摘要:

AbstractRaw and drinking waters collected from three surface supplies in northern Italy (River Po at Turin and Ferrara, Lake Como at Como) were extracted using XAD resins to concentrate organic micropollutants. The extracts were tested for their ability to cause mutations in theSalmonellareversion system and mitotic gene‐conversion or recombination inSaccharomyces. Ferrara and Como extracts were found to have mutagenic activity in both theSalmonellaandSaccharomycestests. Turin water was never found to be mutagenic. Toxic and nontoxic extracts were then analyzed by GLC and HPLC to identify the mutagenic compounds. Although the mutagenic activity could not be explained by analytical measurements, some anthropogenic compounds, probably related to the observed effects, were identified in genotoxic sample

ISSN:0730-7268    

DOI:10.1002/etc.5620080201

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe use of sequential measurements of plasma cholinesterase (ChE) activity for monitoring exposure to organophosphorus pesticides was investigated in the mallard (Anas platyrhynchos). At the onset of incubation, birds were assigned to treated (400 ppm methyl parathion in the diet), pair‐fed (same daily food allotment on a g/kg/d basis as consumed by the treated bird of the pair), control or nonincubating control groups. Blood samples were collected weekly during egglaying and every 3 d during incubation periods. Both plasma and brain samples were taken on day 24 of incubation. Plasma ChE was more variable than brain ChE among the birds and there were no significant correlations (p>0.05) between plasma and brain samples within treatment groups. Reduced food consumption during incubation did not affect plasma ChE activity (p= 0.77). Birds that abandoned their nests had significantly increased (pairedt= ‐2.39,d.f. = 9,p<0.05) ChE activity at the time of abandonment. There were significant differences (p<0.01) in plasma ChE activity between untreated birds, but within‐bird variation was 2 and 11 times less than betweenbird variation during egg‐laying and incubation, respectively. Methyl parathion significantly (p<0.0001) reduced plasma ChE activity. Measurement of plasma ChE activity provides a noninvasive, nonlethal technique for assessing the exposure of animals to ChE inh

ISSN:0730-7268    

DOI:10.1002/etc.5620080202

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe coprophagic behavior of rodents has been used in a model examining the potential health effects of environmentally released microorganisms. Mutant polychlorinated biphenyl (PCB) degrading pseudomonads, isolated from a commercial product for PCB elimination, were used to evaluate the method. The PCB‐degrading component of the product was composed of onePseudomonas maltophiliaand threePseudomonas aeruginosastrains enhanced for PCB degradation through nitrosoguanidine mutagenesis. Multiple ingestions of the biodegraders were compared with a single exposure. The direct health effects monitored were changes in weight, appetite and overall appearance. The indirect health effects monitored included recovery of the organisms from intestinal contents as well as competition with and alteration of the normal intestinal flora. When animals received a single dose by gavage of 109colony forming units of an individualPseudomonassp., none of the four dosed strains were detected 14 d after dosing when animals were housed in metabolism cages. The use of these metabolism cages, which had wire flooring, limited coprophagy. When animals were housed in conventional cages, which allowed coprophagy, two of the four PCB degraders tested were recovered (104/g intestine). The lactose‐fermenting and total aerobic counts were unaffected when animals received a single dose of the biodegrader. In the multiple exposure model,P. maltophiliaaltered the lactose‐fermenting population. The total aerobic counts differed significantly from values for control animals when the animals were exposed toP. aeruginosastrains BC16, BC17 and BC18. Obligately anaerobic gram‐negative rod populations were affected inP. aeruginosastrain BC17‐dosed animals. Strains BC16 and BC18 altered both the obligately anaerobic rod populations and total anaerob

ISSN:0730-7268    

DOI:10.1002/etc.5620080203

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractResponse of the aquatic macrophyte hydrilla (Hydrilla verticillata(L.f.) Royle) to the herbicide diquat was measured by dissolved oxygen concentration in the surrounding water, chlorophyllaconcentration in plant tissue and membrane permeability of hydrilla cells. Dissolved oxygen concentration was the most rapid and sensitive measure of response, followed by membrane permeability. Chlorophyllawas an inadequate measure of response because of high variability in measurements and slow response time. The lethal concentration of diquat in hydrilla tissue was approximately 600 μg/g dry weight. The uptake of diquat by hydrilla was modeled under nonequilibrium conditions and assuming exponential decay of diquat from the surrounding water. The modeled uptake depended on the rate of decay of diquat from the water column, the rate of uptake of diquat by hydrilla and the rate of depuration of diquat from hydrilla. The observed uptake closely matched the calibrated, predicted uptake

ISSN:0730-7268    

DOI:10.1002/etc.5620080204

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe effect of dissolved organic matter (DOM) on the apparent solubility and bioavailability of 1,3,6,8‐tetrachlorodibenzo‐p‐dioxin (1,3,6,8‐TCDD) was examined in epilimnetic and sediment interstitial waters collected from the Canadian Shield lakes in the Experimental Lakes Area of Northwestern Ontario. DOM enhanced the apparent solubility of 1,3,6,8‐TCDD by as much as three times over the reference DOM‐free water (DOM<0.24 mg/L). The percentage of 1,3,6,8‐TCDD bound to DOM increased as the dissolved organic carbon (DOC) concentration increased. Uptake rate constants of 1,3,6,8‐TCDD inCrangonyx laurentianusdecreased in the presence of DOM. Only the 1,3,6,8‐TCDD that was truly in solution was apparently available for uptake by biota. The quality or site of collection of the DOM was also an important factor. Sediment interstitial waters had a greater affinity for 1,3,6,8‐TCDD than did epilimnetic waters, as indicated by the DOC partition coefficients. Although the DOM may enhance the apparent solubility of 1,3,6,8‐TCDD, DOM also reduces the amount of 1,3,6,8‐TCDD truly free in solution and therefore bioavailable. Solubility enhancement may, however, lead to greater dispersion of 1,3,6,8‐TCDD and low‐level exposure of biota as the 1,3,6,8‐TCDD gradually deso

ISSN:0730-7268    

DOI:10.1002/etc.5620080205

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractA large‐volume, easily handled exposure vessel for juvenile fish for use in bioaccumulation studies of water‐borne contaminants in larger rivers was designed and tested in the Hudson River in New York. The exposure vessel minimized stress to the fish and allowed representative contaminant accumulation during time‐series subsampling and a long‐termin situe

ISSN:0730-7268    

DOI:10.1002/etc.5620080206

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractExperiments were conducted to determine if a correlation exists between acclimation‐induced alterations in Zn toxicity and the concentration of metallothionein‐like proteins (MTP) in a cyprinid fish. Populations of subadult fathead minnows,Pimephales promelas, were maintained in dechlorinated tap water and exposed to 0, 0.60 and 1.80 mg Zn/L for 35 d. Groups of animals (120 each) were removed from each acclimation population after 0, 7, 14, 21 and 35 d to conduct 96‐h acute tests. Tolerance and resistance were monitored as changes in the 96‐h LC50 and LT50 values, respectively. Tolerance increased a significant 28% above control values after 14 d of exposure to 0.60 mg Zn/L, but decreased significantly to 63 and 74% of control values following exposure to 1.80 mg Zn/L for 7 and 14 d (p<0.05). Acute toxicity values returned to control levels in both treatment groups after 21 d of exposure and remained stable to 35 d. The concentration of MTP was measured in the viscera (i.e., liver, spleen, intestine and pancreas) indirectly as the total Zn‐binding capacity in MTP‐containing fractions. MTP levels increased after 7, 14 and 21 d and plateaued to 35 d. Metal concentration in the MTP fraction reached a maximum of 31.6 μg Zn/g viscera, and following 28 d of exposure to 1.80 mg Zn/L concentrations declined to control levels after 7 d in diluent water. Whole‐body residues of Zn reached steady state after 7 d of exposure to 0.60 mg Zn/L but continued to increase after 35 d of exposure to 1.80 mg Zn/L. Zn‐acclimated animals were cross‐resistant but not cross‐tolerant to acute Cd challenge. There was no correlation of alterations in toxicity with observed changes in MTP concentration. Growth effects were observed at both acclima

ISSN:0730-7268    

DOI:10.1002/etc.5620080207

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe importance of nitroaromatic compounds as aquatic contaminants and the association of superoxide (O−2) mediated toxicity with the mammalian metabolism of a number of these compounds has led our laboratory to conduct an in vitro investigation of nitroaromatic‐stimulated production by freshwater fish. Utilizing cytochrome c reduction and cyanide‐insensitive oxygen consumption assays for O−2, channel catfish (Ictalurus punctatus), largemouth bass (Micropterus salmoides) and rainbow trout (Salmo gairdneri) hepatic microsomes were exposed to nitrofurantoin (NF),p‐nitrobenzoic acid (PNBA) andm‐dinitrobenzene (MDNB). NF and PNBA were chosen for study as model nitroaromatic compounds, known to stimulate microsomal O−2generation in mammals; MDNB was chosen because it frequently contaminates aquatic systems. The results demonstrated that each of the three nitroaromatics is capable of significantly enhancing superoxide dismutase (SOD) inhibitable cytochromecreduction and oxygen consumption, providing specific evidence of stimulated microsomal production of O−2by the fish species examined. The results also indicated chemical‐ and species‐specific differences in stimulated O−2production. In both assay systems, enhancement by NF exceeded that produced by MDNB and, more pronouncedly, PNBA. Furthermore, although similar responses to all nitroaromatics were observed in microsomes isolated from catfish and bass, the assays employing trout microsomes demonstrated the greatest enhancement in NF and MDNB exposures. These findings suggest that the stimulation of O−2production may be an important mode of action for these common aquatic pollutants that merits further ecot

ISSN:0730-7268    

DOI:10.1002/etc.5620080208

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractPhilosophical considerations in the interpretation of probability can confuse the meaning of interval estimates. Most techniques for calculating interval estimates for the median effective dose (LC50) have been developed under a Neyman‐Pearson probability structure, which requires interpretation in terms of asymptotic mathematics. Fiducial probability, designed to allow the inductive use of a single experiment, fails to resolve this major difficulty in interpretation. In the evaluation of LC50 estimators, care should be exercised to ensure correct identification of random variables, consistent partitioning of sources of variability and proper choice of criteria for comparing estimators. Despite the difficulties raised by these issues, the calculation of interval estimates in short‐term toxicity testing remains an important benchmark in assessing the potentially harmful effects of chemical compounds in the environm

ISSN:0730-7268    

DOI:10.1002/etc.5620080209

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY