Department of Urban Environmental Management, Kotebe University of Education, Addis Ababa, Ethiopia.
Department of Water and Public Health, Institute of Ethiopian Water Resources, Addis Ababa University, Addis Ababa, Ethiopia.
Front Public Health. 2022 Oct 18;10:977721. doi: 10.3389/fpubh.2022.977721. eCollection 2022.
Lead (Pb) from different sources accumulate in the irrigation water, irrigated soil and in different parts of plants. Reports show contradictory findings and high variability of lead accumulation and associated public health risks. We hypothesized that lead accumulation in irrigation water, soil and edible plants is high enough to be a public health risk. By using the standard procedures for meta-analysis, 24 studies were qualified. The studies included in the meta-analysis are concentrated in few countries with strong authors' key words co-occurrence relationship. The mean concentration of Pb in the irrigation wastewater ranged from 0.0196 ± 0.01 mg/l to 52.4 ± 0.02 mg/l in wastewater and about 50% of the values are beyond the limits for irrigation water standard. The study also showed that the concentration of Pb in the irrigated soil vary significantly from a minimum of 0.04 ± 2.3 mg/l in Ethiopia to a maximum of 441 ± 19.8 mg/l in Iran ( < 0.01). Based on effect size analysis, the weight of the studies ranged from 0.1 to 5.4% indicating that the studies' contribution to the overall effect is barely different. The heterogeneity test statistics also indicates considerable variability between the studies (I = 98%, -value < 0.001). The subgroup analysis showed large between-studies heterogeneity in both groups (Tau = 28.64; T = 98%). A total of 44 crops were studied, of which 38 were leafy and non-leafy vegetables. Most popular crops including spinach, cabbage and lettuce are most frequently studied crops. In all crops, the Pb level in crops produced by using untreated wastewater are beyond the WHO limit for edibility. In all of the studies, the pollution load index (PLI) and soil accumulation factor (SAF) is much higher indicating that there is a buildup of Pb concentration in wastewater irrigated soil. The plant concentration factor (PCF) calculated shows the high Pb accumulation potential of the edible parts of the crops. The health risk index (HRI) calculated shows that in all of the studied crops from India, Iraq, Morocco and Egypt are much higher than one indicating the high health risk of consumption.
铅（Pb）来自不同的来源，会在灌溉水中、灌溉土壤中和植物的不同部位积累。报告显示，铅的积累和相关的公共健康风险存在相互矛盾的发现和高度的可变性。我们假设灌溉水、土壤和食用植物中的铅积累量高到足以构成公共健康风险。通过使用元分析的标准程序，有 24 项研究符合条件。纳入元分析的研究集中在少数几个作者关键词共现关系较强的国家。灌溉废水中 Pb 的平均浓度范围为 0.0196 ± 0.01mg/L 至 52.4 ± 0.02mg/L，约 50%的数值超过灌溉用水标准限值。研究还表明，灌溉土壤中 Pb 的浓度差异很大，从埃塞俄比亚的最低 0.04 ± 2.3mg/L 到伊朗的最高 441 ± 19.8mg/L（<0.01）。基于效应量分析，研究的权重范围为 0.1%至 5.4%，表明研究对总体效应的贡献几乎没有差异。异质性检验统计数据也表明研究之间存在相当大的变异性（I = 98%，-值<0.001）。亚组分析表明，两组之间的组间异质性很大（Tau = 28.64；T = 98%）。共研究了 44 种作物，其中 38 种为叶菜类和非叶菜类蔬菜。最受欢迎的作物包括菠菜、白菜和生菜，是最常研究的作物。在所有作物中，使用未经处理的废水生产的作物的 Pb 含量超过了世界卫生组织对可食用性的限制。在所有研究中，污染负荷指数（PLI）和土壤积累因子（SAF）都高得多，表明在灌溉废水的土壤中 Pb 浓度有积累。计算得出的植物浓缩因子（PCF）表明，作物可食用部分具有很强的 Pb 积累潜力。计算得出的健康风险指数（HRI）表明，在印度、伊拉克、摩洛哥和埃及的所有研究作物中，HRI 都远高于 1，表明食用这些作物存在很高的健康风险。
