Abiotic transformation of triclosan (TCS) was investigated by incubating TCS with Fe(III)- and Na-montmorillonite at 40% relative humidity and room temperature for up to 100 days. The TCS transformation products were characterized using LC/MS, GC/MS, and computational modeling and quantified using HPLC/UV and GC/MS. Within 1-5 days, depending on the initial TCS concentrations, about 55% of the TCS was rapidly transformed in the presence of Fe(III)-montmorillonite, producing 2,4-dichlorophenol, 3-chlorophenol, 2,4-dichlorophenol dimer, chlorophenoxy phenols, and TCS dimers and trimers. Computational modeling based on density functional theory confirmed the formation of four TCS dimer conformers and six TCS trimer conformers. The TCS phenoxy radicals, produced by Fe(III) oxidation of TCS, react with other TCS molecules to form TCS dimers. The TCS trimers were formed by attachment of TCS dimer phenoxy radicals, produced by Fe(III) oxidation of TCS dimers, with TCS molecules. Significantly smaller quantities of TCS transformation products were detected in the reactions with Na-montmorillonite compared to the reactions with Fe(III)-montmorillonite. Formation of a significant amount of 2,4-dichlorophenol, especially in reaction with Fe(III)-montmorillonite, may have negative impact on the environment because of its toxicity. However, mineral-facilitated TCS polymerization may reduce its mobility and bioavailability in soils.

The role of metals in breast cancer is of interest because of their carcinogenic and endocrine disrupting capabilities. Evidence from epidemiologic studies remains elusive and prior studies have not investigated metal mixtures. In a case-cohort nested within the Sister Study cohort (enrolled 2003-2009; followed through September 2017), we measured 15 metals in toenails collected at enrollment in a race-stratified sample of 1495 cases and a sub-cohort of 1605 women. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for each metal using Cox regression and robust variance. We used quantile g-computation to estimate the joint association between multiple metals and breast cancer risk. Average follow-up was 7.5 years. There was little evidence supporting an association for individual metals and breast cancer. An exception was molybdenum, which was associated with reduced incidence of overall breast cancer risk (3rd vs. 1st tertile HR=0.82 (95% CI: 0.67, 1.00)). An inverse association for antimony was observed among non-Hispanic Black women. Pre-defined groups of metals (all, non-essential, essential, and metalloestrogens) were not strongly associated with breast cancer. This study offers little support for metals individually or as mixtures as risk factors for breast cancer. Mechanisms for inverse associations with some metals warrant further study.

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Eighteen private well users in North Carolina were recruited to test the performance of under-sink, activated carbon block water filters to remove per-and polyfluoroalkyl substances (PFAS). Monthly sampling was conducted for 8 months. Filters were certified for removal of perfluorooctanoic acid and perfluorooctanesulfonic acid under NSF International certification P473, but not for additional short-chain perfluoroalkyl acids or perfluoroalkyl ether acids (PFEAs) evaluated in this study. Out of 47 targeted analytes, 17 PFAS were detected in filter influent samples (influent P PFAS 4.7-131 ng/L). Mixed-effects Tobit regression models showed that the filters effectively removed 97%-99% of all influent PFAS, including short-chain PFEAs, for the entire manufacturer-recommended lifetime of the device. The prevalence of PFAS above the minimum reporting limits was reduced by 99.5%, and the prevalence of any PFAS above the method detection limits was reduced by 92%. The results provide increased confidence in NSF P473-certified filters for the removal of PFAS from private well water.activated carbon, PFAS, point-of-use water treatment, private wells | INTRODUCTIONPer-and polyfluoroalkyl substances (PFAS)-including perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkyl sulfonic acids (PFSAs) (together referred to as perfluoroalkyl acids (PFAAs)), and replacement perfluoroalkyl ether acids (PFEAs)-have generated concern in recent decades for their widespread environmental

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