Polychlorinated biphenyls in broiler diets: their digestibility and incorporation in body tissues

The influence of dietary amounts of polychlorinated biphenyls (PCBs) was studied on performance, apparent PCB digestibility and PCB accumulation in broiler chickens that were maintained until 42 days of age. Dietary concentrations of supplemented PCBs, based on the sum of seven reference congeners, ranged from 0 to 12 ng/g, which was below the legal maximum of 200 ng PCBs/g fat in Belgian feeds. PCB ingestion did not significantly affect body weight and feed intake. Apparent PCB digestibility was not influenced by dietary levels of added fat varying between 4% and 8%, but was significantly higher in broilers fed diets containing added PCBs. Accumulation of PCBs in the fat fraction of abdominal adipose tissue and breast and thigh muscle greatly depended upon PCB intake. However, PCB contents in the various body fat fractions within the same animal differed, even within muscle tissues, indicating an unequal PCB distribution in body fats.     

Fenton''s type reaction and chemical pretreatment of PCBs

This study evaluates the effects of Fenton's reagent (FR) on the rate and extent of the oxidative degradation of individual mono, di-, tri- and tetrachlorobiphenyls in the commercial mixture DELOR 103, equivalent to AROCLOR 1248. The oxidation effect of FR strongly increased with increasing the molar ratio of Fe²⁺/H₂O₂. The most effective oxidation of DELOR 103 (10 μg.ml⁻¹) was achieved in a solution containing 1M H₂O₂ and 1 mM Fe²⁺. The FR elimination rate constants of PCB congeners decrease with increasing number of chlorine substituents in the biphenyl molecule and show a good correlation with the values of molecular weights of the PCB congeners and their 1-octanol/water partition coefficients.     

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.     

A survey of PCB congeners in U.K. cows'' milk

Samples of unpasteurised bulked milk, taken directly from ten herds of dairy cattle on rural and urban farms in the north west of England on five separate sampling occasions, were analysed for a range of PCB congeners. ΣPCB concentrations (sum of 37 congeners) ranged from 3.4–16.4 ng/g milk fat with a mean ΣPCB concentration of 8.4 ng/g milk fat. The dominating congeners were 118, 153, 138 and 180, which contributed 15%, 20%, 17% and 9% of the ΣPCB load respectively. The chlorine pattern of the congeners which made moderate or major contributions to the ΣPCB concentration were typically substituted at both para positions (4, 4′), while the PCB congeners not detected in the milk had at least one ring that was not 4-substituted. These results indicate the 4,4′ substitution pattern as being the key to PCB persistence in cows. It is estimated that consumption of typical daily intakes of milk with the PCB concentrations measured in this study would contribute 11 % of the average daily ΣPCB intake for individuals in the UK. This contribution would increase to 30% when exposure through the consumption of dairy products prepared from such milk (e.g. cheese, butter) is taken into account. It is estimated that the inclusion of the TEF assigned PCBs would typically increase the TEQ rating of cows' milk by approximately 40% over that attributed to PCDD/Fs alone.     

Polychlorinated biphenyls in digested UK sewage sludges

Twelve sewage sludges from rural, urban and industrial waste water treatment works in north west England were analysed for polychlorinated biphenyls by capillary GC-ECD. The total polychlorinated biphenyl content ranged between 106 to 712 μg/kg, with a mean of 292 μg/kg. Di- and penta-chlorinated congeners made the greatest contribution to the ΣPCB concentrations at most sites. The 6 IUPAC congeners were found in the following order of abundance, 101>180>153>138>52>28. Industrial inputs would appear to influence levels of ΣPCB in the sludge.

If these sludges were ploughed into arable land at typical rates only a slight elevation in soil ΣPCB levels would result. Alternatively, if the same quantity of sludge were applied to the surface of pasture grassland, significant elevations in the potential transfer of PCBs to grazing livestock may result.     

Polychlorinated biphenyls (PCBs) and hydroxy-PCBs in adipose tissue of women in Southeast Spain

Polychlorinated biphenyls (PCBs) and hydroxylated PCBs (OH-PCBs) were investigated in human adipose tissue samples collected from 20 women undergoing surgery. Mean sum of PCB and sum of OH-PCB levels were 737ng/g of lipid and 8pg/g of lipid, respectively. Among PCBs, congeners 180, 153, 138 and 170 were the most frequent and abundant, and together constituted 72% of the total amount of PCBs in adipose tissue. The PCB congener pattern and the frequencies and concentrations of non-dioxin-like and non-hydroxylated congeners observed in adipose tissue were similar in distribution and order of magnitude to the profile previously published in Spain but lower than that found in other European countries. Among OH-PCB congeners studied, 4-OH-PCB 107/118 was found at the highest concentrations followed by 3'-OH-PCB 180 and 3-OH-PCB 138. To date, no information on levels of PCB metabolites in the Spanish population is available for comparison. These three predominant OH-PCBs contributed 97% of all OH-PCBs. Twelve dioxin-like PCBs contributed around 8% of the total PCB exposure, and all were present in all study subjects. Further research is required to determine trends in human exposure to PCBs and OH-PCBs and how existing banning measures affect exposure.     

Concentration of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and dioxin-like PCBs in human adipose tissue from Turkish men

There is no previous report from Turkey on chemically determined polychlorinated dibenzo-para-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) in human tissues expressed as World Health Organization (WHO) toxic equivalents (TEQs). The objective of this study was to determine the occurrence of PCDDs/Fs, and dioxin-like PCBs in the general adult Turkish population. For this reason we measured adipose tissue concentrations of PCDDs/Fs and dioxin-like PCBs in 23 Turkish men living in Ankara,Turkey in 2004. PCDD/F concentrations ranged between 3.2 and 19.7 pg WHO-TEQ/g fat (5.34 and 42.7 WHO-TEQ/g fat, respectively, including dioxin-like PCBs). The mean concentrations of WHO(PCDD/F)-TEQ and WHO(PCB)-TEQ were 9.2 and 6.67 pg/g on a lipid basis , respectively. Samples were analyzed for PCDD/F and twelve dioxin-like PCB congeners using high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). This study is very important since it is the first report on PCDDs/Fs and dioxin-like PCB contamination in human adipose tissue from Turkey.     

Tissue distribution and bioconcentration factors of PCDD/Fs in the liver and adipose tissue following chronic ingestion of contaminated milk in rats

The aim of this study was to determine the tissue distribution of 17 PCDD/Fs following the chronic ingestion of contaminated milk in rats and to assess the "target tissue/milk" BioConcentration Factors (BCFs) of these molecules. Contaminated milk, collected in a polluted area, has been incorporated into the diet of male rats at a low dose (31 pg I-TEQ/day/rat). For this exposure, the accumulation of PCDD/Fs in target tissues (liver and adipose tissue) was limited, the tissue concentrations stabilising between 90 and 120 days of daily intake to levels close to 3 pg/g of tissue (all tissues and molecules combined). The tissue distribution seemed to be governed by the congeners properties and by the tissue characteristics. An increase in the chlorination degree of dioxins caused a decrease in their incorporation in the adipose tissue, and consequently of the BCF values. Moreover, the distribution of dioxins between hepatocytes and adipocytes differed: unlike the liver, the quantities of dioxins in the adipose tissue were significantly (P<0.05) correlated to the quantity of tissue fat. Only in the liver, the incorporation of PCDDs seemed to be facilitated when the chlorination degree of these congeners increased, the reverse phenomenon having been observed for PCDFs. However, for the same level of chlorination, the BCFs of PCDFs were 2.4 times higher than those of PCDDs in this tissue. The absence of correlation between the quantity of dioxins and that of fat and the BCFs differences of theses congeners suggested that dioxins fixation process in the liver was selective.     

Determination of coplanar and ortho substituted PCBs in some sewage sludges of Switzerland using HRGC/ECD and HRGC/MSD

The three most toxic coplanar PCB congeners PCB 77, 126 and 169 as well as 7 mono-and di-ortho-PCBs (PCB 28, 52, 101, 118, 153, 138, 180) were measured in 19 sewage sludges. Concentrations of the coplanar PCBs ranged between 231–5050 ng/kg dw for PCB 77, 43–1511 ng/kg dw for PCB 126 and 29–273 ng/kg dw for PCB 169. Comparable results were obtained with mass selective detection in the single ion monitoring mode (MSD-SIM) except for PCB 169, where MSD-SIM was less sensitive than ECD. The sum of the 7 mono-and di-ortho-PCBs, which are routinely measured as representatives of the PCB fraction, reached levels between 43–550 μg/kg dw and agreed well with results previously obtained in our laboratory. Based on our data, a selective accumulation of the coplanar PCBs could not be observed. Sludges that received industrial effluents clearly showed higher PCB levels than rural ones. Finally, calculation of TEQ equivalents of the coplanar PCBs in the sewage sludges revealed that, based on application rates normally used in Switzerland, the contribution of the sludges to soil pollution seems to be of minor importance.     

Metabolism and body-burden of PCBs in lactating dairy cows.

This paper uses data from a detailed 4 month PCB mass balance study on lactating cows fed a naturally contaminated background diet to quantify the metabolism and body-burdens of a range of PCB congeners. Dietary intake fluxes and milk and faecal output fluxes reported previously are combined with subcutaneous fat and blood PCB concentrations and with data from tissue/organ samples from a slaughtered animal to estimate the degree of metabolism within the cow. A total body burden is derived, showing that fat deposits account for approximately 98% of total PCB present in the lactating cow. The daily intake through feed (ng day-1) accounted for between 0.9 and 1.5% of the total body burden for persistent congeners (e.g. PCB 153) and up to 43% for those congeners which are readily metabolised (e.g. PCB 52). Detailed balances for a range of tri- to octa-chlorinated PCBs are presented and clearly demonstrate that many congeners are metabolised effectively by lactating dairy cows (e.g. PCB 149) whilst others are efficiently transferred to human dairy food products. An approach to predicting the degree of metabolism for individual PCB congeners is presented which gives good agreement with observations.     

Chlorohydrocarbons, PCB congeners, polychlorodioxins, furans and dibenzothiophenes in pine needles in the vicinity of a metal reclamation plant

Chlorohydrocarbons, PCB congeners, polychlorodioxins, furans and dibenzothiophenes in pine needles in the vicinity of a metal reclamation plant were analyzed by GC/ECD and GC/MS. Wax and the rest of the needles were analyzed separately. As a rule the concentrations of -HCH (0.5–13.6 ng/g), γ-HCH (0.4–7.3 ng/g), HCB (0.2–3.4 ng/g), PCB congeners (0.2–67 ng/g), PCDDs and PCDFs were higher in the older needles. The ratio of the concentration in the wax to the concentration in the rest of the needles was higher in the younger needles. The concentrations of PCB congeners, TeCDDs and TeCDFs were higher in the needles collected in the area nearest to the plant. The samples, obviously, contained tri- and tetrachlorodibenzothiophenes but these were not determined quantitatively due to interfering peaks in GC/MS.     

Microscale analytical methods for the quantitative detection of PCBs and PAHs in small tissue masses

Microscale methods (MM) were evaluated and compared to traditional methods (TM) for measuring polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in spiked and standard reference fish and mussel tissues. MMs are advantageous because they use small tissue masses (ca. 100 mg), and maintain sensitivity through reducing final extract volume (traditionally 1 ml) by an order of magnitude or more (40 μl—PCBs; 100 μl—PAHs). Procedural losses occurred in the MMs’ combined cleanup/primary evaporation step (19% PAHs; 6% PCBs), and the final extract concentration (14% PAHs; 22% PCBs). The PAH MM performed comparably to the TM. Although most PCBs had recoveries >50%, the PCB MM generally yielded lower recoveries than the TM. Average method detection limits were 0.6 μg/kg (TM) and 1.0 μg/kg (MM) for PCBs and 25.7 μg/kg (TM) and 27.7 μg/kg (MM) for PAHs. MMs described for PCB and PAH tissue samples are potentially viable alternatives to TMs, and could lead to cost savings in bioaccumulation/toxicity tests.     

Determination of tissue-blood partition coefficients for a physiological model for humans, and estimation of dioxin concentration in tissues

The tissue-blood partition coefficients for a physiologically based pharmacokinetic (PBPK) model were determined, and the concentrations of 17 congeners of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in tissues in Japanese people were estimated using the model. According to the PBPK model established by Lawrence and Gobas [Chemosphere 35 (1997) 427-452], we assumed a steady-state fugacity model for Japanese people in general, and set the route of PCDD/Fs exposure only from food intake. The required partition coefficients for liver, kidney, adipose, muscle, skin, bile, gut and viscera (richly perfused tissue) were calculated using available autopsy data from eight Japanese men and women who were not accidentally exposed to PCDD/Fs. For validation of the partition coefficients, estimated PCDD/F concentrations in liver, kidney, fat, blood and muscle using the model were compared to other two sets of measured concentration data in Japanese tissues. Good agreement was obtained between estimated data and measured data, and most of the measured data were within the simulated concentration range in liver, kidney, blood and muscle. From these results, our model and calculated partition coefficients seem applicable for the estimation of congener-specific concentrations in human tissues.     

Comparison of PCDD/F and coplanar PCB concentrations in Japanese human adipose tissue collected in 1970-1971, 1994-1996 and 2000

Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and coplanar biphenyls (Co-PCBs) were determined in Japanese human adipose tissues. Temporal trends were assessed by comparing data collected during 1970-1971, 1994-1996 and 2000. Mean TEQ levels of PCDD/Fs in human adipose tissue showed a significant decrease from 31.6 +/- 9.2 pg-TEQ/g fat wt in 1970-1971 to 11.9 +/- 7.4 pg-TEQ/g fat wt in 2000, and coplanar PCBs decreased from 35.4 +/- 21.9 pg-TEQ/g fat wt in 1970-1971 to 15.3 +/- 8.2 pg-TEQ/g fat wt in 2000. However, some PCB congener concentrations did not change during this time. A comparison of data using the latest PCB-TEQ showed no significant changes. Therefore, research on source characterization and monitoring of short-term temporal trends on these compounds should be carried out continuously.     

Behavior and source characteristic of PCBS in urban ambient air of Yokohama, Japan

To understand the behavior and sources of polychlorinated biphenyls (PCBs) in ambient air, gaseous and particulate phase concentrations were measured at Yokohama City, Japan, during March 2002 and February 2003. The concentration of total PCB and TEQ ranged from 62 to 250 pg/m(3) and from 2 to 14 fgTEQ/m(3), respectively. The gas-particle partition coefficient (K(p)) was obtained as a function of temperature. The relationship between the partition coefficient and the sub-cooled liquid vapor pressure (P(L)) was also established (coefficients of determination for log K(p) versus log P(L) plot were >0.76, except for three samples). As a result, the partition ratio of gaseous and particulate phase PCBs can be estimated for an arbitrary temperature. Principal component analysis (PCA) was applied to the source identification of PCBs in ambient air. The concentrations of 122 congeners between tetra-CBs and deca-CB were used as input variables, and three PCs with eigenvalue more than 10 were obtained. The principal component 1 (PC 1) accounted for 43.4% of the total variance, and was interpreted as volatilization from PCB products and/or sites polluted by PCBs. The concentrations of PCB congeners were strongly related with PC 1 which showed high correlation with temperature. PC 2 accounted for 22.3%, and was interpreted as PCBs from incineration sources, while PC 3 accounted for 10.8%, but could not be interpreted.     

PBDEs in the San Francisco Bay Area: measurements in harbor seal blubber and human breast adipose tissue

To explore the levels of polybrominated diphenyl ethers (PBDEs) in California, samples from 11 archived harbor seals (Phoca vitulina Richardsi) from the San Francisco Bay and breast adipose tissue samples from 23 women were analyzed. The levels of PBDEs in human tissue samples were in the low ng/g fat range, with PBDEs 47, 153, 154, 99, and 100 as the major congeners. Average sigma PBDEs (86 ng/g fat) in these California women are the highest human levels reported to date. An inverse relationship between concentration of PBDEs and age of these women was apparent. The levels of PBDEs measured in harbor seal blubber were in the low ng/g to low microg/g fat range, with the same major congeners as those measured in the human tissues. PBDE 47 was the highest among all congeners measured in both human tissue and seal blubber samples. The concentrations of PBDEs in harbor seals in the San Francisco Bay have increased dramatically over the past decade, with current levels among the highest reported for this species.     

Polychlorinated naphthalenes in human adipose tissue from New York, USA

Polychlorinated naphthalenes (PCNs) are persistent, bioaccumulative, and toxic contaminants. Prior to this study, the occurrence of PCNs in human adipose tissues from the USA has not been analyzed. Here, we have measured concentrations of PCNs in human adipose tissue samples collected in New York City during 2003-2005. Concentrations of PCNs were in the range of 61-2500 pg/g lipid wt. in males and 21-910 pg/g lipid wt. in females. PCN congeners 52/60 (1,2,3,5,7/1,2,4,6,7) and 66/67 (1,2,3,4,6,7/1,2,3,5,6,7) were predominant, collectively accounting for 66% of the total PCN concentrations. Concentrations of PCNs in human adipose tissues were 2-3 orders of magnitude lower than the previously reported concentrations of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). Concentrations of PCNs were not correlated with PCB concentrations. The contribution of PCNs to dioxin-like toxic equivalents (TEQs) in human adipose tissues was estimated to be <1% of the polychlorinated dibenzo-p-dioxin/dibenzofuran (PCDD/F)-TEQs.     

Pharmacok inetics and metabolism of 1,2,3,7,8-pentachlorodibenzo-p-dioxin in the rat

¹⁴C-1,2,3,7,8-Pentachloroaibenzodioxin (P₅CDD), administered to rats as single oral dose (1.69–1.75 μg/animal, 8.42–10.06 μg/kg) was eliminated with a half life of 29.5±2.7 days from the body of the animals. Residual P₅CDD was located mainly in the liver and the adipose tissue. In the bile, polar metabolites of P₅CDD were detected but no unmetabolized P₅CDD.     

Polychlorinated biphenyl distribution and faecal excretion in rats fed wheat bran

Polychlorinated biphenyls (PCBs) are abundant and persistent environmental contaminants, which tend to accumulate through the food chain. Because of the toxic potential of these compounds, body burden should be kept as low as possible e.g. by taking dietary measures. In the present report, the effect of wheat bran consumption on absorption of dietary PCBs as well as on excretion of previously absorbed PCBs was investigated in rats. Moreover, the accumulation of 7 reference PCB congeners in liver and abdominal adipose tissue was studied. Faecal excretion of dietary PCBs was significantly higher in rats fed wheat bran compared to its placebo. As a result, apparent PCB digestibility was diminished, but not enough to significantly affect PCB accumulation in liver and abdominal adipose tissue. Furthermore, excretion of previously absorbed PCBs following switching of the rats to a control diet without added PCBs was enhanced by wheat bran fibre intake, although to a much lesser extent than excretion of PCBs originating directly from the diet. Consequently, stimulation of PCB clearance from liver and abdominal adipose tissue due to wheat bran consumption was not detectable. Although no preferential absorption of PCB congeners was observed, PCB patterns in tissues obviously differed from the dietary PCB pattern. This was mainly due to PCBs 52 and 101, which were metabolised in the body. Moreover, reduced levels of PCB 138 were found in liver, while PCB 28 and 138 were predominantly present in adipose tissue. The experiment also demonstrated that PCB redistribution from the liver to the adipose tissue occurs.     

Routine, automated determination of inorganic and total mercury in multimedia using cold vapour atomic absorption spectrometry

A routine, automated analytical method for simultaneous determination of total and inorganic mercury by cold vapour atomic absorption spectrometry in multimedia is described. Excellent accuracy and precision results were obtained with human hair certified reference materials namely, BCR-397 and IAEA-086. The reproducibility relative standard deviation for total mercury was 4% and 22%, respectively. The limit of detection for total and inorganic mercury was 0.2 μg/g hair. The described method has been successfully applied in determination of total and inorganic mercury as well as organic mercury in human hair, urine and fish tissue samples.