Toxicology of Parathion and Other

Phosphatic Insecticides and Precautions
 For Their Use on Citrus

JAMES T. GRIFFITHS, JOHN W. WILLIAMS, W. L. THOMPSON, AND
 C. R. STEARNS, JR.'


 Introduction
 In 1947 early trials with the insecticide parathion (22)2 indi-
cated that this material offered promise of satisfactorily replac-
ing oil as a scalicide for citrus. It was known that parathion
was a poisonous substance and it remained to be determined
whether it could be safely used in commercial spraying opera-
tions. Since that time much research has been completed, con-
cerned not only with the action of parathion and other organic
phosphatic insecticides on human beings but also with ways and
means to handle these insecticides safely.
 This bulletin is intended to explain the action of phosphatic
insecticides upon the human body, to clarify some of the mis-
information that has existed concerning phosphatic insecticides,
and finally to suggest specific precautions for the use of parathion
so that it can be handled safely by grove labor under field con-
ditions.
 It is realized that parathion may be an insecticide of only
 transitory importance, used for a few years and then discarded
 in favor of a still better material. However, it is probable that
 the replacement for parathion will be another phosphatic insecti-
 cide with similar pharmacological characteristics. Thus, the in-
 formation that has been gathered concerning parathion may also
 be applicable to other newly developed insecticides.
 Shortly after the close of World War II a new material known
 as HETP (hexaethyl tetraphosphate) appeared on the market
 for use as a replacement for nicotine. It proved to be the fore-
 runner of a number of new insecticidal compounds, all related
 as esters of phosphoric acid and all with similar pharmacological
 effects in their toxicity to warm-blooded animals. HETP was
 shortly replaced by TEPP tetraethyll pyrophosphate), which was
 1 Asso. Entomologist, Citrus Experiment Station; Pathologist (M.D.),
 Morrell Memorial Hospital, Lakeland; Entomologist, Citrus Experiment
 Station; and Associate Chemist, Citrus Experiment Station, respectively.
 2 Italic figures in parentheses refer to Literature Cited in thz back of
 this bulletin.