Pesticides contact

Uses Manufacture of acrolein, allyl compounds, glycerol, plasticizers, resins, military poison gas contact pesticide for weed seeds and certain fungi intermediate for pharmaceuticals and other organic compounds herbicide. 

Tn applying pesticide sprays, the first problem is that of distributing a small quantity of active material over a large target area. The uniformity and extent of the distribution required depend on the type of pest to be controlled and the mode of action of the toxicant a patchy distribution may be satisfactory to control mobile insects or to apply systemic pesticides to foliage, whereas for static pests and contact pesticides, a more uniform spray deposit may be required. The degree of distribution attained depends on ... 

EXPOSURE ROUTES air water food inhalation skin adsorption ingestion eye and skin contact pesticide manufacturers, formulators, and applicators... 

Most of the technological processes used in fruit and vegetable processing include washing and blanching. The decrease in the levels of pesticide residues is possible particularly in the case of pesticides that are soluble in water, or in the case of contact pesticides deposited on the plant surface that can be mechanically removed. The overall effects resulting in a reduction of pesticide residues depend on a number of factors, the most important of which are ... 

Aerosol products are hermetically sealed, ensuring that the contents caimot leak, spill, or be contaminated. The packages can be considered to be tamper-proof. They deUver the product in an efficient manner generating Httie waste, often to sites of difficult access. By control of particle size, spray pattern, and volume deUvered per second, the product can be appHed directiy without contact by the user. For example, use of aerosol pesticides can minimize user exposure and aerosol first-aid products can soothe without applying painful pressure to a wound. Spray contact lens solutions can be appHed directiy and aerosol lubricants (qv) can be used on machinery in operation. Some preparations, such as stable foams, can only be packaged as aerosols. 

Encapsulated dia2innon sold as Knox-Out 2FM is a commercial encapsulated pesticide formulation said to have reduced dermal and oral toxicity as well as prolonged effectiveness. The capsules, prepared by interfacial polymeri2ation, are claimed to be highly effective against cockroaches with no objectionable odor and low insect repeUence. The capsules are beheved to function as a contact poison when insects walk on it and as a stomach poison when insects preen capsules stuck to their legs and ingest them (71). 

The alkah flame-ionisation detector (AFID), sometimes called a thermionic (TID) or nitrogen—phosphoms detector (NPD), has as its basis the fact that a phosphoms- or nitrogen-containing organic material, when placed ia contact with an alkaU salt above a flame, forms ions ia excess of thermal ionic formation, which can then be detected as a current. Such a detector at the end of a column then reports on the elution of these compounds. The mechanism of the process is not clearly understood, but the enhanced current makes this type of detector popular for trace analysis of materials such as phosphoms-containing pesticides. 

Air-poUutant effects on neural and sensory functions in humans vary widely. Odorous pollutants cause only minor annoyance yet, if persistent, they can lead to irritation, emotional upset, anorexia, and mental depression. Carbon monoxide can cause death secondary to the depression of the respiratory centers of the central nervous system. Short of death, repeated and prolonged exposure to carbon monoxide can alter sensory protection, temporal perception, and higher mental functions. Lipid-soluble aerosols can enter the body and be absorbed in the lipids of the central nervous system. Once there, their effects may persist long after the initial contact has been removed. Examples of agents of long-term chronic effects are organic phosphate pesticides and aerosols carrying the metals lead, mercury, and cadmium. 

Lisi P, Caraffmi S, Assalve D. 1987. Irritation and sensitization potential of pesticides. Contact Dermatitis 17 212-218. 

The most important routes of exposure to endosulfan for the general population are ingestion of food and the use of tobacco products with endosulfan residues remaining after treatment. Farmers, pesticide applicators, and individuals living in the vicinity of hazardous waste disposal sites contaminated with endosulfan may receive additional exposure through dermal contact and inhalation. 

For most chemicals, inhalation is the main route of entry into the body. However, certain chemicals (e.g. phenol, aniline, certain pesticides) can penetrate intact skin and so become absorbed into the body. This may occur through local contamination, e.g. from a liquid splash, or through exposure to high vapour concentrations. Special precautions to avoid skin contact are required with these chemicals and potential exposure via skin absorption has to be taken into account when assessing the adequacy of control measures. Chemicals able to penetrate intact skin are listed in Table 4.2. 

As more sensitive analytical methods for pesticides are developed, greater care must be taken to avoid sample contamination and misidentification of residues. For example, in pesticide leaching or field dissipation studies, small amounts of surface soil coming in contact with soil core or soil pore water samples taken from further below the ground surface can sometimes lead to wildly inaccurate analytical results. This is probably the cause of isolated, high-level detections of pesticides in the lower part of the vadose zone or in groundwater in samples taken soon after application when other data (weather, soil permeability determinations and other pesticide or tracer analytical results) imply that such results are highly improbable. 

Exposure of organisms to pesticides occurs through contact or inhalation. Inhalation exposure can be assessed using some of the active samplers discussed in the previous section, for example air samplers mimicking respiratory systems. Contact exposure can be assessed using samplers that represent collection by horizontal or vertical surfaces, or combinations of these orientations. This article addresses only the first part of this process, i.e., consideration of techniques for sampling sprays in the environment. 

Water-sensitive papers are readily available in most countries and provide a convenient system for visually assessing spray drift performance. These papers are coated with bromoethyl blue, which turns from yellow to blue when contacted with water. " However, since any water can cause this change in color, care needs to be taken to prevent accidental exposure to sources of water other than the pesticide. Such cards do not work well under humid conditions, and are not appropriate for sampling droplets with diameter below 15 qm. Quantitative estimates of droplet size distributions must take account of the exponential increase in droplet volume as the droplet diameter increases. As droplets strike the paper, the liquid spreads over the surface and leaves a stain with a size that is dependent on the volume of the droplet. The apparent droplet size will be greater for large droplets than for small droplets, and the size determination must be corrected to avoid bias. 

---