Persistence of malathion residues on treated food grains under different conditions of storage and processing.

Malalhion, a phosphatic insect'cide, was found to control somt: stored grain
pests within its permisgihk lim'l. Application of Malathion in the pre_harvest
and post-harvest storagc as a grain protectanl ha3 also been found to be pro_
mising because of it, low mammalian to"icity and high t(.,,,i<:ity to insects. The
breeding of TriobaHum CIlJlanellm could be inhibiter! even at a concentration of
2 p.p.m. which is far below the permissible limit, <'i"" 8 p.p.m. Studies were
carl"ied Ollt on the decay and pel'3istence of Malathion applied on mature grain
panicles in the pre-harvest period, on wheat flour during storage, find dudng
proc{'--\sing of whent, rice alld jowflr floUis by s\eam cooking and baking:,
enlploying the colorimetric analytical method desCl'ibed by Norris ft ai., with
slight modif¥,ation to suit the convenience. Effect of the particle siu of the
treated malrrial on the persistence of l\labthion was also investigateo. The
results revealed that moisture contents of the matcrialg s~m to play some role
in ,h:e deCDmp'-'silion of Malathion and particle size had no effect on the loss of
Malathion. Both temperature and relative humidity resulted in loss of
Malathion on the grain and the milled materials during storage. Steam
cooking destroyed Malathion at a higher rate than that or baking of the flours
prepanccl from sorghum, wheat and rice.