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Archives of Environmental Contamination and Toxicology (v.33, #1)
Molecular Models for the Stereochemical Structures of Fumonisin B1 and B2 by R. C. Beier; L. H. Stanker (pp. 1-8).
Assessment of the structural configuration of fumonisin B1 (FB1) and B2 (FB2) would allow better understanding of the behavior of these molecules during isolation or other handling procedures, and their interaction with binding sites or antibodies. Molecular models of the absolute configurations of FB1 and FB2 were calculated using a CAChe WorkSystem™. The electrostatic potential energy surfaces of the minimum potential energy conformations for FB1 and FB2 also were obtained. The models reveal that the backbone and acid side chains for FB1 and FB2 form a spherical globular model. The folded region forms a cage-like feature. It is this feature that suggests that these molecules may be potential chelators. The electrostatic potential surfaces show that most of the exposed surfaces of these molecules are hydrophobic in nature, and that there is a distinct difference between the electrostatic potential surfaces of the FB1 models resulting from the stereochemistry proposed by Shier et al. (1995) and Boyle and Kishi (1995a). The electrostatic surfaces clearly show a different orientation of the hydrophobic tail region of the backbone for FB2 than in the models for FB1.
The Effects of Motorway Runoff on Freshwater Ecosystems: 3. Toxicant Confirmation by A. B. A. Boxall; L. Maltby (pp. 9-16).
Previous studies have demonstrated that small streams receiving road runoff have reduced water and sediment quality. These changes in quality are associated with alterations in the structure and functioning of stream communities. Laboratory studies have indicated that the community changes are due to sediment-associated contaminants, and toxicant identification evaluations have shown that the major toxicants are contained probably in a fraction of sediment extract that contains polycyclic aromatic hydrocarbons (PAHs). The aim of the present study was to determine whether PAHs were indeed the major toxicants in sediment extracts. Toxicity tests were performed with PAH mixtures, the toxic fraction of an extract of runoff-contaminated sediment, and a whole sediment extract. These indicated that three PAHs accounted for the toxicity of a sediment extract: pyrene, fluoranthene, and phenanthrene. The possibility of spatial or temporal variation in major toxicants was also investigated and tests on a number of sediment extracts obtained from a number of sites at different times demonstrated that the three PAHs accounted for 30.8 to 120% of an extract's toxicity. When the PAHs were considered individually, pyrene was shown to account for most of the toxicity (44.9%), followed by fluoranthene (16%) and phenanthrene (3.5%).
The Urgent Need for Environmental Sanitation and a Safe Drinking Water Supply in Mbandjock, Cameroon by P. B. Tchounwou; D. M. Lantum; A. Monkiedje; I. Takougang; Ph. Barbazan (pp. 17-22).
Studies were conducted to assess the physical, chemical, and bacteriological qualities of drinking water in Mbandjock, Cameroon. Study results indicated that the vast majority of drinking water sources possessed acceptable physical and chemical qualities, according to the World Health Organization standards. However, microbiological analyses revealed that only the waters treated by the Cameroon National Water Company (SNEC) and the Sugar Processing Company (SOSUCAM) were acceptable for human consumption. All spring and well waters presented evidences of fecal contamination from human and/or animal origin. Water from these sources should, therefore, be treated before use for drinking. Since the majority of the population gets its water from wells and springs, there is an urgent need to develop a health education program, within the framework of primary health care, with respect to environmental sanitation and safe drinking water supply in this community.
Diffusive Sampling and Biological Monitoring of 2-Bromopropane by T. Kawai; Y. Okada; T. Odachi; S. Horiguchi; Z.-W. Zhang; C.-S. Moon; M. Ikeda (pp. 23-28).
The possibilities to apply personal ambient air monitoring by diffusive sampling and biological exposure monitoring by urinalysis for 2-bromopropane or its metabolites were explored. The abilities of carbon cloth to adsorb 2-bromopropane was examined by experimental vapor exposure followed by solvent extraction and FID-GC. Urine from factory workers and rats exposed to 2-bromopropane were analyzed for 2-bromopropane, acetone and isopropyl alcohol by FID-GC, and for bromide ion by ECD-GC after chemical methylation. Carbon cloth adsorbed 2-bromopropane in a manner linearly related to exposures up to 1500 mg/m3 and to 8 h. The adsorption could quantitatively detect a 15 min peak exposure at 3,000 mg/m3. In rat experiments, analyses of urine samples collected over a 4-h period after termination of a 4-h exposure to 2-bromopropane at 500, 1,000 or 1,500 mg/m3 showed that acetone and bromide ion were excreted dose-dependently. Essentially, no 2-bromopropane or isopropyl alcohol was detected. When the analytical methods were applied to urine samples from 5 male workers exposed to 2-bromopropane at a low level (3 mg/m3 as a geometric mean), acetone and bromide ion levels were within respective normal ranges in four cases, but were higher than the upper limits of the normal ranges in the fifth case of a foreman who probably had the highest exposure. Thus, diffusive sampling is applicable to monitor exposure to 2-bromopropane. Urinalysis for acetone and bromide ion in combination appears to be a promising selective tool for biological monitoring of occupational exposure to 2-bromopropane.
Recovery Following Pulsed Exposure to Organophosphorus and Carbamate Insecticides in the Midge, Chironomus riparius by D. B. Kallander; S. W. Fisher; M. J. Lydy (pp. 29-33).
The importance of recovery following pulsed and continuous exposure was determined by measuring the acute toxicity of two organophosphorus (parathion and malathion) and four carbamate (aldicarb, carbaryl, carbofuran and propoxur) insecticides. Two 1-h pulses caused significantly fewer symptoms of intoxication than 2 h of continuous exposure if at least 2 to 6 h in clean water were provided between doses for the four carbamates. Two 1-h pulses were equally toxic as a single 2-h continuous exposure for the two organophosphorus insecticides. Acetylcholinesterase activity in midges given two 1-h pulses of carbaryl separated by 24 h in clean water showed reactivation to control levels between the two exposures. These results contribute to the belief that episodic exposure to insecticides is less toxic if recovery in clean water is provided.
Effect of Soil Moisture on Pesticide Toxicity to an Enchytraeid Worm, Enchytraeus sp. by H. M. Puurtinen; E. A. T. Martikainen (pp. 34-41).
The aim of the study was to find out whether soil moisture affects toxicity of organic pesticides to an enchytraeid worm. Laboratory experiments were carried out with dimethoate and benomyl, using a small Enchytraeus sp. as the test species. Substrate was natural agricultural field soil cultivated without pesticides for several years. Experimental design consisted of three soil moistures (40, 55, and 70% of water holding capacity) and five pesticide concentrations, plus controls. Measured parameters were survival, size of the parent worms and number and size of juveniles produced. Dimethoate was relatively non-toxic to this species. Dimethoate did not decrease survival, but sublethal effects on adult size and number of juveniles were observed. Adverse conditions in dry soil masked these effects; dimethoate appeared to be less toxic in dry soil than in moist soil. Benomyl caused significant mortality and the effects were very abrupt. Toxicity of benomyl decreased with increasing soil moisture content; in moist soil the worms survived at higher benomyl concentrations than in drier soils.
Organophosphates in the Zebra Mussel Dreissena polymorpha: Subacute Exposure, Body Burdens, and Organ Concentrations by C. Dauberschmidt; D. R. Dietrich; C. Schlatter (pp. 42-46).
Subacute exposures (10 d) of the freshwater mollusc Dreissena polymorpha to disulfoton (10 mg/L), thiometon (6 mg/L), and its activated oxygen analogue demeton-S-methyl (6 mg/L) corroborate earlier findings of organophosphate resistance and accumulation in the organism. Mortality occurred not before the ninth day of exposure. Mortality was induced at high ambient water concentrations and must be due to unknown specific organophosphate effects. Body burdens reached saturation levels within one week being around 40 mg/kg wet weight for thiometon and 60 mg/kg for disulfoton. Mussels dying during the tests showed lower tissue concentrations. Elimination of accumulated organophosphates was so low in the mussel, that an efficient metabolism of these compounds in the mussel was unlikely. Different organs of Dreissena previously acutely exposed (96 h) to the organophosphate thiometon (6, 12, 25, 50 mg/L) were analyzed for their thiometon content. Thiometon could be found in all organs, but were highest in the anterior part of the viscera (230 mg/kg), where it was accumulated either in the digestive gland and/or in the gonadal tissue.
Bioconcentration and Depuration of Chlorpyrifos in the Marine Mollusc Mytilus edulis by R. Serrano; F. Hernández; F. J. López; J. B. Peña (pp. 47-52).
The bioconcentration and depuration of chlorpyrifos [O,O-diethyl-O-(3,5,6-trichloro-2-pyridil) phosphorothioate] for the marine mollusc Mytilus edulis was investigated under laboratory conditions in experimental aquaria. Renewal tests at concentrations of 1 and 3.2 mg/L followed by depuration tests were conducted. Organisms were exposed to pesticide concentrations for 38 days and then were maintained in clean sea water until the chlorpyrifos were eliminated.Two different methods to estimate toxicokinetic rate constants of chlorpyrifos were compared. Toxicokinetic rate constants appeared to be dependent upon the level of exposure, probably due to the toxic stress produced by the high exposure level assayed. Lipid based Bioconcentration Factor (BCF) calculated by first order kinetic fit was found to be 482 ± 86. The depuration of chlorpyrifos by mussels maintained in clean sea water was fitted to first order one-compartment model, and the depuration rate constant estimated was similar to that calculated in the bioconcentration phase. The BCF obtained was lower than expected for K ow of chlorpyrifos, suggesting metabolic biotransformation of the parent pesticide.
Metallothionein-Like Protein: Is It an Efficient Biomarker of Metal Contamination? A Case Study Based on Fish From the Tunisian Coast by A. Hamza-Chaffai; C. Amiard-Triquet; A. El Abed (pp. 53-62).
The aim of this work was to assess the relative importance of natural fluctuations in metallothionein-like protein (MTLP) levels associated with the sexual status of fish versus fluctuations due to metal exposure. In order to see fluctuations due to metal exposure, comparisons were made on the same fish species Scorpaena porcus sampled in polluted and unpolluted sites. The hermaphrodite fish Serranus scriba and Scorpaena porcus, in which sexes are separate, were compared at the unpolluted site to see fluctuations caused by the sexual status. In both species, metals and the MTLP levels were determined in the gills and liver. In these organs, Cd, Cu, and Zn distributions were examined in different fractions: the insoluble fraction (IF) and the cytosol divided into thermolabile compounds (HDF) and the heat stable compounds including MTLP. MTLP levels were higher in the liver (3.09 mg/g in S. porcus, 1.59 mg/g in S. scriba) than in gills (0.13 mg/g in S. porcus, 0.40 mg/g in S. scriba). For Scorpaena porcus, metals and MTLP levels varied with sex, whereas in Serranus scriba, which is a hermaphrodite species, inherent variations were also observed. At the polluted site, MTLP, Cd, and Cu concentrations in the gills of S. porcus increased but the supplementary metals were not associated with the heat stable compounds including MTLP. At this site, hepatic MTLP bound more metals than at the unpolluted site, but its binding capacity was not sufficient to avoid the binding of metals to the insoluble and the heat denaturable fractions. In light of these results and in spite of its hermaphrodism, it is questionable whether to consider S. scriba as a good candidate for biomonitoring based on MTLP. S. porcus could be useful for this purpose only if the MTLP capacity in binding metals is not exceeded. The MTLP could be considered as a biomarker only if it is investigated in relatively unpolluted sites.
Spatial Patterns in a Bioindicator: Heavy Metal and Selenium Concentration in Eggs of Herring Gulls (Larus argentatus) in the New York Bight by M. Gochfeld (pp. 63-70).
Concentrations of selenium and five heavy metals (lead, cadmium, mercury, chromium, and manganese) in the eggs of herring gulls (Larus argentatus) were studied at six breeding colonies in the New York Bight to detect locational differences and to explore their use as a bioindicator of point source or nonpoint source pollution. The herring gull is widespread in North America, Europe, and Asia, and has urban-adapted counterparts in the southern hemisphere as well. We anticipated that the chromium contamination at Jersey City and high levels of manganese in industrial releases to the Passaic River would be reflected in the nearest colony (Shooter's Island), and that lead contamination from bridge remediation would be apparent in the Jamaica Bay colonies. There were significant locational differences in all metal levels, although the patterns were not the same for all metals. Shooter's Island in Newark Bay ranked first or second for five of the elements, but inexplicably had the lowest mercury level. Cadmium levels were highest at Canarsie Pol in Jamaica Bay, but mercury levels were highest at the relatively isolated Lavallette colony in northern Barnegat Bay. Chromium and manganese levels were indeed highest at Shooter's Island, but the lead levels in Jamaica Bay were only intermediate. We predicted that the essential trace elements, manganese, chromium, and selenium, which are known to be present at relatively high concentrations in various animal species, would have relatively low coefficients of variation, reflecting homeostatic mechanisms. This was confirmed. In conclusion, herring gull egg contents can be used to monitor metal concentrations at nearby colonies to indicate areas of concern for particular metals. They may confirm suspected associations or identify hitherto unsuspected problems.
Inter- and Intraclutch Variability in Heavy Metals and Selenium Levels in Audouin's Gull Eggs from the Ebro Delta, Spain by M. Morera; C. Sanpera; S. Crespo; L. Jover; X. Ruiz (pp. 71-75).
Heavy metal (Zn, Cu, Mn, Cd, Pb, Hg) and Se concentrations were analyzed in 57 Audouin's gull (Larus audouinii) eggs belonging to different clutch sizes. Inter- and intraclutch variability in metal concentrations was investigated as a potential source of bias in the assessment of pollution levels. Moreover, we analyzed the relationship between metal levels in the shell and in the contents, to evaluate the reliability of museum eggshells as indicators of historical changes of these pollutants. An outstanding female effect and/or a laying order effect underlies egg Hg levels; the fact that eggs in a clutch are not independent observations needs to be taken into account both when designing sampling strategies and when performing any analysis or interpretation of the results. The relationship between Hg in shells and contents is not sufficiently accurate to allow the use of egg-shell concentration as a reliable predictor of egg-contents concentration. However, if changes in the ecosystems are large enough it could be used to trace gross historical trends of these pollutants.
Environmental Exposure and Distribution of Lead in Four Species of Raptors in Southeastern Spain by A. J. García-Fernández; M. Motas-Guzmán; I. Navas; P. María-Mojica; A. Luna; J. A. Sánchez-García (pp. 76-82).
The purpose of this study was to monitor exposure to lead in four species of raptors in Southeastern Spain (Murcia Region). Samples of liver, kidney, brain, blood, and bone from two species of diurnal raptors (European kestrel (Falco tinnunculus) and European buzzard (Buteo buteo)) and two species of nocturnal raptors (Eagle owl (Bubo bubo) and Little owl (Athene noctua)) were obtained during 1994. Relationships were found between size and age of the birds, the nearness to areas of human activity and lead concentrations in tissues. The lead distribution pattern reveals that the bone is the principle organ for accumulation (0.62–43 mg/Kg, dry weight), followed by the kidney (0.03–0.66 mg/Kg, wet weight), and liver (0.017–0.05 mg/Kg, w.w.), and to lesser extent, the brain (0.013–0.223 mg/Kg, w.w.). This distribution pattern indicates that raptors in Southeastern Spain were exposed to environmental low lead levels continuously over an extended period of time. Correlations between lead in bone and lead in soft tissues were higher in European buzzards (r = 0.87–0.95) and Eagle owl (r = 0.71–0.86) than those found in European kestrels (r = 0.53–0.58) and Little owls (r < 0). However, correlations between lead concentrations in soft tissues and in blood were high (r = 0.85–0.99).
Mixed Function Oxidases in an Australian Marsupial, the Brushtail Possum (Trichosurus vulpecula) by R. M. Bolton; J. T. Ahokas (pp. 83-89).
Investigation of the mixed function oxidase system of the brushtail possum was undertaken to provide fundamental information about this detoxication enzyme system in a marsupial. Brushtail possum hepatic cytochrome P450, cytochrome b 5 and NADPH-cytochrome c reductase levels, 7-ethoxyresorufin O-deethylase and (EROD) 7-ethoxycoumarin O-deethylase (ECOD) activities were in the range of values reported for eutherian mammals. Hepatic cyrochrome P450 content was significantly greater (p < 0.01) in brushtail possums from a non-urban population in comparison to an urban population, as was ECOD activity (p < 0.0001). EROD activity was significantly greater in female brushtail possums in comparison to males (p < 0.01). The factors potentially influencing the population- and sex-specific expression of cytochrome P450 isoenzymes in the brushtail possum are discussed and include exogenous dietary xenobiotics and endogenous hormonal alterations influenced by reproductive status.
Effect of the Day of Administration on the Developmental Toxicity of Tributyltin Chloride in Rats by M. Ema; A. Harazono; E. Miyawaki; Y. Ogawa (pp. 90-96).
The objective of this study was to determine the susceptible day for the teratogenicity of tributyltin chloride (TBTCI) by a single administration on one of the days during organogenesis. Pregnant rats were given a single dose of TBTCI by gastric intubation at 100 mg/kg on either day 7, day 8, or day 9 and at 200 mg/kg on either day 7, day 8, day 9, day 10, day 11, day 12, day 13, day 14, or day 15 of pregnancy. The maternal body weight gain in the period immediately following administration in all TBTCI-treated groups was significantly decreased. A significant increase in the incidence of postimplantation loss was found after administration of TBTCI on day 7, day 8, and day 9 at 100 and 200 mg/kg and on day 10 and day 11 at 200 mg/kg. A significantly increased incidence of fetuses with external malformations was detected when TBTCI was given on day 8 at 100 and 200 mg/kg and on day 11, day 12, day 13, and day 14 at 200 mg/kg, and the most pronounced effect occurred after administration on day 13 of pregnancy. Cleft palate was observed exclusively after administration during late organogenesis. It could be concluded that the manifestation and susceptibility of the developmental toxicity of TBTCI vary with the developmental stages at the time of administration and that TBTCI has the biphasic sensitivity to teratogenicity on day 8 and days 11–14 of pregnancy.
Variation of PCB Congener Levels During Lactation Period and Relationship to Their Molecular Structure by L. Ramos; L. M. Hernández; M. J. González (pp. 97-103).
The levels of 22 polychlorinated biphenyl (PCB) congeners, including 13 coplanars (non-, mono-, and di-ortho–substituted chlorine) and 9 noncoplanar chirals (tri- and tetra-ortho–substituted chlorine), were measured in mothers milk from different mothers throughout their lactation periods. Important variations were found in the total PCB levels and PCB congener levels. The maximum PCB variations were found during the first weeks of lactation. Of the 22 PCBs analyzed, the most abundant, and those which had the highest variations were PCB-101, 118, 138, 151, 170, and 180, while the least abundant were the PCB-77, 126, 169, and 167, which also showed the lowest variation. Among the nonortho-substituted PCB congeners, PCB-77 was the predominant PCB in three of the four lactation periods studied, while PCB-126 was dominant in the last case. A relationship has been found between the levels and variations of total PCBs in the milk supplied by the different mothers and their dietary habits, weight changes and illness suffered during their pregnancy and lactation. The 22 PCB congeners investigated have been grouped in five categories according to their concentration variations in milk throughout the four different lactation periods. The PCB congeners included in each of the five groups have similar molecular structures. It has been found that coplanarity, number of chlorines and their molecular distribution, and neighbor H atoms were determinant factors in the process of PCB mobilization from the mothers' fats (where it had been able to accumulate throughout her life in the case of her first child) to the breast milk she delivered.
Blood Serum Levels of PCBs and PCDFs in Yucheng Women 14 Years After Exposure to a Toxic Rice Oil by Y. L. Guo; J. J. Ryan; B. P. Y. Lau; M. L. Yu; C. C. Hsu (pp. 104-108).
In 1979, a mass poisoning of more than 2000 people occurred in central Taiwan due to consumption of rice-bran oil contaminated with PCBs and their heat-degraded byproducts. The incident was later referred to as Yucheng (oil disease). Serum samples from 56 women with the 1979 exposure were collected in February 1992 and analyzed for their contaminant content using sample enrichment and isotope dilution mass spectrometry. In most of the samples, levels of PCDFs and PCBs were detectable, and the median values of 2,3,4,7,8-PCDFs and 1,2,3,4,7,8-PCDFs were 1,030 and 2,220 ng/kg serum lipid, respectively. The median level of the total PCBs on a whole weight basis was 8,730 ng/kg. The PCB/PCDF concentrations in Yucheng women 14 years after the toxic exposure were still one to two orders of magnitude higher than controls. Concentrations of PCB levels in 1992 were positively correlated with the 1980–1981 measured PCB levels in these women and both PCBs and PCDFs were negatively correlated with the total duration when these women breast fed their children between 1979 and 1992. It is concluded that serum levels of congener-specific PCBs/PCDFs in exposed women are good indicators of previous exposure and may provide important information for more reliable estimation of dose-response relationship.