Bioaccumulation of 2,4,6‐trinitrotoluene and polychlorinated biphenyls through two routes of exposure in a terrestrial amphibian: Is the dermal route significant?

Abstract

Abstract-Tiger salamanders (Ambystoma tigrinum) were exposed via soil and/or food (earthworms) to 2,4,6-trinitrotoluene (TNT) and a PCB mixture (Aroclor 1260) at environmentally relevant concentrations. Four exposures were considered: (1) uncontaminated food ϩ uncontaminated soil (control group); (2) contaminated soil ϩ uncontaminated food (dermal group); (3) contaminated food ϩ uncontaminated soil (oral group); and, (4) contaminated soil ϩ contaminated food (dual-exposure group). The chemical exposure was estimated for each group by analysis of both soil and earthworms. Body burdens of TNT and its primary metabolites were highest in the dermal groups while PCB burdens were highest in the oral groups. Concentrations of the primary TNT metabolites evaluated, 2-amino-dinitrotoluene (DNT) and 4-amino-DNT, exceeded that of unmetabolized TNT and accumulated to 116 and 670 ng/g, respectively. These results provide evidence that dermal exposures to nitroaromatics in terrestrial salamanders may make an important contribution to total body burden and thus may be important when considering the health consequences of such exposures. Further, the demonstration of the accumulation of TNT and TNT metabolites in a primitive vertebrate may have food web modeling implications.

Congener‐specific analysis of polychlorinated dibenzo‐p‐dioxins, dibenzofurans, and coplanar polychlorinated biphenyls in frogs and their habitats, Kitakyushu, Japan

“…It is well known that bioaccumulation of PCDDs/PCDFs and coplanar PCBs depends on the number of chlorine atoms and their substitution patterns. Since the oral route is the main exposure route of lipophilic chemicals in terrestrial amphibians [20], dioxins in soils do not directly affect their concentrations in frogs. However, the trophic level of frogs is low, i.e., the prey of frogs in this study are insects and their larvae, earthworms, and slugs.…”

Soils contaminated with explosives: Environmental fate and evaluation of state-of-the-art remediation processes (IUPAC Technical Report)

“…The salamander (Ambystoma tigrinum) has been suggested as a bioindicator of effects in the evaluation of toxicity of explosives at contaminated sites [217][218][219]. Dermal exposure was determined to be the most important exposure pathway for uptake of TNT from contaminated soil by the salamander.…”

Effects of 2,4,6-Trinitrotoluene in a Holistic Environmental Exposure Regime on a Terrestrial Salamander, Ambystoma tigrinum

“…This scavenging function has been attributed to MMOs in fish, where density and size of MMOs increase proportionally with anemic state and subsequently decrease with recovery of the erythroid population (14). In Many site-specific short-term evaluations of amphibian health have been less than diagnostic (4,13 (19). Xenobiotics acting in these ways may be more insidious in terms of being diagnostic of exposure.…”

“…Toxic effects of 2,4,6-trinitrotoluene (TNT) exposure on mammals have been investigated (9,21,22); however, information specific to amphibian exposures is lacking. Yet, TNT and metabolites have been shown to bioaccumulate in terrestrial salamanders in a soil matrix (19). These Earthworms contained consistently higher levels of the primary reduction products than of parent compound.…”