Heavy Metal Pollution and Health Risk Assessment of Gastrodia elata Bl. and Its Cultivation Soil in Guizhou

Purpose The aim of this study was to systematically assess heavy metal pollution and human health risks of Gastrodia elata Bl. in Guizhou for consuming as a vegetable, so as to provide a reference for its safety evaluation as both food and herbal medicine.

Methods Tuber and soil samples of G. elata were collected from 21 cultivation sites across Guizhou Province. Contents of five heavy metals, including lead (Pb), cadmium (Cd), arsenic (As), mercury (Hg), and copper (Cu) were determined. Single factor pollution index, Nemerow comprehensive pollution index and geo-accumulation index were used to assess heavy metal contamination in soils. Furthermore, a health risk assessment model combined with Monte Carlo simulation was applied to characterize human non-carcinogenic health risks posed by heavy metals of soil and G. elata tuber.

Results Soil Cd and Cu contents at partial cultivation sites exceeded the soil pollution risk screening values, both with a point exceedance rate of 14.29%. The average content of Hg in soil reached 0.33 mg/kg, higher than the local soil background value of Guizhou Province (0.11 mg/kg), while the tuber Hg content at several sampling sites surpassed the food safety limit standard, with an exceedance rate of 9.52%. Health risk assessment of heavy metals revealed that soil heavy metal accumulation exerted no non-carcinogenic health risks to either adults or children. The total hazard index of tuber heavy metals was 0.68 for adults and 1.57 for children, suggesting negligible non-carcinogenic risks for adults yet light potential non-carcinogenic risks for children. Cd and Hg accumulated in tubers were the predominant contributors to such health risks.

Conclusion Soil Cd and Hg contents at several G. elata cultivation sites in Guizhou exceed the soil pollution risk screening values, and the average content of soil Hg were higher than the regional background values of Guizhou Province. Cd and Hg were the primary contributors to heavy metal pollution and human health risks. Accordingly, soil Cd and Hg accumulation should be prioritized for monitoring prior to selecting planting locations of G. elata.