Coplanar Polychlorinated Biphenyls Research Articles

Referent Concentrations of PCDD/Fs and Dioxin-Like PCBs in Sera of Persons in the U.S. Based on the New Who 2006 TEFs and 2001–2002 NHANES Data

Reference values for PCDD/Fs and dioxin-like PCBs in serum were recently published based on the WHO 1998 TEFs and NHANES data. In 2006, the World Health Organization (WHO) revised toxic equivalency factors (TEFs) for a number of congeners. In accordance with these changes, we calculated new reference statistics using the WHO 2006 TEFs. Additionally, the contribution of individual congeners to the total TCDD TEQ and the effect that the revised TEFs had on total TEQ serum concentrations for the general U.S. population were also determined. All 2,3,7,8-substituted PCDD/F and nine dioxin-like PCB serum concentration data examined in this study are from the 2001–2002 NHANES survey. Total TCDD TEQ for each individual volunteer was calculated by summing the product of each congener's concentration and the associated 2006 WHO TEF. Calculation of reference values and all statistical analyses were conducted using SAS and SUDAAN software. 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 1,2,3,6,7,8-HxCDD, 2,3,4,7,8-PeCDF, and PCB 126 still contributed the greatest percentage to the total TEQ. However, both PCBs 156 and 157 were no longer significant contributors, instead being displaced by 1,2,3,4,7,8-HxCDF and PCB 169. Using the new TEF scheme, TEQ 17–9 was approximately equal to TEQ 17–3 . Average total TEQ estimates were 5–12 ppt lower than average estimates calculated using the WHO 1998 TEFs, and 95 th percentile estimates were reduced by 5 to 25 ppt with the largest reductions in total TEQ for older individuals. The updated TEFs had little impact on the percent contribution of the dioxin, furan, and co-planar PCB congeners to the total TEQ. However, the decrease in TEFs for the mono- ortho substituted PCBs decreased their contribution to total TEQ appreciably as well as reduced estimates of total TEQ body burden.

Formation of PCDDs, PCDFs, and Coplanar PCBs from Plastic Containing Curtains during Combustion in an Incinerator

Formation of PCDDs, PCDFs, and Coplanar PCBs from Plastic Containing Curtains during Combustion in an Incinerator

Levels and congener distributions of PCDDs, PCDFs and dioxin-like PCBs in environmental and human samples: a review

The term “dioxins” is often used in a confusing way. In toxicological considerations—and also in the present report—the term is used to designate the PCDDs, the PCDFs and the coplanar (“dioxin-like”) PCBs, since these classes of compounds show the same type of toxicity. Because of the large number of congeners, relevant individual congeners are assigned with a toxic equivalency factor (TEF) that relate their toxicity to that of tetrachlorodibenzo-p-dioxin (TCDD) (2,3,7,8-TCDD) and are to be evaluated as dioxins. Each concentration of an individual congener in a mixture is multiplied with its TEF, and the resulting TCDD equivalents are added up and expressed as WHO-endorsed toxic equivalents (WHO-TEQ). Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are mainly the by-products of industrial processes (such as metallurgical processing, bleaching of paper pulp, and the manufacturing of some herbicides and pesticides) but they can also result from natural processes like volcanic eruptions and forest fires. Waste incineration, particularly if combustion is incomplete, is among the largest contributors to the release of PCDDs and PCDFs into the environment. Due to their persistence, PCDDs, PCDFs and PCBs are part of the so-called persistent organic pollutants group of compounds that also include some chlorinated pesticides. Since they have a high lipophilicity and resist transformation, they bio-accumulate in animal and human adipose tissues. Consumption of food is considered as the major source of non-occupational human exposure to PCDD/Fs with foodstuffs from animal origin accounting for more than 90% of the human body burden. With meat, dairy, and fish products being the main contributors. The aim of the present review was to summarize experimental data regarding dioxin emissions from contaminated and uncontaminated biological and environmental samples, from the available literature. The information will be presented chronologically with respect to distribution in human milk, serum; food, water, air, soils and sediments.

コプラナ-PCBsの妊娠ラット曝露による影響：新生子ラットの血漿低分子領域タンパク質の変動

コプラナ-PCBsの妊娠ラット曝露による影響：新生子ラットの血漿低分子領域タンパク質の変動

Non-coplanar PCBs Induce Calcium Mobilization in Bottlenose Dolphin and Beluga Whale, but not in Mouse Leukocytes

Polychlorinated biphenyls (PCBs) have been demonstrated to modulate marine mammal immune functions; however, the underlying mechanisms involved are poorly understood. Cytosolic calcium (Ca2+) is an important second messenger involved in numerous leukocyte functions. The direct effects of in vitro exposure to PCBs on Ca2+ mobilization were evaluated in leukocytes isolated from bottlenose dolphins, beluga whales, and B6C3F1 mice. Concentration- and time-response experiments with three non-coplanar PCBs (138, 153, 180), one coplanar PCB (169), and TCDD were tested. Exposure to the three non-coplanar PCBs significantly increased cytosolic Ca2+ in dolphin neutrophils, while PCB 180 significantly increased cytosolic Ca2+ in beluga neutrophils. Two non-coplanar PCBs (138 and 153) significantly increased Ca2+ in beluga monocytes, yet the response was delayed compared to that in neutrophils. Neither PCBs nor TCDD increased cytosolic Ca2+ in mouse neutrophils or monocytes. In experiments with Ca2+-free medium, only PCB 153 increased cytosolic Ca2+ in dolphin neutrophils, though the increase was less than that observed with Ca2+-supplemented medium, suggesting that extracellular Ca2+ was the predominant source for the rise in cytosolic Ca2+. Furthermore, in cells incubated with Ca2+-free medium, a significant increase in cytosolic Ca2+ was induced by thapsigargin following PCB exposure, indicating that intracellular Ca2+ was available, yet not mobilized by the PCBs, and further suggesting that PCBs mobilize extracellular Ca2+. These results demonstrate for the first time the direct effects of non-coplanar PCBs on Ca2+ mobilization in marine mammals, which may be involved in the modulation of phagocytosis previously observed in these species.

Differential inhibition of hepatic microsomal alkoxyresorufin O-dealkylation activities by tetrachlorobiphenyls

Polychlorinated biphenyls (PCBs) elicit a spectrum of biochemical and toxic effects in exposed animals. In the present study, we assessed the effect of PCB structure, using four symmetrically-substituted PCBs, on cytochrome P450 (CYP)-mediated methoxy-, ethoxy- and benzyloxyresorufin O-dealkylase (MROD, EROD and BROD, respectively) activities. We found that 2,2′,4,4′-tetrachlorobiphenyl (PCB 47), 2,2′,5,5′-tetrachlorobiphenyl (PCB 52), 2,2′,6,6′-tetrachlorobiphenyl (PCB 54) and 3,3′,4,4′-tetrachlorobiphenyl (PCB 77) inhibited alkoxyresorufin O-dealkylase activities in hepatic microsomes from 3-methylcholanthrene (MC) or phenobarbital (PB)-treated rats. Measurement of the in vitro inhibitory potencies of the tetrachlorobiphenyls revealed that MROD, EROD and BROD activities were differentially inhibited and the degree of inhibition was determined by the chlorination pattern of the PCB. PCB 77 was more potent than PCB 47 or PCB 52 at inhibiting MROD and EROD activities in hepatic microsomes from MC-treated rats, while no inhibition of either activity was observed with PCB 54. In contrast, BROD activity measured in hepatic microsomes from PB-treated rats was inhibited by PCB 47, PCB 52 and PCB 54 but not by PCB 77. The mode of inhibition for each activity was also evaluated statistically. Inhibition of the alkoxyresorufin O-dealkylase activities could not be discerned in hepatic microsomes from corn oil-treated rats because the activities were inherently too low. No evidence for mechanism-based inhibition of MROD, EROD or BROD activities or an effect via CYP reductase was found. The results demonstrate that relatively coplanar PCBs such as PCB 77 preferentially inhibit EROD and MROD activities, whereas noncoplanar PCBs such as PCB 54 preferentially inhibit BROD activity.

Human Exposure to Dioxin-Like Compounds in Fish and Shellfish Consumed in South Korea

Dietary intake is the most important source of exposure to dioxins for the general population. This pathway contributes more than 90% of the daily intake for the general population of Korea. The objective of this study was to assess current exposure to dioxin-like compounds in fish and shellfish consumed by the general population in Korea. Residues of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), and dioxin-like, non-, and mono-substituted polychlorinated biphenyls (co-planar PCBs) were quantified in 32 fish and shellfish collected from domestic fisheries markets. The contributions of individual DL-PCB congeners to the total 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents (TEQ) were greater than 50%. Concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents based on the TCDD equivalency factors (TEFs) developed by the World Health Organization (TEQWHO) were compared to guidelines suggested for the protection of human health by the World Health Organization (WHO). The greatest TEQ concentration was observed in herring, followed by that in dried anchovy and Sailfin sandfish. The exposure to dioxin-like compounds from current fish consumption patterns was estimated to be 72 pg TEQWHO/day, which is equal to 1.2 pg TEQWHO/kg, bw/d, a value that is less than the current tolerable daily intake (TDI) guideline in Korea, which is 4 pg TEQWHO/kg, bw/d. The relatively great exposure was determined to be due to greater fish consumption rate in Korea, rather than greater concentrations of residues in food.

Sentinel health department project in Baden-Wuerttemberg (Germany) – a useful tool for monitoring children's health and environment

In the Federal State of Baden-Wuerttemberg, Germany, an environmental health surveillance system has been established focusing on children aged 10 years. Four study regions (two larger cities, one small city, and one rural area) were designated in order to get information about the body burden of persistent chemicals (toxic metals and chlorinated compounds) in children and about lung function, frequency of respiratory diseases, and allergies. From 1992/1993 to 2002/2003, seven cross-sectional investigations were carried out, and more than 10,000 children took part in the study. DDE, HCB, PCB-138, PCB-153 and PCB-180 were measured in individual blood samples of about 400 children per year, whereas PCDD/PCDF and coplanar PCBs were determined in pooled blood samples. From 1993 to 2003, blood concentrations of these compounds decreased 2 to 4-fold. Concerning regional differences, slightly lower concentrations of DDE, PCBs and PCDD/PCDF could be seen in children from the municipal population of Mannheim compared to other regions. Breast feeding was associated with considerably higher concentrations of PCBs and most other chlorinated compounds. Static and dynamic lung function parameters showed no differences between the investigated areas. For prevalences of respiratory diseases and allergies, no time trend was observed except for pertussis, which showed a decrease in 2002/2003 probably due to an increase of vaccination rates. In addition, the prevalence of atopic sensitization against aero allergenes remained unchanged at about 35% during the observation period. In conclusion, this environmental health survey delivers objective data about spatial and temporal trends and provides information about possible sources of children's exposure to toxic compounds in the environment. Adaptations of the survey to new problems are discussed.

Simultaneous extraction of polychlorinated dibenzo- p-dioxins, polychlorinated dibenzofurans and coplanar polychlorinated biphenyls from contaminated soil using pressurized liquid extraction

Pressurized liquid extraction (PLE) was studied for simultaneous extractions of polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/PCDFs), and of coplanar polychlorinated biphenyls (Co-PCBs) from a tightly bounded condition in the soil matrix. Temperatures were maintained at 175 and 200 °C, respectively, and two or three static cycles for single PLE with toluene and acetone/ n-hexane were studied using a certified reference material to compare the effects of those conditions on recoveries. A single PLE with two static cycles at 150 °C and the repeated single PLE (additional PLE) were reference methods. Satisfactory recoveries were not obtained using tested single PLE (2,3,7,8-substituted PCDD/PCDFs and Co-PCBs average, average (avg.) 79–103%), but they were achieved using additional PLE (acetone/ n-hexane, avg. 115–128%; toluene, avg. 111–132%). In addition, these methods and additional PLE of the reference method using acetone/ n-hexane were not markedly different (avg. 123–128%). That fact suggests that the use of mixed solvents and additional PLE were more important factors than temperatures and static cycles of single PLE for quantitative and simultaneous extractions of those compounds from the soil.

Impact of Iron and Steel Industry and Waste Incinerators on Human Exposure to Dioxins, PCBs, and Heavy Metals: Results of a Cross-Sectional Study in Belgium

We evaluated the impact of two iron and steel plants and two municipal solid waste incinerators (MSWI) in Wallonia (Belgium) on the exposure of residents to dioxins, polychlorinated biphenyls (PCBs), and heavy metals. In total, 142 volunteers living around these facilities were recruited and compared with 63 referents from a rural area with no industrial source of pollution. Information about smoking habits, dietary habits, anthropometric characteristics, residential history, and health status was obtained from a self-administered questionnaire. The volunteers provided blood under fasting conditions in order to evaluate the body burden of dioxins (17 polychlorinated dibenzo-p-dioxins/dibenzofurans [PCDD/Fs] congeners) and PCBs. Samples of blood and urine were also taken for the determination of cadmium, mercury, and lead. After adjustment for covariates, concentrations of cadmium, mercury, and lead in urine or blood were not increased in subjects living in the vicinity of MSWIs or sinter plants by comparison with referents. Residents around the sinter plants and the MSWI located in the industrial area had concentrations of dioxins and PCBs in serum similar to that of referents. By contrast, subjects living in the vicinity of the MSWI in the rural area showed significantly higher serum levels of dioxins (geometric mean, 38 vs. 24 pg TEQ/g fat) and coplanar PCBs (geometric mean, 10.8 vs. 7.0 pg TEQ/g fat). Although age-adjusted dioxin levels in referents did not vary with local animal fat consumption, concentrations of dioxins in subjects living around the incinerators correlated positively with their intake of local animal fat, with almost a doubling in subjects with the highest fat intake. These results indicate that dioxins and coplanar PCBs emitted by MSWIs can indeed accumulate in the body of residents who regularly consume animal products of local origin.

Congener profiles of PCB and a proposed new set of indicator congeners

In this study, a new method for calculating total PCB and toxic equivalents (TEQ) of coplanar PCB (Co-PCB) was proposed, called the 'PCB dual method'. This method analysed various kinds of technical PCB, samples contaminated by technical PCB and byproduct PCB. In the PCB dual method, a data set of 15 indicator congeners was utilized for the calculations, having IUPAC nos. #3, #8, #28, #52, #77, #101, #105, #118, #126, #138, #153, #180, #194, #206 and #209. The 15 congener set was chosen from the major congeners, determined by HRGC/HRMS analysis, in 18 technical PCB, Kanechlor, Aroclor, Clophen and Chlorofen, and 20 other samples, such as indoor air, flue gases, emission gases, municipal solid waste (MSW), ash and sealant. To obtain total PCB and TEQ of Co-PCB, the intermediate sum for the concentration of the 15 congeners was multiplied by each multiplication factor. As a result, we obtained the average factor used to calculate total PCB in technical PCB and other samples. For technical PCB, the factor was 3.01, while for indoor air samples, flue and emission gases, MSW, ash and sealants, the factors were 3.92, 4.16, 3.68, 4.52 and 4.77, respectively. Moreover, the factor used to calculate the TEQ of Co-PCB in Kanechlor and other source samples were also obtained. The factors for Kanechlor, indoor air samples and emission gases from a cement plant were in the order of 10(-5), while the factor for flue gases in a MSW incinerator was in the order of 10(-3). These data were valuable for the rough estimation of the TEQ of Co-PCB without separation from other PCB before individual measurements.

Health risk assessment for polychlorinated biphenyls, polychlorinated dibenzo- p-dioxins and dibenzofurans, and polychlorinated naphthalenes in seafood from Guangzhou and Zhoushan, China

This study determined the concentrations of organochlorine contaminants in common seafood in two Chinese coastal cities (Guangzhou and Zhoushan), and assessed the health risk due to the daily consumption of contaminated seafood. Twenty-six pooled samples, belonging to five food categories (fish, bivalves, shrimp, crab, and cephalopods), were purchased from local markets in Guangzhou and Zhoushan in 2003 and 2004. These samples were analyzed for total polychlorinated biphenyls (PCBs), non- and mono- ortho-PCBs (coplanar PCBs), polychlorinated naphthalenes (PCNs), and polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDDs/DFs). The concentrations of total PCBs and coplanar PCBs in fish samples were higher in Guangzhou than in Zhoushan, while the levels of PCNs and PCDDs/DFs were comparable between the two cities. The total daily intake values of dioxin-like compounds were 1.05 and 0.86 pg WHO-TEQ/kg body weight in Guangzhou and Zhoushan, respectively. Hazard ratios of non-cancer risk in the two cities were all less than unity.

Exoenzymes of Trametes versicolor can metabolize coplanar PCB congeners and hydroxy PCB

Two fractions containing the oxidase activity toward 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) were obtained using ion-exchange DEAE-Sepharose column chromatography of the culture fluid of white-rot fungus, Trametes versicolor. These two fractions can reduce the level of coplanar PCB congeners (Co-PCBs). The ABTS oxidase in the first fraction passed through the DEAE-Sepharose column. The ABTS oxidase in the second fraction was adsorbed to the column at <pH 5.6. Overall, the first fraction has a higher activity to reduce each level of Co-PCBs than the second fraction does. In equally chlorinated congeners, non-ortho congeners were less metabolized than ortho congeners; a 4-hydroxy-pentachlorobiphenyl (hydroxy PeCB) was more susceptible to metabolism than a structurally related non-hydroxy PeCB or HxCB.

Polychlorinated biphenyls and other chlorinated organic contaminants in the tissues of Mediterranean loggerhead turtle Caretta caretta

Polychlorinated biphenyls including coplanar congeners and DDT compounds were measured in different organs and tissues (liver, kidney, lung and muscle tissue) of loggerhead turtles Caretta caretta from the eastern Mediterranean Sea. The highest levels of these compounds were found in liver (PCBs: 52.32 ng/g; DDTs: 18.27 ng/g), followed by kidney (PCBs: 19.05 ng/g; DDTs: 5.70 ng/g), lung (PCBs: 12.75 ng/g; DDTs: 3.76 ng/g ) and muscle tissue (PCBs: 4.65 ng/g; DDTs: 1.45 ng/g). PCBs revealed a profile dominated by hexa-, penta- and hepta-chlorinated congeners, while among DDTs, the compound in the greatest concentration was p,p'-DDE, (liver: 85.2%, kidney: 93.6%, lung: 86.4%, muscle tissue: 93.2%). The estimated toxic equivalents (pg TEQs/g wet wt) of non- and mono-ortho PCBs were in the range of 1.54-5.86 pg TEQs/g wet wt. Non-ortho coplanar PCB 77 accounted for more than 90% of the total TEQs leaving to mono-ortho only 2.6-6.2%.

A General Indication of the Contemporary Background Levels of PCDDs, PCDFs, and Coplanar PCBs in the Ambient Air over Rural and Remote Areas of the United States

Long-term measurements of the atmospheric concentrations of PCDDs, PCDFs, and coplanar PCBs were taken in rural and remote areas of the United States by the National Dioxin Air Monitoring Network (NDAMN). A total of 21 quarterly sampling moments occurred from June, 1998 to December, 2002 at 34 locations geographically distributed throughout the United States. Sampling sites were located in rural and remote areas to obtain background air concentrations of dioxin-like compounds. Results were reported as the toxic equivalent (TEQ) of the mix of PCDDs/ PCDFs (TEQDF) and the mix of coplanar PCBs (TEQPCB). At the studied rural sites the mean annual TEQDF for each of the NDAMN sampling years was 10.43, 11.39, 10.40, and 10.47 fg m(-3) for 1999, 2000, 2001, and 2002, respectively. There was no statistically significant difference in the rural mean TEQDF air concentrations across the sampling years (at 0.05 level of significance), although the mean concentration in sampling year 2000 increased 10% relative to the other sampling years. The 95th percent confidence interval of TEQDF air concentrations in rural areas of the United States is from 6.4 to 15.4 fg m(-3), indicating there is a 95% probability that the true mean falls within this range. Mean annual atmospheric concentrations (TEQDF) at the remote sites were 1.41, 0.99, 0.7, and 1.07 fg m(-3) in 1999, 2000, 2001, and 2002, respectively, The 95th percent confidence interval of TEQDF air concentrations suggest that the true mean annual atmospheric TEQDF concentration in remote areas of the United States is between 0.1 and 3 fg m(-3). The remote sites have average air TEQDF concentrations that are approximately 10 times lower than those of the rural sites. For the rural sites, there was close agreement in the mean annual air concentrations of coplanar PCBs (TEQPCB) among the years 1999, 2000, 2001, and 2002 (i.e., 0.62, 0.69, 0.59, and 0.7 fg m(-3), respectively). However, as is the case with PCDDs/PCDFs, there was a marked increase (i.e., approximately equal to 13%) in the annual rural mean air concentration in 2000 as compared to the other sampling years. The confidence intervals across the NDAMN sampling years suggests a 95% probability that mean TEQPcB atmospheric concentrations in rural and remote areas of the United States are within the range of 0.5-0.9 fg m(-3) and 0.1-0.5 fg m(-3), respectively. The congener distributional patterns of PCDDs/PCDFs in air were relatively constant at all locations, and match the profile of urban air. We propose the hypothesis that urban areas are regional sources of PCDDs/PCDFs and are affecting atmospheric levels in rural and remote areas of the United States.

Endocrine effects generated by photooxidation of coplanar biphenyls in water using titanium dioxide

The oxidative photodegradation behaviors of selected three coplanar polychlorinated biphenyls (PCBs), (CB77, CB81, and CB169) using titanium dioxide (TiO 2) in water were investigated. The main purposes were to clarify the structural relation between the original PCBs and the intermediates derived by TiO 2 oxidation and to evaluate the estrogenic and thyroid hormonal activity in the treated three coplanar PCBs during the oxidative reactions. Approximately 90% of the three coplanar PCBs decomposed within 180 min. Intermediates from the decomposition of the three coplanar PCBs, such as some hydroxylated-PCBs (OH-PCBs), carboxylic intermediates, phenolic intermediates, and other intermediates produced by the cleavage of a benzene ring were identified and quantified. In the degradation pathways, the produced amounts of OH-PCBs increased within 60 min of irradiation time. The estrogenic activity and thyroid hormonal activity of the intermediates from the three coplanar PCBs in water at 0, 60, 120, 180 and 240 min of irradiation time were assessed by using a yeast two-hybrid assay system for human estrogen receptor α (hERα) and human thyroid hormone receptor α (hTRα). The maximal estrogenic activities were induced by the solutions of decomposed PCBs with irradiation time at 60–120 min similar and slightly lower than those after the irradiation time. We found that the solutions occuring during the irradiation times of 60–120 min contained several 4-OH-PCBs substituted with OH and Cl at para- and para′- positions having estrogenic activity. The thyroid hormonal activity was not detected in the decomposed three coplanar PCBs solutions.

環境大気中のダイオキシン類の濃度推移とＣｏ‐ＰＣＢｓの汚染原因

Continuous sampling of dioxins in ambient air was carried out using a low-volume air sampler at the southeast site in Tokyo during a period of FY 2000 to FY 2004. The temporal trend of toxic equivalency quantity (TEQ) was evaluated the relation with Tokyo's inventory which was estimated to be almost completely emitted from combustion sources. The annual average of TEQ was observed to have a more similar tendency to a variation in the inventory than that of regular monitoring with a short term sampling. However, the reduction rate of TEQ for 5 years was less than that of the inventory. Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) increased from late autumn to winter, whereas those of coplanar polychlorinated biphenyls (Co-PCBs) elevated in summer and the seasonal variation seemed to be dependent on temperature. As PCB products and combustion were known to be the major sources of Co-PCBs, we have attempted to estimate the source contribution rates using the method of Bayesian chemical mass balance. Though Co-PCBs derived from PCB products were extrapolated a significant contributor at total concentration base, Co-PCBs emitted from combustion seemed to constitute over 90 % based on TEQ as consequence of higher toxic equivalency factor of their isomers.

Modulation of the Respiratory Burst by Organochlorine Mixtures in Marine Mammals, Humans, and Mice

The effects of organochlorines (OC) on the immune systems of marine mammals and humans are poorly understood. One important innate immune function of peripheral blood neutrophils and monocytes is the respiratory burst, which generates reactive oxygen species (ROS) used to kill engulfed microorganisms. The present study characterized the immunomodulatory potential for mixtures of OCs, compared to that of individual OCs, on the respiratory burst in several marine mammals, humans, and B6C3F1 mice. The effects of three non-coplanar polychlorinated biphenyls (PCBs) (138, 153, 180), one coplanar PCB (169), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and all possible mixtures were tested upon in vitro exposure for 1 h, and their effects on the generation of a respiratory burst were measured by flow cytometry. The final concentration for each congener, alone or in a mixture, was 5 ppm for PCBs and 0.05 ppb for TCDD. Both significant enhancement and suppression of the respiratory burst occurred in all species tested, but the pattern was different between species and cell types (neutrophils vs. monocytes). Both coplanar and non-coplanar OCs were involved in the modulation of the respiratory burst. Regression analysis was not able to elucidate which OCs were involved in modulating the responses, highlighting the difficulty of developing models to predict the immunotoxic effects attributed to OC mixtures. The traditional mouse model and toxic equivalency (TEQ) approach both failed to consistently predict the toxicity of OCs in all species tested, questioning their applicability in the risk assessment process for all species. Elucidating the relative sensitivities to the immunomodulatory effects of OC mixtures between different species may have important implications for risk assessment as well as conservation and management strategies.

Potential Hazards of Environmental Contaminants to Avifauna Residing in the Chesapeake Bay Estuary

A search of the Contaminant Exposure and Effects-Terrestrial Vertebrates (CEE-TV) database revealed that 70% of the 839 Chesapeake Bay records deal with avian species. Studies conducted on waterbirds in the past 15 years indicate that organochlorine contaminants have declined in eggs and tissues, although p,p’-DDE, total polychlorinated biphenyls (PCBs) and coplanar PCB congeners may still exert sublethal and reproductive effects in some locations. There have been numerous reports of avian die-off events related to organophosphorus and carbamate pesticides. More contemporary contaminants (e.g., alkylphenols, ethoxylates, perfluorinated compounds, polybrominated diphenyl ethers) are detectable in bird eggs in the most industrialized portions of the Bay, but interpretation of these data is difficult because adverse effect levels are incompletely known for birds. Two moderate-sized oil spills resulted in the death of several hundred birds, and about 500 smaller spill events occur annually in the watershed. With the exception of lead, concentrations of cadmium, mercury, and selenium in eggs and tissues appear to be below toxic thresholds for waterbirds. Fishing tackle and discarded plastics, that can entangle and kill young and adults, are prevalent in nests in some Bay tributaries. It is apparent that exposure and potential effects of several classes of contaminants (e.g., dioxins, dibenzofurans, rodenticides, pharmaceuticals, personal care products, lead shot, and some metals) have not been systematically examined in the past 15 years, highlighting the need for toxicological evaluation of birds found dead, and perhaps an avian ecotoxicological monitoring program. Although oil spills, spent lead shot, some pesticides, and industrial pollutants occasionally harm Chesapeake avifauna, contaminants no longer evoke the population level effects that were observed in Ospreys (Pandion haliaetus) and Bald Eagles (Haliaeetus leucocephalus) through the 1970s.

Fungal bioconversion of toxic polychlorinated biphenyls by white-rot fungus, Phlebia brevispora

Toxic coplanar polychlorinated biphenyls (Co-PCBs) were used as substrates for a degradation experiment with white-rot fungus, Phlebia brevispora TMIC33929, which is capable of degrading polychlorinated dibenzo-p-dioxins. Eleven PCB congener mixtures (7 mono-ortho- and 4 non-ortho-PCBs) were added to the cultures of P. brevispora and monitored by high resolution gas chromatography and mass spectrometry (HRGC/HRMS). Five PCB congeners, 3,3',4,4'-tetrachlorobiphenyl, 2,3,3',4,4'-pentachlorobiphenyl, 2,3',4,4',5-pentachlorobiphenyl, 3,3',4,4',5-pentachlorobiphenyl, and 2,3',4,4',5,5'-hexachlorobiphenyl were degraded by P. brevispora. To investigate the fungal metabolism of PCB, each Co-PCB was treated separately by P. brevispora and the metabolites were analyzed by gas chromatography and mass spectrometry (GC/MS) and identified on the basis of the GC/MS comparison with the authentic compound. Meta-methoxylated metabolite was detected from the culture containing each compound. Additionally, para-dechlorinated and -methoxylated metabolite was also detected from the culture with 2,3,3',4,4'-pentachlorobiphenyl, 2,3',4,4',5-pentachlorobiphenyl, and 2,3',4,4',5,5'-hexachlorobiphenyl, which are mono-ortho-PCBs. In this paper, we identified the congener specific degradation of coplanar PCBs by P. brevispora, and clearly proved for the first time by identifying the metabolites that the white-rot fungus, P. brevispora, transformed recalcitrant coplanar PCBs.