Department of Geosciences, University of Lagos, Akoka, Lagos, Nigeria.
Inorganic Geochemistry, Centre for Environmental Geochemistry, British Geological Survey, Nottingham, UK.
Environ Geochem Health. 2022 Mar;44(3):893-909. doi: 10.1007/s10653-021-00991-2. Epub 2021 Jun 11.
The occurrence of mercury (Hg) in the environment globally has been linked largely to its use for gold processing. In this research, ore samples, agricultural soil and mine wastes were taken within the vicinity of an artisanal gold mine and processing sites in Niger state, a north-central part of Nigeria to determine Hg contamination in the environment and estimate the potential hazard to health. The values of Hg measured in ore, agricultural soil and mine wastes ranged between 0.03 and 5.9, 0.002 and 5.57 and 0.19 and 20.99 mg/kg, respectively, with the majority of samples observed above the crustal average values of 0.003 mg/kg. All of the samples were 100 times greater than the USEPA residential soil screening level of 0.0023 mg/kg, but were lower than comparable mine sites within the same region. Contamination indices were used to demonstrate the potential exposure to Hg contamination in the study area which ranged from a medium to high level of contamination. Average daily dose and hazard quotient (HQ) were calculated for adults and children in the study area and decreased in the following order: ADDvapour > ADDingestion > ADDdermal > ADDinhalation. The non-carcinogenic health risk index (HI) of Hg calculated for children and adults in the study area was children: 7.42, 2.19, 1.49 and adults: 4.45, 1.26, 1.19, for mine wastes, agricultural soil and ore, respectively. All of these values were higher than a considered safe level (= 1) and therefore showed that Hg posed a serious non-carcinogenic HI for both adults and children exposed to the soil in the study area. The bioaccessible fraction as a measure of ingestion for Hg was generally < 13% across all sample matrices, suggesting a low bioaccessibility. An HQ incorporating bioaccessible data (BHQ) ranged between 0.000005 and 4.06 with a mean value of 0.62. Values for the BHQ were still > 1, threshold limit in some samples and showed that Hg could present a risk to health via ingestion, although further research is required to assess dermal and inhalation bioaccessibility to assess fully the risk to residents. However, the values were lower than the non-carcinogenic health risk index, which is assumed to be overestimated.
汞(Hg)在全球环境中的存在主要与它在金矿加工中的应用有关。在这项研究中,在尼日利亚中北部尼日尔州的一家手工金矿和加工点附近采集了矿石样本、农业土壤和矿山废物,以确定环境中的 Hg 污染情况,并评估对健康的潜在危害。矿石、农业土壤和矿山废物中测量的 Hg 值范围分别为 0.03 至 5.9、0.002 至 5.57 和 0.19 至 20.99mg/kg,大多数样本的含量均高于地壳平均值 0.003mg/kg。所有样本的含量均是美国环保署规定的住宅土壤筛选值 0.0023mg/kg 的 100 倍,但低于同一地区的可比矿山。污染指数用于表明研究区域内潜在的 Hg 污染暴露水平,污染水平从中等到高度不等。成人和儿童在研究区域的平均日剂量和危害商(HQ)按以下顺序计算: vapour > ingestion > dermal > inhalation。对研究区域内儿童和成人计算的 Hg 非致癌健康风险指数(HI)分别为儿童:7.42、2.19、1.49 和成人:4.45、1.26、1.19,对于矿山废物、农业土壤和矿石。这些值均高于安全考虑值(=1),这表明 Hg 对暴露于研究区域土壤的成人和儿童构成了严重的非致癌 HI。作为摄入的衡量标准,可提取分数(Bioaccessible Fraction)对于 Hg 通常低于所有样本矩阵的 13%,表明其生物可利用性较低。包含可生物利用数据(BHQ)的 HQ 值范围在 0.000005 至 4.06 之间,平均值为 0.62。BHQ 的值仍>1,在一些样本中超过了阈值极限,表明 Hg 可能通过摄入对健康构成风险,尽管需要进一步研究来评估皮肤和吸入的生物可利用性,以全面评估居民的风险。然而,这些值低于非致癌健康风险指数,该指数被认为被高估了。