*3.3. Human Health Risk Assessment*

The health risks of groundwater in the study area were assessed based on the model introduced previously. The calculated health risks for adults and children through drinking water and dermal contact are shown in Table 6. For adult males, the HQoral values range from 0.285 to 0.827, with a mean of 0.521. The HQoral values for adult females and children range from 0.336 to 0.976 and 0.693–2.012, with an average of 0.615 and 1.269, respectively. The HQdermal values are smaller than the HQoral, ranging from 0.017 to 0.104 for males, 0.018 to 0.109 for females, and 0.026 to 0.156 for children, with means of 0.034, 0.036, and 0.051, respectively. This suggests that non-carcinogenic risk is mainly caused by oral exposure. The HItotal values for males and females range from 0.302 to 0.902 and 0.354–1.051, with means of 0.555 and 0.651, respectively. For children, the HItotal values are 0.719–2.100, with an average value of 1.320. For males, females, and children, HItotal values of 0%, 20%, and 80% of the samples exceed 1, indicating that males in the study area do not have associated non-carcinogenic health risks. In contrast, females and children face higher non-carcinogenic risks. Females and children have smaller body weights and therefore have higher average daily exposure dose of contaminants than males [50,60].

**Table 6.** The non-carcinogenic and carcinogenic risk results from drinking water and dermal contact.


Contaminants in groundwater contribute differently to health risks. Concerning each water quality parameter, the non-carcinogenic HQ values of F−, NO3-N, NO2-N, NH4-N, Fe, Mn, Hg, Pb, Cr6+, As, and Cd are in the ranges of 0.090–1.501, 1.809 <sup>×</sup> <sup>10</sup>−5–0.248, 5.789 <sup>×</sup> <sup>10</sup>−4–0.025, 3.730 <sup>×</sup> <sup>10</sup>−4–5.793 <sup>×</sup> <sup>10</sup>−<sup>3</sup> , 1.447 <sup>×</sup> <sup>10</sup>−3–0.165, 1.034 <sup>×</sup> <sup>10</sup>−3–3.487 <sup>×</sup> <sup>10</sup>−<sup>2</sup> , 5.288 <sup>×</sup> <sup>10</sup>−4–7.444 <sup>×</sup> <sup>10</sup>−<sup>3</sup> , 0.114–0.276, 0.030–0.540, 9.648 <sup>×</sup> <sup>10</sup>−3–0.023 and 0.033–0.076, respectively. This result suggests that besides F−, the non-carcinogenic risks of other contaminants are acceptable to both adults and children. As shown in Figure 4, the contribution of pollutants in groundwater to the HItotal value is observed in the following order: F<sup>−</sup> > Pb > Cr6+ > NO3-N > Cd > As > Fe > Mn > NO2-N > NH4-N > Hg. F<sup>−</sup> contributes the most to non-carcinogenic risk (46.86%), followed by Pb (22.78%) and Cr6+ (11.22%). Contribution

**Sample** 

**The Carcinogenic Risk** 

*Water* **2022**, *14*, x FOR PEER REVIEW 13 of 19

S7 0.455 0.536 1.106 0.027 0.028 0.040 0.481 0.564 1.146 S8 0.528 0.623 1.285 0.030 0.032 0.046 0.558 0.655 1.330 S9 0.401 0.473 0.975 0.043 0.045 0.065 0.443 0.518 1.040 S10 0.562 0.663 1.368 0.019 0.020 0.029 0.582 0.684 1.397 Mean 0.521 0.615 1.269 0.034 0.036 0.051 0.555 0.651 1.320

**CRoral CRdermal CRtotal Males Females Children Males Females Children Males Females Children** 

S1 6.169 × 10−5 7.278 × 10−5 3.914 × 10−5 1.201 × 10−5 1.263 × 10−5 4.725 × 10−6 7.371 × 10−5 8.541 × 10−5 4.386 × 10−<sup>5</sup> S2 6.169 × 10−5 7.278 × 10−5 3.914 × 10−5 1.201 × 10−5 1.263 × 10−5 4.725 × 10−6 7.371 × 10−5 8.541 × 10−5 4.386 × 10−<sup>5</sup> S3 6.169 × 10−5 7.278 × 10−5 3.914 × 10−5 1.201 × 10−5 1.263 × 10−5 4.725 × 10−6 7.371 × 10−5 8.541 × 10−5 4.386 × 10−<sup>5</sup> S4 6.169 × 10−5 7.278 × 10−5 3.914 × 10−5 1.201 × 10−5 1.263 × 10−5 4.725 × 10−6 7.371 × 10−5 8.541 × 10−5 4.386 × 10−<sup>5</sup> S5 7.631 × 10−5 9.000 × 10−5 4.841 × 10−5 2.054 × 10−5 2.160 × 10−5 8.079 × 10−6 9.686 × 10−5 1.116 × 10−4 5.648 × 10−<sup>5</sup> S6 1.165 × 10−4 1.370 × 10−4 7.391 × 10−5 4.400 × 10−5 4.625 × 10−5 1.730 × 10−5 1.605 × 10−4 1.837 × 10−4 9.121 × 10−<sup>5</sup> S7 6.718 × 10−5 7.924 × 10−5 4.261 × 10−5 1.521 × 10−5 1.599 × 10−5 5.983 × 10−6 8.239 × 10−5 9.524 × 10−5 4.860 × 10−<sup>5</sup> S8 6.900 × 10−5 8.140 × 10−5 4.377 × 10−5 1.628 × 10−5 1.711 × 10−5 6.402 × 10−6 8.528 × 10−5 9.851 × 10−5 5.018 × 10−<sup>5</sup> S9 7.814 × 10−5 9.218 × 10−5 4.957 × 10−5 2.161 × 10−5 2.272 × 10−5 8.498 × 10−6 9.975 × 10−5 1.149 × 10−4 5.807 × 10−<sup>5</sup> S10 6.169 × 10−5 7.278 × 10−5 3.914 × 10−5 1.201 × 10−5 1.263 × 10−5 4.725 × 10−6 7.371 × 10−5 8.541 × 10−5 4.386 × 10−<sup>5</sup> Mean 7.156 × 10−5 8.442 × 10−5 4.540 × 10−5 1.777 × 10−5 1.868 × 10−5 6.989 × 10−6 8.933 × 10−5 1.031 × 10−4 5.239 × 10−<sup>5</sup>

> of other pollutants to the non-carcinogenic risk is less than 10%, indicating that F−, Pb, and Cr6+ may be drivers of adverse effects on human health. other pollutants to the non-carcinogenic risk is less than 10%, indicating that F−, Pb, and Cr6+ may be drivers of adverse effects on human health.

> Contaminants in groundwater contribute differently to health risks. Concerning each water quality parameter, the non-carcinogenic HQ values of F−, NO3-N, NO2-N, NH4-N, Fe, Mn, Hg, Pb, Cr6+, As, and Cd are in the ranges of 0.090–1.501, 1.809 × 10−5–0.248, 5.789 × 10−4–0.025, 3.730 × 10−4–5.793 × 10−3, 1.447 × 10−3–0.165, 1.034 × 10−3–3.487 × 10−2, 5.288 × 10−4–7.444 × 10−3, 0.114–0.276, 0.030–0.540, 9.648 × 10−3–0.023 and 0.033–0.076, respectively. This result suggests that besides F−, the non-carcinogenic risks of other contaminants are acceptable to both adults and children. As shown in Figure 4, the contribution of pollutants in groundwater to the HItotal value is observed in the following order: F− > Pb > Cr6+ > NO3-N > Cd > As > Fe > Mn > NO2-N > NH4-N > Hg. F− contributes the most to noncarcinogenic risk (46.86%), followed by Pb (22.78%) and Cr6+ (11.22%). Contribution of

**Figure 4.** Contributive ratios of contaminants in groundwater to health risks (**a**) non-carcinogenic risk; and (**b**) carcinogenic risk. **Figure 4.** Contributive ratios of contaminants in groundwater to health risks (**a**) non-carcinogenic risk; and (**b**) carcinogenic risk.

The spatial distribution of HItotal values for males, females, and children is consistent with fluoride concentration (Figure 5). Higher HItotal and F− concentration mainly appear in the Yaodu, midwest of the study area. Groundwater with high F− is found in semi-arid and arid areas of northern China, such as the middle Loess Plateau [16], Ningxia plain [61], Guanzhong Plain [1,36], Hetao Plain [78], and Tianjin [17]. The respective HQ mean values of F− for males, females, and children are 0.503, 0.593, and 1.220 in the Yaodu, The spatial distribution of HItotal values for males, females, and children is consistent with fluoride concentration (Figure 5). Higher HItotal and F<sup>−</sup> concentration mainly appear in the Yaodu, midwest of the study area. Groundwater with high F− is found in semi-arid and arid areas of northern China, such as the middle Loess Plateau [16], Ningxia plain [61], Guanzhong Plain [1,36], Hetao Plain [78], and Tianjin [17]. The respective HQ mean values of F− for males, females, and children are 0.503, 0.593, and 1.220 in the Yaodu, indicating that children are exposed to health risks from fluoride. Fluoride-bearing minerals are enriched in magmatic rocks and aluminosilicates exposed to the surface of the area, such as fluorite (CaF2), villiaumite (NaF), and biotite [79,80]. There are also many active fault zones in and around Yaodu, and fluorine-containing volatile gas or hydrothermal fluid migrates upward along the faults and penetrates groundwater, increasing the fluorine content [79]. In addition, areas with high F− in groundwater have a higher population density, and industries such as coal mining, metallurgy, and coking are concentrated. Discharge of domestic sewage and industrial wastewater is the other reason for the increase in F<sup>−</sup> concentration in groundwater. Although the Cr6+ concentration of all groundwater samples is within the desirable limit for drinking, it contributes more than 10% to the health risk, similar to Pb. *Water* **2022**, *14*, x FOR PEER REVIEW 14 of 19 indicating that children are exposed to health risks from fluoride. Fluoride-bearing minerals are enriched in magmatic rocks and aluminosilicates exposed to the surface of the area, such as fluorite (CaF2), villiaumite (NaF), and biotite [79,80]. There are also many active fault zones in and around Yaodu, and fluorine-containing volatile gas or hydrothermal fluid migrates upward along the faults and penetrates groundwater, increasing the fluorine content [79]. In addition, areas with high F− in groundwater have a higher population density, and industries such as coal mining, metallurgy, and coking are concentrated. Discharge of domestic sewage and industrial wastewater is the other reason for the increase in F− concentration in groundwater. Although the Cr6+ concentration of all groundwater samples is within the desirable limit for drinking, it contributes more than 10% to the health risk, similar to Pb.

**Figure 5.** Spatial distribution of non-carcinogenic health risks for males (**a**), females (**b**), and chil-**Figure 5.** Spatial distribution of non-carcinogenic health risks for males (**a**), females (**b**), and children (**c**).

The carcinogenic risks due to exposure to As, Cd, and Cr6+ through drinking water

For each contaminant, only the carcinogenic risk of As to children is below the acceptable limit, with an average of 8.317 × 10−7. As per the average values of the CRtotal, Cd contributes 72.63% to the total CR, Cr6+ and As account for 25.77% and 1.60% of the CRtotal, respectively. From the spatial distribution map of carcinogenic risk, it can be seen that the south-central part of the study area has a higher CRtotal value for both adults and children, especially in Xiangfen and the west Yaodu areas. The coal-bearing formations are distributed all over the Linfen Basin, except Huoshan Mountain in the east of Yaodu and

children are 6.169 × 10−5–1.165 × 10−4, 7.278 × 10−5–1.370 × 10−4, and 3.914 × 10−5–7.391 × 10−5, with means of 7.156 × 10−5, 8.442 × 10−5, and 4.540 × 10−5, respectively. The results of the CRdermal are slightly smaller than CRoral, ranging from 1.201 × 10−5–4.400 × 10−5 for males, 1.263 × 10−5–4.625 × 10−5 for females, and 4.725 × 10−6–1.730 × 10−5 for children, with means of 1.777 × 10−5, 1.868 × 10−5, and 6.989 × 10−6, respectively. As a result, the CRtotal values for males and females are 7.371 × 10−5–1.605 × 10−4 and 8.541 × 10−5–1.837 × 10−4, with means of 8.933 × 10−5 and 1.031 × 10−4. Concerning children, the CRtotal values range from 4.386 × 10−5– 9.121 × 10−5 with an average value of 5.239 × 10−5. The carcinogenic risk values of all samples exceed the acceptable limit (1 × 10−6) recommended by the Ministry of Ecology and Environment of the P. R. China [64] for both adults and children. Additionally, the carcinogenic risk for adults is higher than for children, especially females. Similar results have also been found by Li et al. [60] and Zhang et al. [50] in Weining Plain and Guan-

dren (**c**).

zhong Plain, respectively.

The carcinogenic risks due to exposure to As, Cd, and Cr6+ through drinking water and dermal contact are shown in Table 6. The ranges of the CRoral for males, females, and children are 6.169 <sup>×</sup> <sup>10</sup>−5–1.165 <sup>×</sup> <sup>10</sup>−<sup>4</sup> , 7.278 <sup>×</sup> <sup>10</sup>−5–1.370 <sup>×</sup> <sup>10</sup>−<sup>4</sup> , and 3.914 <sup>×</sup> <sup>10</sup>−5–7.391 <sup>×</sup> <sup>10</sup>−<sup>5</sup> , with means of 7.156 <sup>×</sup> <sup>10</sup>−<sup>5</sup> , 8.442 <sup>×</sup> <sup>10</sup>−<sup>5</sup> , and 4.540 <sup>×</sup> <sup>10</sup>−<sup>5</sup> , respectively. The results of the CRdermal are slightly smaller than CRoral, ranging from 1.201 <sup>×</sup> <sup>10</sup>−5–4.400 <sup>×</sup> 10−<sup>5</sup> for males, 1.263 <sup>×</sup> <sup>10</sup>−5–4.625 <sup>×</sup> <sup>10</sup>−<sup>5</sup> for females, and 4.725 <sup>×</sup> <sup>10</sup>−6–1.730 <sup>×</sup> <sup>10</sup>−<sup>5</sup> for children, with means of 1.777 <sup>×</sup> <sup>10</sup>−<sup>5</sup> , 1.868 <sup>×</sup> <sup>10</sup>−<sup>5</sup> , and 6.989 <sup>×</sup> <sup>10</sup>−<sup>6</sup> , respectively. As a result, the CRtotal values for males and females are 7.371 <sup>×</sup> <sup>10</sup>−5–1.605 <sup>×</sup> <sup>10</sup>−<sup>4</sup> and 8.541 <sup>×</sup> <sup>10</sup>−5–1.837 <sup>×</sup> <sup>10</sup>−<sup>4</sup> , with means of 8.933 <sup>×</sup> <sup>10</sup>−<sup>5</sup> and 1.031 <sup>×</sup> <sup>10</sup>−<sup>4</sup> . Concerning children, the CRtotal values range from 4.386 <sup>×</sup> <sup>10</sup>−5–9.121 <sup>×</sup> <sup>10</sup>−<sup>5</sup> with an average value of 5.239 <sup>×</sup> <sup>10</sup>−<sup>5</sup> . The carcinogenic risk values of all samples exceed the acceptable limit (1 <sup>×</sup> <sup>10</sup>−<sup>6</sup> ) recommended by the Ministry of Ecology and Environment of the P. R. China [64] for both adults and children. Additionally, the carcinogenic risk for adults is higher than for children, especially females. Similar results have also been found by Li et al. [60] and Zhang et al. [50] in Weining Plain and Guanzhong Plain, respectively.

For each contaminant, only the carcinogenic risk of As to children is below the acceptable limit, with an average of 8.317 <sup>×</sup> <sup>10</sup>−<sup>7</sup> . As per the average values of the CRtotal, Cd contributes 72.63% to the total CR, Cr6+ and As account for 25.77% and 1.60% of the CRtotal, respectively. From the spatial distribution map of carcinogenic risk, it can be seen that the south-central part of the study area has a higher CRtotal value for both adults and children, especially in Xiangfen and the west Yaodu areas. The coal-bearing formations are distributed all over the Linfen Basin, except Huoshan Mountain in the east of Yaodu and Ta'ershan-Erfengshan Mountain in the south of the study area. The areas with lower CRtotal values in Figure 6 correspond to regions lacking coal-bearing formations. This result suggests that the carcinogenic risk is closely related to the regional geological environment. The natural leaching process and human mining activities will cause many hazardous substances to enter the groundwater. In agricultural activities, the application of N-bearing fertilizers and phosphorous (P)-bearing fertilizers will increase PTEs concentrations such as Cd, Cr, As, and Pb in groundwater under the appropriate favoring geochemical conditions [46,47]. Long-term drinking of such groundwater by residents will increase the risk of visceral cancers such as lung, liver, skin, and kidney [18]. *Water* **2022**, *14*, x FOR PEER REVIEW 15 of 19 Ta'ershan-Erfengshan Mountain in the south of the study area. The areas with lower CRtotal values in Figure 6 correspond to regions lacking coal-bearing formations. This result suggests that the carcinogenic risk is closely related to the regional geological environment. The natural leaching process and human mining activities will cause many hazardous substances to enter the groundwater. In agricultural activities, the application of Nbearing fertilizers and phosphorous (P)-bearing fertilizers will increase PTEs concentrations such as Cd, Cr, As, and Pb in groundwater under the appropriate favoring geochemical conditions [46,47]. Long-term drinking of such groundwater by residents will increase the risk of visceral cancers such as lung, liver, skin, and kidney [18].

**Figure 6.** Spatial distribution of carcinogenic health risks for males (**a**), females (**b**), and children (**c**).

**Figure 6.** Spatial distribution of carcinogenic health risks for males (**a**), females (**b**), and children (**c**). Residents living in the central part of the study area face high health risks (HItotal > 1 and CRtotal > 1 × 10−6) due to the groundwater being affected by the geological environment and human activities. Therefore, government officials should pay more attention to PTEs pollution in groundwater caused by mining and the production of mineral resources. Fur-Residents living in the central part of the study area face high health risks (HItotal > 1 and CRtotal > 1 <sup>×</sup> <sup>10</sup>−<sup>6</sup> ) due to the groundwater being affected by the geological environment and human activities. Therefore, government officials should pay more attention to PTEs pollution in groundwater caused by mining and the production of mineral resources. Furthermore, supplying residents with high-quality drinking water with safe concentrations of F− should be the goal of sustainable groundwater management

thermore, supplying residents with high-quality drinking water with safe concentrations

Additionally, compared with the results of groundwater quality assessment, we found that although most of the water quality of the study area is in good condition, both adults and children face great health risks, especially carcinogenic. Therefore, the overall groundwater assessment should be accompanied by a health risk assessment to better

In this study, groundwater samples from Linfen Basin were collected and analyzed for physicochemical parameters. The water quality index was used to evaluate the groundwater quality, while the health risk was assessed for adults and children concerning different exposure pathways. The main conclusions of the study are as follows:

1. The groundwater in the study area is weakly alkaline, with TH and TDS ranging between 167–869 and 280–1312 mg/L. Compared with the Chinese national standards, 30%, 10%, 20%, 20%, 10%, 10%, and 100% of the total samples exceeded the standard limits of drinking water in terms of TH, TDS, SO42−, F−, Fe, Mn, and Pb. Higher TH, TDS, SO42−,

evaluate the suitability of groundwater for drinking.

**4. Conclusions** 

tion by residents to ensure water safety and people's health.

in the Yaodu area. It is urgent to take various measures to treat the polluted groundwater before direct consumption by residents to ensure water safety and people's health.

Additionally, compared with the results of groundwater quality assessment, we found that although most of the water quality of the study area is in good condition, both adults and children face great health risks, especially carcinogenic. Therefore, the overall groundwater assessment should be accompanied by a health risk assessment to better evaluate the suitability of groundwater for drinking.
