OBJECTIVETo investigate the relationship between genetic polymorphism of X-ray repair cross-complementing gene 3 (XRCC3) and susceptibility to lead poisoning in male lead-exposed workers.

METHODSPeripheral venous blood and morning urine samples were collected from 326 male lead-exposed workers in a storage battery factory in Fuzhou. Blood lead, urine lead, blood zinc protoporphyrin (ZPP), blood calcium, and blood iron were measured. The genotype of XRCC3 was determined by polymerase chain reaction-restriction fragment length polymorphism method. The relationship between XRCC3 gene polymorphism and susceptibility to lead poisoning in male lead-exposed workers was analyzed.

RESULTSGenetic polymorphism of XRCC3 was seen in the 326 subjects. The frequency distribution of XRCC3 genotypes, XRCC3-241CC (wild type), XRCC3-241CT (heterozygous mutation), and XRCC3-241TT (homozygous mutation), was in accordance with the Hardy-Weinberg equilibrium (P > 0.05). There were no significant differences in urine lead, blood ZPP, blood calcium, and blood iron between the lead-exposed workers with different XRCC3 genotypes (P > 0.05). The workers with XRCC3-241CT/TT had a significantly higher mean blood lead level than those with XRCC3-241CC (P < 0.05). With a blood lead level of 1.90 µmol/L as the cutoff value, the chi-square test and logistic regression analysis showed that the proportion of workers with XRCC3-241CT/TT was significantly higher than that of workers with XRCC3-241CC in the subjects with high blood leads (P < 0.05) and that the risk of high blood lead was significantly higher in the workers with XRCC3-241CT/TT than in those with XRCC3-241CC (OR = 2.34, 95%CI = 1.61 ∼ 5.13); the multivariate linear regression analysis showed that the workers with XRCC3-241CT/TT had high blood lead levels (β = 0.116, P < 0.05), the workers with smoking habit demonstrated marked lead absorption (β = 0.188, P < 0.05), good individual protection could reduce lead absorption (β = -0.247, P < 0.05), and the individuals with low serum Ca²⁺ levels had high blood lead levels (β = -0.145, P < 0.05).

CONCLUSIONWhen exposed to the same level of lead at workplace, the workers with XRCC3-241CT/TT have a significantly higher blood lead level than those with XRCC3-241CC, so the genotype of XRCC3-241CT/TT accounts for higher susceptibility to lead poisoning.