The 2013-2016 Ebola epidemic revived concerns about infection risks to wastewater workers. Prior research has shown that wastewater can contain a variety of known and emerging pathogens and that wastewater workers are at increased risk of infectious illnesses. However, guidelines on using personal protective equipment (PPE) to decrease these risks are lacking. We engaged 34 wastewater utility personnel and public health experts to conduct a job safety analysis identifying tasks in which workers could be exposed to pathogens and to develop a PPE selection matrix for preventing those exposures. We identified 43 relevant job tasks. Recommended PPE ranges from durable gloves (all tasks) to safety glasses (24 tasks), Tyvek suits or coveralls (4 tasks), and respiratory protection (N95 mask or face mask, depending on the activity, 10 tasks). The PPE selection matrix can serve as a guide for protecting the 120,000 wastewater workers in the United States from known and emerging pathogens. PRACTITIONER POINTS: Wastewater workers are at increased risk of infectious illnesses. Policies to protect wastewater workers from these illnesses are lacking. We developed guidelines for use of personal protective equipment by wastewater workers to prevent exposure to infectious agents.

U.S. military and allied contingency operations are increasingly occurring in locations with limited, unstable or compromised fresh water supplies. Non-potable graywater reuse is currently under assessment as a viable means to increase mission sustainability while significantly reducing the resources, logistics and attack vulnerabilities posed by transport of fresh water. Development of health-based (non-potable) exposure guidelines for the potential microbial components of graywater would provide a logical and consistent human-health basis for water reuse strategies. Such health-based strategies will support not only improved water security for contingency operations, but also sustainable military operations. Dose-response assessment of Vibrio cholerae based on adult human oral exposure data were coupled with operational water exposure scenario parameters common to numerous military activities, and then used to derive health risk-based water concentrations. The microbial risk assessment approach utilized oral human exposure V. cholerae dose studies in open literature. Selected studies focused on gastrointestinal illness associated with experimental infection by specific V. cholerae serogroups most often associated with epidemics and pandemics (O1 and O139). Nonlinear dose-response model analyses estimated V. cholerae effective doses (EDs) aligned with gastrointestinal illness severity categories characterized by diarrheal purge volume. The EDs and water exposure assumptions were used to derive Risk-Based Water Concentrations (CFU/100mL) for mission-critical illness severity levels over a range of water use activities common to military operations. Human dose-response studies, data and analyses indicate that ingestion exposures at the estimated ED1 (50CFU) are unlikely to be associated with diarrheal illness while ingestion exposures at the lower limit (200CFU) of the estimated ED10 are not expected to result in a level of diarrheal illness associated with degraded individual capability. The current analysis indicates that the estimated ED20 (approximately 1000CFU) represents initiation of a more advanced stage of diarrheal illness associated with clinical care.