Frances L. Bonner

Rate of Hydrolysis of Seven Organophosphate Pesticides

ConclusionAll of the organophosphates studied were degraded by hydrolysis at varying rates in a slightly acidic aqueous medium. Of course the conditions of this study were not intended to duplicate conditions in the field, but the results indicate that, while all of these pesticides are eventually hydrolyzed, most of them seem to have a much greater residual life than might have been anticipated. This is especially surprising when it is realized that the hydrolysis conditions in our study were probably more rigorous than those encountered in the field.Organophosphate pesticides may therefore retain their toxicity for a longer period than expected after application, and as a consequence are more hazardous than commonly supposed.It should also be remembered, as pointed out earlier, that the products of hydrolysis (such as p-nitrophenol in the case of parathion) are, in themselves, quite toxic.

Reproductive Success of Mallard Ducks Fed Mirex

Mirex (a polycyclic organochlorine) bait was incorporated in rations at 0, 1, and 100 ppm and fed to mallards (Anas platyrhynchos) for 25 weeks. Comparative measurements were obtained on egg production, shell thickness, shell weight, embryonation, hatchability, and duckling survival. Analysis of variance revealed nonsignificant differences (P > 0.05) among treatments for all parameters except duckling survival, which was reduced in the 100 ppm group to a highly significant (P < 0.01) degree. Percentage of ducklings surviving a 2-week post-hatch period was 72.6 in the 100 ppm treatment, compared to 93.8 and 95.7 for the 1 ppm and control groups, respectively. Results of gas-liquid chromatographic analyses revealed that mirex accumulated in eggs at levels approaching 2.8 times the level fed. The concentration factor of mirex in liver, wings, and fat ranged from 1.5 to 30 times the dietary level, whereas residues in brain and muscle were consistently below the amount administered. J. WILDL. MANAGE. 37(4):479-484 Mirex, a persistent polycyclic organochlorine, has been approved for use in a control program against the red imported fire ant (Solenopsis invicta) (USDA 1971). Since 1964 millions of acres in the southeastern United States have been subjected to aerial applications of mirex (0.3 percent technical mirex, dodecachloroactahydro-1, 3, 5-metheno-1 H-cyclobuta [cd] pentalene, impregnated with soybean oil or corncob granules) in a bait formulation (1.25 lb/acre). Most of the southeastern United States will be treated similarly in the future. It is imperaative that the environmental impact of this program be determined, especially for waterfowl which comprise an integral part of the avifauna of the region. Reproductive failure of birds exposed to organochlorine substances has been reviewed by Cramp et al. (1964), Moore (1965), Robinson (1969), and Peakall (1970) and is perhaps the most alarming aspect of chronic toxicity of insecticides. Declining avian populations are often characterized by reduced egg production, eggshel thinning, egg breakage, decreased hatchability, and reduced fledgling survival (Wurs er 1969). Long-term studies with birds and mirex have been reported for gallinaceous species only. Naber and Ware (1965) attributed reduced hatching and survival rates in the domestic fowl (Gallus domesticus) to high levels (300 or 600 ppm) of mirex exposure. Baker (1964) investigated effects of mirex on bobwhite quail (Colinus virginianus) in field and pen studies and concluded that mirex had no direct influence on their populat ons, although percent fertility and hatchability were inversely related to rate of ex-

Dieldrin residues in the gallinulesPorphyrula martinica L. andGallinula chloropas L. and its effect on clutch size and hatchability

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The Effect of Mirex on Channel Catfish Production

Abstract Three applications of mirex bait (0.3% technical material) were made at the rate of 1.4 kg per ha to four ponds containing channel catfish, Ictalurus punctatus (Rafinesque). Percent survival, weight, and length of fish reared in the treated ponds were not significantly different (P > 3660.05) from that observed in fish from four untreated ponds. However, percent survival in the mirex treated ponds was significantly less than in the untreated ponds at the P < 0.10 level and approached significance at the P < 0.05 level. After final application of mirex, residues in fish from treated ponds averaged 0.015 μg/g in fillets and 0.255 μg/g in fat. Based on the fat content of fillets and assuming that all mirex is present in the fat, the observed average residue in fillets (0.015 μg/g) would be equivalent to 0.49 μg/g in fat of meat, well above the government established tolerance of 0.1 μg/g in fat of red meat.