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Mutagenicity of nitroaromatic degradation compounds
Ranjit S Padda1, Chuanyue Wang, Joseph B Hughes
1Department of Biochemistry and Cell Biology, MS-140, Rice University, 6100 Main Street, Houston, Texas 77005-1892, USA.
Environmental Toxicology and Chemistry
|October 14, 2003
Summary
Mutagenicity testing of dinitrotoluenes (DNTs) and their byproducts revealed that hydroxylamine intermediates are mutagenic, while DNTs and their amine metabolites are not. Bioremediation should extend beyond these hydroxylamine stages.
Area of Science:
- Environmental Microbiology
- Toxicology
- Bioremediation
Background:
- Dinitrotoluenes (DNTs) are environmental contaminants with potential mutagenic risks.
- Previous studies identified mutagenicity in trinitrotoluene (TNT) and its hydroxylamine derivatives.
- Understanding the transformation products of DNTs is crucial for assessing their environmental impact.
Purpose of the Study:
- To evaluate the mutagenicity of 2,4-dinitrotoluene (24DNT) and 2,6-dinitrotoluene (26DNT) and their transformation products.
- To investigate the mutagenicity of hydroxylamine and amine derivatives formed during anaerobic transformation.
- To compare the mutagenic profiles of DNTs and TNT transformation products.
Main Methods:
- Bacterial mutagenicity testing using Salmonella typhimurium TA100 in crude cell extracts.
- Anaerobic transformation of 24DNT, 26DNT, and TNT by Clostridium acetobutylicum.
- Time-course analysis of mutagenicity during anaerobic degradation.
Main Results:
- Monohydroxylamino intermediates (2HA4NT, 4HA2NT, 2HA6NT) formed during DNT anaerobic transformation are mutagenic in the Ames test.
- 4HA2NT is the most stable hydroxylamine derivative; 2HA4NT and 2HA6NT are less stable but mutagenic.
- 24DNT, 26DNT, and their final amine metabolites (24DAT, 26DAT) were nonmutagenic.
- The most mutagenic sample during TNT degradation contained 2,4-dihydroxylamino-6-nitrotoluene (24HA6NT).
Conclusions:
- Hydroxylamine intermediates of DNTs are the primary mutagenic compounds.
- Bioremediation strategies for DNT-contaminated sites should be optimized to degrade these hydroxylamine intermediates.
- The mutagenicity of TNT transformation products shares similarities with DNT transformation products.