Mitigating cadmium-induced body burden for residents in southern China based on soil-food-urine system and physiologically based toxicokinetic model

Abstract

The risks of Cd intake from dietary sources are often estimated without fully considering Cd bioavailability in food. Based on the data from paired soil, vegetable, rice and urine samples from southern China, this study quantified the transfer of Cd in the soil-food-human system. There were probabilities of 75​% that the urinary Cd from local residents (3.11 ​± ​1.98 ​μg ​g⁻¹ creatinine) would exceed the safety threshold, with rice consumption being the largest contributor at 94​%. A probabilistic physiologically based toxicokinetic (PBTK) model was used to optimize the strategies for reducing the Cd body burden through the food-blood-plasma-liver-kidney pathway. The liver (21%) and kidneys (37%) are the principal sites of Cd accumulation in the humans, with age and gender being the major controlling factors. Kidney Cd significantly correlates with urinary excretion, making urinary Cd a crucial biomarker for Cd dietary intake. Adult females who consume less rice are more susceptible to Cd exposure due to lower Zn levels in their bodies, which enhance Cd absorption. Even with lower rice consumption, the reduced Zn storage in females increases the risk of Cd accumulation because Zn normally helps reduce Cd absorption. To protect 74% of adult males and 81% of adult females from excessive Cd body burden, it is recommended that local residents consume more food rich in Zn, targeting at least 6.25 ​mg Zn ​d⁻¹ for adult females and 5.15 ​mg Zn ​d⁻¹ for adult males.