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Abstract Exposure to polycyclic aromatic hydrocarbons (PAHs) is linked with increased risk of diabetes, whereas socioeconomic status (SES) may contribute to the development of diabetes. However, the mechanisms underlying the relationships between them are unclear. We used structural equation modeling (SEM) to identify mediating factors in the associations of PAHs exposure, low SES with diabetes risk. Data were collected from 2751 Wuhan participants at baseline from the Wuhan-Zhuhai Cohort Study (n = 3053). They answered the questionnaires regarding socio-demographic, participated physical examinations and provided urine samples for measurements of urinary monohydroxy-polycyclic aromatic hydrocarbons (OH-PAHs) levels. SEM was used to identify the mediating factors (such as hypertension, body mass index (BMI), triglycerides (TG) and total cholesterol (TCHO)) in the associations of low SES or PAHs exposure with diabetes risk. We observed that partial effect of PAHs exposure (β = 0.281, p = 0.034), BMI (β = 0.182, p = 0.000), TG (β = 0.358, p = 0.000), TCHO (β = 0.203, p = 0.009) or hypertension (β = 0.385, p = 0.000) on diabetes was directive. Moreover, low SES also exhibited a directive effect on PAHs exposure (β = −0.084, p = 0.000), BMI (β = 0.301, p = 0.000), hypertension (β = 0.134, p = 0.003) and TG (β = 0.087, p = 0.001). PAHs exposure directly affected TCHO levels (β = 0.080, p = 0.002) and TG (β = 0.076, p = 0.017). The proportion of the effect of PAHs exposure on diabetes mediated by TG and TCHO was 15.6%. The proportion of the effect of low SES on diabetes mediated by BMI, hypertension and TG was 89.1%. The results suggested that low SES increased diabetes risk, which may be partially explained by BMI, hypertension and triglycerides, and exposure to high levels of PAHs may have indirect contribution to increased risk for diabetes with dyslipidemia. Graphical abstract Unlabelled Image Highlights • Urinary OH-PAHs levels were positively related to diabetes risk in community adults. • BMI, TG and hypertension mediated the linkage of low SES and diabetes risk. • TG and TCHO mediated the association of PAHs exposure with diabetes risk. [ABSTRACT FROM AUTHOR]

Abstract: The degradation of chlortoluron by monochloramination was investigated in the pH range of 4–9. The degradation kinetics can be well described by a second-order kinetic model, first-order in monochloramine (NH2Cl) and first-order in chlortoluron. NH2Cl was found not to be very reactive with chlortoluron, and the apparent rate constants in the studied conditions were 2.5–66.3M−1 h−1. The apparent rate constants were determined to be maximum at pH 6, minimum at pH 4 and medium at alkaline conditions. The main disinfection by-products (DBPs) formed after chlortoluron monochloramination were identified by ultra performance liquid chromatography-ESI-MS and GC-electron capture detector. N-Nitrosodimethylamine (NDMA) and 5 volatile chlorination DBPs including chloroform (CF), dichloroacetonitrile, 1,1-dichloropropanone, 1,1,1-trichloropropanone and trichloronitromethane were identified. The distributions of DBPs formed at different solution pH were quite distinct. Concentrations of NDMA and CF were high at pH 7–9, where NH2Cl was the main disinfectant in the solution. NDMA formation during chlortoluron monochloramination with the presence of nitrogenous salts increased in the order of nitrite

Although polycyclic aromatic hydrocarbons (PAHs) and phthalates separately related to oxidative DNA damage have been reported, the joint effect of them on oxidative DNA damage need to be evaluated. In this pilot study, 106 participants were recruited from the community-dwelling residents (n = 1240) of Wuhan city, China. Each individual provided three continuous days of spot urine samples for measuring the urinary monohydroxylated PAHs (OH-PAHs), phthalates metabolites and 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels in the two seasons. Linear mixed effect model and Bayesian Kernel Machine Regression (BKMR) were used to analyze joint effect of urinary PAHs and phthalates metabolites on urinary 8-OHdG levels. We measured cellular and mitochondrial reactive oxygen species (ROS), malondialdehyde (MDA) and glutathione peroxidase (GSH-Px) levels as well as IL-6 and IL-8 secretions by the corresponding commercial kits in HepG2 cells treated with di (2-ethylhexyl) phthalate (DEHP, 62.5, 125.00, 250.00, 500.00 or 1000.00 μM) alone, benzo[ a ]pyrene (BaP, 50.00 μM) alone or both DEHP and BaP. Linear mixed effect model showed that each of urinary PAHs metabolite was positively associated with urinary 8-OHdG levels; urinary level of mono (2-ethylhexyl) phthalate or monoisononyl phthalate was positively associated with urinary 8-OHdG levels; BKMR model indicated that a positive association of eight OH-PAHs with urinary 8-OHdG levels, nine urinary phthalates metabolites enhanced the association. We found that DEHP at the indicated concentration plus 50.00 μM BaP increased cellular and mitochondrial ROS levels, IL-6 and IL-8 secretions at 24 and 48 h as well as MDA levels and GSH-Px activities at 48 h, compared to the solvent control. Exposure to certain dose phthalates may attenuate the positive association of PAHs exposure with oxidative DNA damage in the body. DEHP at the certain concentrations enhanced BaP-induced mitochondrial ROS, pro-inflammatory response and the activation of the antioxidant defense system in HepG2 cells. Unlabelled Image • Eight OH-PAHs levels was positively associated with urinary 8-OHdG levels. • Urinary phthalate metabolites enhanced effect of urinary OH-PAHs on 8-OHdG levels. • Urinary 2 plus 3-OHPhe was the most contributors to urinary 8-OHdG levels. • DEHP enhanced BaP-induced increase of mitochondrial ROS in HepG2 cells. • U-curve effect of DEHP with BaP on cellular ROS formation was found in HepG2 cells. [ABSTRACT FROM AUTHOR]

Chloramine disinfection is one of the most common disinfection methods in drinking water treatment. In this study, the temporal variability of water odors during monochloramine auto-decomposition was investigated to elucidate the characteristics of odor problems caused by adopting chloramine disinfection in tap water. Odor intensities and dominant odorant contributions were determined using the flavor profile analysis (FPA) and odor active value (OAV), respectively. During auto-decomposition of monochloramine, Cl 2 /N molar ratio, pH, temperature, and the presence of NOM all affected odor intensity and odor temporal variation in drinking water. In general, decreasing pH from 8.5 to 6.0 led to increasing perceived odor intensity due to the formation of dichloramine. The major odorants responsible for chlorinous odor under acidic and non-acidic conditions were dichloramine and monochloramine, respectively. Chloraminated water with a Cl 2 /N molar ratio of 0.6 or NOM concentration <2 mg-C L −1 inhibited odor intensity. Furthermore, the influence of rechlorination on chlorinous odor intensity for chloraminated water should not be neglected. The results of this study will be beneficial for the control of chlorinous odors caused by chloramine disinfection in drinking water. [ABSTRACT FROM AUTHOR]

Exposure to polycyclic aromatic hydrocarbons (PAHs) could cause high blood pressure (BP) and increased risk for atherosclerotic cardiovascular disease (ASCVD). However, the mechanisms underlying the relationship between them were unclear. We investigated potential mediation effect of obesity on the association of exposure to PAHs with high BP and increased risk for ASCVD. In the repeated measures study, 106 community-dwelling residents in Wuhan, China finished the physical examination in the winter and summer seasons, eight urinary PAHs metabolites were measured. Associations of urinary PAHs with high BP and increased risk for ASCVD were assessed using either linear mixed effect models or generalized estimating equations models. Mediation analysis was performed to evaluate the mediating effect of obesity on the association of urinary PAHs metabolites with high BP or increased risk of ASCVD. We observed the positive association between urinary PAHs metabolites and BP or the odds ratios for high BP (all P < 0.05). Additionally, each one-unit increase in ln-transformed urinary levels of 4-hydroxyphenanthrene or the total of PAH metabolites was associated with a 12.63% or 11.91% increase in the estimated 10-year ASCVD risk (both P < 0.05). The waist-to-height ratio mediated 29.0% of the association of urinary 4-hydroxyphenanthrene with increased risk of ASCVD ( P < 0.05). The findings suggest that PAHs exposure may be associated with elevated BP and an increased risk of ASCVD. Obesity may partially mediate the association between PAHs exposure and higher BP or increased risk of ASCVD. [ABSTRACT FROM AUTHOR]

Acrylamide is a monomer of polyacrylamide, which is widely used in the water treatment process as a flocculant. The degradation kinetics and formation of disinfection by-products (DBPs) during acrylamide chlorination were investigated in this study. The reaction between chlorine and acrylamide followed a pseudo-first-order kinetics. A kinetic model regarding acrylamide chlorination was established and the rate constants of each predominant elementary reaction (i.e., the base-catalyzed reaction of acrylamide with ClO − as well as the reactions of acrylamide with HOCl and ClO − ) were calculated as 7.89 × 10 7 M − 2 h − 1 , 7.72 × 10 1 M − 1 h − 1 , and 1.65 × 10 3 M − 1 h − 1 , respectively. The presence of Br − in water led to the formation of HOBr and accelerated the rate of acrylamide degradation by chlorine. The reaction rate constant of acrylamide with HOBr was calculated as 1.33 × 10 3 M − 1 h − 1 . The degradation pathways of acrylamide chlorination were proposed according to the intermediates identified using ultra-performance liquid chromatography and electrospray ionization-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS). Five chlorinated DBPs including chloroform (CF), dichloroacetonitrile (DCAN), trichloroacetonitrile (TCAN), dichloroacetamide (DCAcAm), and trichloroacetamide (TCAcAm) were identified during acrylamide chlorination. The formation of CF, DCAN, DCAcAm, and TCAcAm kept increasing, while that of TCAN increased and then decreased with increasing reaction time. As the chlorine dosage increased from 0.75 to 4.5 mM, DCAN became the dominant DBP. Large amounts of CF, DCAN, and TCAN were formed at basic pHs. The hydrolysis of DCAN and TCAN led to the formation of DCAcAm and TCAcAm, respectively. The results of this study elucidated that acrylamide can be a precursor for the formation of haloacetonitriles (HANs) and haloacetamides (HAcAms) during drinking water treatment. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the characteristics of dissolved organic nitrogen (DON) in raw water from the Huangpu River and also in water undergoing treatment in the full-scale Yangshupu drinking water treatment plant (YDWTP) in Shanghai, China. The average DON concentration of the raw water was 0.34mg/L, which comprised a relatively small portion (~5%) of the mass of total dissolved nitrogen (TDN). The molecular weight (MW) distribution of dissolved organic matter (DOM) was divided into five groups: >30, 10–30, 3–10, 1–3 and <1kDa using a series of ultrafiltration membranes. Dissolved organic carbon (DOC), UV absorbance at wavelength of 254nm (UV254) and DON of each MW fraction were analyzed. DON showed a similar fraction distribution as DOC and UV254. The <1kDa fraction dominated the composition of DON, DOC and UV254 as well as the major N-nitrosodimethylamine formation potential (NDMAFP) in the raw water. However, this DON fraction cannot be effectively removed in the treatment line at the YDWTP including pre-ozonation, clarification and sand filtration processes. The results from linear regression analysis showed that DON is moderately correlated to DOC, UV254 and trihalomethane formation potential (FP), and strongly correlated to haloacetic acids FP and NDMAFP. Therefore, DON could serve as a surrogate parameter to evaluate the reactivity of DOM and disinfection by-products FP. [ABSTRACT FROM AUTHOR]