摘要:

AbstractExposure of bacterial cells to selected azaarenes causes respiratory inhibition, membrane damage, decreased cellular ATP synthesis, and decreased cell viability. The purpose of this work was to examine the chemical mechanisms of acute toxicity of azaarenes and provide a preliminary model of azaarene cellular effects. Results of bioassays andin vitrospectrochemical and electrochemical experiments suggest that azaarenes alter membranes and electron transfer (ET) molecular assemblies primarily through noncovalent interactions not involving organic or oxy free radicals. The data suggest that membranes and membrane‐linked systems are altered via azaarene‐mediated chelation of divalent cations (Ca and Mg) found in the lipopolysaccharide matrix of the bacterial outer membrane. This gives rise to altered structure/function of periplasmic and inner membrane systems, and may contribute to changes in ET. Electrochemical analyses indicate that azaarenes also change the redox chemistry of flavin centers and seem to increase the ease with which ET processes occur between biochemical electron donors (NADH) and tetrazolium acceptors (iodonitrotetrazoli

ISSN:1053-4725    

DOI:10.1002/tox.2530070102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractBacterial biosensors incorporating the cyanobacterium Synechoccus as the biocatalyst have been evaluated by three laboratories as potential biomonitors for detecting water pollutants. The biosensors were capable of detecting at low concentrations herbicides that interact with photosynthetic electron transfer chains. Statistical evaluation of the interlaboratory comparison results for linuron and atrazine indicated that these compounds can be detected rapidly at 50 μg/L concentrations

ISSN:1053-4725    

DOI:10.1002/tox.2530070103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractFour reference toxicants (Cr6+, Cu2+, Zn2+, phenol) and 9 herbicides (imazamethabenz, 2,4‐dichlorophenoxyacetic acid, picloram, glyphosate, bromoxynil, metolachlor, diquat dibromide, hexazinone, cyanazine) were appraised using both the microplate and flask assay Ninety‐six hour EC50s determined withSelenastrum capricornutumas the indicator species essentially demonstrated good intermethodological data concordance for all chemicals, with the exception of diquat dibromide, whose phytotoxicity in the microplate assay (EC50= 4.9 μg · L−1) was nearly 7 times that of the flask assay (EC50= 34.2 μg · L−1). Comparisons with other data in the scientific literature relating to similar herbicides with the same or different green algal indicator species appeared to corroborate the overall data obtained in our study. More than 4 orders of magnitude separated the most toxic (cyanazine, flask, and microplate EC50s of 17.6 and 16.9 μg · L−1, respectively) and the least toxic (imazamethabenz, flask, and microplate EC50s of 89.1 and 91.1 mg · L−1, respectively) herbicides. The biprocedural phytotoxicity comparison described in this work suggests that the simpler algal microplate assay can be an appropriate alternative to the flask technique to evaluate the algal growth inhibition eff

ISSN:1053-4725    

DOI:10.1002/tox.2530070104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractRoutine testing of sediments or suspended sediments for toxicant or genotoxicants by the bioassay route often involves time‐consuming and expensive organic extraction procedures. In most instances these extraction procedures are more time‐consuming and costly than the bioassays that will be used on these extracts. A direct sediment test procedure (DSTP) was developed to alleviate the problem and thus returning bioassays to one of their original roles, i.e., short, quick, screening tests to identify priority samples for more intensive chemical analysis. The DSTP was developed in conjunction with the Toxi‐Chromotest and SOS Chromotest kits. The SOS Chromotest can be used with or without S9. Our results presented in this paper indicate the sensitivity of DSTP and cost effectiveness compared to some commonly used sediment extraction proce

ISSN:1053-4725    

DOI:10.1002/tox.2530070105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractBacterial viruses are prevalent in nature. The coliphage counts in any wastewater sample might show very significant diversity in numbers, due to use of variousEscherichia colistrains. In this study coliphage (E. coliB host) coliform, fecal coliform, and fecal streptococci densities were estimated from chlorinated secondary effluent being carried in a 30‐km long pipeline. Comparison of die‐off of the various indicators was performed between controlled and uncontrolled chlorination at slow and fast flow in the pipe. In addition, a swab technique was applied from which a rough estimation of the ratios of coliphage to the other indicators could be made, as well as coliphage to salmonella ratio. The results showed that there was a decrease in coliphage number at higher levels of chlorine residual, and wherever aftergrowth of coliform occurred, the number of coliphage did not cha

ISSN:1053-4725    

DOI:10.1002/tox.2530070106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractFourteen series of toxic wastes from various origins (metallurgy, chemical industries, incinerators, industrial treatment plants, etc.) have been studied for their genotoxic properties with theSalmonellareversion assay. To consider realism of environmental impact, a strategy is proposed to assess genotoxicity of the water‐soluble fraction of the wastes. Water‐extractable micropollutants were further concentrated by liquid–liquid extraction or lyophilization prior to genotoxicity testing.None of the 14 crude aqueous fractions was shown to be mutagenic. On the contrary, positive responses were registered on the concentrated phases of two solid wastes derived from one chemical industry and from the treatment of organophosphorus wastewaters. Chemical analysis did not reveal the presence of known mutagens in the positive extracts. Interacting effects between micropollutants is thus hypothesized to explain genotox

ISSN:1053-4725    

DOI:10.1002/tox.2530070107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractMany species of cyanobacteria produce hepatotoxic peptides called microcystins. Toxic cyanobacteria have caused fish, wildlife, and cattle mortality in many countries, but the distribution and fate of toxins and their ecological effects are poorly known. Toxic cyanobacteria may affect sensitive organisms and populations, but also fundamental ecological processes, e.g., primary production and microbial activity. Many studies show negative effects of cyanobacteria on zooplankton, but information on the type and quantity of toxin(s) involved is usually missing. Mussels accumulate peptide toxins but accumulation in other organisms remains to be studied. Cyanobacterial blooms often affect the littoral zones, which are important reproduction and feeding areas for fish and birds.

ISSN:1053-4725    

DOI:10.1002/tox.2530070108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractSewage discharge to the marine environment constitutes an important problem faced by public health and environmental managers, and exerts great economic and social impact on shellfish‐producing areas. This study aims at characterizing the water quality and shellfish sanitary conditions of different growing areas on the northern coast of the São Paulo State. Seventy‐two samples of water and shellfish were enumerated for total and fecal coliforms, and were analyzed for the presence ofSalmonella. The most probable number ofVibrio parahaemolyticuswas also determined for shellfish samples. Shellfish contamination was directly related to the bacteriological pollution of the water, such that in growing areas not contaminated with sewage discharges, 100% of shellfish samples presented themselves as being safe to be consumed.Salmonellawas absent in all samples analyzed andV. parahaemolyticuswas present in lower densities in shellfish samples. The percentage of water samples that did not comply to the standard were much higher than those of shellfish samples, indicating the need to reevaluate the permitted values of the Brazilian legislation both for shellfish “in natura” and for growing waters. This study also establishes the need for a better management of shellfish‐producing areas, especially those more polluted, in parallel with the development of a Brazilian Shellfish Sanitation Program, in order to protect the quality of these organisms and consequently hu

ISSN:1053-4725    

DOI:10.1002/tox.2530070109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:1053-4725    

DOI:10.1002/tox.2530070101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY