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Herskowitz等报告了低剂量氟化物的致肿瘤作用,果蝇接触20～50 ppm的氟化物能够诱发5～90%的果蝇发生肿瘤。Taylor等观察给易发癌症的小鼠饮用含1 ppm氟的水,肿瘤发生率增加13～17%。最近报告在小鼠饮水中加低剂量氟化物能引起染色体畸变。将低至1～5 ppm的氟化物给吃低氟饲料的小鼠3～6周,小鼠的睾丸和骨髓染色体畸变率明显增加。另外,体内和体外实验表明1 ppm的氟化物可干扰DNA的修复,低浓度的氟化物能改变RNA的鸟嘌呤与胞嘧啶的比例。作者将美国10个饮水加氟城市与另10个不加氟城市居民癌症死亡率进行比较分析,以观察氟化物对人是否有致癌性。[方法] 10个加氟大城市作为实验组,均在1960
Herskowitz et al. Reported on the tumorigenic effects of low-dose fluoride. Drosophila exposure to 20-50 ppm of fluoride can induce tumors in 5-90% of flies. Taylor et al. Observed that mice prone to develop cancer treated with water containing 1 ppm of fluoride showed an increase in tumor incidence of 13-17%. Recently reported in mice with low doses of fluoride in drinking water can cause chromosomal aberrations. As low as 1 to 5 ppm of fluoride was administered to mice fed the low-fluoride diet for 3 to 6 weeks, there was a significant increase in the chromosomal aberrations in testes and bone marrow of mice. In addition, in vivo and in vitro experiments showed that 1 ppm of fluoride interfered with DNA repair and low concentrations of fluoride altered the ratio of guanine to cytosine in RNA. The author compares the cancer mortality rates among 10 drinking-water-addicted cities in the United States and 10 non-fluoride urban dwellers to see whether fluoride is carcinogenic to humans. [Method] Ten large cities with fluoridation as experimental groups, all in 1960