即将到来的新的放射性核素最高污染物水平（MCL），加上人们对室内空气中氡的日益关注，引发了人们对这些物质的新兴趣。对研究需求的评估还提供了已完成和正在进行的研究项目的背景信息，该评估显示，在饮用水中的所有放射性核素中，Rn-222是对健康的最严重威胁，因此预计这些物质的新MCL可能会设定在相对较低的水平。小型公共和私人用品被确定为比服务于数百人以上的公共系统更容易受到放射性核素污染，但需要进行更多调查，以评估暴露程度及其相关风险。此前认为高水平的Rn-222仅限于少数地理区域的观点被认为是错误的，这主要是因为缺乏全国性的数据库。 包括93个参考资料、表格和照片。

Impending new maximum contaminant levels (MCLs) for radionuclides, plus increased concern for radon in the air inside homes, have sparked new interest in these substances. An assessment of research needs, which also provided background information on completed and ongoing research projects, showed that Rn-222 represents the most serious threat to health of all the radionuclides in drinking water, leading to the anticipation that the new MCLs for these substances could be set at a relatively low level. Small public and private supplies were identified as being more vulnerable to radionuclide contamination than public systems serving more than a few hundred people, but more investigation is needed to assess the extent of the exposure and its associated risk. The previous belief that high levels of Rn-222 are confined to a few geographic areas was found to be false, largely because of a lack of a nationwide data base. Includes 93 references, tables, photos.