GENERAL49967 - Laserfiche WebLink

Home Browse Search

pottaat m rare that the amine, ester, aDd sodium formulations of 2,4D are all also rapidly cleared because of their rapid con- version to 2,4D acid oo absorption into the body. The rapid clearance of un- changed 2,4D from the body, coupled with itt lack of genotoxiciry, further sup- pmu the coochtsion that there is no plau- sible toxicological evidence whereby 2,4D can be expected m be a carcinogen (27). Netuvtoricity High and repeated dose resting in numer- ous sallies with multiple species have not deretted oeraological impacts from expo- sure tu 2,4D (22w7). Subehronic oral studies in rats with 2,4D acid, estea, and amine salt derivatives found oo evidence of hismlogical lesions or clinical signs of mxiciry to the nervous system (13,16). In additiog oeurolo®cal effects have not been reported in a 13-week oral sub- chronic study of 2,4D acid in mice, not in dogs treated with single oral doses up to 125 mg/kg (3 p, nor in a 1-year chronic feeding study in dogs, nor in several 2- year chronic studies in rodents (16,17). Na neurological effects were indi- cated in a recent 1-year chronic neraomx- icological study in tats (16). The tats were evaluated by functional observational baz- tery, momr activity assay, and netnopath- ology assessment The only effect noted in tats exposed to 75 mg/kg/day was a slight declirte (496) in average body weight Reproduction/Ti~ratolagy No birth defear have been observed re- lated m 2,4D or is derivatives in several reproductive and developmental studies conducted in laboratory animals (16). Available studies suggest that exposures high enough m be toxic to the moths may also be toxic tu the Beats, with tesulliog effect ao rtproduction and tlevehtpment however, tro effects wain seen at borer doses. These effects omtr only when the dose is so Ltrge as ro overwhehn the pro- cessing capaciry of the motber's kidneys. The substantially lower exposttms sus- tained by humans could not plausbly te- SUI[ In these CffeCLS. Environmental Tot~cology Exposures of wildlife to 2,4D, whether from dirut spraying or consumption of treated vegetating is so low as m have m toxicological significance (26). Indeed, the greatest effect of 2,4D oo wildlife is likely to be the presentation of an en- hanced habitat foQowmg spraying, which allows the infilnatioo of lower-growing, Emit-bearing plmts. As docr>menred in one long-trim study (3), many common game species oaarpied the habitat created by a sprayed ntiliry rightof-way oat of an apparent preference and prospered them over a period of mom than two de- cades. Ctinrent studies show rbaz 2,4D is practically nontoxic to fish and only slightly toxic to aquatic invertebrates (Table 2). The compound is considered practically nontoxic to the mallard duck and bobwhite quail in 8-day dietary stud- ies, only slightly toxic [o buds in acute oral resting, ptacdcally nontoxic to hon- eybees, and slightly mxic m earthworms at high doses (lti). EXPOSURE RIDUCTION U addition m generating new studies, the Task Fartx has coached an agreement with the EPA to initiate a 2,4D exposure re- duction program (11). The program re- quires safety procedures in the mixing, handling, and application of 2,4-D; the use of protective clothing; improved per- sonal hygiene practices; and an extensive user education program. All 2,4-D prod- ucts shipped by registrants in 1995 are being packaged under the new label speci- fied by this progi-dID. BENEFITS in response to concern by the EPA about the health effects of farm worker expo- sum to 2,4D and the phenoxy class of herbicides, the USDA initiarod a benefits assessment in 1993 to detertnine the etro- nomie implications of a complete ban of TABLE 2 Envlratntarttal to:kilt' suntrrrrry for 2,4D (axld). eoo.mta w~ anus oral tny,• son mono tz~o pra9 ~~` nine Yauard dark ear der ~` ~582o t~ P~keaY ~~ 9ee.dits goal se+ratsry tea a6a2o ppm Pr+~rs~osr~ RenUw rtov 96tnur tCa 96a rngiL paeirallr rgnbrda eweo® o~nom t.ca zta mW- ~+~ Fatherd rrQVn~ 86-true ~s 3aa mg0. Pry mmodc OgrMa 4a-huu I.G,a a mplL tEph[M/ tmrk Aaeudran rani ABhov ~i sn ~r1 prarslullr ridtadc FMOYBae tapicW L6a to yyDee R°°i'~' nwoda e.ra.ams r+darutoECe taomyhoo ~iyrytmie e17re LDS vafue ind4ates the 4rhat dose ofan active ingrcdent which it e>pected ro muse death fa 5096 ofthr tart animals txated The higher dte LDy de tower dre acute taanry of the compound °Dimethylamine soh of 2.4-D. `The LCy ua7ue nsdicaves the 4rhel ca.centrmbn ofan actise ingredient which is espNesf to carat deaM ro 50% of the test anurmis treated eNDEC is the rm ahsmed effect concemration. Studies rhrsw that 2,4-D is practically nontoxic to mallard ducks.