Hi all…Leaching of chemical contaminants (e.g. copper, lead) and growth of pathogens (e.g. Legionella) have been clearly implicated in the degradation of safe drinking water in domestic plumbing. We also know that some contaminants can be harmful through aerosolization (pathogens, chlorine/bromine-based THMs); however, this just-released article is the first example I’m aware of where a group of disinfection by-products (DBP) in water is created by adding salt during cooking. The five newly identified DBPs are iodinated, present at low concentrations (from about 1 to 7.6 µg/L), and the phenolic forms may be of concern with respect to human health.
Bill
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Identification, toxicity and control of iodinated disinfection byproducts in cooking with simulated chlor(am)inated tap water and iodized table salt
Yang Pan, Xiangru Zhang, Yu Li
Water Research, 2016; 88: 60 DOI: 10.1016/j.watres.2015.10.002
Abstract
“Chlorine/chloramine residuals are maintained in drinking water distribution systems to prevent microbial contamination and microorganism regrowth. During household cooking processes (e.g., soup making), the residual chlorine/chloramines in tap water may react with the iodide in iodized table salt to form hypoiodous acid, which could react with remaining natural organic matter in tap water and organic matter in food to generate iodinated disinfection byproducts (I-DBPs). However, I-DBPs formed during cooking with chloraminated/chlorinated tap water are almost completely new to researchers. In this work, by adopting precursor ion scan of m/z 127 using ultra performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry, many new polar I-DBPs formed during cooking with chloraminated/chlorinated tap water were detected and proposed with structures, of which 3-iodo-4-hydroxybenzaldehyde, 3-iodo-4-hydroxybenzoic acid, 3-iodo-4-hydroxy-5-methylbenzoic acid, diiodoacetic acid, 3,5-diiodo-4-hydroxybenzaldehyde, 3,5-diiodo-4-hydroxybenzoic acid, 2,6-diiodo-4-nitrophenol, 2,4-diiodo-6-nitrophenol, and 2,4,6-triiodophenol were confirmed with standard compounds. With the aid of ultra fast liquid chromatography/ion trap-time of flight-mass spectrometry, molecular formula identification of five new I-DBPs (C8H5O4I, C7H4NO4I, C8H5O5I, C7H4NO5I, and C8H6O3I2) was achieved. A developmental toxicity with a recently developed sensitive bioassay was conducted for the newly identified I-DBPs, suggesting that phenolic I-DBPs (except for iodinated carboxyphenols) were about 50–200 times more developmentally toxic than aliphatic I-DBPs. The major I-DBPs in a baseline simulated cooking water sample were determined to be from 0.72 to 7.63 μg/L. Polar I-DBPs formed under various disinfection and cooking conditions were compared, and suggestions for controlling their formation were provided.”
