Herbicides aerial application

From January 1962 to April 1970, a program of aerial application of herbicides was conducted in Southeast Asia by the United States Air Force (USAF). At the conclusion of this program, considerable amounts of herbicide were left unused. 

For this purpose an elaborate testing Installation, designed to measure deposition parameters, was established on the Eglln Reservation with the place of direct aerial application restricted to an area of approximately 3 km within Test Area C-52A In the southeastern part of the reservation. Massive quantities of herbicides, used In the testing of aerial defoliation spray equipment from 1962 through 1970, were released and fell within the Instrumented test area. The uniqueness of the area prompted the United States Air Force to set aside the area In 1970 for research Investigations. Numerous ecological surveys have been conducted since 1970. As a result, the ecosystem of this unique site has been well studied and documented (2,3). 

Young, A. L., C. E. Thalken and W. E. Ward, 1975. "Studies of the Ecological Impact of Repetitive Aerial Applications of Herbicides on the Ecosystem of Test Area C-52A, Eglln,... 

Commercial herbicide handlers who use the herbicides in aerial applications... 

This study found that some crew members involved in the aerial application of 2,4-D for forestry purposes absorbed low levels of 2,4-D, but the doses as indicated by urine analyses were several orders of magnitude below the 24 mg/kg noobservable-effect-level determined in toxicology studies. These results are in agreement with those of Nash et al. (1982). The doses were comparable to those found in an earlier test involving aerial application of 2,4,5-T but were substantially lower than those found for ground application of that herbicide (Lavy et al., 1980). 

One problem that has arisen with the use of herbicides in agriculture is spray or vapor drift. When fine spray droplets are released, especially if applied aerially, they may be deposited beyond the target area due to air movements to cause damage there. In the first place, this is a question of application technique. Herbicides, like other pesticides, should not be applied as sprays under windy conditions. In most... 

The principle public concern with regard to risk from herbicide application in the forest is not the overt, or occupational, exposure to pesticide applicators or to persons who might be in the spray zone. It is the possible injury from pesticide drift at a distance of a few hundred yards or a quarter of a mile, up to 5 to 20 miles. All aerially-applied pesticides will drift for some distance, whether they be applied by fixed-wing craft or helicopter. 

In general, workers involved in the manufacture of 2,4,5-TCP and subsequent products were exposed to far greater levels of 2,3,7,8-TCDD than those involved in the handling and application of chlorinated pesticides containing CDDs. Current serum lipid levels of 2,3,7,8-TCDD in a small number of U.S. Air Force veterans who were directly involved in the aerial spraying of herbicides (Agent Orange contaminated with 2,3,7,8-TCDD) in Vietnam as part of Operation Ranch Hand,... 

TCDD. A maximum of 0.15% (0.12 ppm) of 2,3,7,8-TCDD present in soils was translocated to the aerial portion of the oat and soybean plants. No detectable amounts of the compound were found in the oat or soybean plants harvested at maturity. The amount of 2,3,7,8-TCDD applied to these soils was many thousands of times greater than that which would occur in soils from herbicide applications containing a few ppm of 2,3,7,8-TCDD as an impurity. Even upon exposure to these high concentrations... 

Drift from aerial or ground applications of herbicides... 

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