A comparison between Agent Orange and Scrub Desiccant TD Volatile.

 

Compiled by N.L.Benefield

 

"Of all the herbicides used in South Vietnam, only Agent Orange was formulated differently from the materials for commercial application, that were readily available in the United States."(1)

 

Principles of Formulation

"Esters of 245T are largely insoluble and so cannot be usefully mixed with water on their own.  Some oil dissolved concentrates are sold but most 245T esters are marketed in an emulsifiable form - an'emulsifiable concentrate' or 'EC'."(2)

 

Uses of the products.

Agent Orange was required to effect total defoliation of hardwood species.  This effect of the dropping of all the leaves of the plant is also referred to as abscission.

 

Scrub Desiccant was usually used on softwoods for a desiccant effect of killing the leaves of the plant which may either drop or remain on the plant, and create a situation suitable for burning.

 

Composition of the Products.

Scrub Desiccant TD Volatile contained 3.73lbs/gal of 24D and 3.73lbs/gal 245T as the butyl esters in the form of an emulsifiable concentrate.(3)

 

The claimed formulation of Agent Orange has been identified in a document submitted to the Australian Royal Commission 1985:

 

"Orange(the finished product) was a reddish-brown to tan coloured liquid soluble in diesel fuel and organic solvents but insoluble in water. One gallon of Agent Orange theoretically contained 4.21lbs of the active ingredient of 24D and 4.41lbs of the active ingredient of 245T...."(4)

 

Comparison of the compositions with Scrub Desiccant identifies that Agent Orange had the higher quantities of the active ingredients prior to application.

 

"Orange was formulated to contain a 50:50 mixture of butyl esters of 24D and 245T."(4)

 

Factually it was Blended to a 1:1 blend.

 

"The percentages of the formulation typically were:

n-butyl esters of 24D                                         49.49

free acid of 24D                                                  0.13

n-butyl esters of 245T                                       48.75

free acid of 245T                                                1.00

inert ingredients (butyl alcohol etc.)                    0.62."(4)

 

 

This presentation of information is identical with the standard testing at the end of the esterification phase of manufacture, prior to formulation. i.e.:

 

"Routine analyses of the product include estimates of:

Total esters, acid equivalent

free acid

free Trichlorophonels

A gas/liquid chromatographic scan is run to check for impurities...."(2)

 

Calculations conducted in this form will always identify only theoretical estimates of the concentrations of the product.    Pure 100% esters are a solid at room temperature. Formulated products are usually identified on labeling by weight/volume, not percentages, whereas  Agent Orange is recorded as esters of 245T and 24D, wieght\wieght. Interestingly the levels of free Trichlorophenols are not identified in reference(4). In 1967 the patent holder of Hexachlorophene is recorded as having difficulty obtaining supplies of unreacted 245Trichlorophenol from its usual supplier, Dow, who at that time was manufacturing Agent Orange, when use in Vietnam was reaching a peak.

 

The Relationship of TCCD(dioxin) and products.

The potential TCCD levels in Agent Orange were still been debated in 1991."....TCCD has been the chemical of greatest concern in exposure to the defoliant Agent Orange, although it was present only as a sparse contaminant(a few parts per million at worse), and generally fractions of parts per million."(5)  The source for this statement, was sampling of Agent Orange remaining on the US mainland, after cessation of the progam.   This product was manufactured after the debate on contamination had been published, and at a time when processes where been utilised to severely reduce  the amount of TCCD in the finished product. 

 

A study published in the Journal of the American Chemical Society 1981, contradicted that the average of TCCD was 2ppm as identified during the destruction of surplus stock of Herbicide Orange on the Vulcanus 1 incineration ship.  In this study samples identified a range up to 47ppm.  More importantly this study identified samples of domestic products in the US at 6ppm, and another product line which stemmed from the contaminated 245Trichlorophenol precursor, Hexachlorophene, which after refining during manufacture of the product contained <0.03ppm.  The highest concentration from sampling were with the Agent Orange.

 

Also in this study regarding  245T products,"only minor amounts of other PCDD's and PCDF's  could be found,(in all 245T samples) primarily lower chlorinated PCDD's in the samples of Agent Orange", is an indication that AO 's manufacture processes differred from the domestic product(6).

Circa 1983 when Scrub Desiccant was used as a defoliant, the Industry/Governmental standard was 0.01ppm.

 

"An estimated 368 pounds of dioxin was sprayed in Vietnam over a six year period"(9)

 

There are wide variations in the recorded accounts of TCCD contamination, but these differences can be explained by method of manufacture, where speed was of essence  1965-1968, and industry changes that occurred in 1969 when it

 was obvious that TCCD contamination had occurred in the finished product, and not only the 245Trichlorophenol precursor to the manufacture of 245T.   Evidence of speed of manufacture has been shown in an admission by James Clary PhD, a former US Government scientist at the Chemical Weapons Branch of the USAF(10).   No information on the quantities of Trichlorophenols that may have been allowed to remain in the product Agent Orange is recorded, but given that there is evidence of higher TCCD levels during the period of high usage 65-68, one would expect these levels to be higher than the domestic product of that time.

 

 To clearly understand why one product was a defoliant and the other a desiccant it is necessary to review the application practices and modes of action of the active ingredients, for an explanation.

 

Modes of Action.

Agent Orange was a systemic plant poison which when absorbed in to the plant through the foliage and translocated throughout the plant caused a rapid withering followed by death of the plant within 2-3weeks."(7)

Note the biological efficiency of Agent Orange.

 

Scrub Desiccant was "Absorbed mainly through the leaves and stems. Very little translocation in the plant.  Causes interference in cell division and enlargement."(3)

Note the biological efficiency of Scrub Desiccant.

 

 

Historical Developments

June 1959"an improvised helicopter spray system delivered a 1:1 mixture(blended??) of 2,4D and 2,45T.....at a quantity of one-half gallon per acre"(9)

"Agent Purple 245T, 24D. as butyl ester and isooctyl ester deployed 1962-64)

There is no indication that this programme used available domestic products or a specific blend.    The unit responsible for this task was the US Army's Biological Warefare Laboratories, the same unit incolved in the early stages of the herbicide program in Vietnam.

 

Application Practices.

 

Agent Orange is recorded as "causing effective defoliation and death of most susceptible vegetation....at a rate of three gals of the active agent per acre.  Agent Orange was applied as a liquid spray mixed  with No1 diesel oil at a rate of 3 gals Orange to 50gal oil for a spray of one acre area."(7)

 

"Results of the test program(in Thailand 64-65)showed that ...24D and 245T were effective for long term defoliation, with more complete......and long term duration.....at higher rates of application"(9)

 

Scrub Desiccant had the highest recommendation as a desiccant against manuka at 5.58gal of product(active ingredients, solvent, emulsifier) to 5.58gal of diesel, further diluted in 200 litres of water per/ha.

Circa 1983 this product was given an Experimental Use Permit(limited sale) for use against"standing native hardwood species to obtain light penetration prior to oversowing..." a defoliation application(although later refoliation of the plants could occur), that used the same application rate for manuka desiccation, except that " for  the most effective coverage apply the total spray mix in two passes moving over only

half of the effective swath width each parallel path."(3) was the only added recommendation.

 

In short, the higher concentrations of the active ingredients determine the difference between the actions of a desiccant or defoliant.

Interestingly it was advocated during this type of use that "aerial application air temperature should not exceed 20 degrees C, humidity should not be lower that 50%, and wind speed should not be above 8km/h."(3)

 

 

 

Aerial application of Agent Orange was "applied mostly by twin engined C123....equipped with 3785litre(1000gal) tanks....with 36 high pressure nozzles....normal spray times was 2minutes but a complete load could be dumped in 30 seconds."(8)

"Under ideal conditions, a 1,000gallon tank permitted a 3 to 4-min spray time at a total distance of about 8.7 statute miles, or about 340 acres treated per aircraft with a deposition rate of 3 gals per acre"(9)

 

 

Summary.

 

The total defoliation caused by Agent Orange was accomplished by the application of high rates of the active ingredients on the target vegetation.  The product did not need to be consistent in content, so long as there were sufficient quantities of esters within the applicable solvent after mixing, to produce the biological effect.

Agent Orange was simply a Blend of the esters of 24D and 245T mixed with diesel oil for application.  High seasonal temperatures allowed the use of esters in quantities that

could not be applied in temperate climates. The term formulation has been used to classify the major compounds of 24D and 245T used in the Agent Orange program in (9)  but not the product.

 

Technically  Agent Orange was a blended,  not a formulated product  to an Emulsifiable form, although it contained the chemical formulations of  245T and 24Dbutyl esters, and as such was a unique product .  For domestic products a small amount of solvent was used in the formulation process. For Agent Orange  the application medium was the solvent.  Most histories suggest the use of desiel oil, kerosene or contaminated JP fuel as the application medium..

 

 As no manufacturing formulation occurred, no definitive quality control assurances could have been applied.  The appropriate Agent Orange product to diesel solvent ratio was determined by calculating the vegetation consistency of the target area, and determining the desired biological effect required..  

 

The conditions of air temperature, humidity and wind speed, which were required prior to defoliation  with Scrub Desiccant TD Volatile, was not a major consideration of the

Ranch Hand applicators of Agent Orange.  "Although missions generally were flown in the early morning when the wind was calm, to minimize spray drift, the NAS(1974) study .......indicating that widespread crop damage resulted from drift."(9)

 

 

References:

 

(1) Young et al., 1978

 

(2) "Production of 245T", Dr O.K. Sewell (IWD) 1972

 

(3) New Zealand Agrichemical Manual 1984 edition

 

(4) Appendix 3 to Annex D to Book 1"Description of Herbicides used by the US

      Forces  in Operation Ranch Hand"

 

(5) "How Dangerous is Dioxin." The New England Journal of Medicine, Jan 24, 1

       1991

 

(6)"Occupational Exposure to Polychlorinated Dioxin and Dibenzofurans." Rappe

       and Buser 1981

 

(7) Final Report, Vegetation Control Program Calendar Year 1968(U) page E2.

 

(8) Spiri 1976

 

(9)  "Veterans and Agent Orange", IOM, NAS, 1994

 

(10) Letter Clary to Senator Tom Daschle, US Senate