Allethrin and Pyrethrins 
Studies have suggested that metabolic pathways for pyrethrins 
and allethrins differ and also that detoxification mechanisms in house- 
flies and roaches differ. 
Initially, it was suggested that decomposition of pyrethrins was 
caused by hydrolytic enzymes. Subsequent studies have shown that 
lipases of roaches and houseflies readily hydrolyze pyrethrin esters 
to keto alcohols, chrysanthemum acids, and several unidentified 
compounds (Woke, 1939; Chamberlain, 1950; Zeid et al., 1953; Winter- 
ingham, 1952a). Some 8-12% of labeled pyrethrin applied to roaches 
was excreted as cl4o,. When applied to houseflies, no cl4o, was detect- 
ed (Winteringham et al., 1955b; Hopkins and Robbins, 1957; Chang and 
Kearns, 1964). Chrysanthemum acid and five unknown metabolites were 
detected. Three of the unknown metabolites had intact chrysanthemum 
acid moiety and an ester linkage. Cinerin I (Chang and Kearns, 1964) 
behaved similarly but differed quantitatively. Thus, it appears that 
initial degradation occurred on the pyrethrolone or cinerolone moiety. 
When pyrethrin I was administered as an anthelmintic, color 
tests on urine of humans indicated the presence of chrysanthemum 
monocarboxylic acid (Audiffren, 1934). Studies with rats suggested 
that barthrin (6-chloropiperonyl chrysanthemumate) was metabolized and 
excreted in urine as metabolites, free and conjugated, having a strong 
reducing effect on Benedict's reagent (Ambrose, 1963; Masri et al., 
1964). Residues from urine gave a positive test for chrysanthemumic 
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