Occurrence And Mammalian Cell Toxicity Of Lodinated Disinfection Byproducts In Drinking Water

摘要

An occurrence study was conducted to measure five iodo-acids (iodoacetic acid, bromoiodoacetic acid, (Z)-3-bromo-3-iodo-propenoic acid, (E)-3-bromo-3-iodo-propenoic acid, and (E)-2-iodo-3-methylbutenedioic acid) and two iodo-trihalomethanes (iodo-THMs), (dichloroiodomethane and bromochloro-iodomethane) in chloraminated and chlorinated drinking waters from 23 cities in the United States and Canada.Since iodoacetic acid was previously found to be genotoxic in mammalian cells, the iodo-acids and iodo-THMs were analyzed for toxicity.A gas chromatography (GC)egative chemical ionization-mass spectrometry (MS) method was developed to measure the iodo-acids; iodo-THMs were measured using GC/high resolution electron ionization-MS with isotope dilution.The iodo-acids and iodo-THMs were found in waters from most plants, at maximum levels of 1.7 μg/L (iodoacetic acid), 1.4 μg/L (bromoiodoacetic acid), 0.50 μg/L ((Z)-3-bromo-3-iodopropenoic acid), 0.28 μg/L ((E)-3-bromo-3-iodopropenoicrnacid), 0.58 μg/L ((E)-2-iodo-3-methylbutenedioic acid), (bromochloroiodomethane), and 7.9 μg/L (dichloroiodomethane).Iodo-acids and iodo-THMs were highest at plants with short free chlorine contact times (＜1 min), and were lowest at a chlorine-only plant or at plants with long free chlorine contact times (＞45 min).Iodide levels in source waters ranged from 0.4 to 104.2 μg/L(when detected), but there was not a consistent correlation between bromide and iodide.The rank order for mammalian cell chronic cytotoxicity of the compounds measured in this study, plus other iodinated compounds, was iodoacetic acid＞(E)-3-bromo-2-iodopropenoic acid ＞iodoform ＞ (E)-3-bromo-3-iodo-propenoic acid＞(Z)-3-bromo-3-iodo-propenoic acid ＞diiodoacetic acid ＞bromoiodoacetic acid ＞ (E)-2-iodo-3-methylbutenedioic acid＞bromodiiodomethane＞dibro-moiodomethane＞ bromochloroiodomethane≈chlorodi-iodomethane＞dichloroiodomethane.With the exception of iodoform, the iodo-THMs were much less cytotoxic than the iodo-acids.Of the 13 compounds analyzed, 7 were genotoxic; their rank order was iodoacetic acid》diiodoacetic acid ＞ chlorodiiodomethane＞bromoiodoacetic acid＞E-2-iodo-3-methylbutenedioic acid＞(E)-3-bromo-3-iodo-propenoic acid ＞ (E)-3-bromo-2-iodopropenoic acid.In general, compounds that contain an iodo-group have enhanced mammalian cell cytotoxicity and genotoxicity as compared to their brominated and chlorinated analogues.