Spraying organophosphates

Developmental Effects. Adverse effects of methyl parathion on hirman fetal development have not been reported. Based on studies in animals, such effects appear to be possible if pregnant women were exposed during the first trimester to high concentrations of methyl parathion that resulted in significant depression of cholinesterase levels, particularly if concomitant signs and symptoms of organophosphate intoxication occur. Such an exposure scenario may occur with occupational exposure, exposure in homes or offices illegally sprayed with methyl parathion, or accidental exposure to methyl parathion, but is less likely as a result of low-level exposure. 

Hooper, M.J. et al. (1989). Organophosphate exposure in hawks inhabiting orchards during winter dormant spraying. Bulletin of Environmental Contamination and Toxicology 42, 651-660. 

Farm workers are especially susceptible to organophosphate insecticide poisoning. Unsafe spraying conditions can lead to accumulated toxicity and chronic symptoms. Since there are many enzymes in the body which are in the serine esterase family along with Achase and can complex... 

The use of ligand exchange has been examined for the analysis of PTH (phenylthio-hydantoin) amino acids separated on silica gel plates [92]. The method is an extension of the procedure developed for organophosphate pesticides [84]. The chromatoplate is sprayed with a solution of palladium(II) chloride and calcein. Palladium complexes with calcein to form a non-fluorescent chelate. However, in the presence of many sulfur-containing compounds, such as PTH-amino acids, the palladium is displaced from the complex liberating free calcein which gives an intense fluorescence. This method is capable of determining 0.1-nmole amounts of PTH-amino acids. 

Method 1 (cellulose layers). The cellulose powder is washed twice with isopropanol-ammonium hydroxide-water (6 3 1), washed once in isopropanol and dried at 10S °C for 8 h. The plates (thickness, 0.25 mm) are prepared with a commercial TLC applicator. The slurry consists of 15 g of prepared cellulose in 85 ml of water which has been homogenized in a blender. The plates are dried at room temperature, and then eluted with diethyl ether in order to remove organic impurities. The plates are dried in air immediately before use. The pesticides are spotted and developed with appropriate solvent systems. The chromatoplate is dried in air and sprayed lightly with a 0.05% solution of fisetin in isopropanol. The separated spots are observed visually under a UV light at 365 nm (excitation, 370 nm emission, 533 nm). This method has been examined for several types of pesticides including carbamates, organophosphates, triazines and chlorinated hydrocarbons. 

In California, mixer-loaders and spray applicators who work with toxicity category I and II organophosphates or N-methyl carbamates more than 30 hours per 30-day period are required to have medical supervision. Supervision consists of an interview and a medical examination to determine if a medical condition exists which would make the worker unusually susceptible to poisoning due to cholinesterase inhibition, and to caution the individual about the use of certain drugs such as the pheno-thiazine tranquilizers vdtich potentiate the effects of cholinesterase (ChE) inhibition. Two blood samples, taken several days apart, are analyzed to determine the individual s preexposure plasma and red blood cell (RBC) ChE activity (baseline value). The physician arranges a routine ChE testing program and provides for extra ChE tests should the worker be accidently exposed to OP s. If ChE activity is depressed to 50 percent of the baseline value, the physician may ask the employer to place the worker on... 

Organophosphate. For the estimation of phosphoric acid esters, the developed plate is sprayed with 0.25% solution of palladium chloride in 0.1 N HC1 and dried in air. After exactly ten minutes, the area of the yellow-brown colored spot developed is measured and compared with that of the spots of standard insecticide solutions run alongside. 

Veterinary medication, sprays and dips. Generally speaking, routine prophylactic treatments are not allowed but animals can be treated with the appropriate veterinary medicines when ill or injured. Withdrawal periods are longer than the statutory ones, and more appropriate management of the stock, such as reduction of the stocking rate, might be necessary to limit dependence on medicine. In the UK, at least, organophosphate dips and treatments are not permitted under any circumstances. 

Jim used his redundancy money to start a small business growing pot plants to supply local shops and offices. He had always been a very successful gardener so he was horrified when plants in his new greenhouse suffered a severe attack of greenfly. He collected a large container of commercial insecticide containing the organophosphate malathion from his supplier and set to work with his spray. 

After a few minutes of spraying, Jim started to feel very ill indeed and soon collapsed. As a relative novice to commercial gardening, he had not realized that organophosphates are very toxic, as they act as anticholinesterases. He did not appreciate that he should have been using protective clothing when spraying these compounds in a confined space. 

The widely used organophosphate Insecticide methyl parathlon was the first material to be formulated as a microencapsulated pesticide. This formulation, sold under the tradename PENNCAP-M Insecticide (a registered trademark of Pennwalt Corporation), consists of nylon-type microcapsules which contain the active Ingredient. The capsules are suspended In water and typically have an average particle size of approximately 25 microns (fifty percent by weight of the capsules have a particle size of 25 microns or more). Upon application by conventional spray equipment the water evaporates, and the active Ingredient Is slowly released over an extended period of time. 

The main products responsible for incidents were those containing the active ingredient endosulfan, accounting for 69% of the cases. The second offending product, causing 14% of poisonings, was a mixture of the pyrethroid lambda-cyhalothrin and an organophosphate - in some cases dimethoate and in others profenofos. This mixture is recommended for farmers to spray at least four times, after the first two sprays of endosulfan ". 

Cotton is one of the crops most heavily reliant upon insecticide use. Although Bt cotton has been introduced in some areas, insecticide sprays remain as important components of cotton pest management programs. In some areas of the cotton belt, the majority of applications are made by aircraft. Issues which have been of regulatory concern in recent years include pest resistance associated with the frequent sprays, beneficial insect effects, worker exposure, and spray drift impacts on surfrice water quality. Products currently in use include organophosphates such as azinphos-methyl, methyl parathion, acephate, and disulfoton, pyrethroids such as lambda-cyhalodirin and carbamates such as methomyl. 

As with drugs, an important factor in the toxicity of OPs can be the effect of simultaneous exposure to other chemicals, including other pesticides and contaminants. The effects may be difficult to predict as some chemicals can increase while others inhibit detoxication, and with some organophosphates there are multiple metabolic pathways. If two or more pesticides are sprayed by the same operator within a short time there could be dangerous and unexpected interactions. The same may apply to wildlife in the vicinity of the spraying. A poisoning incident in Pakistan illustrates this problem and the difficulty of predicting such events. 

Techniques. In 1962, McKinley and Read (42) developed an esterase-inhibition technique for the detection of organophosphate pesticide residues on paper chromatograms. The procedure involved conversion of the thiophosphates with bromine to yield active esterase inhibitors, the inhibition by the pesticide of the esterases from a beef liver homogenate sprayed onto the chromatogram, the hydrolysis of the substrate (a-naph-thyl acetate) which was sprayed onto the paper after the liver homogenate had dried, and the development of a background color between Fast Blue RR and the hydrolysis product, a-naphthol. 

A major route of contamination of surface waters by naled is spray drift and direct application for mosquito abatement. There are no data on the fate and transport of degradates containing only the organophosphate group, which form by cleavage of the P-O bond in naled and/or DDVP. 

Organophosphate Dimpylate (diazinon) Dichlorvos Fenitrothion Fenthion Phosmet (dogs) Fleas, ticks Solution (spot on) collars aerosol spray liquid concentrate (sponge on)... 

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