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A systematic study of heavy metal levels, bioaccessibilities, and gastrointestinal cytotoxicity in two popular consumed vegetables mint (Mentha spicata Linn.) and pea sprouts (Pisum sativum Linn.) from three major producing cities in Yunnan, Southwest China were conducted for evaluating potential health risk to local inhabitants. The mean concentrations of As, Cd, Cr, and Pb were 0.34, 0.06, 1.04, and 0.79 mg/kg, respectively, with Cr and Pb exceeding 1.86-2.63 folds greater than the limit of Chinese National Standards and WHO/FAO. Their average gastric and intestinal bioaccessibilities varied within 12.1-59.4% and 9-53.3%, 0-93.3% and 0-82%, 41.8-71.1% and 19.1-62.9%, 16.1-93.6% and 9.5-81.7%, respectively. Cd in mint was the highest (86.8% and 39%, in the gastric phase and intestinal phase), while Pb had the highest bioaccessibility of 69.9% and 48.7% in pea sprouts. The bioaccessible target hazard quotient (BTHQ) of As, Cr, and Pb from vegetables reflected no potential health risks. However, toxicity assays showed intestinal digesta induced significant cytotoxicity in human intestinal Caco-2 cells, indicating the existing models based on total or bioaccessible heavy metals may be not accurate enough to assess their human health risk, especially for adverse effects evaluation. Taken together, the human risk assessment should be modified by taking their gastrointestinal cytotoxicity into account. [ABSTRACT FROM AUTHOR]

The toxicity of arsenic (As) in different polluted areas and its effects on human and animal health is a big concern all over the world. Although a wetland ecosystem is a "green filter," this specific function would be impaired by high As content in wetland sediments. The distribution of As in wetland sediments and its linkages to environmental factors have not been fully explored. In this study, sediment samples (0-10 cm) and water samples were collected from different locations along the Yangzonghai lakeside, located in the city of Yuxi, Yunnan province of China, and were analyzed for As fractions. Results showed that As content in sediments ranged from 7.550 to 89.83 mg·kg-1 (with a mean value of 16.11 mg·kg-1). The As fractions were dominated by residual fraction (B4) (up to 62.67%), and the mean contents from high to low were: B4 (10.10) > oxidizable fraction (B3) (2.600) > acid extractable fraction (B1) (2.270) > reducible fraction (B2) (2.170). The distribution of As in sediments was mainly influenced by point-source pollution. In addition, the lack of significant correlation between As content and the different landscapes in the buffer zone of Yangzonghai lakeside indicated that the land use around the lakeside wetland (mainly non-point source pollution) may not have a significant impact on As fractions. Among environmental factors, As contents were positively (p<0.05) correlated to dicalcium phosphate (Ca2-P) and octacalcium phosphate (Ca8-P). However, phosphorus distribution revealed that phosphorus in sediments was mainly caused by non-point source pollution, and thus farmland fertilizer, domestic waste, and livestock manure should be controlled. As fractions such as B1, B2, and B3 in wetland sediments were positively correlated with dissolved oxygen (DO) and redox potential (Eh), but negatively correlated to organic matter (OM), pH, and lime-type phosphorus (Ca10-P) when the upstream area was dominated by agricultural lands, indicating that these parameters may affect the release of As into sediments. [ABSTRACT FROM AUTHOR]