Tefera Molla, Aderajew Habtamu, Ezez Dessie, Dikamu Mamo, Lakew Worku
Department of Chemistry, University of Gondar, P.O.Box 196, Gondar, Ethiopia.
Department of Chemistry, Arba Minch University, P.O.Box 21, Arba Minch, Ethiopia.
Toxicol Rep. 2025 Aug 30;15:102121. doi: 10.1016/j.toxrep.2025.102121. eCollection 2025 Dec.
Heavy metal contamination is a serious concern affecting the safety of tap water sources. Hence, this study evaluated physicochemical quality indices, carcinogenic and non-carcinogenic health hazard derived from the level of toxic metals in tap water in Gondar city, Ethiopia. The results revealed that except dissolved oxygen, salinity and nitrite, all quality attributes were below the allowable quality standards. The average concentrations for iron (Fe), copper (Cu), lead (Pb), chromium (Cr) and cadmium (Cd) were ranged from 0.003 mg/L to 5 mg/L, 0.475 mg/L to 0.752 mg/L, 0.14 mg/L to 0.703 mg/L, 0.261 mg/L to 2.182 mg/L, and 0.035 mg/L to 4.286 mg/L, respectively. The mean levels of metals in different areas decreased in the order: AR > AZ1 > PS1 > AZ3 > PS2 > MR > PS3 > SHD > AZ2 > CL. Except for Cu, the concentration of Fe, Pb, Cr, and Cd exceeded the safe limits described by WHO/FAO. According to principal component analysis and cluster analysis, anthropogenic activities were found to be the major source of metals. Chronic daily intake (CDI), target hazard quotient (THQ), hazard index (HI), and incremental lifetime cancer risk assessment (ILCR) were employed to evaluate human health risks. Except for Pb in AZ1, PS3, and AR, the values of THQ for both ingestion and dermal pathways from the analysed metals for adults were within the safety limits (THQ 1). However, the distribution pattern of HI values were presented in the decreasing order: PS1 > PS2 > AZ3 > MR > PS3 > AR > AZ2 > AZ1 > SHD > CL. Except, the HI values in CL, all values were greater than one (HI > 1), indicating that tap water in these areas may pose non-carcinogenic health risk. The analysis of carcinogenic health risks indicated that the lifetime cancer risk (ingestion and dermal exposure pathways) of heavy metals were in accordance with the acceptable range for tap water (10 - 10). This finding provides valuable input for the development of precise action plans aimed at elevating water quality standards in the studied areas.
重金属污染是影响自来水水源安全的一个严重问题。因此，本研究评估了埃塞俄比亚贡德尔市自来水中有毒金属含量所衍生的理化质量指标、致癌和非致癌健康危害。结果显示，除溶解氧、盐度和亚硝酸盐外，所有质量属性均低于允许的质量标准。铁（Fe）、铜（Cu）、铅（Pb）、铬（Cr）和镉（Cd）的平均浓度分别在0.003毫克/升至5毫克/升、0.475毫克/升至0.752毫克/升、0.14毫克/升至0.703毫克/升、0.261毫克/升至2.182毫克/升、以及0.035毫克/升至4.286毫克/升之间。不同区域金属的平均含量排序为：AR > AZ1 > PS1 > AZ3 > PS2 > MR > PS3 > SHD > AZ2 > CL。除铜外，铁、铅、铬和镉的浓度超过了世界卫生组织/联合国粮食及农业组织规定的安全限值。根据主成分分析和聚类分析，发现人为活动是金属的主要来源。采用慢性每日摄入量（CDI）、目标危害商数（THQ）、危害指数（HI）和终生癌症风险增量评估（ILCR）来评估人类健康风险。除AZ1、PS3和AR中的铅外，分析得出的成人摄入和皮肤接触途径中金属的THQ值均在安全限值内（THQ < 1）。然而，HI值的分布模式排序为：PS1＞PS2＞AZ3＞MR＞PS3＞AR＞AZ2＞AZ1＞SHD＞CL。除CL中的HI值外，所有值均大于1（HI > 1），表明这些地区的自来水可能会带来非致癌健康风险。致癌健康风险分析表明，重金属的终生癌症风险（摄入和皮肤接触途径）符合自来水的可接受范围（10⁻⁶ - 10⁻⁴）。这一发现为制定旨在提高研究区域水质标准的精确行动计划提供了有价值的参考。
