Corn and pepper fluorine survey in Zhenxiong county, a coal-burning borne endemic fluorosis area of Yunnan province

Abstract

Objective To investigate the com and pepper fluorine in Zhenxiong county of Yunnan province, as well as the change of com and pepper fluorine after baked by coal, clay-mixed with cual for a relatively long-term, in order to provide a scientific basis for reducing fluorine intake. Methods The endemic areas of Yile, Wufeng's Songlinwan, Tangfang and Wufeng's Wugu in Zhenxiong county, and a non-endemic area Xiaguan in Dali city were selected as study sites. Ten samples of fresh corn and pepper were collected in each region, and fluorine was determined using acid leaching/potentiometry freshly and after baking or drying for 10 days or 4 months, respectively. Results The fluorine content of local fresh corn in Xiaguan of Dali city and Yile,Wufeng's Songlinwan, Tangfang, Wufeng's Wugu in Zhenxiong county were (1.31 ± 0.13),(1.65 ± 0.64),(1.92 ±0.37), (2.32 ± 0.49), (1.98 ± 0.66)mg/kg, respectively, and there were statistically significant differences across the regions(H = 27.871, P ＜ 0.05). The fluorine content of corn samples after baking or drying for 4 months were ( 1.82 ± 0.17), (26.43 ± 12.03), (39.27 ± 8.09), ( 14.27 ± 4.37), ( 14.33 ± 1.73)mg/kg, respectively, which were significantly higher than that of the fresh com in the corresponding region(all P ＜ 0.05 ), and there were statistically significant differences across the regions(H = 42.512, P＜ 0.05). The fluorine content of the local fresh chili were (3.34 ± 1.08), (3.44 ± 0.55), (3.47 ± 0.74), (3.46 ± 0.93)mg/kg, respectively, in the 4 observed places in Xiaguan of Dali city and Yile, Wufeng's Songlinwan, Tangfang in Zhenxiong county, and there were no statistically significant differences across the regions (F = 0.052, P ＞ 0.05 ). The fluorine content of pepper samples after baking or drying for 4 months were (7.01 ± 1.64), (226.07 ± 83.69), (179.36 ± 148.37), (54.51 ± 34.67)mg/kg,respectively, which were significantly higher than that of the fresh pepper in the corresponding region(all P ＜ 0.05 ),and there were statistically significant differences across the regions(H = 28.822, P ＜ 0.05). Conclusion Corn and chili fluorine is significantly increased after baked with coal and clay-mixed with coal by farmers in Zhenxiong county, a coal- burning borne endemic fluorosis area of Yunnan province. Key words: Fluorine;  Capsicum;  Zea mays;  Curing-baking processing