Characteristics of sorption losses of polychlorinated biphenyl congeners onto glass surfaces

Sorption losses to glass surfaces of five polychlorinated biphenyl (PCB) congeners in aqueous solutions were investigated. Adsorption/desorption experiments were conducted under conditions that simulated actual sample handling procedures for environmental samples. It was found that the adsorption loss is related to the degree of chlorination. PCB congener 180 lost the most onto glass surfaces, followed by congeners 138, 101/28, and 52, in decreasing order. More PCB adsorption occurred onto glass under conditions of agitation and higher temperature (22°C) during the five-day experimental period. The salinity effect (“salting out effect”) was also observed in this work. The efficiency of desorption (rinsing three times with solvent) was found to be ineffective in extracting adsorbed PCBs. It was necessary to use mechanical shaking for extraction. Storage of samples up to five days resulted in sorption losses as much as 30%, 17%, 30%, 40%, and 55% of PCB 28, 52, 101, 138, and 180, respectively. Sorption losses need to be considered when conducting water sampling or toxicological studies to avoid underestimation of the actual PCB concentrations and their toxic effects.     

Formation of polychlorobiphenyls in silicone rubber

In silicone rubber crosslinked with bis(2,4-dichlorobenzoyl) peroxide (DCBP) as initiator about 0.1% of DCBP is converted into polychlorobiphenyls (PCBs). The PCB content in silicone rubber determined by high resolution gas chromatography (HRGC) after its destruction by HF is around 10 mg/kg. 29 PCB congeners were detected. Instead of the expected PCB-47, lower chlorinated congeners are predominant. Some possible pathways of their origin are presented.     

利用紫外光降解多氯联苯(PCBs)的研究进展

本文综述了PCBs在各种溶剂中的紫外光化学反应特性和降解途径 :PCB的光化学反应以氢取代氯的脱氯反应为主 ,除此之外 ,在水或醇等极性溶液中 ,还存在羟基化反应 ;PCB的光化学反应活性与其氯原子的数量和取代位置有关。文章最后还简述了光降解在治理受PCB污染土壤方面的应用     

Polychlorinated biphenyls and dibenzofurans retained in the tissues of a deceased patient with Yucheng in Taiwan

Various tissues from a deceased Yucheng (oil disease) patient were analyzed for individual polychlorinated biphenyl (PCB) and dibenzofuran (PCDF) congeners. With a few exceptions, PCBs with 5 or less chlorine atoms were almost completely excreted from the patient's tissues about two years after the ingestion of the toxic oil. In contrast, most PCB congeners with 6 or more chlorine atoms were retained in the tissues. The intestinal fat contains the highest level of PCBs while the liver contains the highest concentration of PCDFs. The major PCDF congeners retained in the tissues were 1,2,3,4,7,8-hexaCDF, 2,3,4,7,8-pentaCDF, and 1,2,4,7,8-pentaCDF. The former two congeners, especially 2,3,4,7,8-pentaCDF, are very toxic PCDFs; they may play important roles in the etiology of Yucheng.     

Distribution characteristics of polychlorinated biphenyls in crucian carp (Carassius auratus) from major rivers in Korea

Polychlorinated biphenyls (PCBs) levels in crucian carp were determined at 20 locations along four major river systems, several small-scale rivers and a wetland in Korea. Twenty-eight congeners, ranging from tri- to hepta-CBs were detected. A gas chromatograph with a mass selective detector was used to quantify the individual PCB congeners. The objectives of this study were to investigate the levels of contamination of PCBs in freshwater fish and to observe the pattern of their distribution. The sampling locations were chosen among 31 sampling sites that are currently used as environmental residue checkpoints by the Korean Ministry of Environment. Concentrations of individual congeners ranged from not detectable (n.d.) to 0.75 ng g(-1) on a wet weight basis. The total concentrations of PCBs at each site ranged from n.d. to 5.41 ng g(-1) of wet weight. The most heavily contaminated site was the Nakdong estuary located near the Shinpyung-Janglim factory district. The PCB 153 and 138 were the principal congeners and penta- and hexa-chlorinated biphenyls comprised the main congener groups.     

Polychlorinated biphenyls in surface sediments of Yueqing Bay, Xiangshan Bay, and Sanmen Bay in East China Sea

The spatial distribution and source of polychlorinated biphenyls (PCBs) in 30 surface sediments of Yueqing Bay, Xiangshan Bay, and Sanmen Bay in Eastern China were analysed. Total concentrations of PCBs ranged from 9.33 to 19.60 ng g⁻¹ dry weight for all the sampling stations. The observed PCB levels were lower than those in areas of high urbanisation or contamination in the bay. Low-chlorinated PCBs, dominated by tri-PCB, were identified as the prevalent contaminate of surface sediments, and the top three PCB congeners were lighter chlorinated congeners (PCB 8, PCB 18 and PCB 28). These results were in agreement with the fact that tri-PCB compounds are the dominant contaminants in China. The result of the principal component analysis revealed that all samples were similar in composition to Aroclor 1242, suggesting they might originate from electrical capacitors and transformers. The levels of PCBs were significantly correlated with the total organic carbon in the sediments.     

Iron-mediated reactions of polychlorinated biphenyls in electrochemical peroxidation process (ECP)

A study was conducted to explore some of the basic processes of polychlorinated biphenyl (PCB) destruction by a new technology termed electrochemical peroxidation process (ECP). ECP represents an enhancement of the classic Fenton reaction (H2O2 + Fe2+) in which iron is electrochemically generated by steel electrodes. Focus was on the extent of adsorption of a mixture of Aroclor 1248 on steel electrodes in comparison to iron filings. Commercially available zero-valent iron filings rapidly adsorbed PCBs from an aqueous solution of Aroclor 1248. Within 4 h, all the PCBs were adsorbed at 1%, 5%, and 10% Fe0 (w/v) concentrations. Little difference in adsorption was found between acidic (2.3) and unamended solutions (pH 5.5), even though significant differences in iron oxidation state and Fe2+ concentrations were measured in solution. PCB adsorption also occurs on steel electrodes regardless of the pH or electric current applied (AC or DC), suggesting the combination of oxidizing (free radical-mediated reactions) and reducing (dechlorination reactions) iron-mediated degradation pathways may be possible. Extraction of the iron powder after 48 h of contact time yielded the progressive recovery of biphenyl with increasing Fe mass(from 0.4% to 3.5%) and changes of the PCB congener-specific pattern as a consequence of dechlorination. A variety of daughter congeners similar to those accumulated during anaerobic microbial dechlorination of Aroclor 1248 in contaminated sediments indicate preferential removal of meta- and para-chlorines.     

Removal of PCBs from wastewater using fly ash

Liquids and sludges containing polychlorinated biphenyls (PCBs) can be treated to concentrate the PCBs in a solid residue. The latter can then be handled to destroy the PCBs. A study on sorption kinetics of PCBs on fly ash was conducted in controlled batch systems. TCB and HeCB are removed at 25 degrees C by adsorption on fly ash up to 97% at pH 7, with an adsorbent dose of 5 g/l. An examination of the thermodynamic parameters shows that the adsorption of TCB and HeCB by fly ash is a process occurring spontaneously at ambient conditions. Activation energies for the sorption process ranged between 5.6 and 49.1 kJ/mol. It was observed that the rate at which TCB and HeCB are adsorbed onto fly ash showed a diffusion limitation. The uptake rate of TCB and HeCB increases with increasing initial concentration and gradually tends to a constant value. A decrease in the adsorption of TCB and HeCB was observed when interfering ions and other PCB congeners were present. Changing the pH in the aqueous solution from 2 to 10 had no effect on the adsorption process. Overall, fly ash can be used for an efficient removal of PCBs from several aqueous solutions.     

Assessment of the daily intake of 62 polychlorinated biphenyls from dietary exposure in South Korea

The dietary intake of polychlorinated biphenyls (PCBs) was estimated using the sum of 62 PCB congeners (∑₆₂PCBs), including seven indicator PCBs and 12 dioxin-like PCBs, in the South Korea. In this study, 200 individual food samples belonging to 40 different foodstuffs were investigated to estimate the distribution of PCB congeners in five sampling cities. PCB exposure was estimated using Korean dietary habits as established by the National Health and Nutrition Examination Survey (NHANES). The PCB concentrations in rice, the most frequently consumed food in Korea, was relatively low in whole food samples. The mean PCB levels measured in fish were the highest in this study, but each fish is consumed in relatively small amounts by the general population. Therefore, the daily dietary intake should also be considered with regard to human exposure to PCBs, especially with the consumption of contaminated foods. Dioxin-like PCB levels were also calculated using TEF values that were established in 2005. The average levels (pg TEQ/g) were 0.0002 for rice and 0.0098 for fish. The dioxin-like PCBs accounted for a relatively small percentage of the total PCBs, compared to previous studies. According to our research, the health risks associated with exposure to PCBs could be estimated using the tolerable daily intake (TDI) of the general population.     

Distribution characteristics of PCBs in the sediments of the lower Nakdong River, Korea

The objective of this study is to investigate the distribution characteristics of polychlorinated biphenyl (PCB) congeners in sediments of the lower Nakdong River of Korea. The sediments were collected using a grab sampler in May 1999. PCBs were extracted in the Soxhlet extractor and cleaned by using adsorption chromatographic techniques and concentrated sulfuric acid. A HP6890 gas chromatograph equipped with an electron capture detector was used for quantification. The results of congener specific analysis showed that the total concentration is ranged over 1.1-141 ng/g dry weight. The levels of PCB congeners are significantly correlated with the total organic carbons (TOC) in the sediments. The major fractions of PCBs in these sediments are congeners containing 4, 5 or 6 chlorine atoms per biphenyl molecule.     

Atmospheric PCDD/F and PCB levels implicated by pine (Cedrus deodara) needles at Dalian, China

Dalian is a seaside city situated in the northeastern monsoon area of China. For the first time, levels of PCDD/F and PCB congeners in pine (Cedrus deodara) needles of Dalian urban areas were investigated. Two sampling campaigns with 17 sampling points were performed in 2002. The summation of tetra- to octachlorinated PCDD/Fs and summation of 209 PCB congeners in Dalian pine needles averaged 127+/-40 ng/kg (dry) and 4389+/-1575 ng/kg (dry), respectively. Average toxic equivalence (TEQ) for PCDD/Fs and PCBs are 2.1 and 0.4 ng/kg (dry), respectively. The pine needles can differentiate spatial variation of the pollutants. The PCDD/F and PCB levels in Dalian pine needles are low or comparable with other international regions that were not impacted by evident point sources. The data can serve as a base for long-term spatial and temporal studies of PCDD/Fs and PCBs in China.     

Polychlorinated biphenyls in different trophic levels from a shallow lake in Argentina

Polychlorinated biphenyls (PCBs) were determined in a aquatic community from Los Padres Lake, Argentina. Twenty four PCB congeners from tri- to octa-chlorinated isomers were detected and quantified using conventional gas chromatography with electron capture detector (GC-ECD). The aim of this study was to investigate the concentrations of PCBs in freshwater organisms from a shallow lake of Argentina. Stems of bulrush (Schoenoplectus californicus), whole tissues of false loosestrife (Ludwigia sp.) and grass shrimp (Palaemonetes argentinus), and liver, gonads, muscle and mesenteric fat (if present) of fish species (Rhamdia sapo) and (Oligosarcus jenynsi) were analyzed. Two areas were selected to macrophytes sampling: the input area, main PCB source of the lake (Station 1), and the output area, a potential anoxic zone (Station 2). Macrophytes from Station 1 bioconcentrated higher total PCB levels than Station 2, showing that the former have received PCBs washed down from upstream areas. Penta- and hexa-congeners were enriched relative to other congeners in animal biota and macrophytes from Station 1, consistent with commercial mixture of Aroclor 1254 used in this region. In bulrush from Station 2 a predominance of tri- and tetra-chlorinated congeners was observed. Grass shrimp showed the lowest PCB values among animal biota. PCB concentrations in fish tissues varied with the species and the gonadal development. Mesenteric fat, only present in post-spawning organisms of R. sapo, had the highest values of PCBs relative to other tissues. A clearance of total PCBs in ovaries of post-spawning females of R. sapo was observed, but not in testes. O. jenynsi/P. argentinus biomagnification factor (BMF) had a mean value of 18.7. Congeners 44, 52 and 151, showed the highest BMF values, being 64, 66 and 62, respectively. These values would be a consequence of the low depuration rate of 44 and 52 congeners with orthochlorine substitution conducted by O. jenynsi and the high depuration rate of congener 151, which lacks 4 4^′- chlorine substitution, carried out by grass shrimp. Although the most of congeners have been biomagnified, they did not clearly displayed a concomitantly increasing with log K_ow.     

Confirmation of polychlorinated biphenyl (PCB) distribution in the blood and verification of simple quantitative method for PCBs based on specific congeners

We measured the concentration of each polychlorinated biphenyl (PCB) congener in whole blood, plasma and blood cells, and investigated the distribution of PCBs in human blood using high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS). The PCB concentrations in plasma and whole blood in terms of lipid concentrations were almost equal, with a correlation coefficient of r = 0.972. In the blood, the ratio of PCBs in blood cells to those in plasma was generally about 1:9 and the congener distribution patterns in blood cells and plasma were similar.We performed verification of a simple mass screening method by obtaining information on the main PCB congeners for investigations on human accumulation and exposure. The total concentration of the seven PCB congeners (UNEP-7) proposed to the United Nations Environment Programme (UNEP) by Muir and Morita was about 50% of the total concentration of all PCB congeners, and UNEP-30 was about 80%. The seven main congeners in the blood (MCB-7) showed a value that was about 60%, and MCB-30 showed a value that was about 90%. Determinations with the main congeners in the blood showed a correlation of r = 0.990 or more between the main eight congeners (MCB-7 plus #74) and the total PCB concentration for all congeners. The results suggest that, although total PCB concentration can be effectively estimated from the main seven congeners, the main eight congeners would be preferable, and that the use of these congeners in the simple mass screening method would be effective for populations in areas uncontaminated by PCBs.     

Congener profiles of PCBs and PCDD/Fs in Yucheng victims fifteen years after exposure to toxic rice-bran oils and their implications for epidemiologic studies

In 1978-1979, a mass poisoning occurred in central Taiwan from rice-bran oil contaminated by heat-degraded PCBs was later called the Yucheng (oil disease in Chinese). Only a few studies have so far investigated the levels of specific polychlorinated biphenyl (PCB) or polychlorinated dibenzodioxin/furan (PCDD/F) congeners in the Yucheng victims. This study aimed to investigate the serum residual levels of thirty-three PCBs and seventeen 2,3,7,8-substituted PCDD/F congeners in the Yucheng victims 15 years after the exposure. Forty-one blood samples were collected from individual Yucheng victims in 1994-1995. The mean levels of total 33 PCBs and 17 PCDD/Fs were 2468 ng/g lipid (13.3 ng/g sample) and 6550 pg/g lipid (30.9 pg/g sample) respectively. The higher levels were found in PCBs #99, #138, #153, #156, #170, #179, and #180 among 33 PCB congeners, while 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, and OCDD had the higher concentrations among 17 PCDD/F congeners. The total TEQ was contributed in decreasing order by 10 PCDFs (44%), three non-ortho-PCBs (24%), six mono-ortho-PCBs (20%), and seven PCDDs (12%). The mean total PCB levels and TEQ value of the 17 PCDD/Fs in the Yucheng victims 15 years after the toxic exposure were still 9 and 46 times higher than those in the general population in Taiwan. Principle component analysis (PCA) indicated that seven PCB congeners, PCBs #99, #138, #153, #156, #170, #179, and #180, accounted for 73% of the total variances in PCBs. On the other hand, six PCDD/F congeners, 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF, 1,2,3,6,7,8-HxCDD, 1,2,3,4,6,7,8-HpCDF, and OCDD, accounted for 97% of the total variances in PCDD/Fs. In addition, PCA revealed that at least three characteristic patterns of congener profiles for PCBs were observed among the Yucheng victims. Similar trend was also observed for PCDD/Fs. These patterns may reflect distinctive exposure scenarios and/or different metabolizing capabilities among the Yucheng victims. We suggest that these patterns, in contrast to total PCB and PCDD/F levels, may be valuable for the future epidemiologic studies when linking exposure with specific health effect.     

PCB levels and congener patterns from Korean municipal waste incinerator stack emissions

Congener specific polychlorinated biphenyl (PCB) data from the stack gas of nine Korean municipal waste incinerators was used to determine characteristic congener patterns of emitted PCBs. Principal component analysis revealed three classes of incinerators according to their pattern of PCB congener emissions: those resembling the background sampling material; those producing large quantities of a few tetra-chlorinated congeners; those producing large proportions of mono (MO-) and non-ortho (NO-) congeners relative to di-ortho (DO-) levels. Also, correlations between individual PCB congeners and polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) were discovered for several NO-PCBs and tetra and penta chlorinated PCDFs. Full PCB congener data is presented along with operating conditions for each incinerator.     

Airborne PCB as a contamination risk on freeze-drying of sediment

In a study of polychlorinated biphenyls (PCB) in freeze-dried sediments from Swedish lakes, the samples were found to contain unexpectedly high concentrations of PCBs. In one of the lakes (Bj?rken), e.g. the concentration of PCB-28 was found to be 189 ng/g dw after freeze-drying compared to 7 ng/g dw after air-drying of the sediment and therefore our hypothesis was that the contamination had occurred during the freeze-drying procedure. Hence, a dry reference sediment (RS) was used in order to identify potential sources of PCB contamination. The investigation included freeze-drying of the dry RS in five different laboratories, exposure to the air in the freeze-drying room, storage at room temperature and air-drying in a certain fume hood and in a laminar flow clean bench. The pattern and concentrations of PCBs detected in the exposed RS were strongly influenced by low chlorinated PCB congeners under all of these conditions with exception for air-drying in the fume hood. Storage in the laboratory air resulted in a slight elevation in the concentrations of low chlorinated PCB congeners, whereas higher concentrations of all PCB congeners were observed after freeze-drying. In all experiments the contamination appeared to be due to adsorption of PCB from the laboratory air. On the basis of these findings we recommend that reference material be subjected to the entire procedure, including sample preparation, in order to monitor contamination and that a procedure involving solvent extraction of wet sediment samples is used, whenever possible, instead of procedures involving dry samples.     

Isotope dilution analysis of polychlorinated biphenyls (PCBs) in transformer oil and global commercial PCB formulations by high resolution gas chromatography-high resolution mass spectrometry

Special polychlorinated biphenyls (PCBs) standards (native and isotope labeled) were analyzed by isotope dilution method using HRGC-HRMS. Multiple analysis of special PCBs standards by three different laboratories produced the relative response factors (RRFs) and relative standard deviations (RSDs %) was in the average of 0.979 and 3.86, respectively. Additionally, inter-laboratory analysis of various forms of transformer oil revealed the PCBs concentrations were in the following order; PCBs fortified transformer oil (940-1300 ng/g)>PCB polluted transformer oil (490-680 ng/g)>chemically degraded-transformer oil (480-490 ng/g) and PCBs free oil (ND-17 ng/g). Chemical degradation resulted in an order of magnitude decrease in the PCB concentrations. Specifically, higher chlorinated PCBs degraded into lower chlorinated PCBs. Also, composition of PCBs have been determined in PCB formulations from Japan (Kanechlor), Germany (Clophen), USA (Aroclor), Russia (Sovol) and Poland (Chlorofen). Major PCBs (24-PCB congeners) contributed 54-67%, 55-68%, 16-69%, 71% and 72% in Kanechlor, Clophen, Aroclor, Sovol and Chlorofen, respectively to total PCBs. The homologue pattern of Kanechlor, Aroclor and Clophen in technical fromulation was similar (e.g., Kanechlor-300 resembled to those of Clophen A-30 and Aroclor-1242). Furthermore, congener-specific distributions of major PCBs/dioxin-like PCBs and toxic equivalency quantities (TEQ) were calculated. Based on our tentative assumption calculations, cumulative production of five different technical PCB formulations, WHO-TEQ emission was estimated to be approximately 16.05 tons.     

Congener-specific approach to human PCB concentrations by serum analysis

The objective of this study was to evaluate all congeners of polychlorinated biphenyls (PCBs) in human serum samples. Concentrations of all PCB congeners in the serum of 87 volunteers were determined by high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS). The participants consisted of 47 males and 40 females, including 25 men working at municipal solid waste incinerators (MSWIs). The mean concentrations of total PCBs and dioxin-like PCBs were 242.77ng/g lipid (median: 180.17ng/g lipid) and 18.57ng/g lipid (median: 15.34ng/g lipid), respectively. Penta-, hexa-, and heptachlorinated biphenyls contributed more than 80% of the total PCBs detected in human serum. Congener-specific analysis indicated that PCB153, PCB138, PCB180, PCB187, and PCB118 contributed 57.3% of the total PCBs detected in human serum samples. A statistical analysis was performed to determine whether there were significant correlations between PCB concentrations and specific variables such as age, gender, smoking habits, occupation, and body mass index (BMI). However, serum PCB concentrations correlated only with age. In addition, we found that total PCBs and dioxin-like PCBs highly correlated with PCB153 (correlation coefficient r=0.93, p<0.01) and PCB118 (correlation coefficient r=0.98, p<0.01), respectively. Thus these two congeners could be satisfactory indicators for total PCBs and dioxin-like PCBs in human serum.     

Background levels of non-ortho-substituted (coplanar) polychlorinated biphenyls in human serum of Missouri residents

This study characterizes the levels of polychlorinated biphenyls (PCB) congeners PCB 77, PCB 81, PCB 126, and PCB 169, in a group of 150 men and women with no documented exposure to PCBs. Its purpose is to provide current referent levels of coplanar PCBs in Missouri residents and to compare those levels to levels reported in the literature from the United States and other countries. Although this study used an extensive questionnaire assessing potential sources of exposure, no positive relations were found between these exposure sources and participants' PCB levels. The PCB levels for the four congeners measured were lower than any reported in the literature. PCBs 126 and 169 are only two of the dioxin-like congeners; however, their contribution makes up 11% of the total TEQ. Age was significantly related to PCB 126 and PCB 169. For every one-year increase in age, both PCB congeners increased by approximately 0.4 parts per trillion (ppt). There was no gender difference for PCB 126; however, PCB 169 levels were 3 ppt higher in males than females.     

Digestibility, retention and incorporation of low-level dietary PCB contents in laying hens

Polychlorinated biphenyls (PCBs) are persistent and hazardous environmental contaminants, which tend to bioaccumulate in the food chain. In the present report the long-term effect of low-level dietary PCB concentrations was studied on performance, egg quality, apparent PCB digestibility, apparent PCB retention and PCB accumulation in laying hens that were fed experimental diets for 41 weeks. The tested dietary concentrations of supplemented PCBs, based on the sum of seven reference congeners, were 0, 1.5 and 6 ng/g. PCB ingestion did not significantly affect performance or egg quality parameters. The PCB concentration in egg yolk reached a nearly constant level after approximately 40 and 70 days of consumption of the diets containing 1.5 and 6 ng PCBs/g, respectively. Apparent faecal PCB digestibility and apparent retention were not influenced by dietary levels of added fat varying between 1.5% and 4.5%, but were significantly higher in hens fed diets containing added PCBs. Moreover, apparent PCB digestibility and retention increased significantly with age. Among the seven individual PCB congeners, no systematically significant differences with regard to apparent faecal digestibility were observed throughout the experiment. Accumulation of PCBs in the fat fraction of egg yolk, abdominal adipose tissue and thigh and breast muscle greatly depended upon PCB intake, but never exceeded the maximally allowed concentration of 200 ng/g. As PCBs 52 and 101 were hardly found in egg yolks and hen tissues, it was concluded that both congeners were greatly metabolised. Comparison of relative contents of individual PCB congeners revealed that PCBs 118, 138 and 153 were preferentially incorporated in yolk and body tissues.