ISEE-0334 Background and Objective: Rates of pulmonary environmental mycobacteriosis (EM) appear to be increasing among developed countries during the past 20 years. EM is caused by multiple species of pathogenic mycobacteria that have been recovered from soil, water, water aerosols, biofilms and drinking water. Humans acquire infection primarily from environmental sources. Drinking water is one documented source of exposure implicated in human EM colonization and infection, but overall, the epidemiology of EM is poorly characterized. Our goal is to summarize and describe the evidence to date of the risk of pulmonary EM from exposure to drinking water sources. Methods: We performed a systematic review of the peer-reviewed literature. We included only those reports describing an epidemiologic and/or molecular association between human pulmonary EM and drinking water. Results: We identified 43 reports of pulmonary EM with documented drinking water sources of exposure in North America, Europe and Japan. Seventeen (40%) of these were associated with nosocomial exposures; 10 isolates from drinking water, 7 isolates from processed or modified drinking water. Fifteen (35%) reports described hot tub exposures. Nine (21%) reports described isolation from home drinking water. Multiple species of mycobacteria were isolated. Conclusion: Drinking water is a well-established source of EM. However, this review identified that many reports describe potential contamination events associated with drinking water quality that was modified after the original point of use; these include water processing, ice making machines, or drinking water further used for recreation or bathing. The extent of detection and reporting bias associated with these published reports is unknown. Population-based studies of individuals are needed to further characterize the risk of EM colonization and infection associated with drinking water exposures. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.