Jafari Negar, Behnami Ali, Ghayurdoost Farhad, Solimani Ali, Mohammadi Amir, Pourakbar Mojtaba, Abdolahnejad Ali
Department of Environmental Health Engineering, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran.
Department of Environmental Health Engineering, Faculty of Health, Iran University of Medical Sciences, Tehran, Iran.
Heliyon. 2024 Jul 14;10(14):e34563. doi: 10.1016/j.heliyon.2024.e34563. eCollection 2024 Jul 30.
Various factors influence the formation of disinfection by-products (DBPs) in drinking water. Therefore, it is crucial to study the formation of DBPs and identify the associated influencing agents in water distribution networks (WDNs) to effectively prevent and control the health risks posed by DBPs. This research aimed to examine THM concentrations in the WDNs of Maragheh, Iran, focusing on seasonal variations. It also compared THM levels between new and old WDNs and assessed the health risks associated with exposure to THMs through various exposure routes. The mean concentrations of Chloroform, BDCM, DBCM, and Bromoform were 44.28 ± 18.25, 12.66 ± 5.19, 3.16 ± 0.89, and 0.302 ± 0.89 μg/L, respectively. Therefore, Chloroform was the predominant compound among the THM species, accounting for over 72 % of the total THMs (TTHMs). The average TTHMs concentration in summer (69.89 μg/L) was significantly higher than in winter (50.97 μg/L) (p < 0.05). Except for Bromoform, concentrations of other THM species in the new WDNs were considerably lower than in the old WDN (p < 0.05). The mean lifetime cancer risk (LTCR) rates for oral and dermal exposure routes to THMs were negligible and within acceptable risk levels. However, the LTCR mean values for inhalation exposure routes to THMs in winter and summer were within low (1 × 10 ≤ LTCR <5.1 × 10) and high acceptable risk levels (5.1 × 10 ≤ LTCR <10), respectively. Inhalation exposure presented the highest cancer risk among the various exposure routes. The hazard index values for oral and dermal contact with THMs were less than 1. Finally, sensitivity analysis revealed that the ingestion rate and exposure duration of THMs had the most significant positive effect on chronic daily intake (CDI) values and cancer risk. However, further comprehensive investigations are needed to develop effective solutions for reducing and controlling the precursors of DBP formation, as well as identifying suitable alternative disinfection compounds that minimize by-product formation.
多种因素会影响饮用水中消毒副产物（DBPs）的形成。因此，研究DBPs的形成并确定配水管网（WDNs）中的相关影响因素对于有效预防和控制DBPs带来的健康风险至关重要。本研究旨在调查伊朗马拉盖WDNs中的三卤甲烷（THM）浓度，重点关注季节变化。研究还比较了新旧WDNs中的THM水平，并评估了通过各种暴露途径接触THMs所带来的健康风险。氯仿、一溴二氯甲烷（BDCM）、二溴一氯甲烷（DBCM）和溴仿的平均浓度分别为44.28±18.25、12.66±5.19、3.16±0.89和0.302±0.89μg/L。因此，氯仿是THM种类中的主要化合物，占总三卤甲烷（TTHMs）的72%以上。夏季的平均TTHMs浓度（69.89μg/L）显著高于冬季（50.97μg/L）（p<0.05）。除溴仿外，新WDNs中其他THM种类的浓度远低于旧WDN（p<0.05）。通过口服和皮肤接触途径接触THMs的终生癌症风险（LTCR）率可忽略不计，且处于可接受的风险水平内。然而，冬季和夏季通过吸入接触THMs的LTCR平均值分别处于低可接受风险水平（1×10≤LTCR<5.1×10）和高可接受风险水平（5.1×10≤LTCR<10）。在各种暴露途径中，吸入暴露带来的癌症风险最高。通过口服和皮肤接触THMs的危害指数值小于1。最后，敏感性分析表明，THMs的摄入率和暴露持续时间对慢性每日摄入量（CDI）值和癌症风险具有最显著的正影响。然而，需要进一步进行全面调查，以制定有效的解决方案来减少和控制DBP形成的前体，并确定合适的替代消毒化合物，以尽量减少副产物的形成。
