Heavy metal concentrations and health risk assessment of vegetables in the high-risk area of atmospheric deposition in Henan Province

Objectives We studied the heavy metal pollution status, health risk, and the sources of cadmium (Cd) and lead (Pb) in vegetables surrounding the high-risk area of atmospheric heavy metal deposition in Jiyuan City, Henan Province. We aimed to scientifically evaluate the health risks caused by vegetable intake among different people (male, female, adolescent and adult) and to select the varieties with relatively low heavy metal concentrations.

Methods The concentrations and bio-enrichment capacity of cadmium (Cd) and lead (Pb) of edible parts in different vegetables were determined and assessed under greenhouse and open-field cultivations in the study area. Further, we used Monte Carlo simulation to evaluate the probabilistic health risk of the edible parts of different vegetable varieties, including leafy (Brassica chinensis L., Brassica rapa var. chinensis (Linnaeus) Kitamura, Coriandrum sativum L.), onion and garlic (Allium sativum L.), eggplant (Solanum melongena L., Capsicum annuum L., Lycopersicon esculentum L.), melon and fruit (Momordica charantia L., Cucumis sativus L.), bean (Vigna unguiculata, Phaseolus vulgaris L.) and tuber (Raphanus sativus L.).

Results The bio-concentration factors of cadmium (Cd) in the edible part of vegetables under greenhouse and open-field cultivations were higher than lead (Pb) due to the higher activity of cadmium (Cd) in the soil. There was variation in the capability of the vegetable varieties to absorb heavy metals. Cd and Pb concentrations in the edible part of vegetables were 0.020 and 0.036 (Cucumis sativus L.) and 0.008 and 0.055 (Momordica charantia L.) mg/kg, respectively, which were all below the limits for heavy metal concentrations. By comparing the pollution rate of the edible parts of the vegetables under greenhouse and open-field cultivations, we found that cadmium (Cd) and lead (Pb) pollution degrees were higher in vegetables under open-field conditions than in greenhouse. Most leafy vegetables were seriously polluted, especially green rape. The comprehensive pollution index (P_N) of cadmium (Cd) and P_N (Pb) reached 10.26 and 10.00 under open-field conditions. According to the probabilistic health risk assessment results, there was little difference between male and female, adolescent and adults, due to the intake of cadmium (Cd) and lead (Pb) contaminated vegetables. The intake of melon and fruit, and tuber vegetables had no obvious negative effect on the human body, especially melon and fruit vegetables. The P₇₅ (the 75^th percentile of the probability distribution of total target hazard quotient) compound health risk caused by the intake of bitter gourd in adult males in greenhouse was 0.120.

Conclusions Vegetable varieties have quite different Cd and Pb accumulation capacities; leafy vegetables are easy to accumulate Cd and Pb, while melons and fruit vegetables are weak to accumulate, especially bitter gourd. Atmospheric deposition is one of the important sources of lead (Pb) pollution in vegetables. Thus, using a vegetable facility is recommended for melon cultivation, with a low accumulation of heavy metals in the high-risk atmospheric heavy metal deposition area. This has the potential to reduce the risk of heavy metals to human health.