in the two series of samplings ( june and july 1973 ) , ddt and its metabolites were detected in appreciable amounts at nearly all sampling sites while the other insecticides : alpha-bhc , gamma-bhc , heptachlor and dieldrin , were found only in a few and at very low concentrations : beta-bhc , aldrin and heptachlor epoxide were absent at all sites .
C0019219
heptachlor
C0019220
heptachlor epoxide