title: Toxicity of 2,4-dinitrotoluene to terrestrial plants in natural soils.
abstract: The presence of energetic materials (used as explosives and propellants) at contaminated sites is a growing international issue, particularly with respect to military base closures and demilitarization policies. Improved understanding of the ecotoxicological effects of these materials is needed in order to accurately assess the potential exposure risks and impacts on the environment and its ecosystems. We studied the toxicity of the nitroaromatic energetic material 2,4-dinitrotoluene (2,4-DNT) on alfalfa (Medicago sativa L.), barnyard grass (Echinochloa crusgalli L. Beauv.), and perennial ryegrass (Lolium perenne L.) using four natural soils varying in properties (organic matter, clay content, and pH) that were hypothesized to affect chemical bioavailability and toxicity. Amended soils were subjected to natural light conditions, and wetting and drying cycles in a greenhouse for 13 weeks prior to toxicity testing to approximate field exposure conditions in terms of bioavailability, transformation, and degradation of 2,4-DNT. Definitive toxicity tests were performed according to standard protocols. The median effective concentration (EC(50)) values for shoot dry mass ranged from 8 to 229 mg kg(-1), depending on the plant species and soil type. Data indicated that 2,4-DNT was most toxic in the Sassafras (SSL) and Teller (TSL) sandy loam soils, with EC(50) values for shoot dry mass ranging between 8 to 44 mg kg(-1), and least toxic in the Webster clay loam soil, with EC(50) values for shoot dry mass ranging between 40 to 229 mg kg(-1). The toxicity of 2,4-DNT for each of the plant species was significantly (p < or = 0.05) and inversely correlated with the soil organic matter content. Toxicity benchmark values determined in the present studies for 2,4-DNT weathered-and-aged in SSL or TSL soils will contribute to development of an Ecological Soil Screening Level for terrestrial plants that can be used for ecological risk assessment at contaminated sites.
authors.affiliation: Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount Avenue, Montreal, Quebec, Canada H4P 2R2.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Rocheleau
authors.forename: Roman G
authors.initials: RG
authors.lastname: Kuperman
authors.forename: Mike
authors.initials: M
authors.lastname: Simini
authors.forename: Jalal
authors.initials: J
authors.lastname: Hawari
authors.forename: Ronald T
authors.initials: RT
authors.lastname: Checkai
authors.forename: Sonia
authors.initials: S
authors.lastname: Thiboutot
authors.forename: Guy
authors.initials: G
authors.lastname: Ampleman
authors.forename: Geoffrey I
authors.initials: GI
authors.lastname: Sunahara
mesh_terms: D004136:Dinitrobenzenes / Q000633:toxicity*; D006109:Poaceae / Q000187:drug effects*; D012989:Soil Pollutants / Q000633:toxicity*
chemical_list: D004136:Dinitrobenzenes; D012989:Soil Pollutants; C016403:2,4-dinitrotoluene