Abstracts: ISEE 22nd Annual Conference, Seoul, Korea, 28 August–1 September 2010: Water Pollution - Exposure to Metals, Emerging and Remerging Diseases
Di(2-ethylhexyl)phthalate (DEHP) is a general-purpose plasticizer for polyvinyl chloride and has become a ubiquitous environmental contaminant. It is suspected to be an endocrine disrupting/modulating substance in humans. China has already been the second county of plastic production and consumption in the whole world. As the universal application and high-out rates of plastics in our daily life, plastics recycling and processing industry have emerged. A large number of abandoned plastic products have been collected and transport to waste plastic recycle areas. According to statistics, the number of plastics recycling businesses in China is up to 10,000 or so, developing a number of large-scale plastics recycling markets and processing areas. The amount of recycling waste plastics of an annual is about more than 600 million tons. However, with the lack of effective market regulation, backward technology and poorly equipped of plastics recycling businesses, the aggravation environment problems and people's health in these areas have become a social issue of common concern, especially burning and depositing plastic waste. The aims of the study were to perform the monitoring of levels ofDEHP in the water samples and 5 PAEs in the soil samples, which were collected from the exposure region and the control region; to measure the levels of oxidative stress and the extent of deoxyribonucleic acid DNA oxidative damage by the biomarkers including levels of malondialdehyde (MDA), super oxide dismutase (SOD), and glutathione peroxides in sera samples and 8-OHdG in the urine samples from the workers who engaged plastic recycle and plastic reclaim, and to analyze the risk factors relating to these biomarkers.
The exposure region was a plastic recycling centers in the Southern city where has had over 20 years in plastics recycle and the control region was 50 km far away from exposure region where it is without known sources of pollution related. The 157 workers in exposure region and 157 residents in control region were selected based on gender and age matched, and the basic information was collected by uniform questionnaire. DEHP levels of collected water samples from the sites (including the river, wells, ponds, tap water, and industrial effluent) in the exposure region and the control region were detected using the solid-phase extraction and gas chromatography method. The column chromatography and gas chromatography techniques were applied to determine the concentrations of DEHP and other PAEs in soil samples. The chemical colorimetric was used to determine serum MDA, glutathione peroxides, and SOD in exposure and control population, which is served as an oxidative stress index of DNA damage. The electrochemical-high performance liquid chromatography was applied to test the level of urinary 8-OHdG, which is served as an index of the extent of DNA oxidative damage. The demography data and related medical index in exposure and control were analyzed by using significance test. Logistic regression was performed to analyze the DNA damage.
The average DEHP level in the river water samples from the polluted section (mean: 2.05 μg/L) was 6.4 fold compared with that from the control section (0.32 μg/L). Average DEHP level in the pond (135.68 μg/L) and the well (14.20 μg/L) water samples from the exposure region were 18 fold and 215 fold compared with those (0.79 μg/L and 0.37 μg/L) in the control region, respectively. The DEHP level in industrial effluent sample ranged from 0.36 μg/L to 161.86 μg/L. The dibutyl phthalate (DBP) (0.94–24.09 mg/kg) and DEHP (0.85–37.23 mg/kg) were indentified in all soil samples from exposure and control regions. In 5 PAEs determined, the DEHP and DBP concentration is the highest one, following by diethyl phthalate, di-n-octyl phthalate (DnOP), and dimethyl phthalate. The average of 5 PAEs in soil of exposure region was 1–19 times of that in control region. The contents of DBP (mean: 9.46 mg/kg) and DEHP (mean: 13.07 mg/kg) in exposure region soil were the 19 and 16 times of that in control region. The detection rate of DBP (range, 0.94–24.09 mg/kg) and DEHP (range, 0.85–37.23 mg/kg) in the exposed soil are 100%. The medians of serum SOD in exposed population and control population were 111.80 U/mL (range, 31.71–167.69 U/mL) and 124.16 U/mL (range, 78.88–181.46 U/mL) respectively, with a significant difference between the 2 groups (P < 0.01).
The study results showed that DEHP exposure concentrations in water and soil samples in plastic recycling centers where occupational workers lived were higher than that where the control residents live. The demological study results showed that the occupational exposure was the main factor, which affects the levels of serum SOD, MDA, GAH-Px, and urine 8-OHdG. Although Urine 8-OHdG levels may be affected by other pollutants from plastic recycling center, the exposure population has shown the oxidative DNA damage.