Occupational hexachloroethane exposure and toxicity : With special reference to the formation of Hexachlorobenzeneiin aluminium degrassing

Sammanfattning: For about half a century, hexachloroethane (HCE) has been used as an essential component of military white smoke munition and as a degassing agent in almninium foundries and secondary aluminium smelters. However, the acute or chronic health risks associated with occupational exposure to HCE have not been investigated in humans.In exposed white smoke munition workers (n=12), the mean plasma level of HCE increased from 0.08 µ/l during a production break to 7.30 µ/1 after five weeks of continuous production, but there was a considerable interindividual variation. HCE was not detected in local controls. Slight irritation of the skin and mucous membranes was also reported, but clinical examination, spirometry and routine biochemical analyses revealed no specific deviations from normal.A wide spectrum of organochlorine compounds was identified -in the emissions from experimental degassing of aluminium with HCE. Chlorobenzenes, notably hexachlorobenzene (4.3 mg/g HCE), octachlorostyrene (0.78 mg/g HCE) and umeacted HCE were the major findings. At considerably lower levels, several congeners of chlorinated dioxins (in total 3 .4· 10·' mg/g HCE) and dibensofurans (3.6·104 mg/g HCE) were also identified.As compared to local controls, increased levels of hexachlorobenzene (313.1 vs 66.9 ng/g lipid) as well as octachlorostyrene (54.6 vs 0.7 ng/g lipid) were found still some years after last exposure in a group of aluminium foundry workers (n~9) with experience of HCE as a degassing agent. These workers also showed some evidence of secondary coproporphyrinuria, the first recognised step in the gradual development of chronic hepatic porphyria.In a cohort (n~6,454) of aluminium foundry and secondary aluminium smelter workers, no clearly increased cancer risk could be attributed to the potential exposure to HCE and its byproducts in aluminium degassing, although a slight excess of non-Hodgkin' s lymphoma was observed among males. This finding was restricted to workers with less than 10 years of employment, red~cing the probability of a causal association. Evidence of a lung cancer hazard related to sand founding of aluminium for I 0 years or more was obtained, however.