Polycyclic aromatic hydrocarbon exposure, oxidative potential in dust, and their relationships to oxidative stress in human body: A case study in the indoor environment of Guangzhou, South China.

A comparative study of internal and external exposure is a good method to comprehensively understand human exposure to environmental contaminants that may trigger oxidative stress in human body. Information is limited regarding the influences of reactive oxygen species (ROS) on human health from the environment. In addition, data on the contribution of polycyclic aromatic hydrocarbons (PAHs) from indoor environments, especially air, to total human exposure are still insufficient. The present study measured PAHs in paired indoor dust (n = 101), gas (polyurethane foams, n = 100), and particle samples (quartz fiber filters, n = 100) and their hydroxy metabolites (OH-PAHs) in 205 urine samples from 101 families in Guangzhou, South China. The oxidative potential (OP) in dust samples was quantified with a dithiothreitol (DTT) assay to reflect the oxidizability of ROSs, and explore the relationship between environmental ROSs and oxidative stress in humans (using urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) as a biomarker). The estimated daily intakes (EDIs) of Σ16PAH via air inhalation were much higher than those from gas dermal contact, dust dermal contact, and dust ingestion (mean: 19.5 > 4.27 > 3.75 > 1.60 ng/kg_bw/day). Generally, approximately 16% of naphthalene, 28% of fluorene, 9% of phenanthrene, and 3% of pyrene were derived from indoor environments for all residents when compared with the total PAH exposure amount from all sources. Significantly positive relationships were found between OH-PAHs and 8-OHdG (coefficients ß: 0.129-0.366, p < 0.05) checked by linear mixed effect models, and males seemed to be more susceptible than females to the DNA oxidative damage related to PAH exposure. The mean OP value in dust was 7.14 ± 6.68 pmol/(min·µg). Individual PAHs in dust gradually intensified the oxidizability of dust particles as their molecular weight increased. A potential but not significant dose-relationship was found between dusty OP and urinary 8-OHdG. Further work should determine the impact of chemical profiles on OP in different environmental media and continuously explore the potential to use OP as a useful indicator to reflect the total oxidizability of several groups of environmental pollutants.

Association of PAHs and BTEX exposure with lung function and respiratory symptoms among a nonoccupational population near the coal chemical industry in Northern China.

Emissions (particularly aromatic compounds) from coal industries and biomass fuels combustion lead to high health risks for neighboring residents. To investigate the association of polycyclic aromatic hydrocarbons (PAHs) and benzene, toluene, ethylbenzene and 1,2-dimethylbenzene (BTEX) exposure with lung function and respiratory symptoms among adults and children near the coal-chemical industry in Northern China, adults and children from a county dotted with coal chemical industry were chosen as subjects for investigation (investigated area, IR). The control group consisted of adults and children from an agricultural county (control area, CR). The environmental and urinary PAH and BTEX levels of adults and children were determined by isotope dilution liquid chromatography coupled with tandem mass spectrometry. The Mann-Whitney U test and multivariate linear regression models were used to analyze the relationship between pollutant exposure and the respiratory system. The results showed that in an ambient environment, levels of PAHs and BTEX in the IR were significantly higher than those in the CR. Particularly, the concentration profiles for air samples were IR > CR and indoor > outdoor. Both for adults and children, the geometric (GM) concentrations of urinary PAHs and BTEX from the IR were significantly higher than those measured in the CR. Additionally, the urinary PAH exposure level profiles of smokers were higher than those of nonsmokers, indicating that indoor air and smoking were both important nonoccupational exposure sources. The decline of the forced expiratory in the first second (FEV1, %) and the forced expiratory middle flow rate (FEF25%) in children were associated with increasing urinary PAH metabolite levels (p < 0.05). The increase in urinary 1-OHN, 3-OHPhe, 4-OHPhe and 1-OHP levels could be linked to a decrease in FEV1 (r = -0.179, p < 0.05) and FEF25% with the coefficient of -0.166, -0.201 and -0.175 (p < 0.05), respectively. Medical examinations and lung function tests indicated that residents in the IR had higher occurrences of chest inflammation or declining lung function than residents in the CR. Moreover, exposure to PAHs and BTEX could decrease child lung function, though decreased lung function was not observed in adults. Both urinary monitoring and lung function data showed that children were more sensitive to PAH and BTEX exposure than adults.

Higher dermal exposure of cashiers to BPA and its association with DNA oxidative damage.

Bisphenol A (BPA) is a widely used chemical in the production of many polycarbonate plastics, epoxy resin linings for food and beverage containers and thermal papers. Oral intakes from the contaminated diets were considered as the predominant source of BPA exposure for humans. However, due to the high levels of BPA on thermal receipts and their wide applications in our daily life, the amount of BPA be transferred to the skin after holding thermal paper should not be underestimated, particularly for cashiers. To investigate the contribution of BPA exposure levels via the dermal contact route and the relationship between BPA exposure level and oxidative DNA damage, six male volunteers were recruited and required to simulate the cashiers' work and handle the thermal receipts during the study period. Triclosan (TCS, an antimicrobial compound used widely in personal health and skin care products) was applied as a reference compound. Their urinary BPA, TCS and 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations were determined by high performance liquid chromatography/ tandem spectrometer (LC/MS/MS). The results showed that after handling the thermal receipts, the urinary BPA concentrations of volunteers increased 3 times of those before the experimental period. But TCS levels in urine kept stable. There existed a correlation between BPA exposure and 8-OHdG (R2=0.237, p<0.001), but not between TCS and 8-OHdG concentrations (R2=0.026, p<0.777), indicating that more BPA exposure could lead to higher oxidative DNA damage. That the increases in 8-OHdG levels in urine being almost consistent with those of BPA suggested that handling thermal receipts resulted in the increasing BPA intakes and BPA exposure was correlated with DNA oxidative damage. After 48h of the end of handling thermal receipts, the urinary BPA levels did not descend to the levels before experiment, suggesting that the excretion of BPA via dermal contact was over 48h. BPA exposure through dermal contact route contributed 51.9% to 84% to urinary BPA levels with the GM ratio of 70.9% for cashiers, indicating that it might be seriously underestimated for cashiers according to the previous studies. More attentions should be paid on the exposure of BPA via dermal penetration for cashiers.

Exposure of children to BPA through dust and the association of urinary BPA and triclosan with oxidative stress in Guangzhou, China.

Both bisphenol A (BPA) and triclosan (TCS) are phenolic compounds widely used in a variety of household applications. These compounds could be released into the environment, enter the human body and cause a series of potential health hazards. Children are sensitive and susceptible to these contaminants. To investigate the potential oxidative DNA damage from exposure to BPA and TCS, ninety six urine samples of children (aged 3-6) and 57 dust samples were collected from a kindergarten in Guangzhou, China. The concentrations of urinary BPA, TCS and 8-hydroxy-2'-deoxyguanosine (8-OHdG, a biomarker of oxidative DNA damage) in urine were determined using a liquid chromatography tandem mass spectrometer. The geometric mean concentrations of urinary BPA, TCS and 8-OHdG were 1.08 µg L-1, 1.34 µg L-1 and 1.90 µg L-1, respectively. The results showed that both BPA and TCS exposures were associated with oxidative damage. Significant dose-effects existed between the urinary BPA, TCS levels and the 8-OHdG concentrations. Multiple linear regression analysis showed that one percent increase in BPA and in TCS could generate 0.15% and 0.081% increase in 8-OHdG in urine for children in Guangzhou. We also determined the concentrations of BPA in dust using high performance liquid chromatography. The mean concentration of BPA was 2.86 µg g-1 in indoor dust and 3.23 µg g-1 in outdoor dust. The dust contributes approximately 9.23% to the urinary BPA exposure for the children. In conclusion, BPA and TCS exposure correlates with oxidative DNA damage.

Co-exposure to polycyclic aromatic hydrocarbons, benzene and toluene and their dose-effects on oxidative stress damage in kindergarten-aged children in Guangzhou, China.

Polycyclic aromatic hydrocarbons (PAHs), benzene and toluene (BT) are ubiquitous toxic pollutants in the environment. Children are sensitive and susceptible to exposure to these contaminants. To investigate the potential oxidative DNA damage from the co-exposure of PAHs and BT in children, 87 children (aged 3-6) from a kindergarten in Guangzhou, China, were recruited. Ten urinary PAHs and four BT metabolites, as well as 8-hydroxy-2'-deoxyguanosine (8-OHdG, a biomarker of oxidative DNA damage)in urine, were determined using a liquid chromatography tandem mass spectrometer. The results demonstrated that the levels of PAHs and BT in children from Guangzhou were 2-30 times higher than those in children from the other countries based on a comparison with recent data from the literature. In particular, the difference is more substantial for pyrene and volatile BT. Co-exposure to PAHs and BT could lead to additive oxidative DNA damage. Significant dose-effects were observed between the sum concentration of urinary monohydroxylated metabolites of PAHs (∑OH-PAHs), the sum concentration of the metabolites of BT (∑BT) and 8-OHdG levels. Every one percent increase in urinary PAHs and BT generated 0.33% and 0.02% increases in urinary 8-OHdG, respectively. We also determined that the urinary levels of PAHs and BT were negatively associated with the age of the children. Moreover, significant differences in the levels of ∑OH-PAHs and ∑BT were determined between 3- and 6-year-old children (p<0.05), which may be caused by different metabolism capabilities or inhalation frequencies. In conclusion, exposure to PAHs or BT could lead to oxidative DNA damage, and 8-OHdG is a good biomarker for indicating the presence of DNA damage. There exists a significant dose-effect relationship between PAH exposure, BT exposure and the concentration of 8-OHdG in urine. Toddlers (3-4 years old) face a higher burden of PAH and BT exposure compared with older children.

Levels of bisphenol-A in different paper products in Guangzhou, China, and assessment of human exposure via dermal contact.

Bisphenol A (BPA) is a chemical widely used both in plastics production as a food and beverage container and in thermal papers as a color developer. Dietary consumption is the main route of human exposure to BPA, but dermal absorption through handling different papers might be underestimated or ignored. In this study, BPA in different paper products, including different types of papers, receipts and Chinese currencies, were investigated. BPA was detected in receipts (n = 87) and Chinese currencies (n = 46) with concentrations of 0.17-2.675 × 10(4) µg per g paper and 0.09-288.55 µg per g paper, respectively. Except for parchment papers (n = 3), copy papers (n = 3) and food contact papers (n = 3), BPA was measured in all of the other paper products, with levels of 0.01-6.67 µg per g paper. BPA transferred from thermal papers to common papers increased with the increasing contact pressure. Compared with that in water, the migration speed of BPA was doubled in the synthetic sweat. Washing hands could reduce BPA dermal exposure, and washing hands with lotion was the most efficient way. However, about 19-47% of BPA was still found on hands after different washing methods. Dermal absorption via handling of receipts and papers was estimated to be 36.45 ng per day for the general population and 1.54 × 10(-3) to 248.73 µg per day for a cashier. These values are below the maximum doses recommended by the U.S. Environmental Protection Agency and the European Food Safety Authority. However, due to its uncertain adverse effects on human beings, long-term BPA exposure through dermal absorption should be paid more attention, particularly for some occupational populations.

Exposure to polycyclic aromatic hydrocarbons could cause their oxidative DNA damage: a case study for college students in Guangzhou, China.

Human exposure to carcinogenic polycyclic aromatic hydrocarbons (PAHs) in cigarette smoking might result in generation of reactive oxygen species (ROS) and induce formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG). This study was designed to examine whether levels of 8-OHdG are associated with levels of urinary metabolites of PAHs. Two groups (smokers and non-smokers) were recruited from college students in Guangzhou, China. Their urine samples were collected and analyzed for ten urinary mono-hydroxylated PAHs (OH-PAHs) and 8-OHdG by liquid chromatography equipped with tandem mass spectrometer (LC/MS/MS). Multiple linear regression analysis was performed to examine correlations between urinary levels of 8-OHdG and OH-PAHs. No significant difference was observed for creatinine-adjusted OH-PAHs between smokers and non-smokers. The levels of 8-OHdG between smokers and non-smokers were comparative. OH-PAH levels in this study were 2-50 times higher than those in populations from other countries and areas. The estimated daily intake (EDI; µg/day) of PAHs ranged from 0.02 to 371.4, which were far lower than the reference doses (RfDs) specified by U.S. Environmental Protection Agency (EPA). Though smoking was a main factor, which affected the PAH exposure, it was not a dominant factor in the exposure to PAHs of Guangzhou college students. The environmental exposure could not be ignored. The sum concentrations of OH-PAHs (∑OH-PAHs) had a dose-increase relationship with 8-OHdG both for smokers and non-smokers, especially for smokers. Though people in Guangzhou bore higher PAH hazards, the estimated environmental risk was still under safe ranges.