Secondary Tests

Only those materials that have passed the primary tests are subjected to secondary testing. These are slightly expensive and include:

Oral Systemic toxicity tests — The test sample is administered daily to rats for 14 days either by oral lavage or by dietary inclusion. If 50% of the animals survive, the product is considered safe.

Inhalation systemic toxicity tests — These tests are performed on rats, rabbits, or guinea pigs in an exposure chamber with aerosol preparations. The spray material is released around the head and upper trunk of the animals for 30 seconds, each at 30 minutes intervals. After ten consecutive exposures, the

animals are observed for four days. If any animal dies within this period, the agent is considered toxic, otherwise safe.

Skin Irritation and Sensitization tests — The test material is held in contact with the shaved skin of albino rats for periods ranging from 24 hrs (one exposure) to 90 days (with repeated exposures) for evaluating irritation effects.

However, for establishing allergic contact sensitization, the guinea pig is the preferred animal. An allergen is defined as a substance that is not primarily irritating on the first exposure but produces reactions on subsequent exposures of similar concentrations. The stain reactions are evaluated after subsequent application of the test material.

Implantation tests — During the implantation techniques, the various physical properties of the product such as form, density, hardness and surface finish, which influence the character of the tissue response is tested. The animals are selected according to the duration of the test. The implant material is packed in plastic tubes and put into subcutaneous tissues or directly into bones in drilled holes. The reactions are evaluated.