29 

 changes (Halter, 1980). Davis and Hardcastle (1959) reported a 48 hour 

 LCr of 375 and 350 mg/1 of the DMA formulation for bluegills ( Lepomis 

 macrochirus ) and largemouth bass ( Micropterus salmoides ) respectively. 

 However, LC 50 values for bluegills as low as 2.1 mg/1 have been reported 

 for the liquid BEE formulation and 34.5 mg/1 for granular BEE (Hughes 

 and Davis, 1965). Halter (1980) indicates that 2,4-D is essentially 

 non-toxic to waterfowl. Duke (1971) reported avoidance by mosquitofish 

 ( Gambusia affinis ) of water treated with the BEE formulation of 2,4-D. 

 Mosquitofish sought water free of 1.0 and 10.0 mg/1 2,4-D, but did 

 not seek water free from 0.1 mg/1 (Duke, 1971). Some formulations may 

 cause skin irritation in humans, but no characteristic symptoms of 

 poisoning are documented for humans (Weed Science Society of America, 

 1979). Moore (1974) reported that electron microscope assay procedures 

 for herbicide and membrane interactions indicated that animals and algae 

 lack biochemical mechanisms (specific binding sites) to respond to 

 2,4-D. Tolerances for residues resulting from the aquatic application 

 of 2,4-D in food and raw agricultural commodities have been established 

 at 0.10 mg/1 for potable water (21 Code of Federal Regulations 123.100, 

 dated December 16, 1975) and 1.0 mg/1 for fish and shellfish (40 Code of 

 Federal Regulations 180.142, dated December 9, 1975). 



Persistence in the Environment 



In terrestrial situations, 2,4-D undergoes microbial breakdown in 

 warm, moist soils in one to four weeks. The actual rate of decom- 

 position depends upon the temperature, moisture, organic matter, and 

 other soil characteristics (Hemmett and Faust, 1969; Weed Science 

 Society of America, 1979; Halter, 1980). Halter (1980) reviewed 



