Chronic Systemic Toxicity Study of Copper Intrauterine Devices in Female Wistar Rats

BACKGROUND The aim of this study was to evaluate the chronic systemic and local toxicity of a copper intrauterine device in a rat model. MATERIAL AND METHODS Cu-IUD fragments were inserted into the uterine horns of female Wistar rats for 26 weeks (equivalent 15.42-17.33 years in humans). We tested copper at 20, 40, and 60 times the clinical dosages to study copper toxicity under severe conditions. Classic chronic systemic toxicity evaluations, including body weight, hematology, organ coefficient, and tissue reactions, were performed. RESULTS The body weight of the rats increased during the 26 weeks, which showed that the Cu-IUD implant had no effect on animal growth. Histological examinations and organ coefficients of the uterus and other major organs indicated no obvious systemic or local impairment. Blood tests confirmed that the hepatic and renal functions remained normal. CONCLUSIONS These results obtained at different dosages and long-term implantation provide solid data confirming the safety of long-term use of Cu-IUDs. However, the elevated leucocyte levels found in this study warrant further investigation.