Formulations, organophosphorus

The expected continued use of famphur in the environment and its vehicular transport along roads that border navigable waters suggest a need for aquatic toxicity data. Famphur data — like those on other organophosphorus insecticides — should reflect the influence of dose, exposure duration, formulation, and other biological and abiotic variables on growth, survival, and metabolism of representative species of aquatic organisms. 

The CNS is the target organ disturbed by all organophosphorus pesticides in different formulations used for the control of crop pests or household pests. It has been observed that exposure to organophosphorous pesticides has caused many neurologic effects. Animals exposed to organophosphorous pesticides have... 

The major classes of pesticides in use in the Region are organochlo-rine and organophosphorus compounds, Ccirbamates, pyrethroids and bacterial larvicides. Organophosphorus compounds are the most common, followed by pyrethroids. Insecticides are available in a variety of formulations, including emulsifiable concentrates (EC), wet-table powders (WP), dustable powders (DP), suspension concentrates (SC), oil-in-water emulsions (EW) and capsule suspensions (CS). 

Organophosphorus compounds such as malathion and fenitrothion were introduced in 1975 and remained in use in 1997 in seven countries. WP formulations are the most common for indoor residual applications. However, in some countries, notably Brazil and Mexico, malathion and fenitrothion ultra-low-volume (UL) sprays and fogging have also been used as space sprays. In Brazil, malaria has been restricted to the Amazonian region, where precarious housing... 

For sometime, phosphinidines, monovalent organophosphorus species with the general formulation (R-P), have been postulated as reactive intermediates in the thermal and photochemical decomposition of several types of stable organophosphorus compounds. While not isolated as stable molecules, these monovalent species can be inferred on the basis of the isolation of products whose structures can be derived rationally from the postulation of such species, as well as on the mass spectra of the transient species themselves. We may view phosphinidines as the phosphorus analogues of nitrenes (R-N), highly reactive monovalent nitrogen species formed as transient intermediates in the thermal decomposition of azides and in the a-elimination reaction of A-tosylates. 

It is generally agreed that the extracted uranium species is U02(N03)2(TBP)2 in which, in contrast to the species extracted into ether, the extractant molecules are directly coordinated to the metal ion. The extraction of uranium(VI) by neutral organophosphorus compounds increases with the number of C—P bonds (as opposed to C—0—P bonds) and with the increased branching of the substituent alkyl groups, as would be expected from the effect of these changes on the electron-donor properties of the phosphoryl group. The extracted thorium(IV) complex has been formulated as Th(N03)4-2S and as Th(N03)4-3S,2 2 and its composition may depend to some extent on the conditions of extraction. The extraction of thorium (like that of... 

Naled is a fast acting, nonsystemic contact and stomach organophosphorus insecticide used to control aphids, mites, mosquitoes, and flies on crops and in greenhouses, mushroom houses, animal and poultry houses, kennels, food processing plants, and aquaria. Naled is also used in outdoor mosquito control. Liquid formulations can be applied to greenhouse heating pipes to kill insects by vapor action. It has been used by veterinarians to kill parasitic worms (other than tapeworms) in dogs. Naled is available in dust, emulsion concentrate, liquid, and ultra-low volume (ULV) formulations. 

Carbamate anticholinesterases these are reversible in as much as their duration of action is short as compared to organophosphorus anticholinesterases, and are used extensively. An example is carbaryl (carbaril) and several analogues of carbaryl are used as insecticides. However, not all carbamates found in garden formulations are cholinesterase inhibitors the dithiocarbamates are fungicidal. 

Polypropylene. The six organophosphorus compounds (Figure 1, 0.05 weight %) were each formulated together with AO-1 (0.10%) in Hercules general purpose Profax 6501 polypropylene and were subjected to multiple extrusion in two series, one at 500 F (260°C) and another at 550°F (288°C). Comparison of the test compounds in the presence of AO-1 were made at each temperature by measuring the melt flow rate and color development after the first, third and fifth extrusions (6,7). The results after the fifth extrusion are shown in Table I. 

Although this aspect is irrelevant to the assessment of residues and their implications for consumer safety, no account of the use of veterinary drugs would be complete without some passing mention which will restrict itself to considerations of safety in use of medicines rather than safety in their manufacture. Many formulations used in veterinary medicine offer very little scope for significant occupational exposure. Tablets and capsules for example ensure that occupational exposure is minimal, if not non-existent. However, operator exposure does occur and means need to be taken to reduce this. Organophosphorus compounds are... 

Controlled-release solid formulations of selected volatile organophosphorus pesticides (malathion, DDVP, sumithion, chlorpyriphos, and sulprofos) were studied by Szente [33]. These solid formulations exhibited negligible vapor pressure and preserved their entrapped pesticide content even at elevated temperature. Malathion and chlorpyriphos formulations showed increased physical stability, and resulted in an effective masking of the unpleasant smell while the complex formulations existed as dry solid. Sulfluramid is an expensive insecticide that is lost by volatilization, but complexation to j8-CyD reduced the loss [21]. 

Diazinon, an organophosphoras compound with an anticholinesterase mode of action, was released for experimental evaluation in the early 1950s. Diazinon is now used extensively hy commercial and home applicators in a variety of formulations to control flies, cockroaches, lice on sheep, insect pests of ornamental plants and food crops (especially com, rice, onions, and sweet potatoes), forage crops such as alfalfa, and nematodes and soil insects in turf, lawns, and croplands. Diazinon is the most widely used organophosphorus pesticide in Pakistan to control cabbage root fly and carrot fly. In 1992, more than 612,000 kg of diazinon were used in California on alfalfa, nuts, stone fmits, vegetables, and other crops. 

One of the best-known and most important reactions in organophosphorus chemistry is the production of P-C linkages by the Arbusov reaction. Originally formulated as a reaction between a trialkyl phosphite and an alkyl halide (3.108), this reaction was later found to be more general and can be written as (3.109), where A, B can be alkyl, aryl, primary or secondary alkoxy, aryloxy, dialkyl-amino and so on. 

Formulations containing inhibiting organophosphorus compounds, which act as sealing agents for phosphated surfaces, have been patented, for example, [(H0)2(0)P-CH2]3 N [14]. 

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