The responses of selected terrestrial plants to short (<12 days) and long term (2, 4 and 6 weeks) hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) exposure. Part I: Growth and developmental effects.

Soils contaminated with explosive materials like hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a concern nation-wide on military installations and sites where explosives are manufactured, stored, or disposed. Terrestrial plants are a vital group of receptor organism, yet limited published information is available on the potential impacts of RDX exposure in terrestrial plants. This research comprised the initial phases in the development of a short-term (<12 days) screening experiment for assessing the environmental impacts of RDX exposure in terrestrial plants. Fifteen plants (dicots and monocots) were exposed to three soils amended with 0-4000 microg g(-1) of RDX during the short-term screening experiments. Growth responses (maximum root and shoot lengths, percent emergence) and adverse developmental effects were the assessment endpoints. Sunflower was identified as the most RDX sensitive plant and selected for evaluation during the long-term (2, 4, and 6 weeks) experiments. Two life stages of sunflower (embryos and 2-week old seedlings) were exposed to Grenada soil amended with 0-100 microg g(-1) of RDX. The assessment endpoints during the long-term experiments included: biomass, maximum shoot and root length, root bio-volume, maximum stem diameter, number of leaves, and adverse developmental effects. Statistically significant differences were measured in several of the growth parameters following the short and long term exposure studies, however there were no consistent patterns. The consistent indicators of detrimental impacts from RDX exposure were the adverse developmental effects observed, regardless of life stage, soil type, or exposure duration. Typically, more adverse developmental effects were observed in dicots than monocots. The efficacy of the short-term screening experiments for estimating the impacts of long-term RDX exposure was validated.