The Association Of Exposure To Arsenic And The Regulations Of DNA Damage Markers

Objective:The objective of the study was to observe the association of exposure to arsentic and the regulations of the DNA damage markers including 8-hydroxy deoxy guanosine (8-OHdG) and 7-methyl guasine (7-MG).Methods:3 typycial villages at the Zhanglao county of Hechi city, Guangxi autonomous region were selected as the fields for this study accorcing to the measurements of heavy metal in the environment. From 2013 to 2014,139 family members aged 6 to 65 years were enrolled in the cross-sectional study to explore the association between the exposure levels of urine total arsenic and the regulations of urine 8-OHdG and urine 7-MG. Behaviour, habbits, risks in the living environment, and health status were collected by the questionnaires. Urine specimens of every subject were collected in heavy metal free plastic bottles. As for urine specimens, total arsenic were measured by Inductive coupled plasma mass spectrometry (ICP-MS) analysis,8-OHdG and 7-MG were tested by specific ELISA kits. Urine levels of total arsenic,8-OHdG, and 7-MG were adjusted by the level of urine creatinine. In addition, urine levels of creatinine were measured immediately at the spot to exclude unqualified urine specimens. Group differences of mean 8-OHdG,7-MG, or total arsenic in the urine were checked by T test or Kruskal-Wallis H test. Controlling for the confounding factors, generalized linear regression analysis were used to test the association between urine levels of total arsenic and the urine levels of 7-MG or 8-OHdG.Results:a. The mean urinary arsenic of the children is 13.5 (95%CI:9.02-20.1)μg/gCr, and the mean urinary arsenic of the adult subjects is 12.6(95% C1:8.80-17.9) μg/gCr. No significant differences of the urine arsenic levels were found between the children and the adults. After controlling for age, sex, smoking and BMI, generalized linear regression analysis showed that the urine arsenic in the children increased significantly with the arsenic levels in the grains (β=29.84, P<0.05), but decreased with the age increasing (β=-0.12,P<0.05). However, sex, passive smoking and BMI were not found to be the risks of arsenic exposure in children; After controlling for age, sex, smoking, BMI, alcohol use, and background of education, the urine arsenic for the adult subjects were significantly associated with the arsenic contents in the soil (β=0.02,P<0.05), age (β=0.13,P<0.05), and BMI (β=-0.17,P<0.05).b. The mean urine 8-OHdG in children (GM=44.24,95%CI:39.11～50.05 μg/gCr) was significantly higher than that of the adults (GM=28.80,95%CI:24.95～33.25μg/gCr). After controlling for age, sex, smoking and BMI, generalized linear regression analysis showed that the exposure level of urine total arsenic was the risks to up regulate the urine 8-OHdG in children. Urine 8-OHdG levels in the children with urine arsenic(?)50μg/L were signicantly higher than those with urine arsenic≤ 50μg/L (P<0.05); the levels of 8-OHdG in children were not significantly associated with age, sex, or BMI; After controlling for age, sex, smoking, BMI, alcohol and education, the urinary 8-OHdG levels in adult were significantly associated with the location of residences (P<0.05), while the levels were not significantly associated with urine total arsenic (P>0.05).c. The mean urine 7-MG in children (GM=10.90,95% CI:9.54-12.46μg/gCr) was significantly higher than that of the adults (GM=6.82,95%CI:6.02-7.72 μg/gCr). After controlling for age, sex, BMI, smoking, and environmental tobacco smoking status, urine 7-MG was significantly associated with the urine total arsenic level in the exposed children (with urine total arsenic(?)50μg/L). The urine 7-MG in the exposed children were significantly higher than those of the controls(with urine arsenic ≤50μ/L, P<0.05). However, generalized linear regression analysis showed that the urine 7-MG levels in adults were not signiciantly associated with the urine arsenic exposure levels (P>0.05).Conclusions:a. Urine 7-MG and urine 8-OHdG in the children might be used as early markers for arsenic exposure.b. Urine 8-OHdG and urine 7-MG for the adult subjects in this study were not found significantly associatied with the levels of urine total arsenic, the associations should be further explored.