A first French assessment of population exposure to tetrachloroethylene from small dry-cleaning facilities.

UNLABELLED: Used as a solvent in the dry-cleaning industry, tetrachloroethylene (C(2)Cl(4)) can be a pollutant of residential indoor air, which can cause long-term harmful exposures because of its neurotoxicity and probable carcinogenicity. In France, dry-cleaning facilities are integrated in urban environments (shopping malls, residential buildings) and can contribute to C(2)Cl(4) exposure for customers and residents. This exploratory work presents the results from five studies carried out in one shopping mall and four residential buildings housing a dry-cleaning facility. These studies involved dry-cleaning machines fitted with a Carbon Adsorber and unfitted, with or without Air Exhaust System. Samples were collected in the cleaning facilities and in the apartments located above with passive samplers allowing measurement of time-integrated concentrations on a 7 days sampling period. It has obviously shown the degradation of indoor air quality in these environments and underlined the contributing role of the machine technology and ventilation system on the amount of released C(2)Cl(4) in the indoor air. To temper these results, it must be pointed out that some parameters (building insulation, amount of solvent used...) which would influence C(2)Cl(4) fugitive release have not been quantified and should be looked at in further studies. PRACTICAL IMPLICATIONS: In France, dry-cleaning facilities are frequently integrated in urban environments (large shopping malls or residential buildings) and can significantly contribute to tetrachloroethylene (C(2)Cl(4)) population exposure. The amount of fugitive releases in these environments depends on several parameters such as the dry-cleaning machine technology (fitted or unfitted with a carbon adsorber) and the ventilation (air exhaust system). To reduce C(2)Cl(4) exposure in residential buildings and other indoor environments with on-site dry cleaners, carbon adsorber unequipped machine should be replaced by newer technology and dry cleaners should be equipped with mechanical air exhaust systems.

Reductive cleavage of demeton-S-methyl by Corynebacterium glutamicum in cometabolism on more readily metabolizable substrates.

Corynebacterium glutamicum is able to biotransform demeton-S-methyl, an organophosphorus compound, during cometabolism with more readily metabolizable substrates. Among the cosubstrates used, fructose is the growth substrate that is most favorable for demeton-S-methyl biotransformation. The reaction mechanism of demeton-S-methyl biotransformation involves reductive cleavage of an S-C bond, which leads to accumulation of dimethyl thiophosphate in the culture medium.