Objective To analyze the polymorphism of calcitonin receptor (CTR) gene in occupational fluoride exposure populations, assess its interaction with factors of fluoride bone injury, and provide a theoretical basis for the making of prevention strategies and measures of fluoride bone injury.
Methods Our study included 245 workers exposed to fluoride at an aluminum plant in Hubei Province for epidemiological investigations and laboratory tests. Workers with fluoride bone injury (n=119) were determined by right forearm and pelvis anteroposterior x-ray films, and the rest workers (n=126) were set as controls. Measurements included CTR gene polymorphism, blood fluoride (BF), urine fluoride (UF), serum osteocalcin (BGP), serum calcitonin (CT), alkaline phosphatase (ALP), and bone specific alkaline phosphatase (BALP).
Results The CTR genotypes of the fluoride exposed workers were CC (169 cases, 69.0%), TC (70 cases, 28.6%), and TT (6 cases, 2.4%); the C and T allele frequencies were 83.3% and 16.7% respectively. Independent risk factors for fluoride bone injury were alcohol consumption, higher levels of UF, BGP, CT, BALP, and CTR gene (except CC genotype), with the OR values of 1.729, 1.217, 1.579, 1.049, 1.024, and 14.620, respectively. The interaction between CTR T allele and UF was fit into a positive additive modelrelative excess risk of interaction (RERI)=14.34 (95%CI:1.47-32.16), attributable proportion of interaction (API)=0.75 (95%CI:0.50-1.00), synergy index (S)=4.7 (95%CI:1.65-14.89).
Conclusion The study findings indicate that alcohol consumption, higher levels of UF, BGP, CT, BALP, and carrying CTR gene (except CC genotype) could be the risk factors of fluoride bone injury and CTR T allele is interacted with UF.
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