Food and medical grades

Food and medical grades

Some standards are related to compatibility for use in contact with foodstuff and medical devices.

FDA, the American Food and Drug Administration have tests for food compatibility, FDA 21 CFR 177.

USP (United States Pharmacopeia XXIII) Sections <87> and <88> define compatibility for plastics, in vitro and in vivo, with bodily tissue and fluids.

There are three different in vitro tests. The choice of test is related to the polymer type. For elastomers there is the Agar test, with cell growth. The direct contact test is performed on all materials except those with very high or very low density. A cell growth test is made. The elution test is performed on all types of materials, especially such with very high density. A solution of the polymer is set in contact with a cell growth.

The in vivo tests are set up to define the biological impact on animals. There are six different classes, the toughest, USP XXIII class VI, is for testing the polymer as an implant.

Recommendations for materials to be used as implants are scarce, partly because of legal implications. A material may generally fulfill the most rigorous specifications, without therefore being classed or approved. Each application will in turn need to pass the tests, although chances by then are auspicious. Specifically, it is the detail, or application, which needs approval rather than the material. To seek and obtain approval is a matter for the enduser (or end producer).