should be used to protect the body and to prevent damage to 



person and clothing. If a painted boat is used, care should be 



taken to protect the paint since it is readily removed by the strongly 



caustic sodium arsenite solution. If spray reaches the eyes, they 



should be rinsed immediately, both with water and with boric acid 



solution. 



The strongly caustic solution has a sweet odor which is 

 attractive to livestock. Cattle will either lick or eat treated 

 vegetation at every opportunity. Therefore, every precaution should 

 be taken to prevent spills on the shores of treated waters, and to 

 prevent access of cattle to treated vegetation. To be on the safe 

 side, cattle should be excluded from a treated pond for at least 

 one week. Treatments of water hyacinths with sodium arsenite in 

 the south was abandoned many years ago because of the danger to 

 cattle which waded out into the waterways to feed on the succulent 

 plants . 



The fatal dose of arsenic (AS2O3) to man is 1 to 3 grains 

 (60 to 180 milligrams per liter, or parts per million). In a 

 fish pond treated at 4.0 p. p.m., a man would have to drink from 

 15 to 45 quarts of freshly treated water to get a fatal dose. The 

 hazard to man is virtually non-existent in most waters where treat- 

 ments are likely to occur. An antidote is British Anti Lewiste 

 (B.A.L.). 



In early treatments with sodium arsenite in upper Mississippi 

 River sloughs, successful control of submersed aquatic plants was 

 obtained with slightly less than 2.0 parts per million, a low rate 

 compared with present day treatments . This rate permitted many 

 plankton organisms and bottom animals to survive (Surber 1932, 

 Surber and Meehean 1931). Midgefly larvae, a staple item in the 

 food of young fishes, even increased in number following treatments. 

 Higher rates of application produce more spectacular results in 

 killing weeds, but rates greater than 4.0 p. p.m. in fish ponds 

 exceed the quantity of sodium arsenite that can be survived by 

 many aquatic animals (Lawrence 1958) . 



Lake Shoreline Spraying with Sodium Arsenite 



Submersed weeds often grow to such density along lake front 

 properties that they interfere with boat passage to and from docks, 

 as well as with bathing and fishing. 



The recreational values of beach areas in lakes invaded by 

 weeds can be restored by treatment with sodium arsenite at con- 

 centrations ranging from 5 to 10 p. p.m., depending upon the size 

 of the lake, average depth of water, and the exposure of the beach 



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