The Relationships Of PCDD/Fs Exposure Level And Oxidative Damage In Foundry Workers

Background:As a kind of persistent organic pollutant, PCDD/Fs are mainly from industrial activity. In China, the ferrous and non-ferrous metal casting and smelting industries were reported to be the leading emission to environment. Once entering the environment, PCDD/Fs can widely and persistently exist in a variety of environmental media, such as atmosphere particulates and food. Human can obtain the PCDD/Fs by kinds of pathway, such as inhalation, dietary and immediate contaction. Once PCDD/Fs are getting into the body, they would accumulate in adipose tissue with the blood circulation. Due to the complex determination methods of PCDD/Fs, the researches always evaluate the possible external exposure dose by measuring the levels of PCDD/Fs in food and air, however,the study of internal exposure is not much.The past researches had reported that PCDD/Fs have many health hazards. Researches on health effects of PCDD/Fs had attracted wide attention. Once entering the cells, PCDD/Fs can combine with the Ahreceptor, resulting in an increase of the reactive oxidative species(ROS). The ROS cause oxidative modifications of DNA and lipids. Oxidative DNA damage and lipid peroxidation occurs. However, the study on oxidative damage in PCDD/Fs exposed population were less.Objective: By measuring and evaluating the external and internal exposure level of PCDD/Fs in foundry workers, the quantitative relationship between the external and internal exposure were establish. And to analyze the potential relationship between PCDD/Fs exposure and oxidative damage.Methods: 311 volunteers were recruited in our study. As exposure group, 105 workers are come from the foundry. As assistant workers group, 104 subjects are come from the same foundry and are far from the production line. As control group another 102 subjects are come from a nature reserve. The questionnaire investigations and health examinations were performed among all subjects. And the blood samples and urine were collected. Air samples, food material in the study area were obtained. The concentrations of PCDD/Fs in these samples were determined by isotope dilution high resolution capillary column gas chromatography/high resolution mass spectrometry(HRGC-HRMS). The inhalational dose and dietary dose of PCDD/Fs were evaluated by the existing formulas. Urinary 8-OHd G was analyzed by high performance liquid chromatographyelectrochemical detector(HPLC-ECD). Urinary 8-iso-PGF2ɑ were determined by ELISA.The differences between the exposure group, the assistant worker group and control group in demographic characteristics, the level of exposure and the biomarker of oxidative damage were compared by the student t-test or single factor analysis of variance as appropriate and categorical variable data use a chi-square test. As the data of oxidative damage showed a skewed distribution, the natural log transformations were conducted. And the multiple regression were used to establish the relations between the internal and external exposure, and to evaluate the relationships of PCDD/Fs exposure level and oxidative damage.Results: The PCDD/Fs concentrations of air and food samples are different in different regions. All kinds of food samples are higher than the Shen nongjia district in level of PCDD/Fs. And the environmental concentrations of PCDD/Fs at the working point of foundry workers is higher than the assistant worker, and higher than the control group. The daily inhalational dose of exposure group(92.54(32.90-264.49) fg TEQ/kg bw) was 5.43 folds higher than the assistant worker group, and was 201 times higher than control group. The daily dietary dose of three groups were 89.44(67.00-121.55) fg TEQ/kg bw, 87.67(68.91-109.46) fg TEQ/kg bw, 43.07(31.92-57.59) fg TEQ/kg bw, respectively(P<0.05). The daily external exposure level of exposure group(167.02(96.53-353.07) fg TEQ/kg bw) is highest, followed by the assistant worker group(111.62(86.43-154.09)fg TEQ/kg bw) and the control group(43.68(32.22-58.08) fg TEQ/kg bw)(P<0.05).The serum concentration of three group have the same trend(P<0.05), exposure group(11.68(2.91-44.76) pg TEQ/g lipid) is highest, followde by the assistant worker group(10.54(2.91-24.13) pg TEQ/g lipid) and the control group(4.44(2.16-12.04) pg TEQ/g lipid) is lowest(P<0.05).The internal exposure were significantly correlated with the inhalational dose and dietary dose(R2=0.32, P<0.05). And the formula can be expressed as Lg(serum) =-8.08 + 1.74×Lg(dietary) + 0.13×Lg(inhalation) + 0.074×BMI + 0.32×sex.Urinary 8-OHd G is as the biomarkers of DNA oxidative damage, the urinary 8-isoPGF2ɑ is as the biomarkers of lipid peroxidation. The levels of urinary 8-OHd G of three groups were 3.53(0.99-19.25) μmol/mol crea, 3.01(1.11-10.56) μmol/mol crea, 1.25(0.42-8.40) μmol/mol crea(P<0.05). And the levels of urinary 8-iso-PGF2ɑ were 21.26(9.79-109.90) μmol/mol crea, 18.91(8.40-76.50) μmol/mol crea, 11.48(4.85-37.80) μmol/mol crea(P<0.05), respectively. The multiple linear regression analysis revealed that there were significantly increased trend for levels of urinary 8-OHd G and 8-iso-PGF2ɑ as PCDD/Fs external exposure levels increased, after adjustment for age, sex, smoking statue, alcohol use and BMI(Ptrend < 0.01). But there’s no evidence that oxidative damage is associated with internal exposure, there was a relationship between oxidative damage and internal exposure among the non smokers.Conclusion: From the point of view of external exposure and internal exposure of PCDD/Fs, the contents of exposure group were highest, and the control is lowest. The foundry workers bear greater health risks. The internal exposure were significantly correlated with the inhalational dose and dietary dose. There was a dose-response relationship between PCDD/Fs external exposure and oxidative damage in foundry workers. Also there was a relationship between oxidative damage and internal exposure among the non smokers.