Coumaphos (Coral, Bayer 21/199, muscatox) [0,0-Diethy1l-0-(3-chloro-4- 
methylumbelliferone) phosphorothioate] 
Dermal administration of CoumaphessPe- to rats gave two peaks of 
radioactivity in the tissues. The first peak appeared between 4 and 6 
hours following administration; the second, 4 to 7 days later. Two thirds 
of the excreted material appeared in the urine within 28 days, compared 
with four fifths within 18 days of subcutaneous and 14 days of oral admini- 
stration (838, 877, 1100). 
Four metabolites were detected in the urine. During the first 96 hours 
after oral treatment, diethyl phosphorothioic acid constituted 50 - 802% of 
excreted radioactivity; phosphoric acid, 10 - 20%; diethyl phosphoric acid, 
10 - 20%; de-ethylated coumaphos and/or its oxygen analog, 5 - 30%. Follow- 
ing subcutaneous administration, only three metabolites were found. There 
was diethyl phosphorothioic acid but no phosphoric acid. After dermal treat- 
ment, none of the de-ethylated derivatives were found. Phosphoric, diethyl 
phosphoric, and diethyl phosphorothioic acids appeared in about equal pro- 
portions (877, 1100, 1446). 
After subcutaneous administration, 17% of the radioactivity in the 
feces appeared to be coumaphos or its oxygen analog. Oral and dermal ad- 
ministration resulted in an increase to 50 - 60%. When the oxygen analog 
was orally administered, 10% appeared as diethyl phosphoric acid and 40Z 
as the de-ethylated analog in the urine within 24 hours (1100). 
p>*_1abeled coumaphos was applied dermally to a cow and a goat. Un- 
extractable residues were significant in tissues of both animals. Hydrolysis 
products were below the limit of sensitivity of the method. Many tissues, 
particularly fat, contained considerable radioactivity that appeared to be 
the oxygen analog of coumaphos. The peak blood level of radioactivity for 
the cow occurred at 6 days; for the goat, at 6 hours and then again at 5 
days. Cow cholinesterase continued to drop for seven days but recovered 
by the end of two weeks (757, 838, 1218). 
Most of the radioactivity appearing in the urine was as hydrolysis 
products. Some of the oxygen derivative of coumaphos was found in the 
initial (up to 6 hours) collections but thereafter hydrolysis products 
were predominant: 35% phosphoric acid, 17% diethyl phosphoric acid, 292% 
diethyl phosphorothioic acid, and 18% as the de-ethylated coumaphos and 
its oxygen analog, primarily. Results obtained from the study with the 
goat were similar to those of the cow (757, 838, 1100, 1186). 
When Rhode Island hens were fed mash containing labeled coumaphos, con- 
siderably more radioactive material appeared in the yolk than in the white 
or shell of eggs. The peak of radioactivity in the eggs appeared 11 to 15 
days after the beginning of the treatment and was present as long as 6 
to 8 days after return to normal diets. The decline in tissue residues 
100 
