PCB Congeners Research Articles

Toxic chemicals and thyroid function: hard facts and lateral thinking.

Increasing quantities of evidence-based data incriminate a large number of environmental pollutants for toxic effects on the thyroid. Among the many chemical contaminants, halogenated organochlorines and pesticides variably affect the hypothalamic-pituitary-thyroid axis and disrupt thyroid function. PCBs and their metabolites and PBDEs bind to thyroid transport proteins, such as transthyretin, displace thyroxine, and disrupt thyroid function. Meanwhile, at the molecular level, PCB congeners may activate phosphorylation of Akt, p-Akt, and forkhead box O3a (FoxO3a) protein resulting in inhibition of the natrium/iodide symporter. Given therefore the growing concern developing around these multiple toxic chemicals today invading numerous environments and their long-term deleterious effects not only on the thyroid but also on general health, we strongly advocate their strict regulation and, moreover, their gradual reduction. A good degree of "lateral thinking", we feel, will lead to a use of chemicals that will enhance life while concurrently carefully protecting the environment.

PCB and PBDE levels in a highly threatened dolphin species from the Southeastern Brazilian coast

In the Northern coast of Rio de Janeiro State is located the major urban centers of the oil and gas industry of Brazil. The intense urbanization in recent decades caused an increase in human use of the coastal areas, which is constantly impacted by agricultural, industrial and wastewater discharges. Franciscana dolphin (Pontoporia blainvillei) is a small cetacean that inhabits coastal regions down to a 30 m depth. This species is considered the most threatened cetacean in the Western South Atlantic Ocean. This study investigated the levels of 52 PCB congeners and 9 PBDE congeners in liver of nine individuals found stranded or accidentally caught between 2011 and 2012 in the Northern coast of Rio de Janeiro. PCB mean levels ranged from 208 to 5543 ng g−1 lw and PBDEs mean concentrations varied between 13.84 and 36.94 ng g−1 lw. Contamination patterns suggest the previous use of Aroclor 1254, 1260 and penta-BDE mixtures in Brazil. While still few studies have assessed the organic contamination in cetaceans from the Southern Hemisphere, including Brazil, the levels found in this study could represent a health risk to these endangered species.

Organochlorine contaminant concentrations in multiple tissues of free-ranging Steller sea lions (Eumetopias jubatus) in Alaska

The relationships of selected organochlorine (OC) contaminants between blubber, blood, feces, and milk of young, free-ranging Steller sea lions (Eumetopias jubatus) were examined. Both between and within each tissue there was considerable individual variation. In spite of the variation, similar patterns were observed across the tissues for most of the selected PCB congeners. In all four tissues, the major PCB congeners were PCB101, PCB118, PCB138, and PCB153. The most prominent congener, both as a weight (ng/g lipid) and as a percentage of summed PCBs (∑PCBs), was PCB 153. Comparisons between paired tissues showed that ∑DDTs in blubber samples were related to concentrations in blood, feces, and milk. The ∑PCBs in blubber were related to concentrations in milk and fecal samples, though the relationship with feces was weak. Our findings show milk samples, in particular, are useful for assessing OCs in young sea lions. Blubber concentrations of PCB101, PCB118, and PCB138 were an order of magnitude higher than those in milk, supporting the biomagnification of these PCB congeners in SSL tissues. The findings indicate alternative tissues may be used as indicators of relative contaminant exposure in lieu of surgical blubber biopsy.

An assessment of PCB and PBDE contamination in two tropical dolphin species from the Southeastern Brazilian coast

PCBs and PBDEs were determined in two dolphin species, Sotalia guianensis and Steno bredanensis, from an upwelling system off the Central-northern coast of Rio de Janeiro, Brazil. PCB levels varied from 0.040 to 0.75μgg−1lw in muscles and from 0.022 to 1.32μgg−1lw in liver samples from S. guianensis. In S. bredanensis, values varied from 0.085 to 11.3μgg−1lw in muscles and from 0.024 to 18.6μgg−1lw in livers. PCB-138, -153 and -180 were the major PCB congeners detected in both species, while BDE-47 was the predominant PBDE congener found in both species. Higher concentrations in S. bredanensis were possibly related to the different feeding habits for both delphinid species. These results contribute to extend the database on organic contamination in cetaceans from the southern hemisphere, understanding their distribution and environmental fate in Southeastern Brazil.

Polychlorinated biphenyls in umbilical cord serum of newborns from Rio Grande do Sul state, Brazil

BackgroundPolychlorinated biphenyls (PCBs) are food-chain contaminants that have been shown to contaminate foods worldwide. The newborn are exposed to these organochlorine compounds across the placenta and through breastfeeding. They are proven to be carcinogenic and may contribute to congenital malformation etiology. MethodsThis study examined levels of five PCB congeners (28, 52, 138, 153 and 180) in umbilical cord serum samples from 148 newborns from Rio Grande do Sul state, Brazil. Serum concentrations of PCBs were analyzed by gas chromatography with electron capture detection and mass spectrometry. ResultsLevels of ∑PCBs ranged from 0.35 to 55.17ng/ml in umbilical cord serum positive samples, and PCB 138 was the most prevalent congener. Only 7.4% of samples presented no PCB congener. ConclusionsSome PCB congener cord serum levels were related to the locale of the mothers' residence, smoking and drinking habits, fruit consumption, and congenital malformation.

Intersex and alterations in reproductive development of a cichlid, Tilapia guineensis, from a municipal domestic water supply lake (Eleyele) in Southwestern Nigeria

The objectives of this study were to develop and validate biomarker techniques for aquatic environmental monitoring of endocrine disrupting chemicals (EDCs) in Nigeria aquatic ecosystems, using the Eleyele Lake, which is a major source of domestic water supply to Ibadan and its surrounding towns, as a model aquatic environment and Tilapia guineensis, as a model organism. A total of 55 male and 28 female fish were used for this study. No significant difference in condition factor was observed between the sexes. Evaluation of gross gonadal morphology of the sampled fish showed 33% intersex prevalence in the sampled population, of which respective 71 and 29% were males and females, with visible testis and ovary developing alongside phenotypic females and males. Plasma concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), 11-ketotestosterone (11-KT) and 17β-estradiol (E2) were performed, showing that male fish had significantly higher plasma LH and E2 concentrations, compared to females. Vitellogenin (Vtg) and zona radiata proteins (Zrp) mRNA levels were significantly higher in males, compared to female fish. Contaminant analysis revealed that PCB 81, 123, 138 and 196 were the only PCB congeners detected in sediment and fish muscle (PCB153 in sediment), while dieldrin was the only organochlorine compound (OC) detected in Eleyele sediment. These responses were used in a multivariate analysis, showing that two principal components were extracted and accounted for 74% of total variation in the dataset. The principal component analysis (PCA) showed that male fish variables were positively correlated with PCB congeners 18 and 123, while female fish showed positive correlations with congener 81, 138, 189, 196, indicating sex-specific pattern of association between PCBs concentrations and biomarker expression. In addition, strong positive correlation between male fish and LH, E2, FSH and Vtg was observed, while female fish positively correlated with 11-KT and GSI. These relationships suggest feminization and masculinization of male and female fish, respectively.

Effect of PCB 126 on aryl hydrocarbon receptor 1 (AHR1) and AHR1 nuclear translocator 1 (ARNT1) mRNA expression and CYP1 monooxygenase activity in chicken (Gallus domesticus) ovarian follicles.

The aim of the experiment was to study the in vitro effect of 3,3',4,4',5-pentachlorobiphenyl (PCB 126; a coplanar PCB congener) on aryl hydrocarbon receptor (AHR1) and AHR1 nuclear translocator (ARNT1) mRNA expression and the activity of CYP1 family monooxygenases in chicken ovarian follicles. White (1-4 mm) and yellowish (4-8 mm) prehierarchical follicles as well as fragments of the theca and granulosa layers of the 3 largest preovulatory follicles (F3-F1) were incubated in a medium supplemented with 0 (control group), 1, 10 or 100 nM PCB 126. The incubation was carried out for 6 h or 24 h for determination of mRNA expression of AHR1 and ARNT1 genes (real-time qPCR) and CYP1 monooxygenase activity (EROD and MROD fluorometric assays), respectively. It was found that chicken ovarian follicles express mRNA of AHR1 and ARNT1 genes. A modulatory effect of PCB 126 on AHR1 and ARNT1 expression depended not only on the biphenyl concentration but also on the follicular layer and the maturational state of the follicle. EROD and MROD activities appeared predominantly in the granulosa layer of the yellow preovulatory follicles. PCB 126 induced these activities in a dose-dependent manner in all ovarian follicles. The obtained results suggest that ovarian follicles, especially the granulosa layer, are involved in the detoxification process of PCBs in the laying hen. Taking this finding into consideration it can be suggested that the granulosa layer of the yellow hierarchical follicles plays a key role in the protective mechanism which reduces the amount of transferred dioxin-like compounds into the yolk of the oocyte.

Geographical distribution and time trends of polychlorinated biphenyls in raft mussel from Galician coast (1998–2013)

PCBs were analyzed in raft mussels cultured in several polygons from Galician Rías (Rías of Ares-Betanzos, Muros-Noia, Arousa, Pontevedra and Vigo) during the period 1998–2013. The main aim of this work is study the quality of culture marine environment in relation to PCBs compounds. We report the results of a monitoring. The mean levels of ΣPCBs (ten congeners) ranged from 7.41 to 59.50ngg−1dw. The isomer concentrations in the Mytilus galloprovincialis cultured in raft were in the order hexachlorobiphenyls>pentachlorobiphenyls>tetrachlorbiphenyls>trichlorobiphenyls. Some biological parameters of mussel were also investigated (shell length, lipid content and condition index) in order to know their influence on ability of PCBs accumulation. ANOVA analysis confirms that levels of most of congeners had a significant relation (p<0.05) with shell length. The geographical patterns and temporal variations of PCBs were also investigated. Principal Component Analysis (PCA) showed differences between geographic areas (Rías) in the distribution of PCBs levels. Samples coming from Rías of Vigo and Ares-Betanzos presented the highest levels of PCBs and samples from Rías of Arousa and Muros-Noia had the lowest levels of these compounds. Time trends (linear regressions) showed a decline of levels of PCB congeners along the period 1998–2013.

The spatial distribution of human exposure to PCBs around a former production site in Slovakia.

We evaluated concentrations of 15 PCB congeners in blood serum of 2047 adults, 431 8-9-year old children and 1134 mother-child pairs born in 2001-2003. These subjects were long-standing residents living up to 70 km (to the north) and up to 50 km (to the south) of the former Chemko Strážske PCB production facility in the Michalovce district of Slovakia. We plotted serum concentration against distance from the plant both with and without consideration of the direction of their homes from the site. The decrease in exposure with distance could be described by an exponential function which was dependent on direction and climatic parameters. By kriging we created maps depicting predicted isoconcentration contours for sex- and age-adjusted serum concentration of ∑PCBs for the same group of children, adults and mothers. The principle of our risk analysis was to relate serum concentration data, reflecting PCB body burden, using the critical concentrations established by the French Agency for Food, Environmental and Occupational Health & Safety (ANSES 2010) as thresholds below which the probability of effects on health is regarded as negligible. We conclude that 10 years ago, around 200,000 residents were at risk in this densely populated area. Exposure has since decreased but the mechanism for this has not yet been studied.

Reprint of: Long-range atmospheric transport of PAHs, PCBs and PBDEs to the central and eastern Mediterranean and changes of PCB and PBDE congener patterns in summer 2010

The central and eastern Mediterranean is a receptor area for persistent organic pollutants (POPs) emitted in western, central and eastern Europe, particularly during summer. Atmospheric concentrations of PCBs, DDXs, PBDEs, penta- and hexachlorobenzene were measured during a ship-borne survey in the summer of 2010. The concentration of PCBs (sum of 7 congeners) was 3.61 (2.08–7.72) pg m−3, of which 6.7% was associated with the particulate phase. The mean concentration of DDT isomers and their metabolites, DDE and DDD, was 2.60 (0.46–7.60) pg m−3 (particulate mass fraction θ = 0.097), of penta- and hexachlorobenzene 0.22 (<0.39–2.80) pg m−3 and 6.29 (2.48–24.16) pg m−3, respectively, and of PBDEs (sum of 8 congeners) 7.31 (2.80–19.89) pg m−3. The air masses studied had been transported mostly across central Europe, some crossing western Europe. The observed changes of PCB congener patterns along transport routes are in agreement with the perception that the reaction with the OH radical is dominating PCB atmospheric lifetime, and indicate an overestimation of the second order gas-phase reaction rate coefficient of PCB153 with OH by structure-activity relationship.

Impact of soil characteristics on relative bioavailability of NDL-PCBs in piglets

Children may be orally exposed to organic pollutants through involuntary soil ingestion. This study was aimed at determining the impact of the characteristics (organic carbon (OC), black carbon (BC), clay contents and pH) of ten contaminated soils on the bioavailability of non-dioxin-like polychlorobiphenyls (NDL-PCBs). Five juvenile male piglets were exposed to increasing amounts of each of the soils. These soil-fed groups were compared by a relative bioavailability approach (RBA) to a reference group fed with corn oil spiked with increasing doses of Aroclor 1254. After 10days of oral exposure, the animals were sacrificed and NDL-PCB concentrations were determined by GC–MS in the adipose tissue. The relative bioavailability (RBA) factors were calculated for PCB 101, 138, 153 and 180. Despite high variations in the amount of black carbon (0.50gkg−1–6.0gkg−1d.w.) and organic matter (12gkg−1–180gkg−1d.w.), only 3 soils exhibited a significantly lower RBA for all NDL-PCBs, compared to the oil-group. High levels of OC (>100gkg−1) and BC content (3.0gkg−1) were related to a significant reduction in RBA. Overall, RBA was higher than 45% independently of the soil and the PCB congener.

Analysis of 19 PCB congeners in catfish tissue using a modified QuEChERS method with GC–MS/MS

A simple approach to determine 19 PCB congeners in catfish tissue was presented. A modified QuEChERS method employing high solvent to sample ratio 10:1 was used to improve the extraction recovery of 19 PCB congeners. After salting out by shaking with anhydrous magnesium sulfate and sodium chloride, 1mL of acetonitrile extract was pipetted into a 2-mL centrifuge tube containing anhydrous magnesium sulfate, primary secondary amine sorbent, and C-18 sorbent. The tube was then shaken and centrifuged to absorb fat and fatty acid residue present in the acetonitrile extract. The acetonitrile extract was analyzed by GC–MS/MS. The excellent sensitivity of GC–MS/MS allows for the direct injection of the samples to detect the low level of the PCB congeners. The method therefore is high throughput, uses fewer consumable lab supplies, and provides excellent sensitivity with an LOQ below 1ng/g.

Longitudinal estimates of sediment-water diffusive flux of PCB congeners in the Houston Ship Channel

Sediment-water diffusive exchange fluxes were estimated for PCB congeners between 2002 and 2012 for the Houston Ship Channel in Texas. These estimations were determined for four different sampling periods representing a unique effort to quantify fluxes, their magnitudes and variability, over a longer time period than similar studies. Total PCB fluxes, on the order of 0.10–250 μg/m2-yr, were most dependent on bulk sediment and total water concentrations and the partitioning models used. Diffusive flux directions were highly variable on a single-PCB analyte basis though they were generally sediment-to-water or indeterminate. Sediment concentrations from after Hurricane Ike (September 2008) were highly elevated (median increase 360%) from immediately before the event leading to much higher diffusive flux estimates. Lastly, sediment-water diffusive flux was 2–3 orders of magnitude less than net deposition and associated desorption fluxes leading to the possibility that burial would eventually lower the sediment impact to the estuary. This is, however, uncertain because depositing sediment still had elevated PCB concentrations.

Human Serum from Urban and Rural Adolescents and Their Mothers Shows Exposure to Polychlorinated Biphenyls Not Found in Commercial Mixtures.

Although polychlorinated biphenyls are no longer sold as commercial mixtures, they are still being produced through modern manufacturing processes. We have previously shown that non-Aroclor PCB 11 is prevalent in indoor and outdoor air and sediment and detected in human serum. Here we report the prevalence of non-Aroclor PCB congeners (≤0.20 wt % in Aroclor) in human serum collected from urban and rural adolescents and their mothers. We hypothesized that additional non-Aroclor congeners are present in serum. Sera were extracted and detected for 209 PCBs using gas chromatography-tandem mass spectrometry. A list of 70 non-Aroclor PCB congeners was determined by measurement of original Aroclors. PCB 11, 14, 35, and 209 are the major dominating and most frequently detected congeners. PCB 14 and 35 have not been previously reported for environmental matrices. Adolescents have significantly lower total non-Aroclor PCB concentrations than mothers in East Chicago (p < 0.001) and Columbus Junction (p = 0.008). There are significant differences in non-Aroclor PCBs between East Chicago community and Columbus Junction community (p < 0.001). Non-Aroclor PCBs represent an average of 10% (and up to 50%) of total PCBs measured in serum. An average of 50% (and up to 100%) of these concentrations may be attributed to aryl azo and phthalocyanine paint pigments.

Capping in situ with activated carbon in Trondheim harbor (Norway) reduces bioaccumulation of PCBs and PAHs in marine sediment fauna

Three types of thin-layer caps with activated carbon (AC) were tested in situ in experimental plots (10 × 10 m) in Trondheim harbor, Norway, using AC + clay, AC-only or AC + sand. One year after capping, intact sediment cores were collected from the amended plots for ex situ surveys of the capping efficiency in reducing the PAH and PCB aqueous concentrations and bioaccumulation by the polychaete Hediste diversicolor and the clam Abra nitida. Reduced pore water concentrations were observed in all AC treatments. The capping efficiency was in general AC + clay > AC-only > AC + sand. AC + clay reduced bioaccumulation of PAH and PCB congeners between 40% and 87% in the worms and between 67% and 97% in the clams. Sediment capped with AC-only also led to reduced bioaccumulation of PCBs, while AC + sand showed no reduction in bioaccumulation. Thus the best thin-layer capping method in this study was AC mixed with clay.

Residual Distribution and Risk Assessment of Polychlorinated Biphenyls in Surface Sediments of the Pearl River Delta, South China.

We analyzed residual PCBs in surface sediments at 19 sites in the Pearl River Delta in the wet and dry seasons. Seven indicative PCB congeners (PCB28, PCB52, PCB101, PCB118, PCB153, PCB138 and PCB180) were detected in the surface sediments, among which the detection rate and mass concentrations of PCB52 were the highest. Total concentrations of the seven PCBs ranged from 19.8 to 111 μg/kg, with an average of 48.2 μg/kg. For the spatial distribution, the sum of the seven PCB (∑PCB) concentrations for the stations that were located in the city region of the Pearl River Delta were significantly higher than the ∑PCB concentrations for the eight outlets of the Pearl River Delta (p < 0.05). According to the US National Oceanic and Atmospheric Administration ERL and ERM guideline concentrations, the PCB concentrations may occasionally lead to adverse effects, especially in the dry season.

Tetrachlorobiphenyl removal from sludge matrix using mixed crystal Ti0.97Fe0.02Ni0.01O2 thin film

In this study, 2,2′,5,5′-tetrachlorobiphenyl removal from activated sludge matrix using thin film (TF)-based photocatalytic (PCT–TF+UVC+H2O2) and UVC+H2O2 (photolytic) treatment systems were investigated for three different initial sludge pHi values of 3.0±0.1; 7.3±0.1 and 10.0±0.1. A novel, visible light active Ti:Fe:Ni nano composite TF was successfully synthesized and used as catalyst. The fabricated TF was characterized by SEM, TEM, XRD, XPS and UV–vis spectroscopy methods. Experimental results indicated that while raw industrial sludge contains only 2,2′,5,5′'-tetrachlorobiphenyl, treated sludge samples contained more chlorinated PCB congeners in descending chlorination order from 2,2′,3,3′,4,4′,5,5′,6,6′ decachlorobiphenyl to 2,3′,4,4′,5 pentachlorobiphenyl. Experimental results also indicated that 2,2′,5,5′-tetrachlorobiphenyl was removed from the sludge matrix by only TF-based PCT that was carried out at neutral pHi. In addition, UVC+H2O2 system caused significant PCB formation at all studied pH levels. PCB generation/degradation reactions followed pseudo-first order reaction kinetics. Obtained results also proposed that UV irradiation can induce CCl bond cleavage in chlorinated compounds yielding Cl radicals, responsible for further chlorination. The kobs value observed in 2,2′,5,5′-tetrachlorobiphenyl degradation by TF-based PCT at pHi=7.3±0.1 was 0.0169±10−3min−1 and 1.5 times higher than at pHi=3.0±0.1. The observed kobs values in TF based PCT for PCB generation at pHi=3.0±0.1 and pHi=10.0±0.1 were 0.0037±10−3 and 0.0015±10−3 min−1, respectively.

Exposure to 27 polychlorinated biphenyls in the indoor environment of a workplace: a controlled bio-monitoring study.

To assess the exposure to a broad-spectrum of polychlorinated biphenyl congeners (PCBs) from the indoor environment through bio-monitoring of people working in a building with PCB-containing materials and elevated PCB levels in the indoor air. A cross-sectional study comparing the plasma concentration of 27 PCB congeners in 15 people working in a PCB-contaminated building and 30 matched controls. Median concentration of eight low-chlorinated PCB congeners was significantly higher in the exposed than in the control group. The sum of median concentrations of tri + tetra-chlorinated PCB was almost ten times higher in the exposed group than in the unexposed, and sums of dioxin-like and non-dioxin-like PCB were both relatively increased by 60 % in the exposed group. The occupational indoor environment may significantly add to PCB exposure, especially to the lower-chlorinated congeners. Health effect from this little-acknowledged exposure has not yet been documented, but data supporting lack of effect are sparse and research generating information on effect of exposure to specific congeners including at levels relevant for the indoor environment should be encouraged.

Long-range atmospheric transport of PAHs, PCBs and PBDEs to the central and eastern Mediterranean and changes of PCB and PBDE congener patterns in summer 2010

The central and eastern Mediterranean is a receptor area for persistent organic pollutants (POPs) emitted in western, central and eastern Europe, particularly during summer. Atmospheric concentrations of PCBs, DDXs, PBDEs, penta- and hexachlorobenzene were measured during a ship-borne survey in the summer of 2010. The concentration of PCBs (sum of 7 congeners) was 3.61 (2.08–7.72) pg m−3, of which 6.7% was associated with the particulate phase. The mean concentration of DDT isomers and their metabolites, DDE and DDD, was 2.60 (0.46–7.60) pg m−3 (particulate mass fraction θ = 0.097), of penta- and hexachlorobenzene 0.22 (<0.39–2.80) pg m−3 and 6.29 (2.48–24.16) pg m−3, respectively, and of PBDEs (sum of 8 congeners) 7.31 (2.80–19.89) pg m−3. The air masses studied had been transported mostly across central Europe, some crossing western Europe. The observed changes of PCB congener patterns along transport routes are in agreement with the perception that the reaction with the OH radical is dominating PCB atmospheric lifetime, and indicate an overestimation of the second order gas-phase reaction rate coefficient of PCB153 with OH by structure-activity relationship.

Degradation of 2,4 dichlorobiphenyl via meta-cleavage pathway by Pseudomonas spp. consortium.

Two bacterial isolates (Pseudomonas sp. GSa and Pseudomonas sp. GSb) were in close association able to assimilate 2,4 dichlorobiphenyl (2,4 CB), a PCB congener. GC-MS analysis of spent culture medium of the consortium with 2,4 CB as substrate showed 90 % degradation (according to Electron capture detection values) with catechol as one of the important intermediate compounds through meta-cleavage pathway. Further, ability of the consortium to utilise PCB congeners, Methoxychlor, Aroclor 1016, Chlorobenzoic acids and Monoaromatic compounds indicated that the consortium of GSa and GSb would be an ideal candidate for in situ bioremediation of PCB.