137Cs contamination of plants used for traditional medicine and implications for human exposure

This paper discusses the use of medicinal plants in traditional medicine practices in the Marshall Islands and measurement data of 137Cs in plants used in medicinal remedies. This previously unexplored contribution to radiation exposure was recognized as one of several potentially important considerations in determining present-day risks to the Marshallese population from residual weapons’ test radioactivity in the environment. The leaves or fruit of five species of plants were sampled at 14 of the 29 atolls of the Marshall Islands. 137Cs concentrations were measured in 295 samples. The concentration of 137Cs in each species generally decreased with increasing distance and decreasing latitude from the atomic weapons testing area in the northern area of the country. Of the species sampled, Polypodium scolopendria exhibited the highest mean 137Cs concentration by several fold. Other species could not be differentiated in terms of 137Cs uptake. The results of calculations to assess possible radiation doses under specific intake scenarios indicate that at most locations in the Marshall Islands, ingestion of these plants for medicinal purposes will not contribute significantly to the total dose received (above background), although the frequency and amount of consumption of these plants is not well known. This study provides the first information of its kind for the assessment of radiation dose to Marshall Islands’ residents from locally grown plants used in traditional medicine.