Pesticide release from

Physical parameters which control the dispersion, deposit, coverage (of target plants) as well as drift losses of liquid pesticides released from aircraft In mountainous forest land are (1) spray drop size and spray formulation, (2) local meteorology, (3) local terrain at spray site and (4) type of application aircraft. 

Pesticides can also be a source of environmental pollution that might migrate toward plastics in the oceans. Pesticides released from storm runoff in Australia were found to damage the Great Barrier Reef Marine... 

The intent of this article is to provide an overview of methodology and materials for sampling airborne pesticide spray and spray collection on surfaces by sedimentation deposition and impaction after release from field sprayers. The term pesticide will be used as a general term to represent chemicals such as herbicides, insecticides, fungicides and related products. 

A second risk zone corresponds to Monzon (17,042 inhabitants), a highly industrialized city in the middle Cinca River. Its industrial activity has caused the historical release of organic and inorganic compounds to the river coming from chlor-alkali industry, from production and utilization of solvents and organochlo-rine pesticides, and from the use of brominated flame retardants in the production processes. Very high concentrations of mercury have been recorded for sediment and fish samples in the downstream of Monzon [2-4]. 

As a result of human health concerns, production of mirex ceased in 1976, at which time industrial releases of this chemical to surface waters were also curtailed. However, releases from waste disposal sites continue to add mirex to the environment. Virtually all industrial releases of mirex were to surface waters, principally Lake Ontario via contamination of the Niagara and Oswego Rivers. About 75% of the mirex produced was used as a fire retardant additive, while 25% was used as a pesticide. As a pesticide, mirex was widely dispersed throughout the southern United States where it was used in the fire ant eradication program for over 10 years. 

On December 3, 1984, a toxic gas release from a pesticide plant in India killed nearly 3000 people and injured at least 100,000 others. The chemical that leaked was methyl isocyanate, a chemical intermediate that was supposed to be stored in a cooled bunker near the plant s outer boundary. The vapor is highly toxic and causes cellular asphyxiation and rapid death. Despite engineering and procedural provisions to prevent its release, a total system breakdown resulted in the release of 40 tons of the deadly material into the densely populated community of Bhopal. Because of this incident, the plant was dismantled and ultimately the parent corporation. Union Carbide, was forced to make a number of organizational changes. The occurrence is considered by many to have been the most tragic chemical accident in history. 

Diazinon air concentrations related to vapors released from pest control strips were measured by Jackson and Lewis (1981). Diazinon levels in indoor air increased from 0.32 pg/m3 at 6 hours after application of the pest strips to 1.34 pg/m3 on day 15, and then declined to 1.21 pg/m3 on day 30. Air sampling in a retail garden store where pesticide containers with diazinon were displayed showed an average diazinon concentration of 3.4 pg/m3 (Wachs et al. 1983). 

One of the worst industrial accidents occurred in Bhopal, India, on December 2 and 3, 1984. It was due to the leakage of methyl isocyanate (MIC) released from the Union Carbide pesticide manufacturing plant. More than 3,000 people who resided in areas adjacent to the manufacturing plant died within a few hours after exposure to MIC. Death was attributed to severe pulmonary toxicity, followed by... 

Insecticides tend to persist longer in soils of high organic matter. In fact, in muck soils (50% or more organic matter), residues have been found bound to soil particles to such an extent that the same amount of toxicant is less effective in muck soil as compared with a sandy type. It has been noted that pesticides are absorbed into crops most readily from sandy soils and least from muck soils. Moisture enhances the release of volatile pesticides from soil particles and also influences the breakdown of other toxicants. Microbial attack has been found to oxidize aldrin to dieldrin, and parathion in the presence of yeast is reduced to the nontoxic aminoparathion in soil. As might be expected, increased soil temperatures can dramatically increase the rate of pesticide loss owing to volatilization and increased breakdown. Cover crops, such as alfalfa, can decrease pesticide volatility from soil whereas cultivation... 

In the case of chemical pesticides, these include factors such as molecular weight and vapor pressure that determine the rate of evaporation into air of the pesticide in an applied material such as paint, or the release from aqueons solntion. In the case of biological agents, these include, for example, pathogenicity to hnmans, allergenicity, infectious dose levels and aerosol particle size distribntion. 

Persons applying pesticides from a vehicle are, in general, separate from the immediate proximity of the pesticide being dispensed. Often they are located above and in front of the point of pesticide release. This factor, combined with the forward motion of the vehicle, reduces the probability that pesticide drift or runoff will contact them. Figure 6.6 show a person in a vehicle applying a contact herbicide with a directed applicator. 

Some possible exposure scenarios exist, however. When the pilot is also the mixer/loader of the pesticides, the pesticide exposure from that activity may be continued in the cockpit through contaminated PPE. The pilot also may be exposed to pesticides when climbing into or out of the cockpit of a contaminated aircraft. Finally, in some situations, a pilot making a sharp turn or flying in strong wind may fly through the pesticide swath just released from the aircraft. If the cockpit is not enclosed or if its air is not filtered, the resultant pesticide exposure could be significant. 

The likelihood that pesticide particles and spray droplets will drift offsite depends partly on the way they are released. Pesticides released close to the ground or floor are not as likely to be caught up in air currents as those released from a greater height. Pesticides applied in an upward direction or from an aircraft are the most likely to be carried on air currents. 

Phenol Red. The first publications of an automated procedure for the measurement of cholinesterase inhibitors are those of Winter 14) and Winter and Ferrari (15). The method employed an Autoanalyzer instrumental system wherein the extracts containing the insecticide were incubated with a standard cholinesterase solution at 37 °G. A continuous sample from the incubation bath is buffered and mixed with acetylcholine iodide. After a second incubation, the acetic acid released by the action of the uninhibited cholinesterase is measured colorimetrically, using phenol red as the indicator. More recently, Fischl et al. 16) reported a method for rapid detection of organic phosphate pesticides in serum. Strips of filter paper were impregnated with a buffered acetylcholine substrate solution containing phenol red as an indicator. When no inhibition is present, the acid released from the action of cholinesterase turns the paper yellow. When cholinesterase has been inhibited, the paper turns pink-to-violet. 

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