Toxicology of materials and medical devices: An Overview

The term ‘medical device’ may conjure up visions of complex, highly technical equipment used in acute hospital care. Medical device covers a broad range of products including the products used everyday in most health care settings such as needles, syringes, infusion pumps, endoscopes, examination gloves, dressings and blood glucose meters. Biomaterials and medical devices constitute an extremely diverse, heterogeneous category of items, because the use of these products normally entails their direct or indirect contact with patients; there is an obligation on the part of manufacturers to establish the safety of their products before they are marketed.

Until recently, the regulations governing the manufacture and sale of medical devices varied greatly among countries. Since January 1995, medical devices to be marketed in the European Union (EU) have been required to comply with EU Medical Devices Directive 93/42/EEC, which specifies requirements for safety assessment issues. The purpose of the directive is to promote a single European market for trade in medical devices, while ensuring that users and patients are not exposed to unnecessary risks. Biological evaluation of medical devices depends on the material used in the device, the intended body contact, and the duration of contact. The ISO 10993-1 document divides medical devices into three main categories: surface devices, externally communicating devices, and implant devices. Each category is further divided into subcategories according to the type of contact to which the patient is exposed.

Due to the diversity of medical devices, it is recognized that not all the tests identified in a category will be necessary or practical for any given device. It is indispensable for testing that each device shall be considered on its own merits. This part of ISO clearly states that the test results should be reproducible by inter laboratory evaluation, as well as repeatable by intra laboratory methods.