An integrated benefit-risk assessment of cobalt-containing alloys used in medical devices: Implications for regulatory requirements in the European Union

Abstract

In 2017, the European Union (EU) Committee for Risk Assessment (RAC) recommended the classification of metallic cobalt (Co) as Category 1B with respect to its carcinogenic and reproductive hazard potential and Category 2 for mutagenicity but did not evaluate the relevance of these classifications for patients exposed to Co-containing alloys (CoCA) used in medical devices. CoCA are inherently different materials from Co metal from a toxicological perspective and thus require a separate assessment. CoCA are biocompatible materials with a unique combination of properties including strength, durability, and a long history of safe use that make them uniquely suited for use in a wide-range of medical devices. Assessments were performed on relevant preclinical and clinical carcinogenicity and reproductive toxicity data for Co and CoCA to meet the requirements under the EU Medical Device Regulation triggered by the ECHA re-classification (adopted in October 2019 under the 14th Adaptation to Technical Progress to CLP) and to address their relevance to patient safety. The objective of this review is to present an integrated overview of these assessments, a benefit-risk assessment and an examination of potential alternative materials. The data support the conclusion that the exposure to CoCA in medical devices via clinically relevant routes does not represent a hazard for carcinogenicity or reproductive toxicity. Additionally, the risk for the adverse effects that are known to occur with elevated Co concentrations (e.g., cardiomyopathy) are very low for CoCA implant devices (infrequent reports often reflecting a unique catastrophic failure event out of millions of patients) and negligible for CoCA non-implant devices (not measurable/no case reports). In conclusion, the favorable benefit-risk profile also in relation to possible alternatives presented herein strongly support continued use of CoCA in medical devices.

Keywords: Alternatives assessment; Benefit-risk assessment; Carcinogenicity; CoCrMo; Cobalt; Cobalt alloy; Medical devices; Reproductive toxicity; Stainless steel; Weight of evidence.