Accumulation characteristics and health risks of heavy metals in vegetables in typical urbanized areas

Heavy metal pollution-related problems due to industrialization and urbanization are of great concern, and they pose severe threats and challenges to environmental quality, food safety, human health, and sustainable socioeconomic development. This study examined vegetables and soils in areas with intensive electroplating and dyeing industries. Vegetable and soil samples were collected, and single-factor pollution assessment and the Nemero comprehensive pollution index were used to evaluate the pollution levels of five heavy metals, i.e., Cd, Ni, Cr, As, and Pb, in vegetable samples. Further, the target hazard quotient method was used to assess health risk. Pollution by Cd was found in the vegetable soil in the study area. Enrichment and absorptive capacity of heavy metals in vegetable samples in the study area were in this order:Cd > Ni > Cr > As > Pb. Leafy vegetables had the highest Cd enrichment, whereas beans had the highest Ni enrichment. Single-factor pollution assessment revealed that the over-standard rate of heavy metals in the vegetable samples was in this order:Ni > Cr > Cd > Pb=As; moreover, the over-standard rates of Ni, Cr, and Cd were 10.53%, 2.63%, and 1.32%, respectively, and the content of Pb and As in the vegetable samples did not exceed the standard content. Nemero evaluation of the samples revealed that leafy vegetables had a mild level of pollution, beans had a moderate level of pollution, and melons were not contaminated by heavy metals. Health risk assessment revealed that the comprehensive target hazard quotient (TTHQ) of leafy vegetables and beans was>1 and that the long-term consumption of leafy vegetables and beans in the study area would adversely affect health. The TTHQ for adults and children was as follows:leafy vegetables > beans > melons. The health risks posed by the intake of heavy metals in food were higher for children than for adults. In general, the health risks posed by heavy metals in vegetables in the study area were within the acceptable range, but the health risks posed by Cd in leafy vegetables and Ni in beans need serious consideration.