Biodegradation, estimation

Suite, the PBT Profiler, and the BIOWIN biodegradability estimation program. He is the recipient of many EPA medals for distinguished service and several EPA Science and Technology Achievement Awards (STAA), including awards for review of new chemical substances under TSCA and the Handbook of Property Estimation Methods for Chemicals Environmental Health Sciences (Lewis/CRC, 2000, with Don Mackay). 

Two years later, a revised version was developed (Boethling et al., 1994) that included five new or redefined substructures and molecular weight, and the coefficients were developed by linear and non-linear regression with 295 chemicals from the BIODEG database as well as primary and ultimate biodegradation estimates from an expert survey of 200 chemicals (total of four models). The survey database was built from the opinions a panel of 17 experts who were asked to provide semi-quantitative (approximate time for complete deg-... 

One of the first experiments in this direction in our laboratories was the development of copolymers containing polyurethanes (PU) and maltose, oligosaccharides, or polysaccharides. The intention was to use the film-forming qualities of PU and its insolubility in water, whereas maltose, or the polysaccharides or oligosaccharides should function as a colon-biodegradable estimated site of separation. Maltose was used as the simplest building block, but it proved too short for an enzymatic attack. It was found that a straight, but not a branched,... 

Biodegradation estimated t,A = 190 h in river, eutrophic pond, eutrophic lake and t,A > 106 h in oligotrophic lake by the one compartment model (Smith et al. 1978). 

Biodegradation estimated t,/2 > 20 h in river, t,/2 < 20 h in eutrophic pond, t,/2 = 20 h in eutrophic lake and very long half-life in oligotrophic lake, based on the biodegradation rate in the presence of alternative carbon sources will be one-half the biodegradation rate of quinoline when quinoline is the only carbon source by the one compartment model (Smith et al. 1978). 

Raymond, J.W., Rogers, T.N., Shonnard, D.R., and Kline, A.A., A review of structure-based biodegradation estimation methods, J. Hazardous Mater., B84, 189-215, 2001. 

Biodegradation estimated half-life of 4.0 h in activated sludge, based on biodegradation of 4-chlorophenyl phenyl ether in activated sewage sludge (Branson 1978 quoted, Callahan et al. 1979). 

Klopman G, S Wang and D M Balthasar 1992. Estimation of Aqueous Solubility of Organic Molecule by the Group Contribution Approach. Application to the Study of Biodegradation. Journal c Chemical Information and Computer Science 32 474-482. 

Typical precautions with trichloroethylene are summarized in Table 5.52. An important factor is that the vapours are much heavier than air they will therefore spread and may accumulate at low levels, particularly in undisturbed areas. Because of its volatility, releases to the environment usually reach the atmosphere. Here it reacts with hydroxyl or other radicals (estimated half-life for reaction with hydroxyl radicals is less than a week) and is not therefore expected to diffuse to the stratosphere to any significant extent. There is some evidence for both aerobic and anaerobic biodegradation of trichloroethylene. 

Special mention must be made of poly(lactic acid), a biodegradable/bio-resorbable polyester, obtained from renewable resources through fermentation of com starch sugar. This polymer can compete with conventional thermoplastics such as PET for conventional textile fibers or engineering plastics applications. Hie first Dow-Cargill PLA manufacturing facility is scheduled to produce up to 140,000 tons of Nature Works PLA per year beginning in 200245 at an estimated price close to that of other thermoplastic resins U.S. l/kg.46 Other plants are planned to be built in the near future.45... 

The categorization as inherently biodegradable together with the values and other physical properties enabled estimates of biodegradation half-lives in water, soil, and sediment to be made by BUSES. Those for soil and sediment were then reduced to be more consistent with the results of Terytze et al. (2000), as shown in Table 8. 

Cripe CR, Walker WW, Pritchard PH, et al. 1987. A shake-flask test for estimation of biodegradability of toxic organic substances in the aquatic environment. Ecotoxicol Environ Safety 14 239-251. 

For a number of reasons, there are some important limitations to the extension of this principle. Biodegradation—as opposed to biotransformation—of complex molecules necessarily involves a number of sequential reactions each of whose rates may be determined by complex regulatory mechanisms. For novel compounds containing structural entities that have not been previously investigated, the level of prediction is necessarily limited by lack of the relevant data. Too Olympian a view of the problem of rates should not, however, be adopted. An overly critical attitude should not be allowed to pervade the discussions—provided that the limitations of the procedures that are used are clearly appreciated and set forth. In view of the great practical importance of quantitative estimates of persistence to microbial attack, any procedure—even if it provides merely orders of magnitude—should not be neglected. 

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