Provenance humans

Benzidine, p-aminodiphenyl, is a solid compound that can be extracted from coal tar. It is highly toxic by oral ingestion, inhalation, and skin sorption and is one of the few proven human carcinogens. Its systemic effects include blood hemolysis, bone marrow depression, and kidney and liver damage. 

Benzo[a]pyrene (BaP) is produced by the incomplete combustion of almost any fuel. This compound is one of the few proven human carcinogens. BaP enters Lake Superior by two mechanisms wet deposition (rain and snow falling into the lake) and dry deposition (particles fall out to the surface of the lake). The concentration of BaP on particles in the air over Lake Superior is 5 pg/m3, and its concentration in rain over the lake is 2 ng/L. The area of Lake Superior is 8.21 x 104 km2. What is the total flow of BaP from the atmosphere to Lake Superior ... 

In the International Agency for Research and Treatment of Cancer (lARC), the vinca alkaloids were classified in group 3, which means that they cannot yet be classified in group 1 (proven human carcinogens), 2A (probably carcinogenic), or 2B (possibly carcinogenic) (86,87). 

Group 1. Proven human carcinogens Group 2A. Probable human carcinogens Group 2B. Possible human carcinogens. 

Strong. However, some of the aerospace aluminum alloys (e.g., 2024-T3) are very prone to corrosion. In order to combat corrosion of aluminum alloys, chromic acid anodization and chromate conversion have thus far proved most effective. Both processes, however, use and release hexavalent chromium, a proven human carcinogen, causing serious environmental and worker health and safety concerns. Thus, a chromium-free alternative with equivalent or superior corrosion performance has long been desired. 

Childs JE, Sumnet JW, Nicholson WL, et al. Outcome of diagnostic tests using samples from patients with culture-proven human monocytic ehtlichiosis Implications for surveillance. J Clin Microbiol. 1999 37 2997-3000. 

To achieve zero exposure to all workplace chemicals is an impossible objective in the light of present day industrial processes. However this approach has been adopted in some countries for proven human carcinogens. 

Substitution is sometimes possible by ublising a less hazardous material instead of a more hazardous one. An example is in the replacement of benzene (WEL1 ppm) that is a proven human carcinogen by toluene (WEE 50 ppm) which is in many cases as good a solvent. This option requires a good xmderstanding of the hazardous properties of both materials to ensure that new or addibonal hazards are not introduced into the workplace by the replacement material. 

Group 1 Proven Human Carcinogenic Exposures Aluminum production Auramine manufacture Boot and shoe manufacture and repair Chimney sweeping Coal gasiUeation Coal tar distillation Coke produetion... 

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