Jin Ma

Association of selected persistent organic pollutants in the placenta with the risk of neural tube defects

Persistent organic pollutants (POPs) have been associated with a wide range of adverse health effects. Our case–control study was performed to explore the association between placental levels of selected POPs and risks for neural tube defects (NTDs) in a Chinese population with a high prevalence of NTDs. Cases included 80 fetuses or newborns with NTDs, whereas the controls were 50 healthy, nonmalformed newborn infants. Placental concentrations of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides, polychlorinated biphenyls, and polybrominated diphenyl ethers were analyzed by gas chromatography–mass spectrometry. The medians of PAHs, o,p′-isomers of dichlorodiphenyltrichloroethane (DDT) and metabolites, α- and γ-hexachlorocyclohexane (HCH), and α-endosulfan were significantly higher in case placentas than in controls. PAH concentrations above the median were associated with a 4.52-fold [95% confidence interval (CI), 2.10–9.74) increased risk for any NTDs, and 5.84- (95% CI, 2.28–14.96) and 3.71-fold (95% CI, 1.57–8.79) increased risks for anencephaly and spina bifida, respectively. A dose–response relationship was observed between PAH levels and the risk of NTDs, with odds ratios for the second, third, and fourth quartiles, compared with the first, of 1.77- (95% CI, 0.66–4.76), 3.83- (95% CI, 1.37–10.75), and 11.67-fold (95% CI, 3.28–41.49), respectively. A dose–response relationship was observed for anencephaly and spina bifida subtypes. Similar results were observed for o,p′-DDT and metabolites, α-HCH, γ-HCH, and α-endosulfan, whereas no dose–response relationship was observed for the last two pollutants. Elevated placental concentrations of PAHs, o,p′-DDT and metabolites, and α-HCH were associated with increased risks of NTDs in this population.

Gridded Field Observations of Polybrominated Diphenyl Ethers and Decabromodiphenyl Ethane in the Atmosphere of North China

Brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) are important pollutants, yet few data on ambient BFRs levels have been available for North China, one of the most developed regions of the country. In this study, we investigated levels and spatial distributions of BFRs based on gridded field observations coupled with passive air sampling in the aforementioned region. A model incorporating both point and nonpoint sources was developed to simulate the spatial distribution and to achieve source apportionment. Although high concentration was observed at an electronic-waste (e-waste) recycling site, the median level of the sum of tri-, tetra-, hepta-, hexa-, and hepta-PBDEs (∑10PBDEs) was 0.56 ng/sample, which was lower than those observed previously in mainland China. Source apportionment revealed that nonpoint emissions contributed nearly 78% of ∑10PBDEs observed in this study. In contrast, high levels of BDE-209 and DBDPE were observed, with median concentrations of 4.0 and 10.2 ng/sample, respectively. Point sources located in the region around Laizhou Bay, Shandong Province were the major sources, which contributed 31% of BDE-209 and 70% of DBDPE observed in this study, indicating that this manufacturing base was the most important source region for atmospheric deca-BFRs in North China. To our knowledge, this is the first study to report source apportionment of atmospheric BFRs based on gridded field observations.

Polybromobenzene Pollutants in the Atmosphere of North China: Levels, Distribution, and Sources

Brominated flame retardants (BFRs) are important persistent organic pollutants. Analysis of BFRs in atmospheric samples in a previous study led us to suspect the presence of unidentified organic bromides, other than polybrominated diphenyl ethers (PBDEs), in the atmosphere. In this study, we identified and quantified polybromobenzenes, a group of organic bromides, in air samples collected through passive sampling in gridded observations in North China. We investigated their concentrations and spatial distribution, and estimated the proportion due to different sources. We detected seven species of polybromobenzenes, including hexabromobenzene (HBB), pentabromotoluene (PBT), pentabromoethylbenzene (PBEB), pentabromobenzene (PeBB), tetrabromobenzenes (TeBBs), and tribromotoluene (TrBT), in all or most of the field samples, indicating widespread occurrence of this class of pollutants. The median concentrations of each pollutant ranged from 20.0 to 144 pg/sample (or from 0.07 to 1.16 pg/m(3)), with relatively high concentrations found near e-waste recycling sites, BFR manufacturing sites, and areas of high population density. Positive matrix factorization (PMF) analysis revealed that ∼70% of HBB, PBT, PBEB, and PeBB was from commercial products, while ∼80% of 1,2,3,5-TeBB, 1,2,4,5-TeBB, and 2,4,5-TrBT was linked with BFR manufacturing. This study provides essential information on widespread polybromobenzene pollutants in the atmosphere, particularly TeBBs and TrBT, for which this is the first report of their presence as atmospheric pollutants.

Atmospheric PAHs in North China: Spatial distribution and sources

Polycyclic aromatic hydrocarbons (PAHs), formed through incomplete combustion process, have adverse health effects. To investigate spatial distribution and sources of PAHs in North China, PAHs with passive sampling in 90 gridded sites during June to September in 2011 were analyzed. The average concentration of the sum of fifteen PAHs in North China is 220±14ng/m(3), with the highest in Shanxi, followed by Shandong and Hebei, and then the Beijing-Tianjin area. Major sources of PAHs are identified for each region of North China, coke process for Shanxi, biomass burning for Hebei and Shandong, and coal combustion for Beijing-Tianjin area, respectively. Emission inventory is combined with back trajectory analysis to study the influence of emissions from surrounding areas at receptor sites. Shanxi and Beijing-Tianjin areas are more influenced by sources nearby while regional sources have more impact on Hebei and Shandong areas. Results from this study suggest the areas where local emission should be the major target for control and areas where both local and regional sources should be considered for PAH abatement in North China.

Using placenta to evaluate the polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) exposure of fetus in a region with high prevalence of neural tube defects

Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants suspected to have various toxic effects, including reproductive toxicity. The aim of this study was to determine the concentrations of PCBs and PBDEs in human placentas and to examine the potential association between in utero exposure to these pollutants and the risk of neural tube defects. Subjects were recruited from a birth defects surveillance program in a rural area of Shanxi Province, China, from 2005 to 2007. 80 placental samples from fetuses/neonates with neural tube defects and 50 samples from healthy newborn infants were analyzed for PCBs and PBDEs using electron-capture negative-ionization gas chromatographic mass spectrometry. The median concentrations were 0.89 and 0.54ng/g lipid for the eight PCB congeners and six PBDE congeners detected, respectively. The median concentration of total PCBs was slightly higher in the case samples than in the controls (0.91 vs. 0.89ng/g lipid), but the difference was not significant (P=0.46), as also found for the median concentration of total PBDEs (0.55 vs. 0.54ng/g lipid, P=0.61). For both PCBs and PBDEs, when their placental concentration was above the median of all samples, it was associated with a non-significantly higher or equal risk of neural tube defects. Low levels of PCBs and PBDEs are not likely risk factors for neural tube defects in this population.