Phase toxicity

Zapit Technology, Inc., developed the Zapit processing unit (ZPU), which uses electron beams to destroy vapor-phase toxic wastes. The ZPU has been developed to treat vapor-phase organic... 

Ringwood, A.H., DeLorenzo, M.E., Ross, P.E., Holland, A.F. (1997). Interpretation of the Microtox solid-phase toxicity tests the effect of sediment composition. Environmental Toxicology and Chemistry. 1997, 1135-40. 

Harley, R. A and G. R. Cass, Modeling the Concentrations of Gas-Phase Toxic Organic Air Pollutants Direct Emissions and Atmospheric Formation, Environ. Sci. Technol., 28, 88-98(1994). 

The development of new models for the prediction of chemical effects in the environment has improved. An Eulerian photochemical air quality model for the prediction of the atmospheric transport and chemical reactions of gas-phase toxic organic air pollutants has been published. The organic compounds were drawn from a list of 189 species selected for control as hazardous air pollutants in the Clean Air Act Amendments of 1990. The species considered include benzene, various alkylbenzenes, phenol, cresols, 1,3-butadiene, acrolein, formaldehyde, acetaldehyde, and perchloroethyl-ene, among others. The finding that photochemical production can be a major contributor to the total concentrations of some toxic organic species implies that control programs for those species must consider more than just direct emissions (Harley and Cass, 1994). This further corroborates the present weakness in many atmospheric models. 

The toxic effect on biocatalytic activity and stability in two-phase reaction system media can be divided into two effects. The first one, called the molecular-toxicity effect, is a direct toxic effect of the solvent molecules, which are dissolved in the aqueous phase and interact with the biocatalyst, particularly with whole cells. The second one, which is created by the presence of an interface between the aqueous and the organic solvent phase, is called the phase-toxicity effect [2, 24]. 

Organic solvents can interact with enzymes in several ways. There can be specific interactions between isolated solvent molecules and enzyme molecules. This kind of interaction also occurs in water containing dissolved solvent molecules. When a separate organic solvent phase is present, interfacial inactivation can also occur. This is sometimes called phase toxicity [55] to distinguish it from the molecular toxicity of isolated solvent molecules. Interfacial inactivation can be studied in detail by bubbling solvent through an aqueous enzyme solution under controlled conditions [56]. 

Kwan, K.K. and Dutka, B.J. (1995) Comparative assessment of two solid-phase toxicity bioassays the direct sediment toxicity testing procedure (DSTTP) and the Microtox solid-phase test (SPT), Bulletin of Environmental Contamination and Toxicology 55 (3), 338-346. 

For each exposure phase, the TIFs are averaged (i.e. arithmetic mean) over all measured endpoints, to generate a weighted average of phase toxicity (WAPT). 

The WAPT values are summed to obtain the cumulative average of phase toxicity (CAPT), which is finally expressed on a logarithmic scale, to generate the SED-TOX score ... 

TIF TU TUdw U.S. ACE U.S. EPA WAPT WS WT Toxicity Incremental Factor Toxic Unit Toxic Unit expressed on a dry weight basis United States Army Corps of Engineers United States Environmental Protection Agency Weighed Average of Phase Toxicity Whole Sediment Wet Sediment. 

Bioassay using a biological system which measures toxic effects of the liquid/aquatic phase of a test material (e.g., porewater, elutriate, leachate) and determines a response (e.g., acute and/or chronic toxicity). See also Solid-phase (toxicity) test. Volume 1(2), Volume 2(9). 

Field-collected sample of whole sediment, taken from a marine, estuarine, or freshwater site thought to be contaminated (or potentially so) with one or more chemicals, and intended for use in solid-phase toxicity tests. In some instances, the term also applies to any solid-phase sample (including reference sediment, artificial sediment, negative control sediment, positive control sediment, or dredged material) used in testing. Volume 1(2). 

Harley RA, Cass GR. 1994. Modeling the concentrations of gas-phase toxic organic air pollutants Direct emissions and atmospheric formation. Environ Sci Technol 28 88-98. 

Dave G, Nilsson E and Wernersson A-S, Sediment and water-phase toxicity and UV-activation of six chemicals used in military explosives, Aquat. Ecosyst. Health... 

However, another criterion that needs to be considered for the selection of a suitable ISPR method is the mode of contact between the microorganisms and the separation phase that removes the product from the vicinity of the cell. Direct contact between the microorganism and a water-immiscible solvent (phase toxicity) or solid adsorbent material can have inhibitory effects on the cell [31,33]. Therefore, this direct contact limits the choice of separative aids. In addition, stability and robustness of a process is reduced if the cells are in direct... 

Bar suggested that the toxicity in two-phase systems was caused by both the presence of a second phase (phase toxicity) and solvent molecules which dissolved in the aqueous phase (molecular toxicity). Basically, both mechanisms are governed by the same principle in that the solvent accumulates in the microbial membrane. In case of the direct contact between cells and pure solvent, the rate of entry of solvents in a membrane will be very high. If the solvent has to diffuse via the water phase, then the accumulation in membranes will be slower. This latter mechanism on the molecular toxicity has been investigated in more detail. In experiments with liposomes from E. coli, and ten representative organic solvents labeled by under aqueous-saturating levels, it was observed that the solvents accumulate... 

Bar R (1987) Phase toxicity in a water-solvent two-liquid phase microbial system. In Laane C, Tramper J, Lilly MD (eds) Studies in organic chemistry, vol 29. Biocatalysis in organic media International symposium, Wageningen, The Netherlands, 7-10 Dec 1986. Xii+426p. Elsevier, Amsterdam, Illus. pp 147-154 (Dist. in the USA and Canada by Elsevier Science Publishing Co., Inc. New York, NY, USA)... 

Y. S. Jang et al. Vapor phase toxicity of marjoram oil compounds and their related monoteipenoids to Blattella germanica (Orthoptera Blattellidae). J Agric Food Chem, 5, 7892, 2005. 

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