Organophosphates synergists

Although bicyclophosphates do not inhibit acetylcholinesterase, they exhibit a synergistic toxic effect with materials that do. Individuals who have had previous exposure to cholinesterase inhibitors such as nerve agents and commercial organophosphate or carbamate pesticides may be at a greater risk from exposure to bicyclophosphates. 

Pape-Lindstrom, P.A. and Lydy, M.J. (1997) Synergistic toxicity of atrazine and organophosphate insecticides contravenes the response addition mixture model, Environmental Toxicology and Chemistry 16 (11), 2415-2420. 

Although examples are known in which synergistic interactions take place at the receptor site, the majority of such interactions appear to involve the inhibition of xenobiotic-metabolizing enzymes. Two examples involve the insecticide synergists, particularly the methylenedioxyphenyl synergists, and the potentiation of the insecticide malathion by a large number of other organophosphate compounds. 

Inhibitors of a herbivore s ability to detoxify plant toxicants may expectedly be more slow-acting than neurotoxicants such as organophosphates. Nevertheless, securance of synergists of dietary toxicants that complement activation reactions and inhibit detoxification reactions in the targeted pests will have potential for IPM, since they should be compatible or moreover, augment plant antibiosis, natural enemies and concurrently used pesticides. 

Examples of these include sesamin and sesamolin, both active principles of sesame oil, and piperonyl butoxide (PBO) and sesamex, both synthetic products. Although initially developed for use with pyrethrins, they have since been observed to synergize some, but not all, carbamates, organophosphates, pyrethroids, and organochlorines. In addition to the MDP compounds, another type of synergist called MGK 264 was developed to synergize the toxicity of pyrethroids and rotenone. The structure of piperonyl butoxide and MGK 264 are as follows ... 

Pyrethrins and synthetic pyrethroids are among the safest of the topically applied ectoparasiticides, because of their selective toxicity for insects (mam-malian-to-insect toxic dose ratio is greater than 1000, compared with 33 for organophosphates and 16 for carbamate insecticides). In contrast to the very wide margin of safety for mammalian species, pyrethroids are toxic to fish. The synergistic action of pyrethrins and piperonyl butoxide (in combination preparations) is due to the inhibition by piperonyl butoxide of the microsomal enzyme system of some arthropods. Preparations of synthetic pyrethroids (permethrin, cypermethrin) often contain a mixture of drug isomers in varying proportions. 

Other flame retardant materials in use include ammonium polyphosphate, organophosphates (112), bromoaromatic phosphates, red phosphorus, aluminum oxide trihydrate, antimony oxide, melamine, and synergistic combinations of two or more of these (110,111). Currently, people are focusing more on phosphorous containing compounds relative to halogens (113-115). The percentage of each of these materials in use today, based on dollar value, is given in Table 14.9. 

As discussed earlier, MPTP has been shown to be causal in the development of PD. The structural similarity between MPTP and organophosphate pesticides sng-gests that such pesticides might also cause PD, and epidemiological studies have demonstrated such relationships [33]. In an in vitro study, it was demonstrated that coadministration to the organophosphate endosnlfan = 3.83) and the dithio-carbamate zineb (A w = 0.39) resnlts in synergistic apoptotic/necrotic process... 

The synergistic corrosion protection reported by Ho, coupled with research indicating that larger size, increased molecular weight and asymmetry of organic inhibitors often improve their effectiveness, " led Markley et al. to investigate other rare earth organophosphate compounds, namely cerium diphenyl phospliate (Ce(dpp)j) and mischmetal diphenyl phosphate (Mm(dpp)3). 

Synergistic Biends of Stericaiiy Hindered Phenois and Organophosph(on)ites 360... 

Synergistic Blends of Sterically Hindered Phenols and Organophosph(on)ites... 

It is state of the art for the stabilization of polymers produced on industrial scale to take advantage of synergistically efficient physical mixtures ( blends ) of stabilizers such as sterically hindered phenols and organophosph(on)ites. 

For color-critical applications requiring phenol-free stabilization synergistic mixtures of sterically hindered amines (HA (L)S) and a hydroxylamine-based stabilizer, used during melt processing, with or without an organophosphate or organo-phosphonite, can be used to avoid the undesired discoloration typically associated with the oxidation of the phenolic antioxidants into products with quinoid stmctures. ... 

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