| Objectives:The study was to determine whether fluoride induced apoptosis and its change of infrared spectroscopy in PBLs of workers exposed to fluoride.Methods:A total of 280 male workers were selected by the cluster random sampling method from the electrolysis,casting,thermoelectricity workshops and mining plant(70 male workers/workplace)which were defined respectively as high,middle and low fluoride exposure workplaces and control workplaces,and the corresponding workers were defined respectively as high,middle and low fluoride exposure groups and control group in a large aluminum factory located in Guangxi.Air fluoride was sampled from the workshop/plant by the acetic acid-cellulose nitrate microporous membrane sampling method.Serum and lymphocytes of the workers’ peripheral blood were collected and then separated.Air and serum fluoride concentrations were measured by the fluoride ion selective electrode method.DNA damage,cellular apoptosis rate and the mRNA expressions of apoptosis relevant gene P53,Bcl2 and Bax of the PBLs were detected by SCGE,flow cytometry and semi-quantitative RT-PCR method.The changes of the molecular structure and/or content of the workers’ PBLs were detected using ATR-FTIR.Results:1.The air fluoride concentrations of the electrolysis,casting,thermoelectricity workshops were 0.25±0.03,0.09±0.02 and 0.06±0.02 mg/m3,respectively.The air fluoride concentrations of the workshops showed decrease trend and the difference were significant between three workshops(all P<0.01).The air fluoride concentrations of the mining plant was under the detected limitation(0.9 ug/m3).2.The serum fluoride concentration of the high,middle,low fluoride exposure groups and control group were 0.09±0.008,0.07±0.014,0.06±0.012 and 0.05±0.011 mg/L,respectively.The serum fluoride concentrations of the high fluoride exposure were significantly higher than that of the control group(P<0.05).The workers’serum fluoride concentration was positively correlated with the air fluoride concentration(R=0.650,P<0.01).3.The comet rate of the PBLs in the high fluoride exposure group was obviously higher than that of the other three groups(38.4%vs 5.1%,2.6%,2.5%,all P<0.01).The comet rate of the PBLs in the middle fluoride exposure group was also significantly higher than that of the low fluoride exposure group and the control group(all P<0.01).The tail DNA%,comet tail length and OTM of the PBLs in the high fluoride exposure group were respectively higher than that of the other three groups(4.62%vs 1.10%,0.81%,0.53%;10.76 v.s 3.87,3.55,3.27 μm;0.98 vs 0.08,0.06,0.04 μm,P<0.01 or 0.05).The tail DNA%and comet tail length of the workers’ PBLs in the high fluoride exposure group were also higher than that of the middle and low fluoride exposure group(4.62%vs 1.107%,0.81%;10.76 vs 3.87,3.55 μm,all P<0.01).The tail DNA%and comet tail length of the PBLs in the middle fluoride exposure group were significantly higher than that of the low fluoride exposure group and control group(all P<0.01).The OTM of the PBLs in the middle fluoride exposure group were significantly higher than that of the control group(P<0.05).The tail DNA%and comet tail length of the PBLs in the low fluoride exposure group were higher than that of the control group(P<0.05).The comet rate,tail DNA%,comet tail length and OTM of the workers’ PBLs were all highly positive correlated with the air fluoride concentration(Spearman correlation coefficient:0.924,0.839,0.828,0.860,all P<0.01).4.The apoptosis rates of the high,middle and low fluoride exposure groups and control group were 19.3%,16.9%,16.4%and 15.9%,respectively.The apoptosis rate of the high fluoride exposure group was higher than that of the other three groups(all P<0.01)and the apoptosis rate of the PBLs was positively correlated with the comet rate(R=0.709,P<0.01).The mRNA expression of P53 and Bax gene of the PBLs in the high fluoride exposure group were all higher than that of the control group(1.63±0.44 vs 1.07±0.36;1.26±0.32vs 1.02±0.34,P<0.01 or 0.05).5.Spectral analysis showed that the relevant wavenumbers’ absorbance of cytoplasmic protein phosphorylation,glycogen,DNA/RNA,DNA/symmetrical phosphate,amide and protein decreased with increasing of the fluoride concentration.The PC1 and PCA-LDA1 scores of the fluoride exposure groups were all lower than that of the control group(-3.30,-0.38,0.25 vs 3.77;-78,-0.39,-0.07vs 0.96,P<0.01 or 0.05).The PC1 and PCA-LDA1 scores of the high and middle fluoride exposure groups were also lower than that of the low fluoride exposure group(P<0.01 or 0.05).The PC2 score of the high fluoride exposure groups were significantly lower than that of the control group(P<0.05).Absorbance of the top 10 contribution wavenumbers for PC 1 in the fluoride exposure groups was all lower than that of the control group(P<0.01 or 0,05)and absorbance of 1030、1038、1045、1053、1065、1080 cm-1 in the high and middle fluoride exposure groups was also lower than the low fluoride exposure group(all P<0.05).In the top 10 contribution wavenumbers for PC2,absorbance of 1616,1650,1655、1674 cm-1 in the high fluoride exposure group and 1628、1650、1655、1674cm-1 in the middle fluoride exposure group was all lower than the control group(P<0.01 or 0.05).Conclusions:1.Fluoride diffused to surrounding from the electrolysis workshop which was the fluoride pollution source.Blood fluoride concentration increases with increasing of the air fluorine concentration,which could be defined as the fluoride exposure index.2.long-term exposed to fluoride may damage workers’ PBLs DNA by different degree.3.Fluoride exposure resulted in increase of the workers’ PBLs apoptosis rate,cellular apoptosis may be induced by DNA damage in the PBLs.4.Long-term exposed to fluoride might change the structure and/or content of DNA/RNA,glycogen,DNA/symmetry phosphate,enzyme and protein and aggravated intracellular molecules phosphorylated.The results also affirm that fluorine might damage DNA and associated with cell apoptosis,and also suggested that fluoride might lead to the abnormality of cellular biochemical metabolism and genetic material. |
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