Risks from Ebolavirus Discharge from Hospitals to Sewer Workers

Abstract

Current World Health Organization and Centers for Disease Control and Prevention guidance for the disposal of liquid waste from patients undergoing treatment for Ebola virus disease at hospitals in the U.S. is to manage patient excreta as ordinary wastewater without pretreatment. The potential for Ebolavirus transmission via liquid waste discharged into the wastewater environment is currently unknown, however. Possible worker inhalation exposure to Ebolavirus-contaminated aerosols in the sewer continues to be a concern within the wastewater treatment community. In this study, a quantitative microbial risk assessment was carried out to assess a sewer worker's potential risk of developing Ebola virus disease from inhalation exposure when performing standard occupational activities in a sewer line serving a hospital receiving Ebola patients where there is no pretreatment of the waste prior to discharge. Risk projections were estimated for four scenarios that considered the infectivity of viral particles and the degree of worker compliance with personal protective equipment guidelines. Under the least-favorable scenario, the median potential risk of developing Ebola virus disease from inhalation exposure to Ebolavirus-contaminated aerosols in the sewer is approximately 10-5.77 (with a first to third quartile range of 10-7.06 to 10-4.65), a value higher than many risk managers may be willing to accept. Although further data gathering efforts are necessary to improve the precision of the risk projections presented here, the results suggest that the potential risk that sewer workers face when operating in a wastewater collection system downstream from a hospital receiving Ebola patients warrants further attention, and that current authoritative guidance for Ebolavirus liquid waste disposal-to dispose in the sanitary sewer without further treatment-may be insufficiently protective of sewer worker safety.

Protecting wastewater workers from disease risks: Personal protective equipment guidelines

“…Finally, developing baseline exposure levels provides a scenario against which the potential benefits of PPE could be assessed. Existing models may be updated with improved knowledge regarding cumulative exposure and develop targeted PPE recommendations based on the efficacy of various personal protections in reducing worker risk (Haas et al, ; Zabinski et al, ). Improved characterization of the efficacy of PPE in reducing infectious disease risks among wastewater and collection system workers will provide wastewater system operators with greater information regarding the effectiveness of alternative PPE approaches and the overall worker benefit of increased PPE in the wastewater industry.…”

“…Carducci and coworkers later reported that exposure to such aerosols may in fact represent a health hazard for plant workers and nearby residents alike (Carducci, Donzelli, Cioni, & Verani, ; Carducci et al, ). New studies are starting to evaluate risks of pathogen exposure for wastewater personnel using quantitative microbial risk assessment (Brooks, McLaughlin, Gerba, & Pepper, ; Haas, Rycroft, Bibby, & Casson, ; Harder et al, ; Heimersson et al, ; Westrell, Schonning, Stenstrom, & Ashbolt, ; Zabinski, Pieper, & MacDonald Gibson, ). However, in general the infectious disease risks from occupational exposures among U.S. wastewater and collection system workers remain poorly understood.…”

Is it safe to use untreated greywater to irrigate vegetables in my backyard?

“…In hospital settings with sewer systems, the CDC and WHO recommended that Ebola wastes from patients be directly disposed of into sewer systems; this recommendation created concern in the United States (Lowe et al, 2014). The risk of Ebola transmission to sewage workers from hospital wastes disposal directly into sewage lines has been estimated, in worst-case scenarios, at less than 0.001% (Haas et al, 2017). However, due to unknowns of Ebola transmission and fear, there is current research into disinfection options to treat Ebola liquid wastes in hospital settings in the United States.…”

Ebola Virus Dose Response Model for Aerosolized Exposures: Insights from Primate Data

“…The virus is known to survive after death and as such, other possible exposures could occur during the preparation of bodies for funerals or in funeral attendance (Funk, Ciglenecki, Tiffany, & Gignoux, 2017). Occupational exposure to hospital wastewater has also been established as a potential means of indirect transmission (Haas, Rycroft, Bibby, & Casson, 2017). Though these transmission routes and human health risks exist, they have not been well studied in a predictive sense.…”