Theoretical risk assessment of magnesium alloys as degradable biomedical implants

The theoretical tolerable implant masses for ten magnesium alloys as degradable biomedical implant materials are evaluated in this study. Dose-response assessment is conducted using toxicological data from authoritative public health agencies such as the US Agency for Toxic Substances and Disease Registry and the USEPA Integrated Risk Information System, and assuming 1 year of even corrosion. Uncertainty factors adopted by the agencies are used. The tolerable limits corresponding to various component elements in an alloy are considered separately, and the lowest tolerable limit is selected as the tolerable limit of the alloy. The results show that aluminum is usually the component element with the lowest tolerance, and the tolerable mass for Al-containing magnesium alloys fall to around or below 1g per person per year, while the limit for other magnesium alloys can well exceed 10 g. Deficits in the toxicological data of some component elements are noted. This study illustrates that toxicological calculations should be taken into consideration when developing novel degradable metallic implants.