UPTAKE AND DISPOSITION OF ENDRIN IN INSECTICIDE-SUSCEPTIBLE AND INSECTICIDE-RESISTANT MOSQUITOFISH (GAMBUSIA-AFFINIS)

Endrin uptake and tissue distribution was studied in insecticide-susceptible (S) and-resistant (R)mosquitofish (Gambusia affinis). Fish were exposed to equal (10.2 ppb) and equitoxic (0.6 ppb for S and 314 ppb for R) levels of [14C]endrin for up to 8 h. The accumulation and tissue disposition patterns of endrin were significantly different between the two fish populations studied. A 13.5-fold greater[14C]endrin concentration in gills of S fish than R fish at the equal exposure levels suggested a barrier to endrin penetration at the organismal level. S/R ratios of tissue radioactivity following 8-h exposure to 10.2 ppb [14C]endrin indicative of tissue membrane barriers in the R fish included : brain, 45.9; liver, 7.7; gall bladder, 9.7; spleen, 20.9; intestine, 4.8; and ova, 4.1. The barrier to endrin penetration into the brain appeared to be most effective. The gall bladder/liver ratios suggested that the R fish could effectively excrete endrin over a wider range of exposure concentrations than S fish. © 1979, American Chemical Society. All rights reserved.