Research Product

Acute (96-hr) flow-through toxicity tests, chronic (entire life-cycle) tests, and bioconcentration studies were conducted on selected estuarine animals with the insecticides, EPN, and leptophos. In the EPN acute toxicity tests, the test animals and their 96-h LC50 values were: Mysidopsis bahia, 3.44 µg/l; Penaeus duorarum, 0.29 µg/l; Cyprinidon variegatus, 188.9 µg/l; Lagodon rhomboides, 18.3 µg/l; and Leiostomus xanthurus, 25.6 µg/l. Test animals and 96-h LC50 values for leptophos were: M. bahia, 3.16 µg/l; P. duorarum, 1.88 µg/l; and L. xanthurus, 4.06 µg/l. In separate chronic tests, M. bahia were exposed to EPN and leptophos. Significant (a=0.05) mortality and fewer young were produced in 4.13 µg/l EPN. In the leptophos chronic test, significant mortality occurred in concentrations > or = 3.63 µg/l and fewer young were produced in concentrations > or = 1.77 µg/l. L. rhomboides, exposed to EPN in a 26-day uptake study, bioconcentrated the insecticide 707 X that measured in the exposure water. When L. rhomboides were held in EPN-free seawater, no EPN was detected in their tissues after eight days. L. xanthurus, exposed to leptophos for 26 days, bioconcentrated the insecticide to only 68 X the concentration in the exposure water. No leptophos residues were detectable in tissues after 4 days depuration. Our results indicate that if either insecticide contaminated an estuarine environment in concentrations > or = 1.0 µg/l, the most profound adverse effects on crustaceans and possibly fishes would result from acute toxicity, rather than from chronic toxicity or bioconcentration of the chemicals.