Science of the Total Environment 548–549 (2016) 402–407
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Exposure Risk of Rural Residents to Copper in the Le’an River Basin, Jiangxi Province, China Yanxin Yu a,⁎, Hui Wang b, Qi Li b, Bin Wang c, Zhenghong Yan b, Aizhong Ding b a b c
School of Environment, Beijing Normal University, Beijing 100875, P. R. China College of Water Science, Beijing Normal University, Beijing 100875, P. R. China Institute of Reproductive and Child Health/Ministry of Health Key Laboratory of Reproductive Health, School of Public Health, Peking University, Beijing 100191, P. R. China
H I G H L I G H T S
G R A P H I C A L
A B S T R A C T
• Soils and food were studied in an area impacted by the largest copper mine in China. • Cu content in various food types were affected by upstream Cu mining activities • Cu intake decreased with increasing distance downstream from the Cu mining zone • Vegetables and rice were the two major contributors to the total dietary intake of Cu • Hazard Quotients indicated across the area N 85% of children will be impacted
a r t i c l e
i n f o
Article history: Received 5 August 2015 Received in revised form 21 November 2015 Accepted 22 November 2015 Available online xxxx Editor: D. Barcelo Keywords: Mining agricultural soil food chronic daily intake CDI exposure risk
⁎ Corresponding author. E-mail address: [email protected] (Y. Yu).
http://dx.doi.org/10.1016/j.scitotenv.2015.11.107 0048-9697/© 2016 Elsevier B.V. All rights reserved.
a b s t r a c t The Dexing copper (Cu) mining zone in Jiangxi Province produces China’s highest annual copper output, and the mineral waste residue and wastewater associated with ore processing are responsible for the Cu contamination of agricultural soil and food produced in the Le’an River Basin. We studied the dietary Cu intake from various foods, and the induced non-carcinogenic risk in rural residents from Dexing, Poyang, and Leping Counties situated along the Le’an River. Different food types based on the local dietary habits and agricultural soils were collected, and their Cu contents were analyzed. The Monte Carlo model was used to simulate the dietary chronic daily intake of Cu (CDICu) and its non-carcinogenic risk in four subgroups (children, adolescents, adults, and seniors). A consistently decreasing trend in the Cu levels in agricultural soil and two local food types (vegetables and eggs) was found with increasing distance downstream from the mining zone from Dexing to Poyang, whereas this trend was not observed in other food types. The order of CDICu among the three counties was Dexing N Leping N Poyang, and the order among the four subgroups was children N adolescents N adults = seniors. The two major contributors to the total CDICu were vegetables and rice. Rural residents from Dexing County had the highest proportion of people with a hazard quotient (HQ) N 1 (i.e., 79%), followed by Leping (60%) and Poyang (48%). For Dexing, ~98% of the children living in rural areas displayed HQ N 1, compared with 97% in Leping and 85% in Poyang. Our results indicated the importance of the potential effects of Cu on the health of the local young population and the need to address such effects. © 2016 Elsevier B.V. All rights reserved.
Y. Yu et al. / Science of the Total Environment 548–549 (2016) 402–407
1. Introduction Mining activities and metal smelting are known to be the main sources of hazardous heavy metals transported to soils and rivers (El Hamiani et al., 2010; Rodriguez et al., 2009). Soil copper (Cu) content has been found to be higher than the global average level (30 mg kg1 ) near mining zones and smelting factories around the world (Cheng et al., 2011; Wcislo et al., 2002; Lim et al., 2008; Cao et al., 2014). Over the past several decades, the dramatic social and economic development taking place in China has stimulated a rapid rise in demand for Cu. Dexing Copper Mine in Jiangxi Province has China’s highest annual copper ore production in Asia (Zhu et al., 2007), of which the Fujiawu copper mine is the biggest with ~ 10,000 tons ore production per day. Cu in Dexing has been intensively exploited, and higher pollution around the mining zone has been reported in the previous studies (Zhu et al., 2007; Wang et al., 2008; Liu et al., 2013). The Le’an River, the primary river of the Le’an River Basin, flows through Dexing County to Poyang Lake, the largest freshwater lake in China. Mineral waste residue, wastewater, and dust containing heavy metals are discharged into the environment during the processes of mining and in mine tailings. Flooding, aerial deposition, and agricultural irrigation can additionally cause serious Cu contamination in nearby agricultural soil (Nan et al., 2002), resulting in elevated Cu levels in crops, livestock, and poultry (Gupta and Gupta, 1998). If agricultural soil, as an important sink of heavy metal pollution, is contaminated by Cu along the Le’an River downstream from the Dexing mining zone, it would be expected to be transferred to humans, with a particularly high risk for rural residents living along the Le’an River (Cheng et al., 2011; Teng et al., 2010). Therefore, it is important to investigate the Cu concentration of agricultural soil along the Le’an River downstream from the mining zone to assess the potential health effects of the Cu mining activities. Three routes of exposure have been widely studied to assess the heavy metal exposure in humans: diet, inhalation, and skin contact (US Environmental Protection Agency, 1997). Results from previous studies suggest that diet was the major exposure route of heavy metals (Cao et al., 2014; Zheng et al., 2007). For example, the estimated risks induced by most heavy metals were mainly from the ingestion of local food, accounting for more than 85% of the three routes, and 98% for copper. Dietary habits, food sources, and the Cu concentrations of different food types can have a considerable influence on dietary Cu intake, and this intake can vary significantly with age group (Zhu et al., 2007). Hence, the selection of which foods to sample should be based on the dietary habits and food sources of the population in question. The spatial variance in the Cu concentrations of agricultural soil along the Le’an River can give rise to different contamination patterns of Cu in agricultural crops and foods. To control the levels of Cu exposure in the local population, knowledge of the relative contributions of different exposure sources to specific age groups is required. Cu is an essential nutrient and a redox-active transition metal that can lead to oxidative stress damage in human body. Excessive intake of Cu can result in weakness, lethargy, and anorexia in the early stages (Winge and Mehra, 1990), as well as the development of acute gastrointestinal symptoms, hepatocellular necrosis in the liver, and acute tubular necrosis in the kidney (Barceloux, 1999). As Cu is a noncarcinogenic heavy metal, its non-carcinogenic risk is typically characterized by the hazard quotient (HQ), taking into consideration the amount of food consumption, the Cu content in various food types, body weight, and the reference exposure dose for humans (US Environmental Protection Agency, 1997). To include all of the influencing factors, the Monte Carlo method is usually used to simulate exposure from the multiple sources and provide a distribution of the exposure risk of the population (Cao et al., 2014). The staple foods (e.g., vegetables, rice, and eggs) of rural residents living along the Le’an River downstream from the Dexing copper mining zone are produced mainly on local farmland. We measured the Cu contents of agricultural soil and various food types in rural areas along the
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Le’an River. The aims of this study were to investigate the following: 1) the Cu levels of agricultural soil and various food types in rural areas along the Le’an River downstream from the Dexing mining zone; 2) the chronic dietary intake of Cu from various food types in local residents living along the Le’an River and their relative contributions to their total Cu intake; and 3) the potential non-carcinogenic risk of Cu for these residents. Our hypothesis was that the dietary exposure risk of Cu for the rural residents along the Le’an River would decrease from the upstream mining zone to downstream and vary with population age groups. 2. Materials and Method 2.1. Study area and sampling The location of the Le’an River and the main mining and smelter area in the Le’an River Basin in Jiangxi Province, China, are shown in Figure S1 (Supporting Information). The rural areas of Dexing County (upstream), Leping County (midstream), and Poyang County (downstream) along the Le’an River were chosen for our study. Agricultural soil samples were collected from rural areas in the three counties, with 30 sampling zones in Dexing County, 13 in Leping County, and 10 in Poyang County. Each sampling zone (approximate size 200 × 200 m) was further divided into a grid of cells using a systematic grid sampling method with regularly spaced intervals (~40 m). Fifteen topsoil samples taken from depths of 0–20 cm were collected in each sampling zone using a random sampling method, and the 15 samples were mixed thoroughly to form a composite sample. The soil samples were air-dried at room temperature, and then pulverized using an agate mortar and sieved through a 0.15-mm polyamide sieve. Six types of food samples were collected in the rural villages of the three counties in 2013 based on the dietary habits of local residents. These comprised vegetables (giant radish, brassica compestris L. var. purpurea Baileysh, potato, green pepper, cucumber, eggplant, tomato, spinach, bok choy, small rape, and lactuca sativa L.); fish (grass carp, yellow-headed catfish, ricefield eel, crucian carp, and chub); meat (pork and mutton); rice; eggs (laid by local hens or purchased from the local market); and milk (liquid milk of six brands purchased locally). Eggs from local hens, homegrown vegetables, and rice were collected from farmers’ homes, and the other food types were purchased from local markets, which were the main places where local residents obtained their food as shown in Figure S1. For each food sub-type, five samples were collected and pooled into one bulk sample. For example, five carp were collected from the local markets and pooled as one representative carp sample. Vegetables, rice, eggs, and milk samples were stored and transferred at 4°C, and meat and fish at -18°C. Vegetables were washed with tap water to remove dust or soil and then further rinsed three times with deionized water, as in previous studies (Cao et al., 2014; Gebrekidan et al., 2013). Washed vegetables were subsequently dried at room temperature. The pretreatment of rice, fish, and meat was conducted according to previous studies (Gebrekidan et al., 2013; Yılmaz et al., 2007). Briefly, rice samples were washed by tap water three times and further by ultrapure water three times, oven-dried to constant weight and ground with a stainless steel grinder to pass through a 100-mesh sieve. Muscle (edible parts) of fish were dissected using a stainless steel scissor. The tissue of fish and meat were frozen-dried at ~80°C to constant weight and ground into powder for further digestion. All food samples were dried at 60–100°C to achieve a constant weight and subsequently ground into powder prior to digestion. 2.2. Copper analysis Approximately 0.1 g of each soil sample or 1 g of each food sample was taken from the composite sample, transferred to a Teflon® tube, and digested in a mixture of HNO3 (65% GR, 5 mL), HF (48% GR, 2 mL), and HClO4 (70% GR, 1 mL) in an automatic graphite digestion
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instrument (Model: ST60, Beijing Polytech Instruments, Ltd., China) with the temperature program: 140°C for 1 hour, 160°C for 1 hour, and further 180°C for 45 min. After cooling the digestion mixture to room temperature, the mixture of digested soil was diluted to 25 mL and that of digested food to 10 mL with deionized water. The Cu concentration was quantified using inductively coupled plasma–atomic emission spectrometry (SPECTRO Analytical Instruments GmbH, Germany) for the soil samples, and inductively coupled plasma–mass spectrometry (NexION300x, PerkinElmer Instruments Co., Ltd, USA). Standard samples of pork (GBW08552), spinach [GBW10014(GSB-6)], cabbage (GBW10014), and rice [GBW10014(GSB–1)] from the National Standard Material Center of China were used for quality control. Each sample was analyzed in triplicate. Three operation blanks were set for each batch of measurements. The limit of quantitation of Cu in the six food matrices ranged from 3.0 × 10-4 to 1.5 × 10-3 μg g-1. The average recoveries of spiked Cu standards in the six food categories and soils ranged from 89.2 to 119.7%.
2.3. Chronic dietary intake and risk assessment The chronic daily intake (CDI, μg kg-1 d-1) from food ingestion was used to indicate chronic exposure to Cu by reference to the US Environmental Protection Agency (EPA) guidelines (US Environmental Protection Agency, 1989), expressed as: CDI ¼ ðC IRÞ=BW;
ð1Þ
3. Results and Discussion 3.1. Concentrations of Cu in agricultural soil The heavy metal content of agricultural soil has been widely used to indicate levels of heavy metal pollution (Rodriguez et al., 2009; Cheng et al., 2011; Guo et al., 2007; Liu et al., 2011). We compared the concentrations of Cu in agricultural soil among the three counties situated along the Le’an River Basin (Fig. 1). Our results indicated no significant difference between Dexing and Leping Counties, although the Cu agricultural soil concentrations of these two counties were 2–3 times higher than that in downstream Poyang County. This implies that Cu from the Dexing mining area is transported along the Le’an River, resulting in considerable Cu contamination in Leping agricultural soil. We further compared the Cu concentrations in agricultural soil from the three counties with previously reported results (Table S1). The comparison revealed that the Cu concentrations in agricultural soil from Dexing and Leping were comparable to samples collected near mining zones (Liu et al., 2011; Xu et al., 2014), and in both counties, the Cu levels were higher than the national background value for soil (35 μg g-1) and the maximum levels of Cu in agricultural soil for organic food production (50 μg g-1) in China. Furthermore, the Cu concentrations were considerably higher than those measured in sites distant from mining zones or mining activities in China and other countries (El Hamiani et al., 2010; Rodriguez et al., 2009). The Le’an River Basin has a humid subtropical monsoon climate, and flooding and agricultural irrigation represent two important routes of Cu transport into agricultural soil. 3.2. Concentrations of Cu in various food types
where C (μg g-1) is the Cu concentration in the food, IR (g d-1) is the ingested rate of the food, and BW (kg) is body weight. The amounts of consumption of various food categories and body weights of the local population were obtained from the 2002 Chinese National Health and Nutrition Survey (CNNS) (Zhai and Yang, 2006). The non-carcinogenic risk of Cu is typically characterized by the HQ. The HQ is defined as the quotient of the CDI divided by the toxicity threshold value: HQ ¼ CDI=RfD 10−3 ;
ð2Þ
where RfD is the chronic reference dose (mg kg-1 d-1). The recommended RfD of Cu by the US EPA is 0.04 mg kg-1 d-1 (US Environmental Protection Agency, 1999). When the HQ of Cu is N 1, Cu may represent an unacceptable non-carcinogenic health risk, whereas a value ≤1 indicates an acceptable non-carcinogenic health risk. 2.4. Data analysis The target population comprised the rural residents living along the Le’an River 2–70 years of age. The population was divided according to gender, and each group was further divided into four subgroups by age: children (2–6 years old), adolescents (7–18 years old), adults (19–65 years old), and seniors (66–70 years old). Cu concentrations in each food type and agricultural soil were assumed to follow a lognormal distribution. Kruskal-Wallis H test was used to compare the three counties, and Mann-Whitney U test was used to assess the differences between groups. Statistical analyses were performed using the SPSS v16.0 software program, applying a significance level of 0.05. A Monte Carlo simulation (20,000 runs) was conducted to estimate the dietary exposure to Cu and to assess the non-carcinogenic risk, taking into consideration the variations in all factors in the calculation. The distributions of body weight and dietary amount for each age were both assumed to follow a normal distribution.
The content of heavy metals in agricultural crops have been reported to be associated with the contamination of soil by heavy metals (Cheng et al., 2011; Liu et al., 2011). Food consumption has been identified as the determinant pathway of human exposure to heavy metals, accounting for more than 90% of intake compared with the two other exposure routes, inhalation and dermal contact (Zheng et al., 2007). Cu concentrations in locally produced foods were measured to investigate the dietary exposure to Cu of local rural residents [see Table S2 (Supporting Information) and Fig. 2]. The concentration patterns of Cu in the rural areas of the three counties varied by food type. The Cu concentrations were found to be statistically different among the three counties only in vegetables and eggs, with no significant differences observed in other food types. The Cu concentrations in vegetables from Dexing were generally higher than those from Leping and Poyang. Overall, this is consistent with the decreasing trend of Cu content of agricultural soil from Dexing to Poyang. Because the vegetables were grown by local farmers, our results suggest that the Cu content of local vegetables is considerably affected by the highly polluted agricultural soil in Dexing County. Cu concentrations in eggs from Dexing and Leping were higher than that in eggs from Poyang. This may be because the hens in the upstream part of Le’an River Basin near the mining zone were fed with
Fig. 1. Concentrations of Cu in the rural agricultural soil of the three counties along Le’an River in Jiangxi Province, China. Data were shown as median value (25%-75% percentiles). # p b 0.01 by Kruskal-Wallis H test; a and b are significant groups.
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Fig. 2. Concentrations (μg g-1) of Cu in the six food types in the three counties along the Le’an River in Jiangxi Province, China. Data were shown as median value (25%-75% percentiles). # p b 0.01 by Kruskal-Wallis H test; a and b are significant groups by LSD multi-comparison test.
agricultural crops and food with adhered soil that had higher Cu content than was found in Poyang County, located downstream. With the exception of giant radish and spinach from Dexing, the Cu contents in other vegetables and food types were lower than the tolerance limits (GB15199–1994) recommended by the Ministry of Health of the People's Republic of China. The heavy metal contents of the various food types were comparable to those reported near mining zones or metallurgical smelter plants (Lim et al., 2008; Cao et al., 2014; Zheng et al., 2007; Bortey-Sam et al., 2015) and higher than those from sites distant from mining and smelter areas (Gebrekidan et al., 2013; Cao et al., 2010; Zhang et al., 2015). This underlines the importance of assessing the contamination levels of Cu in local foods.
was higher than the values observed in Poyang County (35.5%) and Dexing County (33.5%). Corn and sea products were found to be the two major contributors to total Cu intake from foods in Huludao City in northeastern China (Zheng et al., 2007), whereas wheat and vegetables were the major contributors in Shanxi Province in northern China (Cao et al., 2014). This demonstrates that the relative contributions of foods to Cu levels vary by location due to differences in dietary habits. An effective strategy to reduce dietary Cu exposure for the rural residents along the Le’an River would therefore be to control the Cu content of their ingested vegetables and rice.
3.3. Dietary exposure to Cu
The relatively high exposure levels to Cu for the rural residents along the Le’an River indicates their potential serious adverse health effects, such as the non-carcinogenic health risk, usually characterized by the HQ (Cao et al., 2014; Zheng et al., 2007). We calculated the distributions of HQ induced by dietary Cu intake for the four age groups in rural areas of the three counties along the Le’an River Basin using a Monte Carlo simulation, as shown in Fig. 5. Similar to the order of the total CDI of dietary Cu, Dexing had the highest proportion (79%) of residents with HQ N1, followed by Leping (60%) and Poyang (48%). Among the four age groups of the total residents living in rural areas along the Le’an River,
The CDI has been widely used to indicate the long-term exposure level to heavy metals (US Environmental Protection Agency, 1989; Liu et al., 2011). We calculated the CDIs of Cu from six individual food categories for eight age subgroups, as shown in Table S3 (Supporting Information). We found only minor differences (b 5%) in the CDI between male and female groups; hence, they were merged into the total population in the following calculations. The total CDIs of Cu for the four age groups, summarized in Fig. 3, followed the order children N adolescents N adults = seniors. The order of the total CDIs of Cu among the three areas was consistent for all four age groups: Dexing N Leping N Poyang. Thus, the residents of Dexing County, especially children, had higher Cu exposure levels. Fig. 4 shows the relative contributions of the six food types to dietary exposure to Cu in the three counties. The two major contributors to the total chronic intake of Cu were vegetables and rice, accounting for 96.5% (Dexing), 96.2% (Leping), and 93.9% (Poyang), of the total intake. The remaining four food types (meat, fish, eggs, milk, fruit) made only small contributions to the total Cu exposure level. This is likely because vegetables and rice not only formed a large portion of food consumed, but they also had Cu contents that were considerably higher than those of the other four food categories. In Dexing and Poyang Counties, vegetables accounted for ~ 61% of the total Cu intake, whereas they accounted for 45% in Leping County. Rice was the largest contributor to total dietary Cu exposure, accounting for 51.0% in Leping, which
3.4. Health risk assessment
Fig. 3. Total chronic dietary intakes (CDIs) of Cu from various food types for the four age groups in the three counties along the Le’an River in Jiangxi Province, China. Data are shown as median (25%-75% percentile).
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Fig. 4. Relative contributions of the six food types to the total dietary exposure of Cu for the whole population of the three counties along the Le’an River in Jiangxi Province, China
the HQ followed the order of children (93%) N adolescents (68%) N adults (46%) N seniors (41%), indicating a high non-carcinogenic risk for children caused by dietary Cu intake. For Dexing, ~ 98% of the children living in rural areas along the Le’an River had HQ N1, compared with 97% in Leping and 85% in Poyang, suggesting the need for greater focus on the health effects caused by Cu on the young population of the area. The decreasing trend of health risk induced by dietary Cu intake and its variation among the four age groups along the Le’an River was overall consistent with our hypothesis. The Dexing Copper Mine in Jiangxi Province, with the highest annual copper ore production in China, situated on a tributary of Le’an River, is the primary source of Cu to downstream ecosystems. Other studies conducted in mining zones [5, 24, 25, 28] or around the industrial areas (Cao et al., 2014; Zheng et al., 2007; Guo et al., 2007; Cao et al., 2010) mostly focused on the Cu contamination of agricultural soil or foods and their health risk to the local residents. Our study presented a profile of the potential adverse health effect of Cu mining from a basin prospective. Results indicated that the transport of Cu from upstream to downstream was positively associated with its health risk on the rural residents living near Le’an River. Effective remediation measures for contaminated soil in the mine area should be taken to control the Cu transport to the downstream of Le’an River Basin.
the portion of dietary Cu mobilized from the human digestion system to the circulatory system was not assessed. However, our study also had several strengths. First, selection bias was minimal because six food categories (i.e., fruits, vegetables, fish, meat, eggs, and milk) were considered systematically based on the dietary habits of local residents. Furthermore, some food types were collected in residents’ homes. Second, we provided a profile of the distribution of exposure risk of rural residents along the Le’an River. Third, the relative contributions of the six food categories for the four age groups were assessed. Therefore, our study offers reference data that could be used to control the chronic dietary intake of Cu in residents of the Le’an River Basin. 4. Conclusions We investigated the Cu contents of agricultural soil and various food types in rural areas along the Le’an River. A consistently decreasing trend in the Cu contents in agricultural soil and local foods (vegetables and eggs) along the Le’an River with increasing distance downstream from the Dexing mining zone indicated the potential effects of mining activities. The two major contributors of total dietary Cu intake were vegetables and rice. The rural residents of Dexing County, especially children, had a higher non-carcinogenic risk from Cu than did those living along the Le’an River Basin downstream from the mining zone.
3.5. Limitations and strengths Conflict of interest This study had several limitations that should be considered when interpreting the findings. Variances in the bioavailability of Cu among food types were not considered in the modeling simulations; therefore,
The authors declare they have no actual or potential competing financial interests.
Fig. 5. Hazard quotient (HQ) of the total dietary Cu intake from the six food types for the four age groups [(A) Children; (B) Adolescents; (C) Adults; and (D) Seniors] of the three individual villages along the Le’an River Basin in Jiangxi Province, China
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Role of the funding sources The funding agencies have no role in study design, implementation, data analysis, and interpretation. Acknowledgement This research was supported by grants from the National Natural Science Foundation of China (No. 41371466 and 41401583) and Fundamental Research Funds for the Central Universities (No. 2013NT45). Appendix A. Supplementary data Supplementary data to this article can be found online at http://dx. doi.org/10.1016/j.scitotenv.2015.11.107. References Barceloux, D.G., 1999. Copper. J. Toxicol. Clin. Toxicol. 37, 217–230. Bortey-Sam, N., Nakayama, S.M., Ikenaka, Y., Akoto, O., Baidoo, E., Yohannes, Y.B., Mizukawa, H., Ishizuka, M., 2015. Human health risks from metals and metalloid via consumption of food animals near gold mines in Tarkwa, Ghana: estimation of the daily intakes and target hazard quotients (THQs). Ecotoxicol. Environ. Saf. 111, 160–167. Cao, H.B., Chen, J.J., Zhang, J., Zhang, H., Qiao, L., Men, L., 2010. Heavy metals in rice and garden vegetables and their potential health risks toinhabitants in the vicinity of an industrial zone in Jiangsu, China. J. Environ. Sci. 22, 1792–1799. Cao, S.Z., Duan, X.L., Zhao, X.G., Ma, J., Dong, T., Huang, N., Sun, C.Y., He, B., Wei, F.S., 2014. Health risks from the exposure of children to As, Se, Pb and other heavy metals near the largest coking plant in China. Sci. Total Environ. 472, 1001–1009. Cheng, Z., Lee, L., Dayan, S., Grinshtein, M., Shaw, R., 2011. Speciation of heavy metals in garden soils: evidences from selective and sequential chemical leaching. J. Soils Sediments 11, 628–638. El Hamiani, O., El Khalil, H., Lounate, K., Sirguey, C., Hafidi, M., Bitton, G., Schwartz, C., Boularbah, A., 2010. Toxicity assessment of garden soils in the vicinity of mining areas in Southern Morocco. J. Hazard. Mater. 177, 755–761. Gebrekidan, A., Weldegebriel, Y., Hadera, A., Van der Bruggen, B., 2013. Toxicological assessment of heavy metals accumulated in vegetables and fruits grown in Ginfel river near Sheba Tannery, Tigray, Northern Ethiopia. Ecotoxicol. Environ. Saf. 95, 171–178. Guo, Z.H., Song, J., Chen, C., Cheng, Y., 2007. Heavy metals contamination for cultivated soils, vegetables and rice in the vicinity of non-ferrous metals industry. Ecol. Environ. 16, 1144–1148 (In Chinese). Gupta, U.C., Gupta, S.C., 1998. Trace element toxicity relationships to crop production and livestock and human health: Implications for management. Commun. Soil Sci. Plan. 29, 1491–1522.
407
Lim, H.S., Lee, J.S., Chon, H.T., Sager, M., 2008. Heavy metal contamination and health risk assessment in the vicinity of the abandoned Songcheon Au-Ag mine in Korea. J. Geochem. Explor. 96, 223–230. Liu, P., Zhao, H., Wang, L., Liu, Z., Wei, J., Wang, Y., Jiang, L., Dong, L., Zhang, Y., 2011. Analysis of heavy metal sources for vegetable soils from Shandong Province, China. Agric. Sci. China 10, 109–119. Liu, G.N., Tao, L., Liu, X.H., Hou, J., Wang, A.J., Li, R.P., 2013. Heavy metal speciation and pollution of agricultural soils along Jishui River in non-ferrous metal mine area in Jiangxi Province, China. J. Geochem. Explor. 132, 156–163. Nan, Z.R., Zhao, C.Y., Li, J.J., Chen, F.H., 2002. and Sun, W. Relations between soil properties and selected heavy metal concentrations in spring wheat (Triticum aestivum L.) grown in contaminated soils. Water Air Soil Pollut. 133, 205–213. Rodriguez, L., Ruiz, E., Alonso-Azcarate, J., Rincon, J., 2009. Heavy metal distribution and chemical speciation in tailings and soils around a Pb-Zn mine in Spain. J. Environ. Manag. 90, 1106–1116. Teng, Y., Ni, S., Wang, J., Zuo, R., Yang, J., 2010. A geochemical survey of trace elements in agricultural and non-agricultural topsoil in Dexing area, China. J. Geochem. Explor. 104, 118–127. US Environmental Protection Agency, 1989. Risk Assessment Guidance for Superfund, Volume I, Human Health Evaluation Manual (Part A), EPA/540/1-89/002. U.S. Office of Emergency and Remedial Response, Washington, DC. US Environmental Protection Agency, 1997. Exposure factors handbook. U.S. Office of Research and Development, Washington, DC. US Environmental Protection Agency, 1999. Risk Assessment Guidance for Superfund (Volume І). U.S. EPA: Washington, DC. (http://www.epa.gov/oswer/riskassessment/ human_health_exposure.htm.). Wang, Y.Z., Yang, Y.H., Chu, N., Zhao, Y.Y., 2008. Clustering analysis for speciation of Cu in soil samples of Dawu River in Dexing copper mine. Prog. Geophys. 23, 233–236 (In Chinese). Wcislo, E., Ioven, D., Kucharski, R., Szdzuj, J., 2002. Human health risk assessment case study: an abandoned metal smelter site in Poland. Chemosphere 47, 507–515. Winge, D.R., Mehra, R.K., 1990. Host defenses against copper toxicity. Int. Rev. Exp. Pathol. 31, 47–83. Xu, Y.N., Zhang, J.H., Ke, H.L., Chen, H.Q., Qiao, G., Liu, R.P., Shi, Y.F., 2014. Human health risk under the condition of farmland soil heavy metals pollution in a gold mining area. Geol. Bull. China 33, 1239–1252 (In Chinese). Yılmaz, F., Özdemir, N., Demirak, A., Tuna, A.L., 2007. Heavy metal levels in two fish species Leuciscus cephalus and Lepomis gibbosus. Food Chem. 100, 830–835. Zhai, F.Y., Yang, X.G., 2006. Report on Nutrient and Health of Chinese Population in 2002 (Part II: Diet Pattern and Nutrient Intake). People's Health Press, Beijing (In Chinese). Zhang, J., Wang, L.H., Yang, J.C., Liu, H., Dai, J.L., 2015. Health risk to residents and stimulation to inherent bacteria of various heavy metals in soil. Sci. Total Environ. 508, 29–36. Zheng, N., Wang, Q.C., Zhang, X.W., Zheng, D.M., Zhang, Z.S., Zhang, S.Q., 2007. Population health risk due to dietary intake of heavy metals in the industrial area of Huludao city, China. Sci. Total Environ. 387, 96–104. Zhu, Z.J., Nie, F.J., Hu, Q.H., 2007. Analysis of soil pollution by heavy metals in Dexing mining area, Jiangxi Province. J. East China Inst. Technol. 30, 332–336 (In Chinese).
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Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv
Exposure Risk of Rural Residents to Copper in the Le’an River Basin, Jiangxi Province, China Yanxin Yu a,⁎, Hui Wang b, Qi Li b, Bin Wang c, Zhenghong Yan b, Aizhong Ding b a b c
School of Environment, Beijing Normal University, Beijing 100875, P. R. China College of Water Science, Beijing Normal University, Beijing 100875, P. R. China Institute of Reproductive and Child Health/Ministry of Health Key Laboratory of Reproductive Health, School of Public Health, Peking University, Beijing 100191, P. R. China
H I G H L I G H T S
G R A P H I C A L
A B S T R A C T
• Soils and food were studied in an area impacted by the largest copper mine in China. • Cu content in various food types were affected by upstream Cu mining activities • Cu intake decreased with increasing distance downstream from the Cu mining zone • Vegetables and rice were the two major contributors to the total dietary intake of Cu • Hazard Quotients indicated across the area N 85% of children will be impacted
a r t i c l e
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Article history: Received 5 August 2015 Received in revised form 21 November 2015 Accepted 22 November 2015 Available online xxxx Editor: D. Barcelo Keywords: Mining agricultural soil food chronic daily intake CDI exposure risk
⁎ Corresponding author. E-mail address: [email protected] (Y. Yu).
http://dx.doi.org/10.1016/j.scitotenv.2015.11.107 0048-9697/© 2016 Elsevier B.V. All rights reserved.
a b s t r a c t The Dexing copper (Cu) mining zone in Jiangxi Province produces China’s highest annual copper output, and the mineral waste residue and wastewater associated with ore processing are responsible for the Cu contamination of agricultural soil and food produced in the Le’an River Basin. We studied the dietary Cu intake from various foods, and the induced non-carcinogenic risk in rural residents from Dexing, Poyang, and Leping Counties situated along the Le’an River. Different food types based on the local dietary habits and agricultural soils were collected, and their Cu contents were analyzed. The Monte Carlo model was used to simulate the dietary chronic daily intake of Cu (CDICu) and its non-carcinogenic risk in four subgroups (children, adolescents, adults, and seniors). A consistently decreasing trend in the Cu levels in agricultural soil and two local food types (vegetables and eggs) was found with increasing distance downstream from the mining zone from Dexing to Poyang, whereas this trend was not observed in other food types. The order of CDICu among the three counties was Dexing N Leping N Poyang, and the order among the four subgroups was children N adolescents N adults = seniors. The two major contributors to the total CDICu were vegetables and rice. Rural residents from Dexing County had the highest proportion of people with a hazard quotient (HQ) N 1 (i.e., 79%), followed by Leping (60%) and Poyang (48%). For Dexing, ~98% of the children living in rural areas displayed HQ N 1, compared with 97% in Leping and 85% in Poyang. Our results indicated the importance of the potential effects of Cu on the health of the local young population and the need to address such effects. © 2016 Elsevier B.V. All rights reserved.
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1. Introduction Mining activities and metal smelting are known to be the main sources of hazardous heavy metals transported to soils and rivers (El Hamiani et al., 2010; Rodriguez et al., 2009). Soil copper (Cu) content has been found to be higher than the global average level (30 mg kg1 ) near mining zones and smelting factories around the world (Cheng et al., 2011; Wcislo et al., 2002; Lim et al., 2008; Cao et al., 2014). Over the past several decades, the dramatic social and economic development taking place in China has stimulated a rapid rise in demand for Cu. Dexing Copper Mine in Jiangxi Province has China’s highest annual copper ore production in Asia (Zhu et al., 2007), of which the Fujiawu copper mine is the biggest with ~ 10,000 tons ore production per day. Cu in Dexing has been intensively exploited, and higher pollution around the mining zone has been reported in the previous studies (Zhu et al., 2007; Wang et al., 2008; Liu et al., 2013). The Le’an River, the primary river of the Le’an River Basin, flows through Dexing County to Poyang Lake, the largest freshwater lake in China. Mineral waste residue, wastewater, and dust containing heavy metals are discharged into the environment during the processes of mining and in mine tailings. Flooding, aerial deposition, and agricultural irrigation can additionally cause serious Cu contamination in nearby agricultural soil (Nan et al., 2002), resulting in elevated Cu levels in crops, livestock, and poultry (Gupta and Gupta, 1998). If agricultural soil, as an important sink of heavy metal pollution, is contaminated by Cu along the Le’an River downstream from the Dexing mining zone, it would be expected to be transferred to humans, with a particularly high risk for rural residents living along the Le’an River (Cheng et al., 2011; Teng et al., 2010). Therefore, it is important to investigate the Cu concentration of agricultural soil along the Le’an River downstream from the mining zone to assess the potential health effects of the Cu mining activities. Three routes of exposure have been widely studied to assess the heavy metal exposure in humans: diet, inhalation, and skin contact (US Environmental Protection Agency, 1997). Results from previous studies suggest that diet was the major exposure route of heavy metals (Cao et al., 2014; Zheng et al., 2007). For example, the estimated risks induced by most heavy metals were mainly from the ingestion of local food, accounting for more than 85% of the three routes, and 98% for copper. Dietary habits, food sources, and the Cu concentrations of different food types can have a considerable influence on dietary Cu intake, and this intake can vary significantly with age group (Zhu et al., 2007). Hence, the selection of which foods to sample should be based on the dietary habits and food sources of the population in question. The spatial variance in the Cu concentrations of agricultural soil along the Le’an River can give rise to different contamination patterns of Cu in agricultural crops and foods. To control the levels of Cu exposure in the local population, knowledge of the relative contributions of different exposure sources to specific age groups is required. Cu is an essential nutrient and a redox-active transition metal that can lead to oxidative stress damage in human body. Excessive intake of Cu can result in weakness, lethargy, and anorexia in the early stages (Winge and Mehra, 1990), as well as the development of acute gastrointestinal symptoms, hepatocellular necrosis in the liver, and acute tubular necrosis in the kidney (Barceloux, 1999). As Cu is a noncarcinogenic heavy metal, its non-carcinogenic risk is typically characterized by the hazard quotient (HQ), taking into consideration the amount of food consumption, the Cu content in various food types, body weight, and the reference exposure dose for humans (US Environmental Protection Agency, 1997). To include all of the influencing factors, the Monte Carlo method is usually used to simulate exposure from the multiple sources and provide a distribution of the exposure risk of the population (Cao et al., 2014). The staple foods (e.g., vegetables, rice, and eggs) of rural residents living along the Le’an River downstream from the Dexing copper mining zone are produced mainly on local farmland. We measured the Cu contents of agricultural soil and various food types in rural areas along the
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Le’an River. The aims of this study were to investigate the following: 1) the Cu levels of agricultural soil and various food types in rural areas along the Le’an River downstream from the Dexing mining zone; 2) the chronic dietary intake of Cu from various food types in local residents living along the Le’an River and their relative contributions to their total Cu intake; and 3) the potential non-carcinogenic risk of Cu for these residents. Our hypothesis was that the dietary exposure risk of Cu for the rural residents along the Le’an River would decrease from the upstream mining zone to downstream and vary with population age groups. 2. Materials and Method 2.1. Study area and sampling The location of the Le’an River and the main mining and smelter area in the Le’an River Basin in Jiangxi Province, China, are shown in Figure S1 (Supporting Information). The rural areas of Dexing County (upstream), Leping County (midstream), and Poyang County (downstream) along the Le’an River were chosen for our study. Agricultural soil samples were collected from rural areas in the three counties, with 30 sampling zones in Dexing County, 13 in Leping County, and 10 in Poyang County. Each sampling zone (approximate size 200 × 200 m) was further divided into a grid of cells using a systematic grid sampling method with regularly spaced intervals (~40 m). Fifteen topsoil samples taken from depths of 0–20 cm were collected in each sampling zone using a random sampling method, and the 15 samples were mixed thoroughly to form a composite sample. The soil samples were air-dried at room temperature, and then pulverized using an agate mortar and sieved through a 0.15-mm polyamide sieve. Six types of food samples were collected in the rural villages of the three counties in 2013 based on the dietary habits of local residents. These comprised vegetables (giant radish, brassica compestris L. var. purpurea Baileysh, potato, green pepper, cucumber, eggplant, tomato, spinach, bok choy, small rape, and lactuca sativa L.); fish (grass carp, yellow-headed catfish, ricefield eel, crucian carp, and chub); meat (pork and mutton); rice; eggs (laid by local hens or purchased from the local market); and milk (liquid milk of six brands purchased locally). Eggs from local hens, homegrown vegetables, and rice were collected from farmers’ homes, and the other food types were purchased from local markets, which were the main places where local residents obtained their food as shown in Figure S1. For each food sub-type, five samples were collected and pooled into one bulk sample. For example, five carp were collected from the local markets and pooled as one representative carp sample. Vegetables, rice, eggs, and milk samples were stored and transferred at 4°C, and meat and fish at -18°C. Vegetables were washed with tap water to remove dust or soil and then further rinsed three times with deionized water, as in previous studies (Cao et al., 2014; Gebrekidan et al., 2013). Washed vegetables were subsequently dried at room temperature. The pretreatment of rice, fish, and meat was conducted according to previous studies (Gebrekidan et al., 2013; Yılmaz et al., 2007). Briefly, rice samples were washed by tap water three times and further by ultrapure water three times, oven-dried to constant weight and ground with a stainless steel grinder to pass through a 100-mesh sieve. Muscle (edible parts) of fish were dissected using a stainless steel scissor. The tissue of fish and meat were frozen-dried at ~80°C to constant weight and ground into powder for further digestion. All food samples were dried at 60–100°C to achieve a constant weight and subsequently ground into powder prior to digestion. 2.2. Copper analysis Approximately 0.1 g of each soil sample or 1 g of each food sample was taken from the composite sample, transferred to a Teflon® tube, and digested in a mixture of HNO3 (65% GR, 5 mL), HF (48% GR, 2 mL), and HClO4 (70% GR, 1 mL) in an automatic graphite digestion
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instrument (Model: ST60, Beijing Polytech Instruments, Ltd., China) with the temperature program: 140°C for 1 hour, 160°C for 1 hour, and further 180°C for 45 min. After cooling the digestion mixture to room temperature, the mixture of digested soil was diluted to 25 mL and that of digested food to 10 mL with deionized water. The Cu concentration was quantified using inductively coupled plasma–atomic emission spectrometry (SPECTRO Analytical Instruments GmbH, Germany) for the soil samples, and inductively coupled plasma–mass spectrometry (NexION300x, PerkinElmer Instruments Co., Ltd, USA). Standard samples of pork (GBW08552), spinach [GBW10014(GSB-6)], cabbage (GBW10014), and rice [GBW10014(GSB–1)] from the National Standard Material Center of China were used for quality control. Each sample was analyzed in triplicate. Three operation blanks were set for each batch of measurements. The limit of quantitation of Cu in the six food matrices ranged from 3.0 × 10-4 to 1.5 × 10-3 μg g-1. The average recoveries of spiked Cu standards in the six food categories and soils ranged from 89.2 to 119.7%.
2.3. Chronic dietary intake and risk assessment The chronic daily intake (CDI, μg kg-1 d-1) from food ingestion was used to indicate chronic exposure to Cu by reference to the US Environmental Protection Agency (EPA) guidelines (US Environmental Protection Agency, 1989), expressed as: CDI ¼ ðC IRÞ=BW;
ð1Þ
3. Results and Discussion 3.1. Concentrations of Cu in agricultural soil The heavy metal content of agricultural soil has been widely used to indicate levels of heavy metal pollution (Rodriguez et al., 2009; Cheng et al., 2011; Guo et al., 2007; Liu et al., 2011). We compared the concentrations of Cu in agricultural soil among the three counties situated along the Le’an River Basin (Fig. 1). Our results indicated no significant difference between Dexing and Leping Counties, although the Cu agricultural soil concentrations of these two counties were 2–3 times higher than that in downstream Poyang County. This implies that Cu from the Dexing mining area is transported along the Le’an River, resulting in considerable Cu contamination in Leping agricultural soil. We further compared the Cu concentrations in agricultural soil from the three counties with previously reported results (Table S1). The comparison revealed that the Cu concentrations in agricultural soil from Dexing and Leping were comparable to samples collected near mining zones (Liu et al., 2011; Xu et al., 2014), and in both counties, the Cu levels were higher than the national background value for soil (35 μg g-1) and the maximum levels of Cu in agricultural soil for organic food production (50 μg g-1) in China. Furthermore, the Cu concentrations were considerably higher than those measured in sites distant from mining zones or mining activities in China and other countries (El Hamiani et al., 2010; Rodriguez et al., 2009). The Le’an River Basin has a humid subtropical monsoon climate, and flooding and agricultural irrigation represent two important routes of Cu transport into agricultural soil. 3.2. Concentrations of Cu in various food types
where C (μg g-1) is the Cu concentration in the food, IR (g d-1) is the ingested rate of the food, and BW (kg) is body weight. The amounts of consumption of various food categories and body weights of the local population were obtained from the 2002 Chinese National Health and Nutrition Survey (CNNS) (Zhai and Yang, 2006). The non-carcinogenic risk of Cu is typically characterized by the HQ. The HQ is defined as the quotient of the CDI divided by the toxicity threshold value: HQ ¼ CDI=RfD 10−3 ;
ð2Þ
where RfD is the chronic reference dose (mg kg-1 d-1). The recommended RfD of Cu by the US EPA is 0.04 mg kg-1 d-1 (US Environmental Protection Agency, 1999). When the HQ of Cu is N 1, Cu may represent an unacceptable non-carcinogenic health risk, whereas a value ≤1 indicates an acceptable non-carcinogenic health risk. 2.4. Data analysis The target population comprised the rural residents living along the Le’an River 2–70 years of age. The population was divided according to gender, and each group was further divided into four subgroups by age: children (2–6 years old), adolescents (7–18 years old), adults (19–65 years old), and seniors (66–70 years old). Cu concentrations in each food type and agricultural soil were assumed to follow a lognormal distribution. Kruskal-Wallis H test was used to compare the three counties, and Mann-Whitney U test was used to assess the differences between groups. Statistical analyses were performed using the SPSS v16.0 software program, applying a significance level of 0.05. A Monte Carlo simulation (20,000 runs) was conducted to estimate the dietary exposure to Cu and to assess the non-carcinogenic risk, taking into consideration the variations in all factors in the calculation. The distributions of body weight and dietary amount for each age were both assumed to follow a normal distribution.
The content of heavy metals in agricultural crops have been reported to be associated with the contamination of soil by heavy metals (Cheng et al., 2011; Liu et al., 2011). Food consumption has been identified as the determinant pathway of human exposure to heavy metals, accounting for more than 90% of intake compared with the two other exposure routes, inhalation and dermal contact (Zheng et al., 2007). Cu concentrations in locally produced foods were measured to investigate the dietary exposure to Cu of local rural residents [see Table S2 (Supporting Information) and Fig. 2]. The concentration patterns of Cu in the rural areas of the three counties varied by food type. The Cu concentrations were found to be statistically different among the three counties only in vegetables and eggs, with no significant differences observed in other food types. The Cu concentrations in vegetables from Dexing were generally higher than those from Leping and Poyang. Overall, this is consistent with the decreasing trend of Cu content of agricultural soil from Dexing to Poyang. Because the vegetables were grown by local farmers, our results suggest that the Cu content of local vegetables is considerably affected by the highly polluted agricultural soil in Dexing County. Cu concentrations in eggs from Dexing and Leping were higher than that in eggs from Poyang. This may be because the hens in the upstream part of Le’an River Basin near the mining zone were fed with
Fig. 1. Concentrations of Cu in the rural agricultural soil of the three counties along Le’an River in Jiangxi Province, China. Data were shown as median value (25%-75% percentiles). # p b 0.01 by Kruskal-Wallis H test; a and b are significant groups.
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Fig. 2. Concentrations (μg g-1) of Cu in the six food types in the three counties along the Le’an River in Jiangxi Province, China. Data were shown as median value (25%-75% percentiles). # p b 0.01 by Kruskal-Wallis H test; a and b are significant groups by LSD multi-comparison test.
agricultural crops and food with adhered soil that had higher Cu content than was found in Poyang County, located downstream. With the exception of giant radish and spinach from Dexing, the Cu contents in other vegetables and food types were lower than the tolerance limits (GB15199–1994) recommended by the Ministry of Health of the People's Republic of China. The heavy metal contents of the various food types were comparable to those reported near mining zones or metallurgical smelter plants (Lim et al., 2008; Cao et al., 2014; Zheng et al., 2007; Bortey-Sam et al., 2015) and higher than those from sites distant from mining and smelter areas (Gebrekidan et al., 2013; Cao et al., 2010; Zhang et al., 2015). This underlines the importance of assessing the contamination levels of Cu in local foods.
was higher than the values observed in Poyang County (35.5%) and Dexing County (33.5%). Corn and sea products were found to be the two major contributors to total Cu intake from foods in Huludao City in northeastern China (Zheng et al., 2007), whereas wheat and vegetables were the major contributors in Shanxi Province in northern China (Cao et al., 2014). This demonstrates that the relative contributions of foods to Cu levels vary by location due to differences in dietary habits. An effective strategy to reduce dietary Cu exposure for the rural residents along the Le’an River would therefore be to control the Cu content of their ingested vegetables and rice.
3.3. Dietary exposure to Cu
The relatively high exposure levels to Cu for the rural residents along the Le’an River indicates their potential serious adverse health effects, such as the non-carcinogenic health risk, usually characterized by the HQ (Cao et al., 2014; Zheng et al., 2007). We calculated the distributions of HQ induced by dietary Cu intake for the four age groups in rural areas of the three counties along the Le’an River Basin using a Monte Carlo simulation, as shown in Fig. 5. Similar to the order of the total CDI of dietary Cu, Dexing had the highest proportion (79%) of residents with HQ N1, followed by Leping (60%) and Poyang (48%). Among the four age groups of the total residents living in rural areas along the Le’an River,
The CDI has been widely used to indicate the long-term exposure level to heavy metals (US Environmental Protection Agency, 1989; Liu et al., 2011). We calculated the CDIs of Cu from six individual food categories for eight age subgroups, as shown in Table S3 (Supporting Information). We found only minor differences (b 5%) in the CDI between male and female groups; hence, they were merged into the total population in the following calculations. The total CDIs of Cu for the four age groups, summarized in Fig. 3, followed the order children N adolescents N adults = seniors. The order of the total CDIs of Cu among the three areas was consistent for all four age groups: Dexing N Leping N Poyang. Thus, the residents of Dexing County, especially children, had higher Cu exposure levels. Fig. 4 shows the relative contributions of the six food types to dietary exposure to Cu in the three counties. The two major contributors to the total chronic intake of Cu were vegetables and rice, accounting for 96.5% (Dexing), 96.2% (Leping), and 93.9% (Poyang), of the total intake. The remaining four food types (meat, fish, eggs, milk, fruit) made only small contributions to the total Cu exposure level. This is likely because vegetables and rice not only formed a large portion of food consumed, but they also had Cu contents that were considerably higher than those of the other four food categories. In Dexing and Poyang Counties, vegetables accounted for ~ 61% of the total Cu intake, whereas they accounted for 45% in Leping County. Rice was the largest contributor to total dietary Cu exposure, accounting for 51.0% in Leping, which
3.4. Health risk assessment
Fig. 3. Total chronic dietary intakes (CDIs) of Cu from various food types for the four age groups in the three counties along the Le’an River in Jiangxi Province, China. Data are shown as median (25%-75% percentile).
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Fig. 4. Relative contributions of the six food types to the total dietary exposure of Cu for the whole population of the three counties along the Le’an River in Jiangxi Province, China
the HQ followed the order of children (93%) N adolescents (68%) N adults (46%) N seniors (41%), indicating a high non-carcinogenic risk for children caused by dietary Cu intake. For Dexing, ~ 98% of the children living in rural areas along the Le’an River had HQ N1, compared with 97% in Leping and 85% in Poyang, suggesting the need for greater focus on the health effects caused by Cu on the young population of the area. The decreasing trend of health risk induced by dietary Cu intake and its variation among the four age groups along the Le’an River was overall consistent with our hypothesis. The Dexing Copper Mine in Jiangxi Province, with the highest annual copper ore production in China, situated on a tributary of Le’an River, is the primary source of Cu to downstream ecosystems. Other studies conducted in mining zones [5, 24, 25, 28] or around the industrial areas (Cao et al., 2014; Zheng et al., 2007; Guo et al., 2007; Cao et al., 2010) mostly focused on the Cu contamination of agricultural soil or foods and their health risk to the local residents. Our study presented a profile of the potential adverse health effect of Cu mining from a basin prospective. Results indicated that the transport of Cu from upstream to downstream was positively associated with its health risk on the rural residents living near Le’an River. Effective remediation measures for contaminated soil in the mine area should be taken to control the Cu transport to the downstream of Le’an River Basin.
the portion of dietary Cu mobilized from the human digestion system to the circulatory system was not assessed. However, our study also had several strengths. First, selection bias was minimal because six food categories (i.e., fruits, vegetables, fish, meat, eggs, and milk) were considered systematically based on the dietary habits of local residents. Furthermore, some food types were collected in residents’ homes. Second, we provided a profile of the distribution of exposure risk of rural residents along the Le’an River. Third, the relative contributions of the six food categories for the four age groups were assessed. Therefore, our study offers reference data that could be used to control the chronic dietary intake of Cu in residents of the Le’an River Basin. 4. Conclusions We investigated the Cu contents of agricultural soil and various food types in rural areas along the Le’an River. A consistently decreasing trend in the Cu contents in agricultural soil and local foods (vegetables and eggs) along the Le’an River with increasing distance downstream from the Dexing mining zone indicated the potential effects of mining activities. The two major contributors of total dietary Cu intake were vegetables and rice. The rural residents of Dexing County, especially children, had a higher non-carcinogenic risk from Cu than did those living along the Le’an River Basin downstream from the mining zone.
3.5. Limitations and strengths Conflict of interest This study had several limitations that should be considered when interpreting the findings. Variances in the bioavailability of Cu among food types were not considered in the modeling simulations; therefore,
The authors declare they have no actual or potential competing financial interests.
Fig. 5. Hazard quotient (HQ) of the total dietary Cu intake from the six food types for the four age groups [(A) Children; (B) Adolescents; (C) Adults; and (D) Seniors] of the three individual villages along the Le’an River Basin in Jiangxi Province, China
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Role of the funding sources The funding agencies have no role in study design, implementation, data analysis, and interpretation. Acknowledgement This research was supported by grants from the National Natural Science Foundation of China (No. 41371466 and 41401583) and Fundamental Research Funds for the Central Universities (No. 2013NT45). Appendix A. Supplementary data Supplementary data to this article can be found online at http://dx. doi.org/10.1016/j.scitotenv.2015.11.107. References Barceloux, D.G., 1999. Copper. J. Toxicol. Clin. Toxicol. 37, 217–230. Bortey-Sam, N., Nakayama, S.M., Ikenaka, Y., Akoto, O., Baidoo, E., Yohannes, Y.B., Mizukawa, H., Ishizuka, M., 2015. Human health risks from metals and metalloid via consumption of food animals near gold mines in Tarkwa, Ghana: estimation of the daily intakes and target hazard quotients (THQs). Ecotoxicol. Environ. Saf. 111, 160–167. Cao, H.B., Chen, J.J., Zhang, J., Zhang, H., Qiao, L., Men, L., 2010. Heavy metals in rice and garden vegetables and their potential health risks toinhabitants in the vicinity of an industrial zone in Jiangsu, China. J. Environ. Sci. 22, 1792–1799. Cao, S.Z., Duan, X.L., Zhao, X.G., Ma, J., Dong, T., Huang, N., Sun, C.Y., He, B., Wei, F.S., 2014. Health risks from the exposure of children to As, Se, Pb and other heavy metals near the largest coking plant in China. Sci. Total Environ. 472, 1001–1009. Cheng, Z., Lee, L., Dayan, S., Grinshtein, M., Shaw, R., 2011. Speciation of heavy metals in garden soils: evidences from selective and sequential chemical leaching. J. Soils Sediments 11, 628–638. El Hamiani, O., El Khalil, H., Lounate, K., Sirguey, C., Hafidi, M., Bitton, G., Schwartz, C., Boularbah, A., 2010. Toxicity assessment of garden soils in the vicinity of mining areas in Southern Morocco. J. Hazard. Mater. 177, 755–761. Gebrekidan, A., Weldegebriel, Y., Hadera, A., Van der Bruggen, B., 2013. Toxicological assessment of heavy metals accumulated in vegetables and fruits grown in Ginfel river near Sheba Tannery, Tigray, Northern Ethiopia. Ecotoxicol. Environ. Saf. 95, 171–178. Guo, Z.H., Song, J., Chen, C., Cheng, Y., 2007. Heavy metals contamination for cultivated soils, vegetables and rice in the vicinity of non-ferrous metals industry. Ecol. Environ. 16, 1144–1148 (In Chinese). Gupta, U.C., Gupta, S.C., 1998. Trace element toxicity relationships to crop production and livestock and human health: Implications for management. Commun. Soil Sci. Plan. 29, 1491–1522.
407
Lim, H.S., Lee, J.S., Chon, H.T., Sager, M., 2008. Heavy metal contamination and health risk assessment in the vicinity of the abandoned Songcheon Au-Ag mine in Korea. J. Geochem. Explor. 96, 223–230. Liu, P., Zhao, H., Wang, L., Liu, Z., Wei, J., Wang, Y., Jiang, L., Dong, L., Zhang, Y., 2011. Analysis of heavy metal sources for vegetable soils from Shandong Province, China. Agric. Sci. China 10, 109–119. Liu, G.N., Tao, L., Liu, X.H., Hou, J., Wang, A.J., Li, R.P., 2013. Heavy metal speciation and pollution of agricultural soils along Jishui River in non-ferrous metal mine area in Jiangxi Province, China. J. Geochem. Explor. 132, 156–163. Nan, Z.R., Zhao, C.Y., Li, J.J., Chen, F.H., 2002. and Sun, W. Relations between soil properties and selected heavy metal concentrations in spring wheat (Triticum aestivum L.) grown in contaminated soils. Water Air Soil Pollut. 133, 205–213. Rodriguez, L., Ruiz, E., Alonso-Azcarate, J., Rincon, J., 2009. Heavy metal distribution and chemical speciation in tailings and soils around a Pb-Zn mine in Spain. J. Environ. Manag. 90, 1106–1116. Teng, Y., Ni, S., Wang, J., Zuo, R., Yang, J., 2010. A geochemical survey of trace elements in agricultural and non-agricultural topsoil in Dexing area, China. J. Geochem. Explor. 104, 118–127. US Environmental Protection Agency, 1989. Risk Assessment Guidance for Superfund, Volume I, Human Health Evaluation Manual (Part A), EPA/540/1-89/002. U.S. Office of Emergency and Remedial Response, Washington, DC. US Environmental Protection Agency, 1997. Exposure factors handbook. U.S. Office of Research and Development, Washington, DC. US Environmental Protection Agency, 1999. Risk Assessment Guidance for Superfund (Volume І). U.S. EPA: Washington, DC. (http://www.epa.gov/oswer/riskassessment/ human_health_exposure.htm.). Wang, Y.Z., Yang, Y.H., Chu, N., Zhao, Y.Y., 2008. Clustering analysis for speciation of Cu in soil samples of Dawu River in Dexing copper mine. Prog. Geophys. 23, 233–236 (In Chinese). Wcislo, E., Ioven, D., Kucharski, R., Szdzuj, J., 2002. Human health risk assessment case study: an abandoned metal smelter site in Poland. Chemosphere 47, 507–515. Winge, D.R., Mehra, R.K., 1990. Host defenses against copper toxicity. Int. Rev. Exp. Pathol. 31, 47–83. Xu, Y.N., Zhang, J.H., Ke, H.L., Chen, H.Q., Qiao, G., Liu, R.P., Shi, Y.F., 2014. Human health risk under the condition of farmland soil heavy metals pollution in a gold mining area. Geol. Bull. China 33, 1239–1252 (In Chinese). Yılmaz, F., Özdemir, N., Demirak, A., Tuna, A.L., 2007. Heavy metal levels in two fish species Leuciscus cephalus and Lepomis gibbosus. Food Chem. 100, 830–835. Zhai, F.Y., Yang, X.G., 2006. Report on Nutrient and Health of Chinese Population in 2002 (Part II: Diet Pattern and Nutrient Intake). People's Health Press, Beijing (In Chinese). Zhang, J., Wang, L.H., Yang, J.C., Liu, H., Dai, J.L., 2015. Health risk to residents and stimulation to inherent bacteria of various heavy metals in soil. Sci. Total Environ. 508, 29–36. Zheng, N., Wang, Q.C., Zhang, X.W., Zheng, D.M., Zhang, Z.S., Zhang, S.Q., 2007. Population health risk due to dietary intake of heavy metals in the industrial area of Huludao city, China. Sci. Total Environ. 387, 96–104. Zhu, Z.J., Nie, F.J., Hu, Q.H., 2007. Analysis of soil pollution by heavy metals in Dexing mining area, Jiangxi Province. J. East China Inst. Technol. 30, 332–336 (In Chinese).
