2.4- Dichlorophenoxyacetic acid herbicide

Haugland RA, DJ Schlemm, RP Lyons, PR Sferra, AM Chakrabarty (1990) Degradation of the chlorinated phenoxyacetate herbicides 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid by pure and mixed bacterial cultures. Appl Environ Microbiol 56 1357-1362. 

The scientists from Hong Kong reported83 on a sol-gel derived molecular imprinted polymers (MIPs) based luminescent sensing material that made use of a photoinduced electron transfer (PET) mechanism for a sensing of a non-fluorescent herbicide - 2,4-dichlorophenoxyacetic acid. A new organosilane, 3 - [N,V-bis(9-anthrylmethyl)amino]propyltriethoxysilane, was synthesized and use as the PET sensor monomer. The sensing MIPs material was fabricated by a conventional sol-gel process. 

Bloemen LJ, Mandel JS, Bond GG, et al An update of mortality among chemical workers potentially exposed to the herbicide 2,4-dichlorophenoxyacetic acid and its derivatives. 7 Occup Med 35 1208-1212, 1993... 

The chlorophenoxy herbicides, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), were used in defoliating operations... 

Furthermore, the use of Ralstonia eutropha JMP134-containing sensors for the determination of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) has been described [118,121]. This sensor was sensitive to 2,4-D and 2,4,5-T (2,4,5-trichlorophenoxyacetic acid) with a detection Emit of 40 mg 1 with a response time of 15 s. Moreover, catechol, benzoic acid, and sahcylaldehyde caused higher signals, but no or very little signal was obtained for phenol, biphenyl, and the usual substrates such as glucose, fructose, ethanol, and acetate. 

Surugiu et al. [67] have introduced an Enzyme Immuno-Like Assays (EzILA) for the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The label was a 2,4-D conjugate with the tobacco peroxidase (TOP) enzyme, which allows for both colorimetric and chemiluminescent detection. In this case, the polymer imprinted with 2,4-D was synthesized in the form of microspheres. In contrast, despite its higher binding capacity for radiolabeled 2,4-D, a conventional MIP prepared by bulk polymerization showed only weak binding of the 2,4-D-TOP tracer. 

HAUPT K, dzgoev A and masbach K (1998), Assay system for the herbicide 2, 4-dichlorophenoxyacetic acid using a molecularly imprinted polymer as artificial recognition element , Anal Chem, 70, 628-631. 

Occupational Exposure. Exposures to 2,3,7,8-TCDD, one of the most potent of the CDD congeners, have occurred occupationally in workers involved in the manufacture and application of trichlorophenols and the chlorophenoxy acid herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichloro-phenoxyacetic acid (2,4,5-T). Holmstedt (1980) has reviewed the history of industrial exposures that have occurred between 1949 and 1976, and Kogevinas et al. (1997) summarized recent data on these cohorts. 

S.K. Hoar, S. Zahm, D.D. Weisenburger, P.A. Babbitt, A case-control study of non-Hodgkin s lymphoma and the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), in Eastern Nebraska. Epidemiology 1 349-356, 1990. 

Boye, B., Brillas, E., Marselli, B., Michaud, P.A., Comninellis, Ch., Farnia, G. and Sandona, G. (2006) Electrochemical incineration of chloromethylphenoxy herbicides in acid medium by anodic oxidation with boron-doped diamond electrode. Electrochim. Acta 51, 2872-2880 Brillas, E., Calpe, J.C. and Cabot, P.L. (2003) Degradation of the herbicide 2,4-dichlorophenoxyacetic acid by ozonation catalyzed with Fe2+ and UVA light. Appl. Catal. B Environ. 46, 381-391. 

The outcome of the widely used lawn-care herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) during the composting of yard trimmings consisting of primarily leaves and grass is an important unexplored question. In their study, Michel Jr. et al. (1995)... 

The metabolism of the herbicide 2,4-dichlorophenoxyacetic acid by A. niger has been examined. The major metabolite was 2,4-dichloro-5-hydroxyphenoxy-acetic add. This was accompanied by a minor product, 2,5-dichloro-4-hydroxy-phenoxyacetic add, in which a chlorine migration had taken place. 

The fates of the herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) 2, 4, 5-trichlorophenoxyacetic acid (2,4,5-T) and the DDT metabolite, bis-(4-chlorophenyl) acetic acid (DDA) were studied in the spiny lobster, Panulirus argus 24). All acids were injected intrapericardially at 10 mg/kg. Both 2,4-D or 2,4,5-T were extensively excreted, unchanged, in urine in the first 24 hours after the dose. About 10% of the dose of 2,4,D and 2,4,5T was taken up by hepatopancreas where the taurine conjugate was formed and subsequently excreted either in urine or feces. Part of the DDA dose was excreted in urine, as unchanged DDA and as DDA-taurine, but DDA was more extensively taken up by shell and hepatopancreas and more slowly excreted than 2,4D or 2,4,5-T. For all three carboxylic acids, muscle concentrations were lower than hemolymph concentrations at 24 hours after the dose, and were less than 5p.g/g. 

The herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and trifluralin are mineralized or degraded at slower rates under anaerobic conditions. Pronounced differences in degradation rates of added, labeled 2,4-D as affected by sediment redox potential were observed (DeLaune and Salinas, 1985). Degradation of 2,4-D was approximately six times faster under aerobic conditions (+500mV) as compared to anaerobic conditions (-200 mV) in sediments. The effect of redox... 

Schulze, G. E., and J. A. Dougherty. 1988. Neu-robehavioral toxicity and tolerance to the herbicide 2,4-dichlorophenoxyacetic acid n-butyl ester (2,4-D ester). Fundam. Appl. Toxicol. 10(3) 413-24. 

Pont, A.R., Charron, A.R., and Brand, R.M. (2004). Active ingredients in sunscreens act as topical penetration enhancers for the herbicide 2,4-dichlorophenoxyacetic acid, Toxicol. Appl. Pharmacol, 195, 348-354. 

Another application involves binding of agricultural chemicals in polymer formulations for slow release at a rate effective for their intended purpose avoiding the risk of the reagents being washed away by rain or irrigation. For example, the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) has been incorporated into polymers either as a chelate with iron (XVIII) or as a hydrolysable pendant ester group on a vinyl polymer (XIX). 

The most toxic member of the dioxin family is 2,3,7,8-TCDD. Agent Orange is an approximately 1 1 mixture of two herbicides—2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid. Dioxin TCDD was present as a contaminant in Agent Orange used as a defoliant in the Vietnam War. 

Many chemicals are applied to soil and crops to control insects, fungi, and weeds. The potential toxi-cities of these substances to humans, wildlife, and beneficial plants is of course a concern. A comprehensive coverage of the toxicological chemistry of agricultural pesticides is beyond the scope of this chapter. However, three important herbicides, 2,4-dichlorophenoxyacetic acid (2,4-D), atrazine, and glyphosate, are mentioned here their structural formulas are shown in Figure 10.4. Herbicides are mentioned because they are so widely used in agriculture and are spread over wide areas. 

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