Antidotes, early developments

Another approach has been to increase the physiological tolerance of crop plants to particular herbicides through the development of chemical antidotes or safeners. Since the introduction of this latter concept by Otto Hoffman (2) in the early 1960 s, at least five antidotes or safeners have been developed commercially (Table I). 

British antilewisite (BAL) or dimercaprol was developed as an antidote for lewisite. It is used in medicine as a chelating agent for heavy metals. Although BAL can cause toxicity itself, evidence suggests that BAL in oil administered intramuscularly will reduce the systemic effects of lewisite. BAL skin and ophthalmic ointment decrease the severity of skin and eye lesions when applied immediately after early decontamination, but neither of these ointments is currently manufactured. 

Monitoring plants for the presence of antidotes would seem to be particularly necessary when disease control involves the use of systemic fungicides (rather than those which act principally as protectants on the surface of the plant), since compounds of this type, which are now widely employed in agriculture, pass into the tissues of the plant where they are more likely to encounter any antidotes that may be present in the cells. If antidotes are detected in crop varieties, and if their presence appears to interfere with the efficiency of certain fungicides, the knowledge may allow different chemical treatments to be selected at an early stage. Alternatively, plant breeders may be able to develop varieties which lack, or contain only low levels of, the antidote compound(s) as, for instance, has already been done for different commercial reasons with crops such as lupin (low-alkaloid content), and sweetclover (low-coumarin content). 

CWAs are manufactured and stored by government facilities for basically two reasons. Stored CWAs serve as an effective deterrent to first use of CWAs by others. Secondly, manufacture of these agents permits necessary research of agent characteristics, and provides a means for research of detection techniques and antidote developments. Early detection and warning of even minute amounts of CWAs and/or TICs in the air are essential to minimize casualties. 

Almost 100 years after the first use of mustard gas (HD) in warfare, there is stiU no available antidote, although there is an antidote (British anti-Lewisite) to the vesicant Lewisite, an arsenical compound developed in 1919. Treatment is therefore based on early recognition of the exposure and immediate decontamination to prevent further injury. This is particularly important in the case of the eyes. 

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