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Archives of Environmental Contamination and Toxicology (v.37, #1)
Determination of Warfarin in Waters and Human Plasma by Solid-Phase Room-Temperature Transmitted Phosphorescence by L. F. Capitán-Vallvey; M. K. A. Deheidel; R. Avidad (pp. 1-6).
A new method for the determination of warfarin in waters and human plasma using solid-phase room-temperature phosphorescence is proposed. The sample was spotted on Whatman No. 4 filter paper, together with iodide and NaOH solutions, after which it was dried and its transmitted phosphorescence intensity measured at 467 nm using two quartz plates to avoid the quenching effect produced by oxygen. The applicable concentration range went from 0.3 to 4.0 mg · L−1, and the detection and quantification limits were 0.08 and 0.28 mg · L−1 respectively. The precision of the method, as a relative standard deviation, was 2.3%. The method was applied in the determination of warfarin in human plasma and different types of water. The interferences produced by the albumin of the human plasma were eliminated by the addition of Na2SO4 saturated solution. Recoveries ranging between 93.0 and 109.0% in the case of water samples, and between 95.0 and 103.0% in the case of human plasma, were obtained. These results were compared with the results obtained by other methods.
Distribution of Trace Elements in Streambed Sediment Associated with Mining Activities in the Upper Colorado River Basin, Colorado, USA, 1995–96 by J. R. Deacon; N. E. Driver (pp. 7-18).
Streambed-sediment samples were collected in the Southern Rocky Mountains physiographic province in the Upper Colorado River Basin in Colorado to characterize the occurrence and distribution of trace elements in mined and nonmined areas of the basin. During October 1995 and September 1996, streambed sediment was collected at 37 sites, and the samples were analyzed for trace elements. The ranges in concentrations of As, Cd, Cu, Pb, and Zn at mining sites generally were orders of magnitude higher than the ranges of concentrations at nonmining sites. Sampling sites located in two predominant rock types in mining areas were not significantly different (p > 0.05) for concentrations of As, Cd, Pb, and Zn. Cu was significantly different (p < 0.05) between sites in the two predominant rock types. Concentrations of As, Cd, Cu, Pb, and Zn were not significantly different (p > 0.05) between main-stem sites and tributary sites. Concentrations of As, Cd, Cu, Pb, and Zn exceeded established guidelines for adverse effects on aquatic biota at some sites in the study area. The patterns in concentrations of Cd and Zn, Cd and Pb, and Pb and Zn were highly correlated to one another in this study. Concentrations of trace elements in the <63-μm fraction were higher than in the total particle-size fraction analysis. Comparison of reference sites to sites affected by a mine source indicated that trace-element concentrations initially increased downstream of the source and then gradually decreased in concentration with distance from the source.
Translocation of Microbenthic Algal Assemblages Used for In Situ Analysis of Metal Pollution in Rivers by N. Ivorra; J. Hettelaar; G. M. J. Tubbing; M. H. S. Kraak; S. Sabater; W. Admiraal (pp. 19-28).
Effects of metal pollution from a zinc factory on microbenthic algal communities were assessed in three neighboring streams on the Dutch-Belgian border. Diatom species composition was experimentally related to water quality by transferring racks with colonized glass discs from a polluted stream to a reference stream and vice versa. The succession of species and the changes in biomass and metal accumulation were measured during experiments in spring, autumn, and winter. Metal concentrations and dry weight in translocated biofilms tended to conform with those in local biofilms within an incubation time of 14 to 18 days. Bray-Curtis similarity values from the different communities indicated that diatom communities responded more completely to the metal-polluted conditions than to the reference water quality. Cymbella minuta, Diatoma vulgare var. ehrenbergii, Navicula sp., and Melosira varians had a lower percentage in assemblages placed in the metal-polluted streams. In contrast, Pinnularia sp. and Neidium ampliatum decreased in assemblages from the polluted streams that were transferred to the reference stream. Achnanthes minutissima and Navicula seminulum (N. atomus) proliferated on any translocation, possibly reflecting an opportunistic strategy and a high tolerance for Zn and Cd. The behavior of the species in relation to metal pollution generally accorded with observations in the literature. However, it seems that metal tolerance is not the only selective factor, and other ecological variables may also influence the composition of microphytobenthic communities.
Toxicity of Formulated Glycol Deicers and Ethylene and Propylene Glycol to Lactuca sativa, Lolium perenne, Selenastrum capricornutum, and Lemna minor by D. A. Pillard; D. L. DuFresne (pp. 29-35).
Laboratory studies were conducted to determine the toxicity of ethylene glycol (EG) and propylene glycol (PG) as well as two formulated glycol aircraft deicing/anti-icing fluids (ADAFs) to lettuce (Lactuca sativa), perennial ryegrass (Lolium perenne), a green alga (Selenastrum capricornutum), and duckweed (Lemna minor). Seedling emergence, root length, and shoot length were measured in lettuce and ryegrass; cell growth of the alga and frond growth, chlorophyll a, and pheophytin a of the duckweed were measured. While both the ADAFs and pure glycols were toxic to the test species, there were substantial differences in how the organisms responded to the test materials. ADAFs affected emergence in ryegrass more than in lettuce. However, when considering the sublethal endpoints of root and shoot length, the ADAFs were significantly more toxic to lettuce. The root length 120-h IC25s for lettuce were 2,710 and 21,270 mg EG/L for the ADAF and pure EG compound, respectively; the root length 120-h IC25s for ryegrass were 4,150 and 3,620 mg EG/L for the ADAF and pure EG compound, respectively. EG and PG ADAFs were more toxic than pure EG or PG to L. minor. To S. capricornutum, EG ADAF toxicity was similar to EG toxicity, however, PG ADAF was substantially more toxic to the alga than pure PG. The greater toxicity of ADAFs is reflective of other studies using animals and suggests that although glycols no doubt contribute to toxicity in deicer formulations, other compounds in the mixtures also contribute to the toxicity of the deicers. However, differences in responses between the four plant species suggest differences in modes of action and/or how the plants metabolize the compounds.
Effect of Atrazine on Growth, Photosynthesis, and Between-Strain Variability in Scenedesmus subspicatus (Chlorophyceae) by R. Behra; G. P. Genoni; A. L. Joseph (pp. 36-41).
The magnitude of between-strain differences in the sensitivity of algal species to toxicants is not well known. Yet, informations obtained with a single strain are used for ecotoxicological assessment and for interspecific comparisons. Using 12 strains, we determined whether intraspecific variability occurs in the green alga Scenedesmus subspicatus. We examined growth, photosynthetic activity, and short-term sensitivity thereof to the herbicide atrazine (500 μg · L−1) as well as how these responses are affected by chronic exposure to low atrazine concentrations (0, 1, 5, and 20 μg · L−1). Independent of chronic exposure to atrazine, the strains differed in growth rate and photosynthesis rate. Yet the short-term sensitivity to atrazine was affected by the chronic treatments. All but one strain became more tolerant, their short-term sensitivity being inversely related to the applied atrazine concentration and dependent on the duration of exposure. Differences in response to increments in atrazine concentration resulted in differences in rank order of sensitivity of strains. Moreover, between-strain variability was markedly higher in the atrazine treatments than in the controls. These results can be explained by the significant role of genotype versus environment interactions in determining intraspecific differences in adaptive physiological responses of S. subspicatus to chronic exposure to atrazine.
Body Residues and Responses of the Midge Chironomus riparius to Sediment-Associated 2,4,5-Trichlorophenol in Subchronic and Chronic Exposures by T. Ristola; J. V. K. Kukkonen; J. Pellinen (pp. 42-49).
Subchronic and chronic toxicity of sediment-associated 2,4,5-trichlorophenol to the midge Chironomus riparius was determined by conducting a 10-day growth and a 50-day emergence tests with spiked lake sediment (nominal initial TCP concentrations were 25, 51, 101, 203, 304 and 405 μmol kg−1 dry weight in the growth test and 25, 76, 152 and 304 μmol kg−1 dry weight the emergence test). In addition, we measured the residue of chlorophenol in larval tissue and made an attempt to relate it with the observed adverse biological responses. The larvae were exposed individually to avoid density-dependent effects of mortality on food ration and growth of the surviving larvae. In the growth test, mortality was low at sediment concentrations ≤193 μmol TCP kg−1, but it increased sharply at the higher concentrations being 37 and 94% at 334 and 441 μmol kg−1 DW, respectively. The effect of sediment TCP concentration on larval mortality was highly significant (10-day LC50 337 μmol TCP kg−1 dry sediment) in the growth test. In the emergence test, however, mortality was low (3–13%) at all concentrations. TCP did not affect larval growth at the concentrations used. The concentration of TCP in the whole larvae after the 10-day exposure was proportional to sediment concentration, being at highest 160 μmol kg−1 fresh weight. When the average body residues of TCP were below 80 μmol kg−1, mortality was low, but it increased when the body residue approached 100 μmol kg−1. After the 10-day exposure, the body residue, at which 50% of the larvae survived (CBR50) was 113 μmol g−1. TCP exposure accelerated larval development and the midges exposed to 171 and 324 μmol TCP kg−1 emerged earlier than those in the other concentrations or in the control sediment. In natural environments, sediment-associated chlorophenolics are probably not a major environmental problem to benthic fauna because concentrations similar to that which we observed to cause adverse effects to C. riparius (>60 mg kg−1 dry sediment) are rare.
Distribution and Specific Bioaccumulation of Butyltin Compounds in a Marine Ecosystem by S. Takahashi; S. Tanabe; I. Takeuchi; N. Miyazaki (pp. 50-61).
Butyltin compounds (BTs), including tributyltin (TBT) and its breakdown products, di- (DBT) and monobutyltin (MBT), were determined in sea water, sediment, and biota at various trophic levels in the food chain collected from Otsuchi Bay, Japan, for understanding distribution and bioaccumulation of BTs in natural marine ecosystems. BT residues were detected in all the compartments analyzed, although their concentrations appeared to be less than those in polluted areas. Concentrations of BTs in sea water were higher in locations near Otsuchi Port, indicating that maritime activities in the harbor has been a major source of BTs in this bay. A specific peak in BT residue levels was found in sediment cores at an estimated depth that dated to be from the 1980s. Lack of significant variation in the composition of BTs at different depths of cores suggests slow degradation rate of these compounds in sediments. BTs were accumulated in plankton and other organisms up to ∼70,000 times higher than in sea water. However, no considerable biomagnification was observed for BTs through the food chain. Relatively high concentrations were found in caprellids and smaller fish, such as gunnels. These organisms accumulated TBT as the predominant compound among BT derivatives and showed higher bioconcentration factors for TBT than in other species reported so far. Our results suggest that certain organisms in the food chain may have a less capacity to degrade TBT, and therefore may accumulate BTs at elevated levels.
An Enzyme-Linked Immunosorbent Assay for Estrogenicity Using Primary Hepatocyte Cultures from the Channel Catfish (Ictalurus punctatus) by G. H. Monteverdi; R. T. Di Giulio (pp. 62-69).
An in vitro assay has been developed to screen for estrogenic activity of single chemicals or complex mixtures. This method combines primary hepatocyte cultures from the channel catfish (Ictalurus punctatus) with an enzyme-linked immunosorbant assay (ELISA) to detect and quantify the production of vitellogenin (VTG), a liver-derived, estrogen-induced lipoprotein. A variety of environmentally relevant chemicals and chemical mixtures were tested, including the polyaromatic hydrocarbon benzo(a)pyrene (BaP), the alkylphenolic surfactants 4-tert-octylphenol (OP) and p-nonylphenol (NP), the chlorinated insecticide o,p′-DDT, the plant derivative stigmastanol, and a number of waste waters from pulp and paper mills. In addition, the effects of estradiol (E2), the synthetic estrogen diethylstilbestrol (DES) and the antiestrogens trans-1-(4-β-dimethylamino-ethoxyphenyl)-1,2-diphenylbut-1-ene (tamoxifen) and 7α-[9-(4,4,5,5,5-pentafluoro-pentylsulfinyl)nonyl]estra-3,17β-diol (ICI-182,780) were also examined. The following compounds were observed to be estrogenic: DES > E2 ≫ OP > o,p′-DDT > NP. Tests with BaP, stigmastanol, tamoxifen, ICI-182,780, and four paper mill effluents exhibited no detectable estrogenic activity. Furthermore, both tamoxifen and ICI-182,780 significantly reduced VTG synthesis by cells incubated with E2 or DES. Stigmastanol and the mill effluents were also tested for anti-estrogenic activity in cells incubated in media containing both DES and stigmastanol or effluent. Compared to DES alone, none of these treatments caused a significant reduction in the media concentrations of VTG. The detection limit for this assay was typically 15–25 ng VTG/ml medium. Screening results and performance characteristics such as inter- and intra-assay variability were similar to those reported for VTG assays for other teleost species. Thus, the present work provides a sensitive, rapid means for screening the estrogenic potency of environmentally relevant chemicals and chemical mixtures in vitro.
Alteration of Leopard Frog (Rana pipiens) Metamorphosis by the Herbicide Acetochlor by A. O. Cheek; C. F. Ide; J. E. Bollinger; C. V. Rider; J. A. McLachlan (pp. 70-77).
Based on the geographic correlation between the use of the pre-emergent herbicide acetochlor [2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl) acetamide] and the natural range of Northern leopard frogs (Rana pipiens), we investigated the effects of acetochlor (ACETO) on frog metamorphosis. We specifically examined the interaction of ACETO with thyroid hormone (T3) and corticosterone (CORT), hormones that regulate natural metamorphosis. ACETO, T3, and CORT were administered via immersion. Growth, developmental stage, and onset of metamorphic climax (forelimb emergence, FLE) were measured. We examined three hypotheses: (1) ACETO may alter metamorphosis. Premetamorphic tadpoles with low endogenous T3 were exposed to ACETO ± 10−9 M T3 for 7 days. 67% of tadpoles exposed to ACETO + T3 attained FLE, while 0% of T3 treated animals did. (2) ACETO mimics T3 action at the thyroid receptor (TR). Tadpoles were pretreated with T3 for 3 days to induce TR expression, then treated for 7 days with vehicle (DMSO), T3, or ACETO ± T3. ACETO treatment after T3 priming did not accelerate FLE, suggesting that ACETO does not interact directly with the TR. Cotreatment with ACETO + T3 after T3 priming accelerated FLE relative to tadpoles primed with T3, then treated with T3. Because the ACETO + T3 acceleration of FLE appeared similar to the effect of CORT, we examined a third hypothesis: (3) ACETO may interact with CORT to accelerate FLE. Premetamorphic tadpoles were exposed to various doses of ACETO ± T3 in the presence or absence of 10−7 M CORT. CORT inhibited growth and hindlimb development and delayed FLE. ACETO never inhibited growth or hindlimb development, but ACETO did counteract the effects of CORT when T3 was present. ACETO consistently accelerated T3-induced metamorphosis, apparently interacting with T3 via a non-TR–mediated mechanism.
Induction of Hsp70 by the Herbicide Oxyfluorfen (Goal) in the Egyptian Nile Fish, Oreochromis niloticus by H. M. A. Hassanein; M. A. Banhawy; F. M. Soliman; S. A. Abdel-Rehim; W. E. G. Müller; H. C. Schröder (pp. 78-84).
This paper deals with the expression of the biomarker hsp70 in the liver and kidney of the freshwater fish Oreochromis niloticus following exposure to the herbicide oxyfluorfen (Goal). Fishes were exposed to three concentrations, the 96-h LC50 (3 mg/L), the 96-h ½LC50 (1.5 mg/L), and the 96-h ¼LC50 (0.75 mg/L) of oxyfluorfen for 6, 15, and 24 days, respectively, and samples were taken at three different time periods for each concentration. The livers responded to the herbicide by an induction of the expression of both the constitutive (hsp75; Mr 75 kDa) and the inducible (hsp73; Mr 73 kDa) hsp70 proteins. In kidney, the herbicide induced a time-dependent increase in the expression of the constitutive hsp70 (hsp75) as well, but the inducible hsp70 (hsp73) required much longer incubation periods to reach maximal levels (15 and 24 days). Our results suggest that expression of hsp70 in fish is a sensitive indicator of cellular responses to herbicide exposure in the aquatic environment.
Toxicity of 4-Chloroaniline in Early Life Stages of Zebrafish (Danio rerio): II. Cytopathology and Regeneration of Liver and Gills After Prolonged Exposure to Waterborne 4-Chloroaniline by P. Burkhardt-Holm; Y. Oulmi; A. Schroeder; V. Storch; T. Braunbeck (pp. 85-102).
Ultrastructural alterations in liver and gills of embryonic and larval zebrafish (Danio rerio) following prolonged exposure to waterborne 0.05, 0.5, and 5 mg/L 4-chloroaniline for up to 31 days as well as after a 14-day regeneration period were investigated by means of light and electron microscopy. Acute toxicity was also tested at 25 and 50 mg/L. Survival of zebrafish embryos and larvae was only impaired from 25 mg/L 4-chloroaniline, but—after a transient stimulation following exposure to 0.5 mg/L—4-chloroaniline hatching was retarded after exposure to ≥5 mg/L, and fish displayed increasing rates of abnormal development and pigmentation. In contrast, hepatocytes displayed a time- and dose-dependent response from 0.05 mg/L 4-chloroaniline, including changes in nuclei, mitochondria, peroxisomes, endoplasmic reticulum, Golgi fields, lysosomes, and hepatic glycogen and lipid stores, as well as invasion of macrophages. In gills, dose-dependent effects were evident from 0.5 mg/L 4-chloroaniline and included deformation of secondary lamellae due to vacuolization and desquamation of respiratory epithelial cells in conjunction with dilation of intercellular spaces. Respiratory epithelial cells displayed progressive mitochondrial changes, induction of cytoplasmic myelinated structures, augmentation of lysosomes, and modifications of Golgi fields. Erythrocytes were severely deformed. A 14-day regeneration period was sufficient for almost complete recovery of pathological symptoms in both liver and gills. Only minor volumetric changes in hepatocellular organelles and a limited number of myelinated bodies, lysosomes, and cytoplasmic vacuoles were reminiscent of prior 4-chloroaniline exposure. In both qualitative and quantitative terms, most effects in hepatocytes after exposure of embryonic and larval zebrafish to waterborne 4-chloroaniline are comparable to the reaction of hepatocytes in adult zebrafish liver after prolonged sublethal exposure as well as in larval zebrafish after microinjection. Morphological changes in erythrocytes indicate disturbance of respiration as an additional mode of action of 4-chloroaniline.
Uptake of Mercury by Fish in an Experimental Boreal Reservoir by R. A. Bodaly; R. J. P. Fudge (pp. 103-109).
We studied the uptake of mercury (Hg) by finescale dace (Phoxinus neogaeus) in an experimental boreal reservoir for 2 years prior to flooding and 3 years after flooding, and in a natural wetland pond over the same 5-year period. Hg uptake was much higher after flooding as compared to uptake before flooding and in the natural pond. After flooding, Hg concentrations in late summer were usually 2–3× higher than concentrations observed prior to flooding. Net uptake of Hg by fish over the summer in the experimental reservoir was 0.25 and −0.07 μg per fish in the 2 years before flooding as compared to 0.63, 0.64, and 0.42 μg per fish in the 3 years after flooding. Thus, Hg uptake by fish responded quickly to flooding and was highest in the first 2 years following impoundment. Uptake in the reference pond ranged from 0.10 to 0.28 μg of Hg per fish over the same 5-year period. Calculated fluxes of Hg on an areal basis ranged from 0.04–0.09 μg m−2 year−1 in the reference pond, were 0.08 and −0.02 μg m−2 year−1 in the experimental reservoir prior to flooding, and ranged from 0.14–0.22 μg m−2 year−1 in the experimental reservoir after flooding. These fluxes were much smaller than fluxes of methyl mercury (MeHg) through the zooplankton and emerging insect communities. Most (71–89%) of the mercury measured in the muscle of finescale dace was MeHg, and the proportion that was MeHg decreased over the summer period prior to flooding, but increased over the summer after flooding. Growth of fish was not significantly affected by flooding. Fish ate predominantly benthic invertebrates (64–84% of food items found in stomachs), with lesser proportions of crustacean zooplankton (16–31% of items found in stomachs) and feeding was similar after as compared to before flooding. Therefore, differences in Hg uptake did not appear to be the result of changes in diet.
Sex-Related Levels of Selenium, Heavy Metals, and Organochlorine Compounds in American White Pelicans (Pelecanus erythrorhyncos) by G. M. Donaldson; B. M. Braune (pp. 110-114).
Liver tissue from male and female adult American white pelicans (Pelecanus erythrorhyncos) were individually analyzed for organochlorine compounds and trace elements. Levels of most organochlorines, specifically ΣDDT, ΣPCB, Σchlordane, Σmirex, dieldrin, and ΣCBz, were significantly higher in male pelicans compared to females. Only concentrations of ΣHCH were not significantly different between sexes. Male livers also contained higher concentrations of mercury, cadmium, and arsenic compared to females. Selenium concentrations were not different between sexes, and lead was not detected in any of the samples. Differences in residue levels between sexes were probably due to the female's ability to excrete organochlorines and some trace elements into the egg prior to laying. In addition, differences in contaminant concentrations in prey available to these birds on their breeding grounds and their wintering areas may be influencing sex-related differences.
Effects of Food Restriction on Food Avoidance and Risk of Acute Poisoning of Captive Feral Pigeons from Fonofos-Treated Seeds by J. A. Pascual; S. L. Fryday; A. D. M. Hart (pp. 115-124).
Fonofos is a highly toxic insecticide to birds that, when used as a cereal seed treatment, has caused mortality of free-living feral pigeons (Columba livia). Pigeons kept individually under ad libitum feeding conditions in the laboratory do not suffer lethal poisoning because they develop a strong avoidance response to fonofos-treated seed, which restricts consumption to below lethal levels. Two laboratory experiments were conducted to assess the role of avoidance in reducing the risk of acute poisoning of captive birds under food stress. In the first experiment, pigeons acclimatized to feed on untreated wheat seeds for 6 h/day were presented with fonofos-treated seeds for 6 h on a testing day, following normal food surplus in one experimental group (eight birds) and 6 days of deprivation in another (eight birds). In the second experiment, different pigeons were acclimatized to a feeding regime of 2 h/day and treated seeds were offered without previous restriction (eight birds) or after 6 days of food restriction in which birds were given 15% of normal intake (eight birds). In the second experiment, six birds in each experimental group were videotaped to study their feeding behavior. Survivors at the end of the testing day were killed, and all birds were dissected and analyzed to determine carcass and pectoral muscle composition. Food-stressed birds lost ∼11% of their initial body weight during 6 days of total or partial food restriction, but they still had visible fat deposits and a high body fat content, indicating that they were in good body condition in terms of energy reserves. Consumption of treated seeds on the testing day was reduced in comparison with normal intake of untreated seed in all birds, but there were differences between experimental groups. In ad libitum–fed birds, consumption of treated seed in each experiment averaged 12% and 19% of normal levels, exposure to fonofos was below lethal levels, and no bird died. In food-stressed birds, consumption was higher (34% or 56% of normal levels for the first and second experiments, respectively) and led to the ingestion of seed containing lethal doses of pesticide. Two birds in the first experiment and three in the second died of acute poisoning within around 2 h of initial exposure. The avoidance response developed quickly in both ad libitum–fed and food-stressed birds. Feeding took place in most birds almost exclusively in the first 9 min of the testing day. Within this interval, birds of the two experimental groups stopped ingesting treated seeds around 6 min after the onset of feeding. The differences between experimental groups in consumption of treated seed were due to the higher feeding rate and effective feeding time in food-stressed birds. It is concluded that although feral pigeons under severe food stress develop an early and strong conditioned food aversion to fonofos-treated seeds, avoidance does not always prevent mortality. The need for including hunger stress as a factor in avian dietary toxicity tests to make testing conditions more representative of those experienced by wild birds is discussed.
Organochlorines in Stranded Pilot Whales (Globicephala melaena) from the Coast of Massachusetts by K. L. Tilbury; N. G. Adams; C. A. Krone; J. P. Meador; G. Early; U. Varanasi (pp. 125-134).
Pilot whales strand periodically along the U.S. coast, and these strandings offer an opportunity for the collection of tissues for biomonitoring of contaminant exposure in cetaceans, as well as for specimen archiving. Concentrations of organochlorine (OC) contaminants (e.g., PCB congeners, pesticides, DDTs) were measured in tissue samples from pilot whales that stranded in 1986 and 1990 along the Massachusetts coast. Adult and fetal samples of blubber, liver, brain, and kidney were collected, as well as ovaries from mature female whales. Many of the OCs found in maternal tissues were detected in corresponding fetal tissues indicating maternal transfer of OCs to the fetus. The concentrations of individual OCs in tissues varied considerably among the animals. Statistically significant differences were found between females and males for the concentrations of certain analytes (e.g.,ΣPCBs, p,p′-DDE) and these differences may be partially due to contaminants being transferred by the female whales during gestation and lactation. The concentrations of OCs in different tissues were similar when based on total lipid weight, except for the brain, which contained the lowest lipid-normalized OC concentrations. The low concentrations in brain may be related to the disparate lipid compositions in this tissue as well as the presence of the blood-brain barrier. The availability of data on these archived and biomonitoring samples provides a baseline for future retrospective studies.
Tissue Distribution of Methylsulfonyl Metabolites Derived from 2,2′,4,5,5′-Penta- and 2,2′,3,4′,5′,6-Hexachlorobiphenyls in Rats by K. Haraguchi; Y. Kato; R. Kimura; Y. Masuda (pp. 135-142).
The time courses of fecal excretion and tissue distribution of metabolites derived from 2,2′,4,5,5′-pentachlorobiphenyl (CB101) and 2,2′,3,4′,5′,6-hexachlorobiphenyl (CB149) were investigated in male Wistar rats. The metabolism of both congeners involved primarily hydroxylation at the 3-position, and methylthiolation at the 4-position. Metabolites distributed in tissue were dominated by different ratios of 3- and 4-methylsulfonyl (MeSO2) metabolites. The 3-/4-MeSO2 metabolite ratios in liver and adipose tissue for both congeners were 0.41–0.61 at day 4, and then increased to 0.85–1.00 for up to day 42. In contrast, the ratios in lung were 0.03–0.04, and then decreased to 0.01. Compared to the unchanged PCBs at day 42, the distribution ratios of 3-MeSO2 metabolites were greater in the order of liver (0.46 for CB101 and 0.21 for CB149) > kidney > blood > lung > adipose tissue, whereas those of 4-MeSO2 metabolites were in the order of lung (9.50 for CB101 and 4.00 for CB149) > kidney > blood > liver > adipose tissue, indicating the different binding affinity of 3-MeSO2 metabolites in liver from that of 4-MeSO2 metabolites in lungs of rats. Furthermore, the structure-tissue affinity relationship for 3-MeSO2 metabolites was investigated, following the administration of 11 3-MeSO2-PCB congeners to rats. The results indicated that the retention potential of 3-MeSO2 metabolites in the liver largely depends on the ortho-chlorine substitution in the biphenyl ring rather than the degree of chlorination.