Dalapon (2,2-Dichloropropionic acid) 
When dairy cows were fed dalapon, less than 14 of the ingested 
dose appeared as residues in the milk, mainly as unchanged dalapon but with 
traces of dalapon glycerides (848). 
Tracer studies with dalapon=22cu" and G12" showed that dalapon was 
absorbed, translocated, and accumulated in higher plants as the original 
molecule or dissociable salt and might remain non-metabolized for long 
periods (22, 124, 469, 470, 471, 472, 473, 474, 856). A small amount of 
decomposition occurred slowly and resulted in release of C12° or incor- 
portation of C!* into other compounds, Tests with tissue homogenates did 
not indicate metabolic incorporation of dalapon into insoluble macromolecutes, 
Some indication of dehalogenation was indicated on chromatograms (470, 473), 
Propionic acid, which could arise through such reactions, competes with @- 
alanine in pantothenic acid synthesis. Studies have shown that dalapon does, 
in fact, inhibit pantothenate synthesis (661). 
Many microorganisms have been found capable of dissimilating dalapon 
(355, 666, 667, 668, 685, 731, 914, 920, 1205) .with release of chloride and 
formation of monochloropropionate (470, 472, 473, 732). 
Pseudomonas dehalogens, nocardia sp., agrobacterium sp. and arthrobacter 
sp. released chloride (665, 668, 732). The latter organism also gave rise to 
pyruvate (776, 777) and incorporated 2-carbon units into cellular components 
(96). The 1-c!4 label was found in protein and lipid. When 2-c!* label was 
used, the label appeared in the lipid, protein and nucleic acid fractions. 
Pyruvate and alanine were shown to be the early metabolites (96). 
Studies with cell free systems indicated metabolism of dalapon to 
a-chloroacrylate, g-chloro-o-hydroxy-propionate and finally pyruvate (776, 
777). 
Anything affecting soil microbial populations may affect persistence 
of organic herbicides. Organic matter, pH, and cation exchange capacity are 
important factors affecting microbial decomposition of dalapon (685, 764). 
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