# Refined Cumulative Risk Assessment of Pb, Cd, and as in TCM Decoction Based on Bioavailability through In Vitro Digestion/MDCK Cells

## TL;DR

This study assesses the health risks of heavy metals in traditional Chinese medicines using bioavailability and a new risk model.

## Contribution

A novel cumulative risk assessment model based on bioavailability for heavy metals in TCM decoctions is introduced.

## Key findings

- Bioavailability of Pb, Cd, and As in TCMs and decoctions ranged from 4.98–72.49%.
- TTD-adjusted HI outcomes for TCMs were below 1, indicating acceptable health risks.
- Pheretima aspergillum and Oldenlandia diffusa showed potential health risks before bioavailability adjustment.

## Abstract

In this study, the oral bioavailability of Pb, Cd, and As in three types of traditional Chinese medicines (TCMs) and TCM decoctions were investigated through in vitro PBET digestion/MDKC cell model. Furthermore, a novel cumulative risk assessment model associated with co-exposure of heavy metal(loid)s in TCM and TCM decoction based on bioavailability was developed using hazard index (HI) for rapid screening and target organ toxicity dose modification of the HI (TTD) method for precise assessment. The results revealed that the bioavailability of Pb, Cd, and As in three types of TCM and TCM decoction was 5.32–72.49% and 4.98–51.97%, respectively. After rapid screening of the co-exposure health risks of heavy metal(loid)s by the HI method, cumulative risk assessment results acquired by TTD method based on total metal contents in TCMs indicated that potential health risks associated with the co-exposure of Pb, Cd, and As in Pheretima aspergillum (E. Perrier) and Oldenlandia diffusa (Willd.) Roxb were of concern. However, considering both the factors of decoction and bioavailability, TTD-adjusted HI outcomes for TCMs in this study were <1, indicating acceptable health risks. Collectively, our innovation on cumulative risk assessment of TCM and TCM decoction provides a novel strategy with the main purpose of improving population health.