Objective To study the oxidative stress induced by consumption of mercury-contaminated rice in rats, and to assess the possible public health risk of mercury contamination in Wanshan mining area. Methods Sprague Dawley rats were fed the mercury-contaminated rice produced from Wanshan area for 90 days. The antioxidant status and the free radicals in rat serum were evaluated. Results High mercury accumulation in organs of rats fed the mercury-contaminated rice confirmed the server pollution of mercury in Wanshan mining area. The intensity of electron spin resonance （ESR） signal increased by 87.38% in rats fed the rice from Wanshan compared with that in the control rats fed the rice from Shanghai, suggesting that chronic dietary consumption of rice from mercury mining area could induce an aggravation of free radicals. Feeding the mercury-contaminated rice was associated with significant decreases in the antioxidant enzymatic activities of superoxide dismutase （SOD） and glutathione peroxidase （GSH-Px） and concentration of serum nitric oxide （NO）, but it had no effect on serum nitric oxide synthase （NOS） activity. Feeding the mercury-contaminated rice raised the level of serum malonyldialdehyde （MDA）, indicating the occurrence of oxidative stress. Conclusion The long-term dietary consumption of mercury-contaminated rice induces the aggravation of free radicals and exerts oxidative stress.
