摘要:

AbstractThe authors adapted microtitration techniques to the SOS Chromotest, and thereby established a simple and reliable modified genotoxicity test: the Microtitration SOS Chromotest. This test employs microtitration techniques and photometric analysis with numerical readout. These data are integrated into the computerized data processing program Statistical Analysis System to obtain genotoxicity and toxicity results of a chemical or chemical mixture within 16 h.In order to test the applicability of the new system, the genotoxicity and toxicity of 22 pesticides were studied. A two‐samplettest was employed to determine the level of significance (pcacodylic acid. The addition of rat liver S9 mix does not transform the nongenotoxic pesticides tested into genotoxic forms but significantly decreases the inducing ability of most positive pesticides.The Microtitration SOS Chromotest is rapid and efficient in providing evidence for decision‐making related to cleanup of chemical spills and discharges where time is a critical factor. This method maintains its high accuracy and sensitivity compared with conventionally used assays. The studies of pesticide genotoxicity using this test confirm the applicability, reliability, and sensitivity of the Microtitration SOS Chromotest as a simple, efficient, and rapid genotoxicity prescreening system as well as an excellent research tool for genotoxic mechanism stud

ISSN:0884-8181    

DOI:10.1002/tox.2540050102

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe kinetics and the influence of soil moisture content (MC) on the mineralization of14C‐labeled linuron were investigated at 15 different MCs in the range from air‐dried soil to 100% of the water‐holding capacity (WHC). For all MCs used, the data on the liberated amount of14C (x) were initially described by Eq. (1)x=k1t+a—after which the data were described by Eq. (2)x=k2t1/2+b—wheretis time,k1andk2are rate constants, andaandbare constants. The rate constantsk1andk2for MCs<100% of WHC were mathematically described by the equationk=l+m. MC12, wherekis either of the rate constants,lis a constant that can account for a threshold value of MC below which no decomposition occurs, andmis a constant. The validity of this equation for first‐order rate constants was tested by using data from the literature. The kinetics of mineralization of14C‐labeled glyphosate were investigated by adding glyphosate after different times of preincubation (tp) of a previously frozen soil. An initial phase of 11 days linear witht[Eq. (1)] was obtained when the herbicide was added immediately after the thawing, after which a phase linear witht1/2[Eq. (2)] ensued. The length of the initial phase decreased andk1increased with increasingtp, and fortp≥ 8 days the initial phase could not be confirmed. The following phase was almost unaffected by the preincubation. Thus, the phases represented by Eqs. (1) and (2) are separate, since they can be affected independently of each other. It is suggested that the initial phase is an induction phase, or lag phase, which reflects the disturbances introduced by handling the soil, and that the second phase is t

ISSN:0884-8181    

DOI:10.1002/tox.2540050103

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

年代:1990

数据来源: WILEY

摘要:

AbstractSamples of marine subtidal sediments collected in 1985 and 1986 from Elliott Bay, Washington, were analyzed at the Environmental Laboratories of the Municipality of Metropolitan Seattle as part of a larger study. Interstitial water and solvent extracts of subtidal sediments were analyzed by the Microtox procedure to determine toxicity. Particle size distribution, and concentration of oil and grease, metals, and polynuclear aromatic hydrocarbons, were compared to toxicity of interstitial water and solvent extracts. Physical and chemical compositions of sediments affects the toxicities of solvent extracts and interstitial water extracts differently. Samples with smaller particle sizes had relatively high concentrations of oil and grease and metals, and less toxic interstitial water. Samples with larger particles had less oil and grease and metals, and more toxic interstitial water. The opposite was true for the solvent extracts: samples with smaller particle sizes with relatively higher concentrations of oil and grease and metals had more toxic solvent extracts. Samples containing larger particles with relatively lower concentrations of oil and grease and metals had less toxic solvent extracts. No correlations were found between the toxicity of the solvent extracts and polynuclear aromatic hydrocarbons. The Microtox procedure has the potential to estimate toxicity of both water‐soluble and solvent‐soluble compounds in marine sediments if two different extraction procedures are u

ISSN:0884-8181    

DOI:10.1002/tox.2540050104

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

年代:1990

数据来源: WILEY

摘要:

AbstractWhole cells, mureinoplasts, and protoplasts of gram‐negative bacteria were used in cadmium biosorption and toxicity determinations. It was shown that whole cells ofPseudomonas fluorescensbind less metal than other bacterial forms, suggesting the outer membrane acts as a barrier toward metals. Such a role was confirmed by toxicity measurements showing a lower toxic effect of cadmium in the presence of the outer membrane. Chemically modified bacteria, with carboxyl groups masked, were used to identify the cadmium binding sites. Results indicate that care is necessary in interpretation since the acid pH used in the blockage reaction was shown to interfere with the cadmium binding. Moreover, the blockage reagents have been shown to modify the cadmium toxicit

ISSN:0884-8181    

DOI:10.1002/tox.2540050105

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

年代:1990

数据来源: WILEY

摘要:

AbstractAs of December 31, 1988, the U.S. Environmental Protection Agency (EPA) had published 49Federal Register(FR) notices acknowledging, proposing, or requiring development of bioconcentration, chemical fate, or environmental effects testing data under Section 4 of the Toxic Substances Control Act (TSCA). These FR notices included 5 Decisions Not to Test (DNTs) that acknowledged industry testing, 19 Notices of Proposed Rulemaking (NPRs) that proposed testing by industry, 9 Notices of Final Rulemaking (NFRs), and 2 Consent Orders (COs) that required industry testing as well as 7 proposed and 7 final Negotiated Testing Agreements (NTAs). Two bioconcentration, 12 chemical fate, and 28 environmental effects tests were submitted to the EPA by industry as a result of issuing DNTs. Industry completed 3 bioconcentration, 86 chemical fate, and 151 environmental effects tests after publication of NTAs. Two bioconcentration, 11 chemical fate, and 14 environmental effects tests were completed as a result of publishing NFRs; 1 chemical fate and 5 environmental effects tests were completed under a CO. As of December 31, 1988, a total of 7 bioconcentration, 110 chemical fate, and 234 environmental effects tests had been completed under TSCA Section 4.

ISSN:0884-8181    

DOI:10.1002/tox.2540050106

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

年代:1990

数据来源: WILEY

摘要:

AbstractBecause the productivity of terrestrial ecosystems is directly related to microbial nutrient cycling, understanding the effects of chemical contaminants on soil microbial processes is important. This study examined the effects of two model chemicals—Roundup (glyphosate) and N‐Serve (nitrapyrin)—on nitrifying organisms in static, perfusion, and continuous‐flow culture systems. Experimental concentrations were approximately 1, 10, and 100 × the spot application rate. Both N‐Serve and Roundup were shown to inhibit nitrification in the treated soils. Roundup significantly reduced nitrification at 6.8 and 68 mg g−1dry soil. N‐Serve (nitrapyrin) completely inhibited nitrification at levels greater than 42 μ g−1dry soil in all cultural methods.In comparative studies with static batch and perfusion culture techniques, the continuous‐flow system proved to be both reliable and useful in the culture of nitrifying bacteria. This method provides an alternative to traditional culture techniques in measuring chemical effects on microbial geochemical cycles and provides a new method for use

ISSN:0884-8181    

DOI:10.1002/tox.2540050107

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

年代:1990

数据来源: WILEY

ISSN:0884-8181    

DOI:10.1002/tox.2540050108

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

年代:1990

数据来源: WILEY

ISSN:0884-8181    

DOI:10.1002/tox.2540050101

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

年代:1990

数据来源: WILEY