Gut Microbiota-Based Risk Assessment of Low-Dose Thallium in Soil Via Food Chain

Abstract

As one of the most toxic trace metals and priority pollutants, low-dose thallium’s threat from soil to human, especially via crop plant consumption, remains poorly understood. As worldwide favorite crop plant, sweet potato is selected, cultivated in soil contained thallium (Tl, 0.283-0.700 mg/kg, no more than crustal average of 0.5-0.7 mg/kg), and absorbed Tl (2.23-41.87 µg/kg, far less than safe consumption for human as 0.3 mg of Tl/kg plant). The uptake of Tl from soil into sweet potato is negative and positive correlation with soil pH (3.75-6.63) and soluble Tl in soils (0.082-0.2122 µg/kg), respectively, with a low bio-concentration factor of 0.0043-0.0594, so both soil acidification and thallium’s solubility should be treated to reduce thallium’s hazards. Via two main dietary patterns, the sweet potato is eaten and pretreated with biomimetic digestion and metabolism. Truly associating with human disease, the gut microbiota is adopted for risk assessment, using 16S rRNA gene techniques. Even if above low-dose Tl is ingested, the composition of gut microbiota is disrupted, influenced the metabolism of carbohydrate and lipid, and then caused inflammatory and metabolic disorder. The further verification of the established standards (i.e., the safe consumption of edible plant for human) is needed.

Keywords: Thallium, Gut microbiota, Sweet potato, Dietary intake, Risk assessment