TOXICITY OF SOIL IODINE TO TERRESTRIAL BIOTA, WITH IMPLICATIONS FOR I-129

The environmental impact of I-129 has traditionally bern assessed by i ts radiological effects on human health; however, protection of human health does not ensure protection of other biota. Because of the very long half-life of I-129, there is a relatively high molar concentratio n of I associated with any specified level of radioactivity. The poten tial exists for chemical toxicity to non-human biota to exceed radiolo gical toxicity in importance. The authors reviewed the literature and conducted laboratory bioassays to obtain information,? on the chemical toxicity of inorganic I to terrestrial biota. Levels as low as 5 mg I kg(-1) soil may have detrimental effects. If this were as I-129, the c orresponding radiological effects to non-human biota may not be as low important as the chemical toxicity. However, because of the very low risk factor applied to protect humans, levels of I-129 in the environm ent acceptable for human health appear to be acceptable for other biot a at the higher risk levels commonly used for them.