Toxicity testing of polymer materials for use in haemodialysis

Toxicity tests, performed during a 10-yr period, were evaluated for 653 polymers intended for use in extracorporeal renal replacement therapy. The test battery used included animal tests, in vitro cell tests and chemical tests. Several different extraction media were used. More than 30% of the materials were not approved for use by a Material Testing Board. Of these, 45% failed on UV absorption and over 63% failed on either UV absorption or inhibition of cell growth. The acute systemic toxicity test in mice with NaCl, ethanol or paraffin oil as extractants were performed on a total of 806 occasions. In only two of these cases the test gave a result above the limit for acceptance. The final outcome of the tests for the majority of materials could be predicted from the results of UV absorption, inhibition of cell growth, and chlorine and Sn analysis. Of the materials that passed these four tests, less than 2% were not approved by the Material Testing Board on the basis of the whole battery. The experiments show that only a limited number of tests have to be performed when assessing polymers intended for use in extracorporeal renal replacement therapy.