Forgot your password?
New user?
New Window Opens on the Secret Life of Microbes: Scientists Develop First Microbial Profiles of Ecosystems
CAS announces the release of SciFinder Scholar for Mac OS X
Press Releases
Press Releases
| Check out our New Publishers' Select for Free Articles |
Archives of Environmental Contamination and Toxicology (v.47, #3)
Environmental Contamination of Chrysotile Asbestos and Its Toxic Effects on Growth and Physiological and Biochemical Parameters of Lemna gibba by A. K. Trivedi; I. Ahmad; M. S. Musthapa; F. A. Ansari; Q. Rahman (pp. 281-289).
Asbestos was monitored in water, sediment, and aquatic plant samples around an asbestos cement factory. Based on asbestos concentration found in aquatic plants during monitoring, and the propensity of asbestos to cause oxidative stress in animal models, laboratory experiments were conducted to assess toxicity of chrysotile asbestos on an aquatic macrophyte, duckweed (Lemna gibba). L. gibba plants were exposed to two concentrations of chrysotile asbestos (0.5 μg and 5.0 μg chrysotile in 5.0 μl double distilled water) twice per week during a period of 28 days and cultured in medium containing 0.1 g chrysotile/L. Control plants were cultured in medium without chrysotile asbestos. Effect of chrysotile exposure on certain growth and physiological and biochemical parameters was evaluated. An inhibition effect of chrysotile exposure was found on the number of fronds, root length, and biomass. Similar alterations in contents of chlorophyll, carotenoid, total free sugar, starch, and protein were also found. Contrary to effect on these parameters, a dose- and time-dependent increase in efflux of electrolytes, lipid peroxidation, cellular hydrogen peroxide, catalase, and superoxide dismutase activity was found. The results indicate oxidative stress and phytotoxicity of chrysotile asbestos on duckweed.
Short-Term Toxicity and Binding of Platinum to Freshwater Periphyton Communities by S. Rauch; M. Paulsson; M. Wilewska; H. Blanck; G. M. Morrison (pp. 290-296).
The release of platinum (Pt) from automobiles equipped with exhaust catalysts has resulted in increasing concentrations of this normally rare metal in the urban and roadside environment. Although concentrations are increasing, little is known about the environmental effects of Pt and its potential toxicity. This study was an investigation of Pt toxicity to naturally grown periphyton communities. Periphyton communities were exposed to Pt(II) and Pt(IV) in reference and stream waters. Uptake increased linearly with Pt concentration for both reference- and stream-water exposure. However, decreased photosynthetic activity was observed only for reference-water exposure. This difference was related to uptake by biotic components in reference water and binding to abiotic components in stream water.
Evaluation of Bioaccumulation and Photo-induced Toxicity of Fluoranthene in Larval and Adult Life-Stages of Chironomus tentans by H.E. Bell; K. Liber; D.J. Call; G.T. Ankley (pp. 297-303).
Laboratory sediment tests were conducted to evaluate the bioaccumulation and photo-induced toxicity of fluoranthene in larval and adult life-stages of the midge, Chironomus tentans. In the first of 2 experiments, fourth-instar and adult C. tentans exposed to spiked sediments (204 μg fluoranthene/g dry weight) were collected for determination of fluoranthene tissue concentrations and toxicity after ultraviolet (UV) radiation treatment in the absence of sediment (water-only). Fluoranthene tissue concentrations in larvae collected after a 72-hour exposure period were 7 times greater than concentrations in adults collected on emergence from the same spiked sediments. Fluoranthene-exposed adults were tolerant of UV exposure (100% survival after 7 hours), whereas larvae were sensitive (0% survival after 1 hour). In the second experiment, C. tentans larvae were exposed for 96 hours to 2 sediment treatments (170 and 54 μg fluoranthene/g dry weight), after which fluoranthene tissue concentrations were determined and UV exposures conducted under water-only versus sediment conditions. Exposure to UV radiation, in conjunction with sediment, provided larvae with significant protection from photo-induced toxicity compared with the water-only exposure. Adults that emerged from the 2 sediment treatments were also analyzed for fluoranthene tissue residues and exposed to UV radiation. Fluoranthene tissue residues were higher in adult female than in adult male midges, but exuviae from both sexes contained higher fluoranthene concentrations than whole-body tissue, thus demonstrating that the molting process is a possible detoxification mechanism. Consistent with the greater tissue residue concentrations, female midges demonstrated a significant decrease in survival under UV exposure compared with male midges. These studies indicated that both the burrowing behavior of the larvae and the elimination of fluoranthene in molted exuviae are protective mechanisms against photo-enhanced PAH toxicity in this species.
Sediment Quality in Freshwater Impoundments at Savannah National Wildlife Refuge by P. V. Winger; P. J. Lasier (pp. 304-313).
Freshwater impoundments at Savannah National Wildlife Refuge (NWR), South Carolina, provide an important habitat for wildlife species, but degraded sediment quality in the Savannah River downstream of the discharge from two impoundments have caused concern about potential contaminant problems within the impoundments. The quality of sediments from five impoundments (impoundments no. 1, 2, 6, 7, and 17) on the NWR was evaluated using physical and chemical characterization, contaminant concentrations (metals, organochlorine pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons), and toxicity testing. Survival of Hyalella azteca (freshwater amphipod) exposed for 28 days to solid-phase sediments was not significantly different from controls, but growth was significantly decreased at several sites. Survival in 96-hour exposures to sediment pore water was significantly decreased at most sites. Factors contributing to the toxic responses were low pH (3.7 to 4.1), ammonia (20 mg/L), and increased concentrations of cations in the pore water. The excess of simultaneously extracted metals over the acid volatile sulfides in the sediments was also typical of sites displaying decreased sediment quality. Elemental concentrations in pore water were negatively correlated with pH, and the highest concentrations were observed in impoundment no. 7. The acidic nature of the sediment in this impoundment was exacerbated by recent draining, burning, and disking, which allowed oxidation of the previously anoxic wetland sediment. Sediment disturbance and mixing of vegetation into the sediments by disking may also have contributed to the formation of ammonia caused by microbial decomposition of the fragmented organic matter. Contaminants were not detected in sediments from the impoundments, but releases of acidic water with increased levels of sediment cations from the impoundments may have contributed to the degraded sediment conditions previously observed in the river. The practice of dewatering sediments for vegetation control may exacerbate the acidification of vulnerable sediments within impoundments of this NWR.
An Assessment of Five Australian Polychaetes and Bivalves for Use in Whole-Sediment Toxicity Tests: Toxicity and Accumulation of Copper and Zinc from Water and Sediment by C. K. King; M. C. Dowse; S. L. Simpson; D. F. Jolley (pp. 314-323).
The suitability of two polychaete worms, Australonereis ehlersi and Nephtys australiensis, and three bivalves, Mysella anomala, Tellina deltoidalis, and Soletellina alba, were assessed for their potential use in whole-sediment toxicity tests. All species except A. ehlersi, which could not be tested because of poor survival in water-only tests, survived in salinities ranging from 18‰ to 34‰ during the 96-hour exposure period. No mortality was observed in any of the species exposed to sediment compositions ranging from 100% silt to 100% sand for 10 days, thus demonstrating the high tolerance of the five species to a wide range of sediment types. All species showed decreased survival after exposure to highly sulfidic sediments in 10-day whole-sediment tests. In 96-hour water-only tests, survival decreased, and copper accumulation in body tissues increased with exposure to increasing copper concentration for all species except A. ehlersi, which again could not be tested because of its poor survival in the absence of sediment. S. alba and T. deltoidalis were the most sensitive species to aqueous copper (LC50s of 120 and 150 μg Cu/L, respectively). All species tested were relatively insensitive to dissolved zinc up to concentrations of approximately 1,000 μg/L. In addition and with the exception of N. australiensis, all species accumulated significant levels of zinc in their body tissues. Whole-sediment tests were conducted over a 10-day period with copper-spiked (1,300 μg/g) and zinc-spiked (4,000 μg/g) sediments equilibrated for sufficient time to ensure that pore water metal concentrations were well below concentrations shown to have any effect on organisms in water-only tests. Survival was decreased in the bivalves T. deltoidalis and S. alba after exposure to copper-spiked sediments, and all species—except T. deltoidalis, in which 100% mortality was observed—accumulated copper in their tissues. Exposure to zinc-spiked sediments significantly decreased the survival of only one species, T. deltoidalis. Both polychaetes appeared to regulate concentrations of zinc in their body tissues with no significant uptake of zinc occurring from the sediment phase. Of the five species assessed in this study, T. deltoidalis was found to be the most sensitive to copper- and zinc-contaminated sediments, and based on commonly used selection criteria (ASTM 2002a, ASTM 2002b, ASTM 2002c) is recommended for development as test species in whole-sediment toxicity tests.
Pyrene Biotransformation and Kinetics in the Hepatopancreas of the Isopod Porcellio scaber by G. J. Stroomberg; F. Ariese; C. A. M. van Gestel; B. van Hattum; N. H. Velthorst; N. M. van Straalen (pp. 324-331).
Various techniques exist for polycyclic aromatic hydrocarbon (PAH) determination in environmental samples, but an adequate risk assessment of PAHs should include aspects such as bioavailability of the contaminant and biotransformation capacity of the species under investigation. In this study, we provided an analysis of the kinetics of pyrene in the terrestrial isopod Porcellio scaber. Isopods were exposed to pyrene in their food (10 μg/g d/w) for 7 days followed by an elimination period of 7 days. The animals were dissected, and the hepatopancreases were analyzed for pyrene biotransformation products; nonmetabolised pyrene in the gut was also monitored. Concentrations of 1-hydroxypyrene in the hepatopancreas were very low. Almost all of the pyrene was found as three conjugates: pyrene-1-glucoside, pyrene-1-sulfate, and a third unknown 1-hydroxypyrene conjugate. Concentrations of the metabolites were extremely variable between individuals because of variable feeding activity. An apparent steady state was reached already after 24 hours of exposure, whereas elimination was complete 48 hours after ending the exposure. This rapid response to changes in the exposure concentration shows that terrestrial isopods have a high biotransformation capacity for PAHs. The data show that concentrations of parent PAHs will not provide a good indication of exposure in rapidly metabolizing invertebrates such as isopods; instead, pyrene metabolites may be considered a promising biomarker for bioavailability of PAH contamination in the field.
Elimination Rate Constants of 46 Polycyclic Aromatic Hydrocarbons in the Unionid Mussel, Elliptio complanata by W. A. Thorsen; D. Forestier; T. Sandifer; P. R. Lazaro; W. G. Cope; D. Shea (pp. 332-340).
Elimination rate constants (k 2), biological half-lives (t1/2), and the time required to reach 95% of steady-state (t 95) are reported for 46 individual polycyclic aromatic hydrocarbons (PAHs) including both parent and alkyl homologues, for the freshwater unionid mussel, Elliptio complanata. Elimination rate constants generally follow first-order kinetics and range from 0.04/day (d) for perylene to 0.26/d for 2,6-dimethylnapthalene, half-lives range from 2.6 to 16.5 d, and t 95 values range from 11.3 to 71.3 d. These values compare well with other k 2, t 1/2, and t 95 values reported in the literature for PAHs and other classes of hydrophobic organic contaminants. A linear regression of k 2 versus logK ow demonstrates dependence of PAH elimination on hydrophobicity, as measured by an r 2 value of 0.83, and produces the following regression equation: k 2 = −0.06 (logK ow) + 0.44. This study provides evidence that mussels experiencing different forms of physiological stress (e.g., handling stress and fungal or bacterial growth) can exhibit large variation in toxicokinetic parameters. These results are particularly relevant to the extrapolation of laboratory results to field situations.
Interspecific Variation of Metal Concentrations in Three Bivalve Mollusks from Galicia by Y. Saavedra; A. González; P. Fernández; J. Blanco (pp. 341-351).
There has been growing concern about the inflow of metals to the coastal areas because they can be toxic to aquatic and human life. Some studies have demonstrated the existence of species-specific differences in the metal concentrations of mollusks. We compared metal concentrations between Mytilus galloprovincialis, used as a water quality indicator, and two other bivalve species collected for human consumption (Venerupis pullastra and Cerastoderma edule) in different locations on the Galician coast (northwest Spain). M. galloprovincialis was found to be the best zinc and lead accumulator, whereas silver and arsenic were preferentially accumulated by V. pullastra and chromium and nickel by C. edule. Bivalve concentrations of mercury, cadmium, chromium, arsenic, silver, and zinc appeared to be linearly related to environmental concentrations, but this was not the case with copper, nickel, and lead in some species, which indicated that there is a nonlinear accumulation of these metals or an influence of the environmental conditions on species accumulation. The relationship between metal concentration in mussels and in the two other species varied with the metal and the species. In some cases the correlation was high, making it possible to use mussels as bioindicators for the other species. In other cases the correlation was moderate or low, therefore rendering mussels of little or no use in predicting the metal concentrations in the two other species. {texp}Commercial fisheries of bivalves are an important source of income to many coastal populations. Nevertheless, achieving compatibility between harvesting these resources and industrial development is a difficult task. Some industrial activities can produce significant heavy-metal contamination of mollusks as was evidenced by the mercury accidents in Japan, Sweden, Iraq, etc. (Mance 1987; Fergusson 1990). Consequently, the implementation of heavy-metal monitoring programs for shellfish is required to ensure the quality of the edible species. The European Union has dealt with this requirement through Council Directive 91/492/EC. Most national monitoring programs do not analyze the metal concentration in each harvested species and instead use the one or a few species that are assumed to be bioindicator species. Following this approach, metal concentrations in a bivalve species (usually mussels) are used to assess water quality, and it is assumed that all bivalves in good-quality water are safe for human consumption. This method does not hold when the metal accumulation characteristics of the target species are not similar to those of the bioindicator species, making the estimation of the risk incorrect. In Galicia, and in many other European areas, cockles (Cerastoderma edule) and clams (Venerupis pullastra) are species commercially important because of their high production and price. To prevent heavy-metal intoxication in these and other species, mussels (Mytilus galloprovincialis Lmk.) from the area were analyzed for heavy-metal content and used as bioindicators of metal contamination. However, the usefulness of M. galloprovincialis as an indicator of metal contamination in C. edule and V. pullastra has not been checked and—taking into account that several studies have demonstrated different bivalve species to differ substantially in their capability to accumulate various metals (Reinfelder et al. 1997; Wang and Fisher 1999; Chong and Wang 2000; Wang 2001)—it should be checked. Therefore, there is a need to evaluate both the usefulness of mussels as bioindicators and the actual concentrations of metals in these two species to guarantee their safety for consumption. In this study, we attempted to determine the how the metal concentrations of two poorly known species (V. pullastra and C. edule) compare with those of M. galloprovincialis in an area (the Galician coast) with diverse sources of metal pollution. We thus obtained an idea of the risk that these species represent as well as the usefulness of the concentrations found in mussels as an indicator for the other two species.
Increased Production and Excretion of Urea in the Kuruma Shrimp (Marsupenaeus japonicus) Exposed to Combined Environments of Increased Ammonia and Nitrite by S.-Y. Cheng; W. C. Lee; L. W. Shieh; J.-C. Chen (pp. 352-362).
Marsupenaeus japonicus (6.37 ± 1.29 g) individually exposed to 9 different combined solutions of ambient ammonia (C) and nitrite (C′) ammonia at 0.003 [control], 0.39, and 1.49 mmol/L combined with nitrite at 0.001 [control], 0.38, and 1.49 mmol/L in 30 ppt were examined for nitrogenous excretion accumulations of ammonia, nitrite, urea, and uric acid in tissues after 48 hours. M. japonicus exposed to 0.39 mmol/L ammonia–0.38 mmol/L nitrite displayed higher levels of urea-nitrogen (UNE) and organic-N (ONE) excretion by a factor of 2.2 and 5.7, respectively, compared with shrimp exposed only to 0.39 mmol/L ammonia. Exposure to 0.39 mmol/L ammonia–0.38 mmol/L nitrite resulted in lower levels of hemolymph uric acid (HUA), gill ammonia (GAM), gill urea (GUE), gill uric acid (GUA), hepatopancreas ammonia (HPAM), hepatopancreas urea (HPUE), and hepatopancreas uric acid (APUA), respectively, compared with shrimp exposed only to 0.39 mmol/L ammonia. We concluded that M. japonicus exposed to combined environments of ammonia and nitrite display increased nitrogen metabolism and production of urea-N and other organic-N.
Reproductive Status of Western Mosquitofish Inhabiting Selenium-Contaminated Waters in the Grassland Water District, Merced County, California by M. K. Saiki; B. A. Martin; T. W. May (pp. 363-369).
This study was implemented to determine if western mosquitofish (Gambusia affinis) populations in the Grassland Water District suffer from impaired reproduction because of seleniferous inflows of agricultural drainwater from the Grassland Bypass Project. During June to July 2001, laboratory trials with pregnant female fish collected from two seleniferous treatment sites exposed to selenium-laden drainwater and two nonseleniferous reference sites yielded fry that averaged >96% survival at birth. In addition, none of the newborn fry exhibited evidence of teratogenesis, a typical consequence of selenium toxicity. Chemical analysis of postpartum female fish and their newborn fry indicated that mosquitofish from seleniferous sites accumulated relatively high body burdens of selenium (3.96 to 17.5 μg selenium/g in postpartum female fish and 5.35 to 29.2 μg selenium/g in their fry), whereas those from nonseleniferous sites contained lower body burdens (0.40 to 2.72 μg selenium/g in postpartum female fish and 0.61 to 4.68 μg selenium/g in their fry). Collectively, these results strongly suggest that mosquitofish inhabiting selenium-contaminated waters are not experiencing adverse reproductive effects at current levels of selenium exposure.
Immunology-Related Perturbations Induced by Copper and Chitosan in Carp (Cyprinus carpio L.) by C. Dautremepuits; S. Betoulle; S. Paris-Palacios; G. Vernet (pp. 370-378).
Copper is used in treatment mixtures to control fungal diseases in vineyards. Its concentrations are relatively high in some aquatic ecosystems, and the main problem observed in this study was the antioxidant stress induced by this heavy metal. Copper toxicologic effects in aquatic organisms have prompted the demand for alternative use of low-toxicity molecules in culture treatments. Chitosan is a polymer with antifungal property similar to copper and may be an interesting biopesticide. Thus, it is necessary to investigate the potential toxicity of chitosan for aquatic animal health, either alone or in conjunction with copper. In this study, carp were exposed to two sublethal chitosan concentrations (75 and 150 mg/L) or to two sublethal copper concentrations (0.1 and 0.25 mg/L) or to a mixture of chitosan plus copper (75 mg/L and 0.1 mg/L, respectively). The results of the present study show that exposure to copper at environmentally realistic levels or to chitosan at sublethal concentrations may significantly stimulate various aspects of immune functions in carp such as nonspecific cellular immunity, represented by total immunoglobulin level, ceruloplasmin activity, and oxidative activity of phagocytes. This acute-phase inflammatory response induced separately by the two treatments was not observed, especially on phagocyte oxidative activity, when carp were exposed to the copper–chitosan mixture. This fact could be explained by a possible chelation of copper by chitosan decreasing the biodisponibility of the two products for immune cells. Thus, the immunotoxicologic impact of copper and chitosan on fish immune response would be less pronounced with the combined treatments than with separate treatments in an aquatic environment.
Influence of Diet and Ration Level on Benzo[a]pyrene Metabolism and Excretion in Rainbow Trout (Oncorhynchus mykiss) by C. J. Kennedy; Dave Higgs; Keith Tierney (pp. 379-386).
Juvenile rainbow trout (Oncorhynchus mykiss) were fasted or fed one of three isoenergetic diets varying in protein and lipid content at full satiation levels or half rations for up to 9 weeks. At 3, 6, and 9 weeks, fish in each treatment group were dosed intraperitoneally with 10 mg tritiated benzo[a]pyrene [3H]-B[a]P/kg (B[a]P) to examine the effects of diet composition and energy intake on xenobiotic biotransformation and excretion. The percent dose eliminated during the experiment did not differ among fish receiving the different diet compositions or rations (range 73% to 84%). However, it was significantly decreased (to 53%) in the group that was fasted for 9 weeks. Examination of fish fasted for 6 and 9 weeks showed a significant increase in the proportion of phase I metabolites and a concomitant decrease in the proportion of phase II metabolites found in bile compared with all other groups. Also, fish that were fasted for 9 weeks produced proportionately less 9,10-dihydroxy-benzo[a]pyrene-trans-9,10-diol, more 3-hydroxybenzo[a]pyrene and 9-hydroxybenzo[a]pyrene, and more glucuronic acid conjugates compared with all other groups. Thus, dietary protein and lipid concentration did not appear to affect either the rate of B[a]P metabolism or its excretion; however, prolonged fasting resulted in a shift in metabolite profiles and decreased excretion.
A Method to Quantify and Analyze the Foraging Activity of Honey Bees: Relevance to the Sublethal Effects Induced by Systemic Insecticides by M. E. Colin; J. M. Bonmatin; I. Moineau; C. Gaimon; S. Brun; J. P. Vermandere (pp. 387-395).
The assessment of agropharmaceuticals’ side effects requires more realistic simulations of field conditions than those deduced from the dose-lethality relation obtained under laboratory conditions. Because the presence of sublethal doses or concentrations may also alter the behavior of foraging insects, we attempted to devise a quantifiable and accurate protocol for evidencing various alterations in free-flying bees. Such a protocol was illustrated by testing new classes of systemic insecticides. The protocol focused on video recording to quantify the foraging activity of small colonies of honey bees confined in insect-proof tunnels. The basis of the protocol was not the colony itself but the change in each colony on a specific day and between days. First, the paradigms of attendance at a safe feeding source were established by observing 8 control colonies at different times of the season during 5 days after the necessary forager training was accomplished. Second, on three different colonies we considered the paradigms on the control day before contamination and during 4 days after the feeding source was contaminated. During the same period, one more colony was exclusively fed with safe food to serve as control. Two plant-systemic insecticides were tested at contamination levels 70 times lower than the 50% of the lethal concentration. Imidacloprid, at 6 μg/kg, clearly induced a decrease in the proportion of active bees. Fipronil, at 2 μg/kg, induced an additional decrease in attendance at the feeder. Such levels are still higher than the corresponding lowest observable effect concentration (LOEC). Our protocol, which provided intermediate conditions between field and laboratory conditions, allowed the quantification, with an enhanced level of sensitivity, of sublethal effects on foraging bees.
Relationship Between DDE Concentrations and Laying Sequence in Eggs of Two Passerine Species by K. D. Reynolds; S. L. Skipper; G. P. Cobb; S. T. McMurry (pp. 396-401).
Passerine eggs make useful biomonitors of environmental pollutants. Among passerines, it is not known whether organochlorine contaminants in eggs within the same clutch are independent observations or follow a laying order effect. Intraclutch variation of DDE (1,1-dichloro-2,2-bis[(p-chlorophenyl)]ethylene) concentrations was studied in eggs collected from prothonotary warblers (Protonotaria citrea) and European starlings (Sturnus vulgaris) nesting on National Priority List sites in lower Alabama and central Colorado, respectively. All 209 eggs collected for this study contained detectable levels of DDE. Mean concentration of DDE across all prothonotary warbler eggs (mean 8.71 μg/g ± 1.19, n = 20) was almost two orders of magnitude greater than mean concentrations of DDE in all starling eggs (mean 0.70 μg/g ± 0.06, n = 189). In both species, there was a large amount of variability among individual eggs of the same clutch and no significant relationship between laying order and DDE concentration. Variation among eggs laid in the same sequential order was high and effectively masked any potential trends in laying order effect. We hypothesized that the variability was caused by the spatial heterogeneity of DDE on our study sites, the nature of egg development within a female passerine, or a combination of these factors. Investigators focusing on lipophilic contaminants should exercise caution when making inferences about contaminant concentrations in an entire clutch of passerine eggs after the collection and analysis of a single egg because our data show that DDE levels in a single egg collected for analysis do not consistently reflect DDE levels in the eggs remaining in the nest.
Detoxification Mechanism of Heavy Metals in Marine Mammals and Seabirds: Interaction of Selenium with Mercury, Silver, Copper, Zinc, and Cadmium in Liver by T. Ikemoto; T. Kunito; H. Tanaka; N. Baba; N. Miyazaki; S. Tanabe (pp. 402-413).
Subcellular distribution of mercury, selenium, silver, copper, zinc, and cadmium was determined in the liver of northern fur seals (Callorhinus ursinus), black-footed albatrosses (Diomedea nigripes), and Dall’s porpoises (Phocoenoides dalli). Mercury, selenium, and silver were preferentially accumulated in nuclear, lysosomal, and mitochondrial fraction with an increase in their hepatic concentrations, whereas copper, zinc, and cadmium were accumulated mainly in cytosol with an increase in the hepatic concentrations for all three species. To gain insight into the existing state of the metals, they were extracted with four extractants—sodium dodecylsulfate (SDS); 2-mercaptoethanol; 2-mercaptoethanol + guanidinium thiocyanate; and copper sulfate (CuSO4)—at several concentrations from nuclear, lysosomal, and mitochondrial fraction in liver from a specimen of northern fur seal. Extraction efficiencies of the metals for 2-mercaptoethanol + guanidinium thiocyanate and CuSO4 were much higher than those for SDS and 2-mercaptoethanol. Also, for all individuals of the three species, metals were extracted by the three extractants—2% SDS; 0.25 mol/L 2-mercaptoethanol + 5 mol/L guanidinium thiocyanate; and 0.1 mol/L CuSO4—from nuclear, lysosomal, and mitochondrial fraction of liver. In the northern fur seals with higher concentration of mercury, the molar ratio of selenium to mercury approached unity in the nonextractable fraction of 0.25 mol/L 2-mercaptoethanol + 5 mol/L guanidinium thiocyanate, suggesting the possible formation of mercuric selenide (HgSe) with increasing hepatic concentration. Because the nonextractable content of mercury and its distribution were larger for black-footed albatross than those for the other two species, it was suggested that the black-footed albatross has a stronger ability to form a stable compound(s) of mercury in the liver. It is notable that the existing state of silver was similar to that of mercury as judged by their subcellular distribution and the extraction tests, suggesting that silver also interacted with selenium in the liver of marine animals used in this study.
Dioxins and Related Compounds in Human Breast Milk Collected Around Open Dumping Sites in Asian Developing Countries: Bovine Milk as a Potential Source by T. Kunisue; M. Watanabe; H. Iwata; A. Subramanian; I. Monirith; T. B. Minh; R. Baburajendran; T. S. Tana; P. H. Viet; M. Prudente; S. Tanabe (pp. 414-426).
In this study, concentrations of dioxins and related compounds (DRCs)—such as polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and coplanar polychlorinated biphenyls—were found in human breast milk from women living near dumping sites of municipal waste and reference sites in India, Cambodia, Vietnam, and the Philippines during 1999 to 2000. DRCs were detected in all human breast milk samples analyzed, demonstrating that residents in these Asian developing countries have been exposed to these contaminants. In India, the concentrations of DRCs in human breast milk from women living near the investigated dumping site were notably higher than those from women living near reference sites and from women in other Asian developing countries. Toxic equivalent quantity (TEQ) levels of DRCs were comparable with or higher than those reported in the general populations of developed countries since 1990. In contrast, levels of these contaminants in human breast milk in women from Cambodia and Vietnam were not significantly different between milk from women living near the dumping and reference sites. These results indicate that significant pollution sources for DRCs are present in Indian dumping sites and that residents there have been exposed to relatively higher levels of these contaminants. TEQ levels in human breast milk from the dumping site in India tended to decrease with an increase in the number of previous deliveries by mothers, whereas no significant relationship was observed in Cambodia, Vietnam, or the Philippines. This suggests that mothers who have been exposed to relatively high levels of DRCs transfer greater amounts of these contaminants to the first infant than later ones through breast-feeding, which in turn implies that the first children of these mothers might be at higher risk from DRCs. When the residue levels of DRCs in bovine milk collected from the Indian dumping site and reference sites were examined, TEQ levels in bovine milk from the dumping site were higher than those from reference sites. This result suggests that bovine milk is a potential source of DRCs for residents living near the dumping site in India. To our knowledge, this is the first comprehensive study on exposure to DRCs of residents living in proximity to open dumping sites of municipal waste in Asian developing countries.