Acute, subacute, and subchronic exposure to 2A-DNT (2-amino-4,6-dinitrotoluene) in the northern bobwhite (Colinus virginianus)

Abstract

2-Amino-4,6-dinitrotoluene (2A-DNT) is a metabolite of the explosive 2,4,6-trinitrotoluene (TNT) which is present in the soil at numerous U.S. Army installations as the result of TNT manufacture or training activities. Although many avian species are known to inhabit areas where 2A-DNT has been found in the environment, no published studies of the effects of 2A-DNT exposure in birds are available. In this study, we conducted an evaluation of the oral toxicity of 2A-DNT in a representative ground foraging species of management concern, the northern bobwhite (Colinus virginianus). Subacute (14 days) and subchronic (60 days) oral gavage exposure studies were conducted following determination of the median acute lethal dose (LD50 = 1167 mg/kg). In the subacute study, survival occurred at 50 mg/kg/day. This helped to determine dose groups for the subchronic study: 0, 0.5, 3, 14, and 30 mg 2A-DNT/kg body weight-d in corn oil. The lowest observed adverse effects level (LOAEL) was determined to be 14 mg/kg/day based on mortality, and the no observed adverse effects level (NOAEL) was determined to be 3 mg/kg/day based on lack of effects at this exposure level.

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

“…Quinn et al [4] conducted an evaluation of the oral toxicity of 2A-DNT in the Northern Bobwhite (Colinus virginianus). Subacute (14 days) and subchronic (60 days) oral gavage exposure studies were conducted following determination of the median acute lethal dose (LD 50 ¼ 1,167 mg/kg).…”

“…Only one study that assessed the toxicity of 2A-DNT following ingestion in birds [4] could be located (see Table 16.4). The approximation approach is required for TRV derivation as the data do not fit the minimum data requirements of TG 254 [1] since the study is subchronic and is the only study available for this taxonomic class.…”

Systems toxicology identifies mechanistic impacts of 2-amino-4,6-dinitrotoluene (2A-DNT) exposure in Northern Bobwhite

“…Wildlife bird species represent important potential receptors of MCs, especially ground foraging birds that may inadvertently consume these chemicals when ingesting grit or soils to assist with digestion [ 5 ]. Quinn et al [ 6 ] examined the toxicological effects of 2A-DNT in the ground foraging bird species, Northern bobwhite ( Colinus virginianus ), and found that it was acutely toxic only at high doses (LD 50 = 1167 mg/kg). However, in subchronic 60d exposures, sustained oral dosing of 2A-DNT was observed to elicit mortality at a much lower dose (14 mg/kg-d, [ 6 ]).…”

“…Quinn et al [ 6 ] examined the toxicological effects of 2A-DNT in the ground foraging bird species, Northern bobwhite ( Colinus virginianus ), and found that it was acutely toxic only at high doses (LD 50 = 1167 mg/kg). However, in subchronic 60d exposures, sustained oral dosing of 2A-DNT was observed to elicit mortality at a much lower dose (14 mg/kg-d, [ 6 ]). In addition to mortality, 2A-DNT dosing caused a variety of sublethal effects in the subchronic exposures including: increased liver weights, decreased leukocyte counts, increased plasma-triglyceride levels and splenic reticular cell hyperplasia [ 6 ].…”

“…However, in subchronic 60d exposures, sustained oral dosing of 2A-DNT was observed to elicit mortality at a much lower dose (14 mg/kg-d, [ 6 ]). In addition to mortality, 2A-DNT dosing caused a variety of sublethal effects in the subchronic exposures including: increased liver weights, decreased leukocyte counts, increased plasma-triglyceride levels and splenic reticular cell hyperplasia [ 6 ]. Northern bobwhite exhibited similar effects when exposed to other nitrotoluenes including 4A-DNT [ 7 ] and 2,6-DNT [ 8 , 9 ], however 2,6-DNT tended to have a broader range of sublethal impacts relative to 2A-DNT and 4A-DNT.…”