Prenatal disinfection by-products (DBPs) exposure is linked with adverse birth outcomes. Genetic susceptibility to DBP metabolism may modify the exposure-outcome associations.To investigate whether CYP2E1 and GSTZ1 genetic polymorphisms modified the associations of prenatal DBP exposures with adverse birth outcomes.Two biomarkers of DBP exposures including trihalomethanes (THMs) in blood and trichloroacetic acid (TCAA) in urine were determined among 426 pregnant women from a Chinese cohort study. CYP2E1 (rs2031920, rs3813867, and rs915906) and GSTZ1 (rs7975) polymorphisms in cord blood were genotyped. Statistical interactions between prenatal DBP exposures and newborns CYP2E1 and GSTZ1 polymorphisms on birth outcomes (birth weight, birth length, and gestational age) were examined by multivariable linear regression with adjustment for potential confounders.We found that newborns CYP2E1 genetic polymorphisms (rs2031920 and rs3813867) modified the associations of maternal blood THMs or urinary TCAA levels with birth outcomes. However, these interactions were nonsignificant after Bonferroni correction for multiple comparisons, except for the interaction between maternal blood BrTHMs [sum of dibromochloromethane (DBCM), bromodichloromethane (BDCM), and bromoform (TBM)] and newborns CYP2E1 gene rs2031920 polymorphisms on birth weight (P for interaction = 0.003).Newborns genetic variations of CYP2E1 rs2031920 may modify the impacts of prenatal BrTHM exposure on birth weight. This finding needs to be further confirmed.

To better understand the precursor of disinfection by-products (DBPs) and provide useful information for water utilities to manage the drinking water, a study of DBP formation was conducted through chlorination of leaf organic matter (OM) from phoenix tree and algal OM from Chlorella vulgaris. DBPs investigated include trichloromethane (TCM), trichloroacetic acid (TCAA), dichloroacetic acid (DCAA), chloroacetic acid (CAA), dichloroacetonitrile (DCAN) and trichloroacetonitrile (TCNM). Results show that the specific yields (μg/mg C) of C-DBPs (TCM, CAA, DCAA and TCAA) from leaf OM were higher but the specific yields of N-DBPs (DCAN and TCNM) were lower than those from algal OM. Correlation analysis revealed that C-DBPs yields (μg/L) were significantly (p < 0.01) interrelated with each other (r = 0.937–0.996), and for each C-DBP, the hydrophobic OM contributed more to their formation (61–90% of total yields) as compared with hydrophilic OM. In spite of these characteristics, an in-depth examination was conducted revealing that the hydrophobicity and aromaticity of C-DBPs precursors were in the order of TCAA > DCAA & TCM > CAA. DCAN precursors were highly variable: they were dominated by hydrophobic OM (leaf OM: 86%) or hydrophilic OM (algal OM: 61%). Hydrophilic OM was the most important precursor for TCNM (76–79% of total yields), followed by hydrophobic neutral and base substances (29–45% of total yields), but the hydrophobic acids exhibited an inhibition role in TCNM formation.

This study evaluated the effect of low-pressure ultraviolet (UV) irradiation on the formation of disinfection by-products (DBPs) from algal organic matter of Microcystis aeruginosa during subsequent chlorination and chloramination. The algal organic matter includes extracellular organic matter (EOM) and intracellular organic matter (IOM). The fluorescence excitation-emission matrix spectra indicated that the humic/fulvic acid-like organics of EOM and the protein-like organics of IOM may be preferentially degraded by UV treatment. UV irradiation with low specific UV absorbance values was effective in reducing the formation of trihalomethanes and dichloroacetic acid from EOM and IOM during the subsequent chlorination. During the UV-chloramine process, higher UV dose (1000 mJ/cm²) led to the decrease of the formation of dichloroacetic acid, trichloroacetic acid, and haloketones from IOM by an average of 24%. Furthermore, UV irradiation can slightly increase the bromine substitution factors (BSFs) of haloacetic acids from EOM during chlorination, including dihaloacetic acids and trihaloacetic acids in the presence of bromide (50 μg/L). However, UV irradiation did not shift the formation of DBPs from IOM to more brominated species, since the BSFs of trihalomethanes, dihaloacetic acids, trihaloacetic acids, and dihaloacetonitriles almost kept unchanged during UV-chlorine process. As for UV-chloramine process, UV irradiation decreased the BSFs of trihalomethanes, while increased the BSFs of dihaloacetic acid for both EOM and IOM. Overall, the UV pretreatment process is a potential technology in treating algae-rich water.