Influence of Oral 2,4-Dinitrotoluene Exposure to the Northern Bobwhite (Colinus virginianus)

Abstract

Military activities associated with training, munitions manufacturing, and demilitarization has resulted in soil residues of munition compounds and their breakdown products. Two isomers of dinitrotoluene (2,4- and 2,6-) are often found in soil associated with those activities at considerable concentrations. Consequently, issues regarding the effects of exposure to birds that visit these habitats require evaluation. To provide data useful to a risk assessment approach, we followed a controlled dosing regime (gavage) using 2,4-dinitrotoluene (2,4-DNT) in the Northern Bobwhite (Colinus virginianus) for 60 days following a 14-day range-finding study and the determination of a LD50 using the up/down method. The LD50 was determined to be 55 mg/kg using corn oil as a vehicle. Individuals dosed exceeding this level were moribund or died within 60 h of exposure. Morbidity and death occurred during the 14-day range-finding study at dosing regimens of 35 and 55, but not at 15, 5, and 0.5 mg/kg-day. Compound-related morbidity/mortality occurred in the 60-day study during the first week of exposure at 25 and 15, but not at 5, 1, and 0 mg/kg-day. Overt signs of toxicity occurred with both sexes at the onset of exposure. Signs included weight loss, diarrhea, and lethargy. Dose-related changes in egg production, ovary, kidney, and brain mass, and body weight, but not feed consumption, were found. Changes in kidney mass and histological observations suggest accumulation of nitrogenous waste may be the cause of morbidity. These data suggest that oral 2,4-DNT exposures are more acutely toxic and has a different etiology than 2,4,6-trinitrotoluene in birds.

Acute toxicity of 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, and 2,6-dinitrotoluene in the adult bullfrog (Lithobates catesbeiana)

“…Ataxia and slight cyanosis was observed in rats and mice exposed to 2,4-DNT (Lane et al 1985). Some of the signs of acute toxicity for 2,4-DNT in Northern bobwhite were similar to the ones observed in bullfrogs such as weight loss and lethargy (Johnson 2005).…”

“…The Northern bobwhite appears to be more sensitive to 2,4-DNT with an LD 50 of 55 mg/kg BW (Johnson 2005), which is almost 20 times less than the LD 50 for bullfrogs. The LD 50 reported in mice after administration of 2,4-DNT ranged from 1,340 to 1,954 mg/kg BW (Ellis et al 1978;Lee et al 1975;Vernot et al 1977), which is near the upper limit confidence interval of 2000 mg/kg BW calculated for the LD 50 in bullfrogs.…”

“…Hispid cotton rats (Sigmodon hispidus) have been exposed to TNT (Reddy et al 2000), effects of oral 2,4-DNT exposure to the Northern bobwhite (Colinus virginianus) have been investigated (Johnson 2005), and rats and mice have been exposed to 2,6-DNT (Lee et al 1975;Ellis et al 1978). However, little is known about the toxicity of explosive residues in amphibian species, particularly in the bullfrog (Lithobates catesbeiana), a native American species.…”

Wildlife Toxicity Assessment for 2,4-Dinitrotoluene and 2,6-Dinitrotoluene

“…Avian Toxicity Oral: Acute 2,4-Dinitrotoluene Northern Bobwhite quail were orally dosed with 96% pure 2,4-DNT in a corn oil vehicle using the up/down procedure [46]. The oral LD 50 was determined to be 55 mg/kg (20-79 mg/kg 95% confidence interval (CI)).…”

Quail Genomics: a knowledgebase for Northern bobwhite

“…Advancing our knowledge in the potential hazards of 2,6-DNT to avian species is important to insure the protection of these wild populations. The utility of Northern bobwhite in various ecological [1], experimental [2] and regulatory [3] scenarios has gained recognition for the species as an excellent experimental avian wildlife model. …”