Pesticide dusts

Keywords Indoor air Indoor environment House dust Pesticides Exposure... 

Biocides should not be present in water used for aquaculture. Sources of herbicides and pesticides are mnoff from agricultural land, contamination of the water table, and spray drift from crop-dusting activity. Excessive levels of phosphoms and nitrogen may occur where mnoff from fertilized land enters an aquaculture faciUty either from surface mnoff or groundwater contamination. Trace metal levels should be low as indicated in Tables 4 and 5. 

Sulfur and its compounds are among the oldest and most widely used pesticides. Elemental sulfur is especially effective as a dust for the control of mites attacking citms, cotton, and field crops and as a protectant against chiggers, Trombicula spp., attacking humans. Sulfur also is a valuable fungicidal diluent for other dust insecticides and is used in wettable form as a spray mixture. Time sulfur has been a standard dormant spray for the control of the San Jose Quadraspidiotuspemiciosus and for other scales and various plant diseases. Time sulfur is a water-soluble mixture of calcium pentasulfide,... 

Pesticides. Many pesticides are highly concentrated and are in a physical form requiring further treatment to permit effective appHcation. Typically carriers or diluents are used (see Insectcontroltechnology). Although these materials are usually considered inert, they have a vital bearing on the potency and efficiency of the dust or spray because the carrier may consist of up to 99% of the final formulation. The physical properties of the carrier or diluent are of great importance in the uniform dispersion, the retention of pesticide by the plant, and in the preservation of the toxicity of the pesticide. The carrier must not, for example, serve as a catalyst for any reaction of the pesticide that would alter its potency. 

Sulfur has long been known for its properties as a pesticide and a curative agent. Homer spoke of the pest-averting sulfur as far back as 800—1000 BC, Hippocrates (400 Bc) considered sulfur sa an antidote against plague, and Dioscorides (100 ad) used sulfur ointment in dermatology (244). In 1803, the use of a lime—sulfur protective treatment for fmit trees was reported, and in 1850 sulfur dust was used to protect foHage (245). In 1891 sulfur dust was used on soil to control onion smut (246). 

The preparation of soils for crops, planting, and tilling raises dust as a fugitive emission. Such operations are shll exempt from air pollution regulations in most parts of the world. The application of fertilizers, pesticides, and herbicides is also exempt from air pollution regulations, but other regulations may cover the drift of these materials or runoff into surface waters. This is particularly true of the materials are hazardous or toxic. 

Compiled from the following reports of the U.S. Department of Interior, Bureau of Mines Rl 5753, The Explosibility of Agricultural Dusts Rl 6516, Explosibility of Metal Powders Rl 5971, Explosibility of Dusts Used in the Plastics Industry Rl 6597, Explosibility of Carbonaceous Dusts Rl 7132, Dust Explosibility of Chemicals, Drugs. Dyes and Pesticides and Rl 7208, Explosibility of Miscellaneous Dusts.)... 

The Environmental Protection Agency (EPA) has prepared a manual of pesticide residue analysis dealing with samples of blood, urine, human tissue, and excreta, as well as water, air. soil, and dust. 

In areas of agricultural methyl parathion usage, both outdoor and indoor air levels of methyl parathion of approximately 12 ng/m have been measured, and household dust was found to contain 21 ppb of methyl parathion. Outdoor and indoor air concentrations of methyl parathion as high as 0.71 and 9.4 pg/m, respectively, have been measured at the homes of individuals employed as pesticide formulators. 

Simcox NJ, Fenske RA, Wolz SA, et al. 1995. Pesticides in household dust and soil Exposure pathways for children of agricultural families. Environ Health Perspect 103 1126-1134. 

Substances hazardous to health include substances labelled as dangerous (i.e. very toxic, toxic, harmful, irritant or corrosive) under any other statutory requirements, agricultural pesticides and other chemicals used on farms, and substances with occupational exposure limits. They include harmful micro-organisms and substantial quantities of dust. Indeed any material, mixture or compound used at work, or arising from work activities, which can harm people s health is apparently covered. 

Spray drift is defined for this topic by the National Coalition On Drift Minimization (NCODM) as The physical movement of pesticide through the air at the time of pesticide application or soon thereafter from the target site to any non- or off-target site . Secondary drift, defined by NCDOM as vapor drift or subsequent dust and particle movement after the application , is only partially addressed, although most key principles discussed will still also apply to such secondary movements. 

SFE. SFE has been established as the extraction method of choice for solid samples. The usefulness of SFE for soil samples has been demonstrated for carbamate,organophosphorus and organochlorine pesticides. However, SFE is more effective in extracting nonpolar than polar residues. In order to obtain a greater extraction efficiency for the polar residues of imidacloprid, the addition of 20% methanol as modifier is required. Extraction at 276 bar and 80 °C with a solvent consisting of supercritical carbon dioxide modified with methanol (5%) for 40 min gives a recovery of 97% (RSD = 3.6%, n = 10). It is possible to use process-scale SFE to decontaminate pesticide residues from dust waste. ... 

The danger to domestic animals, including pets, is an important hazard in the use of all newer economic poisons. Drift dusts or sprays from carelessly applied materials may set back the useful development of many valuable chemicals. Only recently have authorities finally decided that we should slow down on the use of DDT on cows until we know more about the occurrence of the chemical in rtiilk, butter, and steaks. Our sportsmen and, incidentally, a major economic factor in our pleasant way of life—the fish, game, and wildlife activities—are part and parcel of the problem of chemical usage in forests and streams. We need continued and expanded investigations of the effects of the newer pesticides on wild life. 

The wide publicity given DDT and the many new pesticides that have been developed during the past few years has made the public aware of the widespread use of spray chemicals. Many misstatements about the poisonous properties of these new products have caused abnormal concern and fear over the possible presence of excessive amounts of spray residues on food crops. This concern is a natural one, because the public does not realize the very small amount of the insecticidal residue that may remain on a single service of food, which usually does not exceed 0.25 pound in weight. Nor does the public realize that only a relatively small percentage of the food we eat has ever been treated with a spray or dust of a specific pesticide. 

The powder-producing collar contains a solid solution of the drug in the resin. Shortly after the collar is processed, the particles or molecules of the pesticide migrate from within the body of the resin and form a coating of particles, known as bloom, resembling a dust or powder on the collar surface. 

Secondary air contamination is caused because pesticides on plant and soil surfaces convert into steam, or disperse by adsorbing on dust particles. Under certain conditions, up to 50% of such OCRs (organochlorine pesticides) as DDT, aldrin, and dieldrin move into the air during the week after a field is treated. DDT evaporates from a treated field at a rate of 10-50 kg/ha a year, depending on temperature, humidity, and air movement [3]. On the second or third day after treatment, OPP concentrations can be higher than on the first day as a result of pesticides converting into steam [22]. 

Due to the low volatility of cyromazine and the use of water-soluble bags for packaging the Trigard formulation, the main routes of exposure were expected to be from direct contact with the product or spray mixture on contaminated surfaces. Previous experience with pesticides worker exposure studies indicated that exposure from vapors or spray mist would be a minor factor. This can easily be confirmed by the PHED or similar published sources however, the extent of exposure from inhaling the product as dust is less well known. This route of exposure was also assumed to be minor, particularly with the use of water-soluble bag packaging. Given the low mammalian toxicity of cyromazine, the operators did not wear respiratory protection. 

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