Long-term toxicity studies of styrene maleic anhydride in rats

In male Charles Foster rats, polymer styrene maleic anhydride was injected into the lumen of the vas deferens at dose levels of 1.0, 2.5, and 5.0 mg in each vas deferens of Groups II, III, and IV, respectively, while controls (Group I) received 0.03 ml dimethyl sulfoxide in each vas deferens. The rats were observed for 6 months for toxicity. No change in any of the toxicity parameters in test animals as compared to controls was revealed. Hence, the polymer is safe at the doses used within 6 months of injection.