Wastewater from Mexico City contains organotin compounds and organotin-resistant bacteria

Organotin compounds are man-made chemicals used worldwide for diverse applications. These organometallic compounds may be released from antifouling paints, polyvinyl chloride and other materials into terrestrial and aquatic environments. Mexico City is a highly populated and industrialized city with many potential sources of environmental pollution. We evaluated the content of butyltins, triphenyltin and bacteria in water from various sites with different water quality in Mexico City, Pachuca City and two towns located between these two cities. Butyltins and/or triphenyltin were detected by gas chromatography and mass spectrometry analysis in samples from 4/4 sites containing wastewater, 1/2 sites containing reclaimed water and 2/5 sites holding accumulated water in open-air deposits. Neither organotin compounds nor bacteria were found in household water samples. However, 80 bacterial strains were isolated from partially treated or untreated wastewater and 72 of them were identified at the genus and species levels by the automated Mass Spectrometry Identification System VITEK MS. In vitro growth of 16 of 28 tested strains was not inhibited by 1 mM tributyltin or triphenyltin, indicating that many environmental bacteria are highly tolerant to organotin compounds.