Novel bioavailability-based risk assessment of Cd in earthworms and leeches utilizing in vitro digestion/Caco-2 and MDCK cells.

In the present study, the oral bioavailability of cadmium (Cd) in earthworms and leeches was investigated through in vitro physiologically based extraction test (PBET) digestion/Caco2 and MDKC cell models. We are the first to create an innovative assessment strategy which has capacity to offer a more precise evaluation of Cd-associated health risks in traditional animal medicines (TAMs), by combinational usage of bioavailable Cd levels, the duration and frequency of the exposure to TAMs obtained by questionnaire data, as well as safety factor of TAMs. Our data showed that the percentage of bioavailability for Caco-2 cells in earthworms and leeches ranged from 3.29 to 14.17% and 4.32 to 12.61%, respectively. The percentage of bioavailability of MDCK cells in earthworms and leeches ranged from 4.83 to 15.74% and 6.53 to 15.04%, respectively. After adjusting by the bioavailability of Cd to target hazard quotient (THQ), excitingly, our findings manifested that the health risks induced by the ingestion of earthworms and leeches were acceptable in the clinic. Our key findings suggest that bioavailability characterization cannot be ruled out and health risks should be assessed on the basis of the bioavailable Cd levels rather than total levels. Our novel strategy provides insight into the bio-accumulation of Cd in organisms as well as a more realistic and accurate assessment of Cd-associated health risks in TAMs, with the main purpose of improving public health by scientifically using TAMs.