of chrysotile, ranging from 2 to 15%, in brake drum dusts, was demonstrated by X-ray diffraction, transmission electron microscopy, selected area electron diffraction, and electron microprobe analyses. Unaltered chrysotile was found, both in fiber and fibril form, in air and brake drum dust samples. The chrysotile asbestos content of personal air samples, taken during automobile brake repair work, was measured both by optical and electron microscopic techniques. While a positive correlation exists between the types of measurements, the present technique of optically counting asbestos fibers may considerably underestimate the levels of total asbestos exposure.

SYMPTOMS AND CLINICAL ABNORMALITIES FOLLOWING INGESTION OF POLYBROMINATED-BIPHENYL-CONTAMINATED FOOD PRODUCTS

Unlike the now ubiquitous halogenated compounds DDT [ 1 , I ,I-tri-chloro-2, 2-bis (4-chlorophenyl) ethane] and PCBs (polychlorinated biphenyls), PBBs (polybrominated biphenyls) are not commonly present in animal or human tissues. PBBs are mixtures of brominated biphenyls, usually with 4-8 bromine atoms per molecule, which have been useful as fire retardants in thermoplastic resins.’ One such mixture, Firemaster FF1 @, mainly hexobromobiphenyl, caused widespread contamination of livestock (dairy and beef cattle, poultry and eggs) after an accidental introduction into cattle feed in Michigan during 1973.* At the time the accident was detected, no guidelines existed for allowable limits of PBBs in food for human consumption. Under rapidly implemented federal and state regulations, more than 500 farms were eventually found to have cattle and/or milk over the newly established allowable limits of PBBs in food which were used as farm quarantine “action limits.” Over 23,000 dairy cattle and 1.6 million chickens died or were destroyed.’ Unfortunately, before the cause and dimensions of the problem were fully appreciated, contamination of milk, beef, pork, eggs and poultry occurred, and ingestion of these foodstuffs resulted in PBB absorption by those who ate these products. Farm families accustomed to eating their own produce were first and perhaps most heavily exposed. I n the interval of more than 9 months between the accident, the identification of its cause, the beginning of statewide testing and the establishment of quarantines, commercially marketed products entered the Michigan food chain; thus the potential existed for wide dissemination of this halogenated hydrocarbon to the general population of the state. No previous instance of human exposure to PBBs, with possible associated health effects, was known. Possessing chemical properties which make it biologically persistent: and having demonstrated toxicity to animals ( l i ~ e r , ~ , ~ endocrine: skin,’ kidney,n and lymphatic tissue’), PBBs were considered to pose a potential health hazard to those exposed. Anecdotal reports of associated disease and widespread public concern prompted health assessments of exposed

Cutaneous effects of exposure to polybrominated biphenyls (PBBs): The Michigan PBB incident

Abstract 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.

Spermatogenesis in Men Exposed to Polybrominated Biphenyl (PBB)

Experience with other halogenated hydrocarbons, animal experiments, and individual complaints indicated that polybrominated biphenyl (PBB) might have an effect on human spermatogenesis. Analysis of semen from 52 PBB-exposed men as compared with analysis of semen from a control group of 52 men not exposed to PBB revealed no differences in the distribution of sperm counts, motility, or morphology.