Are there other persistent organic pollutants? A challenge for environmental chemists.
ABSTRACT The past 5 years have seen some major successes in terms of global measurement and regulation of persistent, bioaccumulative, and toxic (PB&T) chemicals and persistent organic pollutants (POPs). The Stockholm Convention, a global agreement on POPs, came into force in 2004. There has been a major expansion of measurements and risk assessments of new chemical contaminants in the global environment, particularly brominated diphenyl ethers and perfluorinated alkyl acids. However, the list of chemicals measured represents only a small fraction of the approximately 30,000 chemicals widely used in commerce (>1 t/y). The vast majority of existing and new chemical substances in commerce are not monitored in environmental media. Assessment and screening of thousands of existing chemicals in commerce in the United States, Europe, and Canada have yielded lists of potentially persistent and bioaccumulative chemicals. Here we review recent screening and categorization studies of chemicals in commerce and address the question of whether there is now sufficient information to permit a broader array of chemicals to be determined in environmental matrices. For example, Environment Canada's recent categorization of the Domestic (existing) Substances list, using a wide array of quantitative structure activity relationships for PB&T characteristics, has identified about 5.5% of 11,317 substances as meeting P & B criteria. Using data from the Environment Canada categorization, we have listed, for discussion purposes, 30 chemicals with high predicted bioconcentration and low rate of biodegradation and 28 with long range atmospheric transport potential based on predicted atmospheric oxidation half-lives >2 days and log air-water partition coefficients > or =5 and < or =1. These chemicals are a diverse group including halogenated organics, cyclic siloxanes, and substituted aromatics. Some of these chemicals and their transformation products may be candidates for future environmental monitoring. However, to improve these predictions data on emissions from end use are needed to refine environmental fate predictions, and analytical methods may need to be developed.
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ABSTRACT: A homeostasis of the glucocorticoid and androgen endocrine system is essential to human health. Their disturbance can lead to various diseases, for example cardiovascular, inflammatory and autoimmune diseases, infertility, cancer. Fifteen widely used industrial chemicals that disrupt endocrine activity were selected for evaluation of potential (anti)glucocorticoid and (anti)androgenic activities. The human breast carcinoma MDA-kb2 cell line was utilized for reporter gene assays, since it expresses both the androgen and the glucocorticoid-responsive reporter. Two new antiandrogens, 4,4′-sulfonylbis(2-methylphenol) (dBPS) and 4,4′-thiodiphenol (THIO), and two new antiglucocorticoids, bisphenol Z and its analog bis[4-(2-hydroxyethoxy)phenyl] sulfone (BHEPS) were identified. Moreover, four new glucocorticoid agonists (methyl paraben, ethyl paraben, propyl paraben and bisphenol F) were found. To elucidate the structure-activity relationship of bisphenols, we performed molecular docking experiments with androgen and glucocorticoid receptor. These docking experiments had shown that bulky structures such as BHEPS and bisphenol Z act as antiglucocorticoid, because they are positioned towards helix H12 in the antagonist conformation and could therefore be responsible for H12 conformational change and the switch between agonistic and antagonistic conformation of receptor. On the other hand smaller structures cannot interact with H12. The results of in vitro screening of fifteen industrial chemicals as modulators of the glucocorticoid and androgen receptor activities demand additional in vivo testing of these chemicals for formulating any relevant hazard identification to human health.Toxicology in Vitro 09/2014; 29(1):8-15. · 3.21 Impact Factor
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ABSTRACT: This research project was carried out to investigate the spatial distributions and temporal trends of selected halogenated organic chemical pollutants (HOPs) of emerging concern in the Laurentian Great Lakes as recorded in the sediments. Sixteen sediment cores were collected from all five Great Lakes in August 2007. These cores were horizontally sectioned into a total of 223 samples. All the samples were characterized for water content and organic matter content. The concentrations of 6 Dechlorane related compounds, 13 polybrominated flame retardants (BFRs) of emerging concerns, 13 octa to deca congeners of polybrominated diphenyl ethers (PBDEs), and 144 congeners of polychlorinated biphenyls (PCBs) were quantitatively analyzed, using procedures which included Soxhlet extraction, multi-phase silica gel cleanup, and instrumental analyses with gas chromatography / mass spectrometry (GC/MS). The Dechlorane related compounds, including Dechlorane (mirex), Dechlorane Plus (DP), Dechlorane 602 (Dec602), Dechlorane 603 (Dec603), and Dechlorane 604 (Dec604) were found in all the sediment cores collected. On dry weight (dw) basis, their concentrations at the top sediment layer (0-1 cm) were in the ranges of <0.01-27 ng g-1 dw for mirex, 0.2-140 ng g-1 dw for DP, 0.02-33 ng g-1 dw for Dec602, 0.03-2.6 ng g-1 dw for Dec603, and <0.006-8.2 ng g-1 dw for Dec604. Lake Ontario sediments have accumulated mirex, DP, Dec602 and Dec604 in amounts 1 to 2 orders of magnitude higher than other Great Lakes. The chemical inventory decreases log-linearly with increasing latitude (N) and longitude (W) of the sampling locations, but Lake Ontario sites are outliers in the regression against latitude. Our findings, combined with those from several other studies, suggest that industrial discharge or dumping, rather than diffuse sources which are often associated with population density, dominates the input of Dechloranes to Lake Ontario. Temporal trends of input differ among lakes. Most sites in Lake Superior are still receiving increasing fluxes of DP and Dec602, while these have been declining in Lake Ontario from the peak around 1990. An important finding of this work is that the relative abundance of the two DP isomers, represented by fsyn, increases with increasing distance from the potential discharge source in Niagara Falls, NY, suggesting the anti-DP isomer is more vulnerable to degradation during the long range atmospheric transport. These results have been published in Yang et al. (Environ. Sci. Technol., 2011, 45, 5156–5163). The 13 emerging BFRs analyzed were 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE or TBE), decabromodiphenylethane (DBDPE), hexabromocyclododecane (HBCD), 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), and hexachlorocyclopentadienyl dibromocyclooctane (HCDBCO), as well as hexabromobenzene (HBB), 1,3,5-Tribromobenzene (TBB), pentabromotoluene (PBT), pentabromoethylbenzene (PBEB), and tetrabromo-o-chlorotoluene (TBCT), 2,3,5,6-tetrabromo-p-xylene (pTBX), pentabromobenzyl bromide (PBBB), and 2,2’,4,4’,5,5’-hexabromobiphenyl (BB153). Among them, BTBPE, DBDPE, HBCD, TBECH and HCDBCO had estimated total burden of >800 kg in the Great Lakes sediments, thus are discussed in detail in this report. The surface (0-1 cm) concentrations ranged 0.05-1.4 ng g-1 dw for BTBPE, 0.2-2.3 ng g-1 dw for DBDPE, 0.04-3.1 ng g-1 dw for HBCD, 0.13-8.3 ng g-1 dw for TBECH and 0.1-2.8 ng g-1 dw for HCDBCO. Logarithm inventories of these 5 BFRs were found to decrease linearly with the increasing latitude (N) of the sampling locations, but with weaker statistics than those for the Dechloranes. Unlike the Dechloranes, Lake Ontario is not an outliner in such correlations. The logarithm surface fluxes, on the other hand, were found to be a better parameter in correlating with the longitude (W). With regard to time trend, the exponential increases in accumulations of these BFRs, particularly DBDPE and BTBPE, in recent years are highly alarming. The sediment concentration of DBDPE doubles every 3-5 years in Lake Michigan, and approximately 7 years in Lake Ontario. The corresponding doubling times for BTBPE are about 7 and 5 years in Lakes Michigan and Ontario, respectively, although decline or leveling off appeared having occurred in the top sediment layers in Lake Ontario. Compared with PCBs, PBDEs, and most Dechloranes, the concentrations of these emerging BFRs depend much weakly on the content of the sediment organic matter (OM). Normalization of the concentration by the OM content does not strengthen the correlations against latitude and longitude, suggesting a source controlled spatial distribution. Comparison among the analytes groups is given in the graph above for the estimated total burden in the Great Lakes sediments. These estimates are provided in this report for comparison purpose only and should be used with caution, because the calculation was based on a limited number of the sampling sites involved in this work. Apparently, PCBs still outweigh others as the dominant contaminant. Dechlorane Plus (DP) have accumulated in a relatively large quantity comparable to that of PBDEs. It is followed by Dec602 and mirex. At present, the accumulations of the emerging BFRs are still much lower than those of PBDEs and Dechloranes. However, as stated above, the inputs of DBDPE, BTBPE and others are increasing rapidly in recent years.
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ABSTRACT: Rockström et al. (2009a, 2009b) have warned that humanity must reduce anthropogenic impacts defined by nine planetary boundaries if “unacceptable global change” is to be avoided. Chemical pollution was identified as one of those boundaries for which continued impacts could erode the resilience of ecosystems and humanity. The central concept of the planetary boundary (or boundaries) for chemical pollution (PBCP or PBCPs) is that the Earth has a finite assimilative capacity for chemical pollution, which includes persistent, as well as readily degradable chemicals released at local to regional scales, which in aggregate threaten ecosystem and human viability. The PBCP allows humanity to explicitly address the increasingly global aspects of chemical pollution throughout a chemical's life cycle and the need for a global response of internationally coordinated control measures. We submit that sufficient evidence shows stresses on ecosystem and human health at local to global scales, suggesting that conditions are transgressing the safe operating space delimited by a PBCP. As such, current local to global pollution control measures are insufficient. However, while the PBCP is an important conceptual step forward, at this point single ormultiple PBCPs are challenging to operationalize due to the extremely large number of commercial chemicals or mixtures of chemicals that cause myriad adverse effects to innumerable species and ecosystems, and the complex linkages between emissions, environmental concentrations, exposures and adverse effects. As well, the normative nature of a PBCP presents challenges of negotiating pollution limits amongst societal groups with differing viewpoints. Thus, a combination of approaches is recommended as follows: develop indicators of chemical pollution, for both control and response variables, that will aid in quantifying a PBCP(s) and gauging progress towards reducing chemical pollution; develop new technologies and technical and social approaches to mitigate global chemical pollution that emphasize a preventative approach; coordinate pollution control and sustainability efforts; and facilitate implementation of multiple (and potentially decentralized) control efforts involving scientists, civil society, government, non-governmental organizations and international bodies.Environment International 02/2015; 78:8-15. · 5.66 Impact Factor