Meanwhile, the military continued to learn just how toxic Agent Orange could be. On
    October 23, 1969, an urgent message was sent from Fort Detrick, Maryland, to MACV
    concerning cleaning of drums containing herbicides. The message provided detailed
    instructions on how to clean the drums and warned that it was particularly important to
    clean Agent Orange drums.
       "Using the (Agent) Orange drums for storing petroleum products without thoroughly
    cleaning of them can result in creation of an orange aerosol when the contaminated
    petroleum products are consumed in internal combustion engines. The Orange aerosol
    thus generated can be most devastating to vegetation in the vicinity of engines. Some
    critics claim that some of the damage to vegetation along Saigon streets can be attributed
    to this source. White and Blue residues are less of a problem in this regard since they are
    not volatile."
       Not only was Agent Orange being sprayed from aircraft, but it was unwittingly being
    sprayed out of the exhausts of trucks, jeeps and gasoline generators.
       In March 1969, Lt. Col. Jim Corey, deputy chief of CORDS in I Corps reported to his
    boss, R.M. Urquhart, unusual defoliation in Da Nang. "A large number of beautiful shade
    trees along the streets in the city of Da Nang are dead or dying," Corey wrote. "This
    damage appears to be entirely a result of defoliation chemicals."
       There was no evidence of insect or fungus damage to the vegetation, according to the
    memo. "In every instance of tree and garden plot damage," Corey wrote, "empty defoliant
    barrels are either present in the area or have been transported along the route of the
       The use of herbicides was not confined to the jungles. It was widely used to suppress
    vegetation around the perimeters of military bases and, in many instances, the interiors of
    those bases.