关注新型环境污染物——溴化阻燃剂

溴化阻燃剂(brominated flame retardants,BFRs)由于其阻燃效果好,被广泛地应用于家庭消费品中,如电子设备(家用电器和计算机等)、日用家具、室内装饰等,是正在受到全球关注的新型环境污染物.     

Proteomic studies in zebrafish liver cells exposed to the brominated flame retardants HBCD and TBBPA

Proteomic effect screening in zebrafish liver cells was performed to generate hypotheses regarding single and mixed exposure to the BFRs HBCD and TBBPA. Responses at sublethal exposure were analysed by two-dimensional gel electrophoresis followed by MALDI-TOF and FT-ICR protein identification. Mixing of HBCD and TBBPA at sublethal doses of individual substances seemed to increase toxicity. Proteomic analyses revealed distinct exposure-specific and overlapping responses suggesting novel mechanisms with regard to HBCD and TBBPA exposure. While distinct HBCD responses were related to decreased protein metabolism, TBBPA revealed effects related to protein folding and NADPH production. Overlapping responses suggest increased gluconeogenesis (GAPDH and aldolase) while distinct mixture effects suggest a pronounced NADPH production and changes in proteins related to cell cycle control (prohibitin and crk-like oncogene). We conclude that mixtures containing HBCD and TBBPA may result in unexpected effects highlighting proteomics as a sensitive tool for detecting and hypothesis generation of mixture effects.     

北京市居民膳食中新型溴代阻燃剂暴露水平研究

目的研究北京市居民通过膳食摄入6种新型溴代阻燃剂暴露特征。方法采用大气压气相色谱-串联质谱法(APGC-MS/MS)测定北京市总膳食样品中二甲基四溴苯(pTBX)、五溴甲苯(PBT)、五溴乙苯(PBEB)、六溴苯(HBB)、六氯环戊二烯-二溴环辛烷(DBHCTD)和1,2-双(2,4,6-三溴苯氧基)乙烷(BTBPE)的含量,并对结果进行分析,计算北京市居民的膳食暴露量。结果 61份总膳食样品中检出PBT、PBEB、HBB和BTBPE等4种新型溴代阻燃剂,含量在1.2~29.4 pg/g(湿重)之间。动物性样品中HBB和BTBPE的含量普遍高于植物性样品,且差异有统计学意义(P0.05);北京市居民6种新型溴代阻燃剂膳食暴露量为296.8 pg/(kg·d)。结论北京市居民总膳食中新型溴代阻燃剂暴露水平较低,动物性样品中的肉类样品是BTBPE膳食摄入的主要来源。     

Exposure to brominated flame retardants,perfluorinated compounds,phthalates and phenols in European birth cohorts: ENRIECO evaluation,first human biomonitoring results,and recommendations

There are emerging concerns about potential effects on child health and development of early-life exposure to substances such as brominated flame retardants (BFRs), perfluorinated compounds (PFCs), phthalates and phenols (including bisphenol A (BPA)); pregnancy and birth cohort studies are ideally designed to study such concerns prospectively. As part of the ENRIECO project, we evaluated existing human biomonitoring data for these substances in European birth cohorts and develop recommendations for more harmonized methods that will enable combination and comparison of cohort data in the future. The ENRIECO inventory shows that 20 European birth cohorts have measured or are measuring BFRs (N = 10), PFCs (N = 11), phthalates (N = 16) or phenols (N = 8). Generally, samples were collected prenatally or at birth and measurements involved few subjects in each cohort (a few hundred maximum). Biological matrices, timing, and analytical methods of the measurements varied between cohorts. Few cohorts have measured at multiple time points or in children. In European cohorts, levels of BFRs were very low and at least 10-fold lower than in US; levels of PFCs and phthalates have decreased over the last decade since the phasing out of certain of these compounds; concentrations of phenols are comparable to those in the US. Although there is little published data in the cohorts now, many measurements are ongoing and we recommend that cohorts start working towards combined and comparison studies. Specific recommendations for use of existing data include the development of conversion models for the different media used for measurement of persistent chemicals, and inter-laboratory comparisons and calibrations. Recommendations for further data collection include more evaluation of exposure to these chemicals in children; repeated measurements of non-persistent chemicals; validation and harmonisation of questionnaires; and the development of mechanisms for fast European birth cohort response for the detection and prioritisation of new chemicals of concern.     

Examining the relationship between brominated flame retardants (BFR) exposure and changes of thyroid hormone levels around e-waste dismantling sites

Brominated flame retardants (BFRs) released from e-waste related activities may affect the health of local people. Assessing the impact of e-waste exposure during recycling and dismantling activities on local people's thyroid hormone levels is an area of ongoing research. During November and December 2008, the process of e-waste recycling and dismantling was investigated, and 236 occupation-exposed people and 89 non-occupation-exposed people approximate to the e-waste recycling sites were surveyed; their thyroid hormone levels (THs), thyrotropins (TSH) and BFRs levels in serum were assayed. Multiple regression models were constructed to analyze the changes of serum THs and TSH in the people living in the exposure area (exposure group) and the people in the control group. Covariates known to be or likely to be associated with THs, TSH and BFRs levels were analyzed. Lower level of Triiodothyronine (T₃) in both occupation-exposed and non-occupation-exposed group were observed (p < 0.01), when compared with the control group, and the same trend was obtained for free triiodothyronine (fT₃) and free thyroxine (fT4) (p < 0.01). However, no significant difference in thyroxine (T₄) was found between the two groups. The level of TSH in the e-waste recycling occupational-exposed group ranged from 0.00 to 5.00 μIU/ml with a mean of 1.26 μIU/ml, whereas the level of TSH in the control group was from 0.03 to 5.54 μIU/ml with a mean of 1.57 μIU/ml. This study revealed that people having worked on e-waste recycling and dismantling had significantly lower TSH compared with the control group (p < 0.01). Moreover, the level of BDE-205 is positively associated with the level of T4, as confirmed by the linear regression model (unstandardized regression coefficient, beta = 0.25, ρ = 0.001) and a weaker positive relation was also found between the levels of BDE-126 and T4. Meanwhile, a weak negative relation was found between the levels of PBB 103 and T3, and between the levels of fT3 and fT4. These results suggest that exposure to BFRs released from primitive e-waste handling may contribute to the changes of THs and TSH levels.     

Gender-specific proteomic responses in zebrafish liver following exposure to a selected mixture of brominated flame retardants

Proteomic effect screening in zebrafish liver was performed to generate hypotheses following exposure (21 days) to a structurally diverse mixture of brominated flame retardants (BFRs). Fish were exposed to two doses (10 and 100 nmol/g feed). Two-dimensional gel-electrophoresis, image analysis and MALDI-TOF mass-spectrometry revealed 13 and 19 significant responses in males and females, respectively. Effects on proteins related to cellular maintenance and stress were observed in both genders. Regulated proteins were gender-specific, but functionally indicated common protective responses (peroxiredoxin 6 and Zgc:92891 in males and transketolase in females) suggesting oxidative stress. Betaine homocysteine methyltransferase (BHMT) was induced in both genders. In addition a female-specific downregulation of ironhomeostatic proteins (iron-regulatory protein 1 and transferrin) were observed. Our proteomic approach revealed novel responses that suggest important gender-specific sensitivity to BFRs that should be considered when interpreting adverse effects of BFRs.     

Analysis of brominated flame retardants in the aquatic environment: a review

The most common and consequently analysed brominated flame retardants (BFRs) are polybrominated biphenyls (PBBs), polybrominated diphenyl ethers (PBDEs), tetrabromobisphenol A (TBBPA), tetrabromobisphenol S (TBBPS), and hexabromocyclododecane (HBCD). As these persistent organic pollutants are widespread in the environment and have a number of harmful effects on human health, the production and use of most has been banned for several years. The aquatic environment is polluted by these compounds through their deposition from the atmosphere, sewage sludge, wastewater treatment plants, and landfills, and higher levels are found in areas with developed industry and agriculture and near landfills. Each compound also seems to show preference for specific compartments of the aquatic environment, i.e. water, sediment, or aquatic organisms, according to their physicochemical properties. The aim of this review was to take a closer look at the analysis of BFRs, as without reliable analysis we would not be able to determine their levels and distribution across the aquatic compartments and assess human exposure and health risks. Particularly worrying are the health risks associated with PBDEs in fish, whose levels generally exceed the permitted values.KEY WORDS: hexabromocyclododecane, HBCD, persistent organic pollutants, PBBs, polybrominated biphenyls, PBDEs, polybrominated diphenyl ethers, TBBPA, tetrabromobisphenol A, TBBPS, tetrabromobisphenol S     

Umbilical cord blood levels of perfluoroalkyl acids and polybrominated flame retardants

Perfluoroalkyl acids (PFAAs) and polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants representing two classes of environmental contaminants of toxicological concern, especially for infants. Canadian biomonitoring data on these chemicals are limited. The objectives of this study were to measure PFAAs and PBDEs in umbilical cord blood from approximately 100 hospital deliveries in Ottawa (Ontario, Canada) and examine associations with characteristics of the mother and infant. Geometric means were 1.469 ng/mL for perfluorooctanoate (PFOA) (95% confidence interval of 1.292–1.671 ng/mL), 4.443 ng/mL for perfluorooctane sulfonate (PFOS) (95% CI of 3.735–5.285 ng/mL), 0.359 ng/mL for perfluorononanoic acid (PFNA) (95% CI of 0.318–0.404 ng/mL), and 0.579 ng/mL for perfluorohexanesulfonate (PFHxS) (95% CI of 0.473–0.709 ng/mL). The final multiple regression models indicated that lower gravida, term gestational age, smoking during pregnancy and vaginal delivery were significantly associated with higher levels of PFOS. Similarly, a vaginal delivery was significantly associated with higher PFOA, while weak associations were found with lower gravida and birth weight less than 2500 g. Furthermore, higher PFNA concentrations were significantly associated with older mothers, and vaginal delivery, while weakly associated with term gestational age. Elevated PFHxS concentrations were significantly associated with smoking during pregnancy and lower gravida. Similar to reports from other countries, the preponderant PBDE congener measured in the cord blood was PBDE-47. Questions remain on why various studies have reported conflicting results on the association between PFAAs and birth weight.     

Prenatal exposure to polybrominated diphenyl ether flame retardants and neonatal thyroid-stimulating hormone levels in the CHAMACOS study

Studies published in the last 3 decades have demonstrated global human exposure to polybrominated diphenyl ether (PBDE) flame retardants. A growing body of literature suggests that PBDEs may disrupt thyroid hormone homeostasis. Although thyroid hormones play an essential role in brain development, few studies have investigated relations between prenatal exposure to PBDEs and neonatal thyroid hormone levels, and none have measured thyroid-stimulating hormone (TSH) levels in neonates. The authors measured 10 PBDE congeners in serum collected between October 1999 and October 2000 from 289 pregnant women living in California's Salinas Valley and abstracted TSH levels from their children's medical records. Individual PBDE congeners showed null or weak nonsignificant inverse relations with neonatal TSH. Total serum PBDE was not associated with neonatal TSH (β = 0.00, 95% confidence interval: -0.06, 0.06). Except for brominated diphenyl ether 153, a higher serum PBDE level was related to elevated odds of high TSH (≥80th percentile), but associations were not statistically significant. Associations were not modified by infant sex, age at TSH measurement, maternal serum polychlorinated biphenyl concentration, or mode of delivery. Results were robust to sensitivity analysis. The authors found no conclusive evidence that prenatal exposure to PBDEs at levels similar to those of the general US population is related to neonatal TSH.     

Exposure to toxic waste sites: an investigative approach

Improper dumping and storage of hazardous substances and whether these practices produce significant human exposure and health effects are growing concerns. A sequential approach has been used by the Centers for Disease Control and the Agency for Toxic Substances and Disease Registry in investigating potential exposure to and health effects resulting from environmental contamination with materials such as heavy metals, volatile organic compounds, and pesticide residues at sites throughout the United States. The strategy consists of four phases: site evaluation, pilot studies of exposure or health effects, analytic epidemiology studies, and public health surveillance. This approach offers a logical, phased strategy to use limited personnel and financial resources of local, State, national, or global health agency jurisdictions optimally in evaluating populations potentially exposed to hazardous materials in waste sites. Primarily, this approach is most helpful in identifying sites for etiologic studies and providing investigative leads to direct and focus these studies. The results of such studies provide information needed for making risk-management decisions to mitigate or eliminate human exposures and for developing interventions to prevent or minimize health problems resulting from exposures that already have occurred.     

Breast-milk levels of polybrominated diphenyl ether flame retardants in relation to women's age and pre-pregnant body mass index

The aim of the present study was to determine associations between the occurrence of PBDEs in breast milk of women and their demographic parameters. Participants were randomly recruited from the general population in southern Taiwan. Thirty two breast milk samples were collected and subsequently 30 congeners of PBDEs were analyzed using a high resolution gas chromatograph with a high resolution mass spectrometer. The mean and median of ΣPBDEs were 3.54 and 3.31 ng/g lipid, respectively. ΣPBDE levels in breast milk were not significantly correlated with age and pre-pregnant BMI of Taiwanese mothers. We did find, however, that the higher hexaBDE level was significantly related to older age (>29 years). Higher levels of ΣPBDEs and higher brominated PBDEs, such as nonaBDEs and decaBDE, had slightly but not significantly negative correlations with lower pre-pregnant BMI (≤21 kg/m²). There were no significant differences in PBDE levels among parity and ethnic groups. ΣPBDE levels in Taiwanese breast milk were lower than those reported from the United States or Canada. ΣPBDE levels of the present study (2007-2008) are significantly lower than those found in our previous report (2000-2001). Although our results were limited by the sampling size, preliminary results suggest the exploratory relations to show positive associations of PBDE homologues (e.g. triBDEs and hexaBDEs) with maternal age. PBDEs pattern of breast milk may have changed after pentaBDEs were stopped to use in Taiwan.