MUNITION TEST RANGE RISK ASSESSMENT IN A HUMID AND ARID CLIMATE-COMPARISON AND LESSONS LEARNED

A human health and ecological risk assessment at two munition test ranges (one in a humid, temperate climate and one in a hot, arid climate) has been completed. The objective was to estimate health risk from exposure to munition residues/constituents. The scope included identifying the nature and extent of constituents in impact areas from firing munitions, analyzing exposure pathways, estimating the constituent dose to living organisms and the response to the dose, and estimating risk from exposure.

Where appropriate, surface water, ground water, soil, sediment, air, and biota samples were collected from the range area and a reference area. Samples were tested for explosives and metals. Risk to humans and ecosystem species were modeled. Results show that munition constituents are not getting into the food chain or being transmitted by direct/indirect exposure in either climate, despite low level detections in some media.

Conclusions are that constituents from munitions fired at these ranges over many decades have had a negligible effect on human health and the environment. For humans, eating shellfish from a nearby estuary, unintentionally ingesting fugitive dust, drinking ground water, and breathing the air in and around the range area are safe activities. For ecosystem species, eating diet items and contacting the soil in the impact area are safe activities. Uncertainty for the range in the arid climate is low. All lines of evidence were consistent. Eco risk conclusions for the range in the humid climate are less certain (chemistry data indicated the potential for impact but actual animal data indicated a healthy community).

Three lessons were learned. Health risk and exposure pathways must be evaluated. Range characterization (chemistry data) alone is insufficient to evaluate the significance of positive constituent detections. Confounding influences must be investigated separately, otherwise the cause of contamination/risk cannot be confidently known. Finally, a sufficient munition loading and a hydrologic driver are needed for significant contamination/risk to develop. Contamination/risk is predicted to first appear at ranges where both conditions are present. Heavily used ranges in climates where precipitation exceeds evaporation are the most likely places for this situation to develop.