Mutation Research 538 (2003) 13–18 Genotoxicity of 2,4- and 2,6-dinitrotoluene as measured by the Tradescantia micronucleus (Trad-MCN) bioassay Ping Gong a , Roman G. Kuperman b , Geoffrey I. Sunahara a,∗ a Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount Avenue, Montreal, Que., Canada H4P 2R2 b US Army Edgewood Chemical Biological Center, 5183 Blackhawk Road, Aberdeen Proving Ground, Aberdeen, MD 21010-5424, USA Received 8 January 2003; received in revised form 14 February 2003; accepted 19 February 2003 Abstract The phytogenotoxicity of 2,4-dinitrotoluene (2,4-DNT) and 2,6-dinitrotoluene (2,6-DNT) was assessed using the Trades- cantia micronucleus (Trad-MCN) bioassay. Tradescantia cuttings bearing young inflorescences were exposed for 6 h to 2,4- or 2,6-DNT amended water solutions up to their respective solubilities. The nominal concentrations were 0, 1.9, 3.8, 7.5, 15, 30, 60, 100, 150, 200 mg/l of 2,4-DNT, and 0, 7.5, 15, 30, 60, 90, 120, 180 mg/l of 2,6-DNT. Each treatment was repeated three or four times. Chemical concentrations in test solutions were analyzed prior to and after the exposure. Cadmium chloride (0–20 mM) was used as the positive control. Micronuclei (MCN) were scored in the tetrad-stage pollen mother cells. The MCN frequency (%), i.e. the number of micronuclei scored in 100 tetrads, was the measurement endpoint. Results indicated that both 2,4-DNT and 2,6-DNT were genotoxic with the minimum effective dose (MED) of 30 and 135mg/l, respectively. Longer exposure (30 h) without recovery time at 150 mg/l of 2,4-DNT and 180 mg/l of 2,6-DNT did not induce significantly higher MCN frequencies. Crown Copyright © 2003 Published by Elsevier Science B.V. All rights reserved. Keywords: Tradescantia; Micronucleus (MCN); 2,4-Dinitrotoluene; 2,6-Dinitrotoluene; Genotoxicity 1. Introduction 2,4-Dinitrotoluene (2,4-DNT) (CAS No. 121-14-2) and 2,6-dinitrotoluene (2,6-DNT) (CAS No. 606-20-2) are two of the six dinitrotoluene isomers that are used primarily as chemical intermediates in the production of toluene diamines and diisocyanates, dyes, explo- sives and propellants. They have been detected in the soil, surface water, or groundwater of at least 122 hazardous waste sites that contain buried munitions ∗ Corresponding author. Tel.: +1-514-496-8030; fax: +1-514-496-6265. E-mail address: geoffrey.sunahara@cnrc-nrc.gc.ca (G.I. Sunahara). wastes out of the 1467 current or former National Priorities List sites [1]. The International Agency for Research on Cancer (IARC) has determined that 2,4- and 2,6-DNT are possibly carcinogenic to humans [2]. 2,6-DNT showed hepatocarcinogenic effects in Fischer-344 rats [3,4], and exposure to high levels of DNTs in animals caused lowered numbers of sperm and reduced fertility [1,3]. Environmental impact of DNT exposure is also a major public concern. Both 2,4- and 2,6-DNT are highly toxic to aquatic organisms including fish, in- vertebrates, algae, protozoa and bacteria with the low- est observed effect concentration being 0.05 mg/l for 2,4-DNT and 1 mg/l for 2,6-DNT [5]. Recently, the 1383-5718/03/$ – see front matter. Crown Copyright © 2003 Published by Elsevier Science B.V. All rights reserved. doi:10.1016/S1383-5718(03)00089-5