This study aimed to evaluate the annual pollution characteristics of trichloromethane (TCM) in Kunshan City’s tap water from 2016 to 2022. This research analyzed 566 tap water samples from centralized water supply units, utilizing the GB 5749-2006 Sanitary Standard for Drinking Water as the evaluation benchmark. Data analysis employed non-parametric tests and Spearman’s correlation analysis using Excel 2017 and SPSS 26.0. The results indicated a 100% compliance rate with the TCM limit (0.06 mg/L), with median annual concentrations ranging from 0.1 to 6.4 μg/L. Significant inter-annual variations were observed (H = 222.5, p < 0.01), with the lowest levels in 2019 and the highest in 2020. Quarterly analysis revealed significant seasonal differences (H = 94.0, p < 0.01), peaking in the third quarter (8.0 μg/L) and bottoming in the first quarter (3.5 μg/L). TCM concentrations showed significant correlations with annual and quarterly trends, turbidity, and chlorides (|rs| > 0.3, p < 0.01) but not with pH (rs = −0.0025, p = 0.55). While Kunshan City’s drinking water demonstrates satisfactory TCM levels, an increasing annual trend and higher concentrations in the latter half of the year warrant continued monitoring and investigation. In this study, we assessed the health risks for households in Kunshan, China, due to trichloromethane (TCM) in drinking water. The overall carcinogenic risk from multiple exposure pathways was slightly above the ideal level, while the non-carcinogenic risk was within an acceptable range.

Formaldehyde poses a critical indoor environmental health hazard, particularly in rapidly urbanizing settings. Residential and public buildings serve as the most significant exposure sites; however, the extent of urban populations’ formaldehyde exposure in these two types of environments remains unclear, posing challenges for precise prevention and control strategies. This study employed a comprehensive exposure assessment by combining personal exposure monitoring with environmental sampling to characterize formaldehyde exposure profiles and contributions apportioned to residential and public microenvironments. The mean personal exposure concentration of formaldehyde of working adults was 36.0 μg/m³ (SD: 30.7 μg/m³). The mean chronic daily intake derived from personal data was 5.1 μg/kg/day. Residential environments were identified as the predominant contributors to overall exposure (>50% of total exposure in working adults, and >80% in children/elderly), followed by public places (contributing to 40% among employed adults). For children under 5 years and the elderly, residential settings accounted for >80% of the contribution of total intake. The home and school environments contributed to approximately 60% and 30% of exposure for children and adolescents aged 5–18 years, respectively. Other microenvironments (such as vehicular and outdoor settings) contributed to less than 10%. Simulation scenarios further suggested that reducing indoor formaldehyde concentrations by 15–30% in both residential and public buildings could avert 10–20% of associated health burdens for targeted populations. These findings underscore the continuous need for formaldehyde exposure control in both residential and public environments as well as indoor health interventions in modern urban areas.

Haloacetonitriles (HANs), toxic disinfection by-products, are unregulated in China, with no standardized analytical methods. This study established a simultaneous quantitative method for six typical HANs in drinking water using an optimized purge-and-trap gas chromatography–mass spectrometry (P&T-GC/MS) system. Key parameters, including sorbent trap selection, purge time, and moisture control settings, were systematically optimized. The OI No. 7 trap and a 13 min purge time were selected to maximize sensitivity while minimizing moisture interference. Under optimal conditions, all target analytes showed good linearity (R² > 0.999). The method detection limits (LODs) ranged from 0.007 to 0.202 μg/L, and the limits of quantitation (LOQs) ranged from 0.2 to 2.0 μg/L. Average spiked recoveries in tap water were 89.5–111.0%, with relative standard deviations (RSDs) below 5% (n = 7). A core optimization was omitting pH adjustment and ascorbic acid quenching to avoid non-target degradation of brominated HANs and ensure accurate in situ concentration determination. Application to 16 Kunshan tap water samples showed total HAN concentrations of 0.59–3.03 μg/L (average: 1.62 μg/L), dominated by bromochloroacetonitrile (BCAN) and dibromoacetonitrile (DBAN). Process analysis indicated significant synergistic HAN removal by sand filtration and activated carbon, while chloramination significantly increased brominated HANs via enhanced bromination. This efficient, sensitive P&T-GC/MS method is suitable for trace HAN monitoring and provides technical support for HAN control in water treatment.