Levels of selected individual polychlorinated biphenyls in different tissues of harbour seals (phoca vitulina) from the Southern coast of Norway

Concentrations of individual polychlorinated biphenyls (PCBs) were determined in blubber, liver, kidney and brain tissues of 10 male harbour seals (Phoca vitulina) of different ages. The animals were found dead or dying on the southern coast of Norway in 1988 during the morbilli virus epizootic. Twenty-three PCB congeners were investigated in all tissues by capillary gas chromatography with electron capture detection and comparison with standards of the respective congeners (IUPAC numbers 28, 52, 74, 99, 101, 105, 110, 114, 118, 128, 138, 141, 149, 153, 156, 157, 170, 180, 183, 187, 194, 206 and 209). In addition, three toxic coplanar congeners (IUPAC numbers 77, 126 and 169) were investigated in the blubber samples. Total PCB (sum of the determined congeners) in kidney (12-60 nmol g(-1)), liver (12-90 nmol g(-1)) and blubber (10-79 nmol g(-1)) were similar on extractable lipid basis, while total PCB in brain lipid was about 1/10 (1.6-12 nmol g(-1)). The absolute concentrations of the individual congeners in brain lipid correlated poorly with the respective concentrations in each of the other tissues, while the individual congener concentrations in the lipid fractions of kidney, liver and blubber tended to correlate with each other. The relative concentrations of the sum of the most persistent congeners (PCB-99, -128, -138, -153, -170, -180, -187 and -194) correlated in all tissues, and an increase of the relative concentrations of these congeners, most distinct in blubber, with higher carcass weight, was shown. Also, total PCB in blubber correlated with carcass weight. When comparing the relative concentration patterns of individual congeners (per cent of total) in the four tissues, six congeners differed significantly between tissues, and the relative brain concentrations showed most deviation from the other tissues. The concentration of the coplanar PCBs was 1 : 1000-1 : 1000 of the total PCB concentration. The results demonstrate a lower accumulation together with a different concentration pattern in the brain as compared to other tissues.     

Distribution and bioconcentration potential of the environmental chemical pentachlorophenol (PCP) in different tissues of humans

The bioconcentration factors (BCFs) of pentachlorophenol (PCP) in different tissues, organs and body fluids of humans were calculated by two methods: 1) from daily intake of PCP and its measured concentrations in different tissues and, 2) from measured half-life and measured PCP concentrations in the human body at steady state using a linear one compartment pharmacokinetic model. The BCFs (based on wet weight) in liver, brain, blood, spleen and adipose tissue of humans as calculated by method 1 were 5.7, 3.3, 1.4, 1.4, and 1.0, respectively. The figures obtained by method 2 were in good agreement to those obtained by method 1.     

Bioaccumulation kinetics and bioconcentration factor of chlorinated pesticides in tissues of Puntius ticto (Ham.)

Bioaccumulation kinetics and bioconcentration factor (BCF) of chlorinated pesticides like Aldrin, Dieldrin, Benzene hexachloride (BHC), and Dichlorodiphenyl-dichloro-ethane (DDT) in fish tissues of Puntius ticto was studied in detail in a continuous fed system. The bioconcentration process is summarized by using a first order uptake model and the steady-state BCF is calculated based on the 30 days exposure. Rate of bioaccumulation of DDT was maximum of 4.6432 microg g(-1) wet weight per day in liver tissue whereas it was minimum of 0.0002 microg g(-1) wet weight per day in case of Dieldrin in the muscle tissue among the pesticides. It was observed that DDT showed maximum BCF of 89.010 in case of liver tissue of the fish exposed to 30 days. The regression coefficient (r2) between pesticide concentration and exposure time varied between 0.6212 and 0.9817 indicating high correlation. Based on actual calculated BCF values, the octanol water partition coefficient (Kow) values were predicted. In order to prove the hydrophobic property of chlorinated compounds and its affinity towards lipid, the Kow is predicted. Results showed that pesticide burden differ from tissue to tissue and can be correlated to the lipid content, size, exposure time, and species.     

Distribution of PCDDs, PCDFs and dioxin-like PCBs in the blood, testis and adipose tissue of suckling beef calves

To determine the distribution of persistent organochlorine compounds in beef cattle, concentrations of 2,3,7,8-substituted PCDDs, PCDFs and dioxin-like PCBs were measured in the blood, testes and adipose tissue of four two-month-old Japanese Black calves. Of 29 congeners analyzed, 19, 20 and 28 were detected in the blood, testes and adipose tissue, respectively, of three or all calves. Total toxic equivalents (TEQs) were similar in the testes and adipose tissue, and approximately two times higher than in the blood on a lipid weight basis (P<0.05). More PCDDs and PCDFs had accumulated in the testes than in adipose tissue (P<0.01), but more dioxin-like PCBs were found in adipose tissue than in the testes (P<0.0001). Accumulation patterns in the testes and adipose tissue varied among the congeners of PCDD and PCDF, whereas the patterns were similar in dioxin-like PCBs. In particular, highly substituted PCDD congeners were detected at high concentrations in the testes but at lower concentrations in adipose tissue compared with other congeners. By contrast, accumulation levels of highly substituted PCDFs were lower in both those tissues than the other congeners. In conclusion, it was demonstrated that PCDDs, PCDFs and dioxin-like PCBs leave the circulation and accumulate in the testes and adipose tissue in bovine calves. It was suggested that congeners of PCDD, especially highly substituted PCDDs, and PCDFs have a tendency to accumulate in the testis and dioxin-like PCB congeners accumulate readily in adipose tissue.     

Polychlorinated dibenzo-p-dioxins and related compounds: correlations of levels in human tissues and in blood

We investigated PCDDs and related compounds levels in human tissue and blood obtained from the general population, and the correlation factor was calculated from the findings. None of the congeners in brain, muscle and lung were correlated except for 2,3,7,8-tetrachlorodibenzo-p-dioxin and octachlorodibenzo-p-dioxin in the brain (p < 0.05). In other tissues, all congeners had relatively good correlations to those in blood (r > 0.707). These congeners detected in blood were at high concentrations in the environment and human body. Therefore, we concluded that these congener levels in the blood might be useful for estimating these congener levels in human tissue.     

The presence of PCDDs and PCDFs in human breast milk from the Netherlands

Sixteen individual and two pooled human milk samples were analyzed for PCDDs and PCDFs. All detected PCDD and PCDF congeners had a 2,3,7,8-chlorine substitution pattern.The PCDDs and PCDFs were associated with the lipid fraction of the milk. Major components were 2,3,4,7,8-PnCDF (0.2 – 2.6 ppt), 1,2,3,6,7,8-HxCDD (0.2 – 5.7 ppt), 1,2,3,4,6,7,8-HpCDD (1.3 – 19.1) and OCDD (1.7 – 37.8 ppt), with concentrations on total milk basis.Minor components were 1,2,3,7,8-PnCDD, 1,2,3,7,8,9- and 1,2,3,4,7,8- HxCDD (⩽ 1 ppt). Qualitatively and quantitatively the milk samples from the Netherlands strongly resemble those from Sweden and West-Germany. A linear relationship was found between some congeners. This correlation was highest for congeners having an equal number of chlorine atoms or those with a difference of one chlorine atom.By using a one compartment open model for multiple doses, a maximum liver concentration of approximately 200 ppt 2,3,4,7,8-PnCDF in the neonate was calculated after six months.     

Predicting bioconcentration factors (BCFs) of polychlorinated bornane (Toxaphene) congeners in fish and comparison with bioaccumulation factors (BAFs) in biota from the aquatic environment.

Polychlorinated bornanes, the main components of Toxaphene, are bioconcentrated in aquatic organisms to a high extent. However, up to this time no bioconcentration tests with individual chlorinated bornanes in aquatic organisms have been performed. Therefore, the bioconcentration factors (BCFs) of seven selected persistent chlorinated bornane congeners which are regularly found in aquatic organisms, were predicted from their n-octanol/water partition coefficients (log Kow). Furthermore, these BCF values were compared with the measured bioaccumulation factors (BAFs) in zooplankton and different fish species from the aquatic environment.     

Congener specific accumulation and toxic assessment of polychlorinated biphenyls in common cormorants, Phalacrocorax carbo, from Lake Biwa, Japan

Isomer-specific accumulation of polychlorinated biphenyls (PCBs) including di-, mono- and non-ortho congeners and hepatic P-450 activities were determined in adult common cormorants from Lake Biwa, Japan. The mean total PCB levels in male and female birds were 7.2 +/- 6.1 and 2.1 +/- 0.74 microg g(-1) wet wt, respectively, in the liver. The highly biomagnified congeners were IUPAC 126, 153, 169, 180 and 194, whereas a higher degree of biotransformation could be observed in both meta-para chlorine unsubstituted congeners in the cormorant liver. The estimated metabolic index also showed that common cormorants had higher PB-type enzyme activities than some avian and marine mammals but poor MC-type enzyme activities. The concentrations of non-ortho coplanar congeners were in the order of IUPAC 126 > IUPAC 169 > IUPAC 77 with mean values 6.1 +/- 5.9, 1.3 +/- 1.4 and 0.43 +/- 0.26 ng g(-1) wet wt, respectively. The calculated mean 2,3,7,8-TCDD toxic equivalent (TEQ) concentration in cormorants was 1.8 +/- 1.7 ng g(-1) wet wt and was dominated by IUPAC 118, followed by IUPAC 126. A significant increase of ethoxyresorufin-O-deethylase (EROD) and pentoxyresorufin-O-deethylase (PROD) activities was observed with estimated TEQ of PCBs in the cormorants, suggesting that the current contamination level is sufficient for altering their biochemical responses.     

Bioaccumulation and critical body residue of PAHs in the amphipod,Diporeia spp: additional evidence to support toxicity additivity for PAH mixtures

Polycyclic aromatic hydrocarbons (PAHs) are considered to act additively when exposed as congener mixtures. Additive internal concentrations at the site of toxic action is the basis for recent efforts to establish a sum PAH guideline for sediment-associated PAH toxicity. This study determined the toxicity of several PAH congeners on a body residue basis in Diporeia spp. These values were compared to the previously established LR(50) value for a PAH mixture based on the molar sum of PAH congeners and demonstrated similar LR(50) values for individual PAH. These results support the contention that the PAH act at the same molar concentration whether present as individual compounds or in mixture. Aqueous exposures were conducted for 28 d, and the water was exchanged daily to maintain the exposure concentration. The concentration in the exposures declined by an average of 22% between water exchanges across all compounds, and ranged from 11% to 32%. The toxicokinetics were determined using both time-weighted-average (TWA) and time-variable water concentrations and were not statistically different between the two source functions. Toxicity was determined for both mortality and immobility (failure to swim on prodding) and on both a TWA water concentration and a body residue basis. The LC(50) values ranged from 1757 microg l(-1) for naphthalene after 10 d exposure to 79.1 microg l(-1) for pyrene after 28 d exposure, and the EC(50) ranged from 1587 microg l(-1) for naphthalene after 10 d exposure to 38.2 microg l(-1) for pyrene after 28 d exposure. The LR(50) values for all congeners at all lengths of exposure were essentially constant and averaged 7.5+/-2.6 micromol g(-1), while the ER(50) for immobility averaged 2.6+/-0.6 micromol g(-1). The bioconcentration factor declined with increasing exposure concentration and was driven primarily by a lower uptake rate with increasing dose, while the elimination remained essentially constant for each compound.     

Distribution of polybrominated diphenyl ethers in Japanese autopsy tissue and body fluid samples

Brominated flame retardants are components of many plastics and are used in products such as cars, textiles, televisions, and personal computers. Human exposure to polybrominated diphenyl ether (PBDE) flame retardants has increased exponentially during the last three decades. Our objective was to measure the body burden and distribution of PBDEs and to determine the concentrations of the predominant PBDE congeners in samples of liver, bile, adipose tissue, and blood obtained from Japanese autopsy cases. Tissues and body fluids obtained from 20 autopsy cases were analyzed. The levels of 25 PBDE congeners, ranging from tri- to hexa-BDEs, were assessed. The geometric means of the sum of the concentrations of PBDE congeners having detection frequencies >50 % (ΣPBDE) in the blood, liver, bile, and adipose tissue were 2.4, 2.6, 1.4, and 4.3 ng/g lipid, respectively. The most abundant congeners were BDE-47 and BDE-153, followed by BDE-100, BDE-99, and BDE-28+33. These concentrations of PBDE congeners were similar to other reports of human exposure in Japan but were notably lower than concentrations than those reported in the USA. Significant positive correlations were observed between the concentrations of predominant congeners and ΣPBDE among the samples analyzed. The ΣPBDE concentration was highest in the adipose tissue, but PBDEs were distributed widely among the tissues and body fluids analyzed. The PBDE levels observed in the present study are similar to those reported in previous studies in Japan and significantly lower than those reported in the USA.     

Some heavy metals, essential elements, and chlorinated hydrocarbons in polar bear (Ursus maritimus) at Svalbard

During the period 1978-1989, samples of liver, kidney and subcutaneous fat from 24 polar bears, Ursus maritimus, from Svalbard were analysed for mercury, cadmium, lead, copper, zinc, selenium, arsenic, HCB, DDE, PCBs (as Aroclor 1260 or Phenoclor DP6). In a selected number of liver (seven) and fat (three) samples, the composition of individual PCB congeners was studied by comparison with 23 individual PCB congeners (IUPAC nos 28, 52, 74, 101, 99, 110, 149, 118, 114, 105, 153, 141, 138, 187, 128, 183, 156, 157, 180, 170, 194, 206 and 209). In the seven liver samples, the concentrations of o,p'- and p,p'-isomers of DDT, TDE, DDE, alpha-, beta- and gamma-HCH, oxychlordane, heptachlor, heptachlorepoxide, aldrin and dieldrin were also determined. The hepatic concentrations of mercury, cadmium and lead in animals of all ages were 0.4-6.0, <0.1-1.2, and <0.5-1.6 microg g(-1), respectively. This indicates a moderate exposure. Concentrations of mercury and selenium were correlated (r=0.80). The levels of copper and zinc represented normal physiological concentrations. The concentrations of HCB, DDE and PCBs in fat were <0.05-1.5, <0.1-3.4 and 2.9-90 microg g(-1), respectively. The corresponding results for liver were <0.01-0.11, <0.1-0.5 and 0.1-78 microg g(-1), respectively. Six PCB congeners, PCB-99, -153, -138, -180, -170, and, -194 accounted for about 99 and 87% of the total PCB content (sum of the 12 congeners, nos. 28, 99, 153, 138, 128 + 187, 156, 157, 180, 170, 194, 206 and 209) in liver and fat, respectively. PCB-153 represented 37+/-3 30+/-16% of the sum PCB (sum of 12 congeners) in liver and fat, respectively. The range of the hepatic concentration of oxychlordane was 5-19 microg g(-1). Quantifiable concentrations of heptachlor, heptachlorepoxide, beta-HCH and dieldrin were also found in all the liver samples analysed. Low concentrations of p,p'- and o,p'-DDT were found in two of seven liver and two of two fat samples. Comparisons are made with investigations from Canada and Greenland. Possible effects of PCBs, especially on reproduction, cannot be excluded. Ringed seal, Foca hispida, and to some extent bearded seal, Erignathus barbatus, are the main food of the polar bear. It is therefore likely that the exposure to environmental pollutants occurs via the consumption of these two species.     

Levels and congener pattern of PCBs in arctic fox, Alopex lagopus, in Svalbard

Levels and congener pattern of polychlorinated biphenyls (PCBs) were determined in samples of subcutaneous fat and liver from 27 polar foxes, Alopex lagopus, caught in Svalbard during the winter 1983-1984. In all the samples analysed the composition of individual PCB congeners was studied by comparison with 12 individual PCB congeners (IUPAC nos. 28, 52, 101, 118, 138, 153, 170, 180, 183, 194, 206 and 209). In addition, the PCB congeners nos. 99, 105, 114, 156 and 157 were determined in the fat samples. In both liver and fat samples the sum PCB was calculated based on the concentrations of seven selected congeners, nos. 138, 153, 170, 180, 194, 206 and 209. These congeners were the same as those used in a corresponding investigation made on arctic fox from Svalbard 10 years earlier. The present study reveals that the PCB levels in arctic fox in Svalbard are high and essentially unchanged in the period from 1973-1974 to 1983-1984. The mean sum PCB levels in fat and liver were 8.3 +/- 11 and 0.4 +/- 0.4 microg g(-1), and the extractable fat was 81.2 +/- 8.4 and 4.5 +/- 1.7% for the two tissues, respectively. In fat, sum PCB ranged from 0.5 to 41.0 microg g(-1). PCB nos. 153 and 180 accounted for approximately 65% of sum PCB. The contributions of PCB nos. 138 and 153 to the sum PCB were found to increase from 1974 to 1984. The PCB congener pattern is similar to that found in polar bears, and is dominated by a few congeners (99, 138, 153, 170, 180 and 194). No significant differences in PCB levels were found between sexes or between age groups. However, significantly higher PCB levels were found in old animals (>/= 3 years) with less than 2 cm of fat on the ramp as compared with young animals (1-2 years) with more than 2 cm of fat on the rump. Effects on vital functions from the observed levels of PCBs cannot be excluded for the most contaminated foxes.     

Bioavailability of PCDDs and PCDFs on fly ash after semi-chronic oral ingestion by guinea pig and syrian golden hamster

Groups of guinea pigs and syrian golden hamster (n = 5) were fed 2.5% HCL pre-treated fly ash from the electrostatic precipitator of a municipal incinerator during one, two and three months, respectively, in the diet. The livers were analyzed for tetra-, penta- and hexa-chlorinated dibenzo(p)dioxins (PCDDs) and dibenzofurans (PCDFs).In the livers of the hamsters 2,3,7,8-substituted PCDDs and PCDFs were the major isomers retained. In the livers of the guinea pigs 2,3,7,8 substituted PCDDs and PCDF congeners were retained, but also a number of otherwise substituted PCDFs. These other PCDF congeners included some having a 2,3,6,7 or alternate chlorine substitution pattern. Those congeners retained in the livers were generally below 5% of the group dose. The PCDF congener which had the highest retention in the livers of guinea pig was 1,2,3,7,8-PnCDF, 11.3% after 95 days. In the livers of the hamsters highest retention was found for 2,3,4,7,8-PnCDF, 8.4% after 95 days. For most 2,3,7,8-substituted PCDDs and PCDFs the retention in the livers of the guinea pigs and hamsters was not significantly different during the whole period, which could indicate a bioconcentration approaching a linear relationship to the administered dose. Constant relative concentrations in the livers were found for the 2,3,7,8- substituted penta- and hexa-chlorinated PCDDs and PCDFs in both species during the three time periods.     

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in human liver and adipose tissue samples from Belgium

Levels of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) were measured in paired human adipose tissue and liver samples (n=25) from Belgium. Average concentrations and standard deviation of sum PBDEs (congeners 28, 47, 99, 100, 153, 154 and 183) were 5.3+/-3.0 (range 1.4-13.2) and 3.6+/-2.1 (range 1.0-10.0)ngg(-1) lipid weight (lw) in adipose tissue and liver, respectively. These concentrations were similar to reported PBDE data from Belgium and were at the lower end of the concentration range reported elsewhere in the world. In both tissues under study, BDE 153 and BDE 47 were the most abundant PBDE congeners, contributing approximately 35% and 25% to the total PBDE content. Average concentrations and range of PCBs (sum of 23 congeners) were 490 (range 70-1130) and 380 (range 90-1140)ngg(-1)lw in adipose tissue and liver, respectively. No correlation between age and concentrations of PBDEs could be found (r=0.04), while PCB concentrations correlated significantly with age (r=0.62, p<0.01, for the sum PCBs; r=0.64, p<0.01 for PCB 153 alone). Factors, such as exposure pathways (food, dust and air), rates of bioaccumulation, metabolism and elimination, influence the concentrations of PBDEs differently than those of PCBs in humans.     

The assimilation of dioxins and PCBs in conventionally reared farm animals: occurrence and biotransfer factors

The assimilation of PCDD/Fs and PCBs in chickens, pigs and sheep was investigated in studies using conventional animal husbandry practices. Closely matched samples of muscle (meat), liver, kidneys, eggs, milk, feed, soil and grass were collected of which 105 were analysed. The data obtained were consistent with the PCB and PCDD/F TEQ concentrations to be expected in rural background locations. A slight decline in TEQ values in meat with increasing age was evident in pigs, sheep and broiler chickens. Higher TEQ values in meat from outdoor pigs compared to those raised indoors, and an increase in TEQs in eggs as a result of free-range conditions might be attributable to additional contaminant intakes from soil. TEQ values in samples of sheep meat were slightly higher than those for pigs and chickens and market ready lowland sheep showed higher meat TEQs than the highland species. PCDD/F TEQs were considerably higher in the liver than meat. Contaminant transfer from dietary sources was investigated using biotransfer factors (BTFs) which tended to be higher in chickens than in sheep or pigs. BTFs for all animals declined in magnitude with age, but on average, BTFs for pigs and chickens showed a sharper initial decline than for sheep. The relative magnitude of the BTFs usually followed the order: (highest first) PCB 153, PCB 169, PCB 126, 1,2,3,7,8-PeCDD/2,3,4,7,8-PeCDF and 2,3,7,8-TCDD. This may suggest that higher chlorinated congeners accumulate more readily in meat tissues. Congener-specific BTF variations were found to be associated with variables such as dietary composition during rearing, differences between feed and animal species.     

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.     

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.     

Bioconcentration of ibuprofen in fathead minnow (Pimephales promelas) and channel catfish (Ictalurus punctatus)

Pharmaceutical products and their metabolites are being widely detected in aquatic environments and there is a growing interest in assessing potential risks of these substances to fish and other non-target species. Ibuprofen is one of the most commonly used analgesic drugs and no peer-reviewed laboratory studies have evaluated the tissue specific bioconcentration of ibuprofen in fish. In the current study, fathead minnow (Pimephales promelas) were exposed to 250 μg L⁻¹ ibuprofen for 28 d followed by a 14 d depuration phase. In a minimized bioconcentration test design, channel catfish (Ictalurus punctatus) were exposed to 250 μg L⁻¹ for a week and allowed to depurate for 7 d. Tissues were collected during uptake and depuration phases of each test and the corresponding proportional and kinetic bioconcentration factors (BCFs) were estimated. The results indicated that the BCF levels were very low (0.08-1.4) implying the lack of bioconcentration potential for ibuprofen in the two species. The highest accumulation of ibuprofen was observed in the catfish plasma as opposed to individual tissues. The minimized test design yielded similar bioconcentration results as those of the standard test and has potential for its use in screening approaches for pharmaceuticals and other classes of chemicals.     

Metabolism of DDT in different tissues of young rats

The bioconcentration and distribution pattern of p,p'-DDT 1,1,1-1trichloro-2,2-bis(2-chlorophenyl-4-chlorophenyl)-ethane] and its main metabolites (p,p'-DDD [1,1-dichloro-2,2-bis (4-chlorophenyl) ethane] and p,p'-DDE [1,1-dichloro-2,2-bis (4-chlorophenyl) in adipose tissue, liver, brain, kidney, thymus, and testis were examined in young rats after 10 days of intraperitoneal injection of 50 and 100 mg of p,p'-DDT/kg of body weight. Analyses were performed by high-resolution gas chromatography. p,p'-DDT was found to be accumulated in a dose-dependent manner with the highest concentration in adipose tissue. However, in brain, the accumulation of pesticide was low and remained unchanged at the higher dose. This difference may relate to the protective role of the blood-brain barrier, which limits the access of the xenobiotic in the cerebral compartment, and to the differential tissue lipid composition. Although tissues concentration of p,p'-DDE and p,p'-DDD correlated positively to total p,p'-DDT levels, the active role in detoxification of pollutants may explain why p,p'-DDD is more abundant in liver than in the rest of organs. On the contrary, in brain, the concentration of p,p'-DDE is higher than that of p,p'-DDD, suggesting that the metabolism of the parent insecticide proceeds via more than one pathway.     

Tissue-specific congener composition of organohalogen and metabolite contaminants in East Greenland polar bears (Ursus maritimus)

Congener patterns of the major organohalogen contaminant classes of PCBs, PBDEs and their metabolites and/or by-products (OH-PCBs, MeSO2-PCBs, OH-PBDEs and MeO-PBDEs) were examined in adipose tissue, liver, brain and blood of East Greenland polar bears (Ursus maritimus). PCB, OH-PCB, MeSO2-PCB and PBDE congener patterns showed significant differences (p相似文献