EFFECTS OF SUBCHRONIC EXPOSURE TO 2,6-DINITROTOLUENE IN THE NORTHERN BOBWHITE (COLINUS VIRGINIANUS)

Abstract

Explosives and their breakdown products are commonly found in soils at U.S. military installations. Many areas where these compounds are found represent useful habitat for ground-foraging birds. Because these birds likely are exposed to such compounds, we evaluated the oral toxicity of 2,6-dinitrotoluene (DNT) in a representative ground-foraging species of management concern. Adult male and female northern bobwhite (Colinus virginianus) were exposed to either 0, 5, 10, 40, or 60 mg/kg/d via gavage for 60 d (subchronic) following determination of the median acute lethal dose (320 mg/kg). Circulating levels of red blood cells and hemoglobin were significantly decreased in a dose-dependent manner; however, levels remained within normal ranges. Plasma concentrations of total protein, albumin, globulin, aspartate aminotransferase, and potassium, sodium, and chlorine ions were significantly decreased, and circulating levels of uric acid were significantly increased. Decreased body weight, enlarged gallbladders, edematous gastrointestinal tracts, pale kidneys, pale and fibrous livers, and loose stools were consistent observations. The effects found in the clinical chemistries taken together with histopathological abnormalities observed in sections of hepatic and renal tissue suggest that the liver and kidneys are major targets for 2,6-DNT. Oral exposures to 2,6-DNT appear to affect northern bobwhite in a manner similar to that of the other main DNT isomer, 2,4-DNT, but in more subtle ways, adversely affecting the gastrointestinal system and leading to diarrhea and, ultimately, emaciation. The lowest-observed-adverse-effect level is 40 mg/ kg/d based on hematological measures, and the no-observed-adverse-effect level is 10 mg/kg/d based on the absence of results indicative of adverse effects.