Human health risks for Legionella and Mycobacterium avium complex (MAC) from potable and non-potable uses of roof-harvested rainwater. (1st August 2017)

• Record Type: Journal Article
• Authors: Hamilton, Kerry A.; Ahmed, Warish; Toze, Simon; Haas, Charles N.
• Is Part Of: Water research. Volume 119(2017)
• Page Start: 288
• Page End: 303
• Publication Date: 2017-08-01
• Subjects: Roof-harvested rainwater -- Opportunistic pathogens -- Quantitative microbial risk assessment (QMRA) -- Legionella pneumophila -- Mycobacterium avium complex; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2017.04.004
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: A quantitative microbial risk assessment (QMRA) of opportunistic pathogens Legionella pneumophila (LP) and Mycobacterium avium complex (MAC) was undertaken for various uses of roof-harvested rainwater (RHRW) reported in Queensland, Australia to identify appropriate usages and guide risk management practices. Risks from inhalation of aerosols due to showering, swimming in pools topped up with RHRW, use of a garden hose, car washing, and toilet flushing with RHRW were considered for LP while both ingestion (drinking, produce consumption, and accidental ingestion from various activities) and inhalation risks were considered for MAC. The drinking water route of exposure presented the greatest risks due to cervical lymphadenitis and disseminated infection health endpoints for children and immune-compromised populations, respectively. It is therefore not recommended that these populations consume untreated rainwater. LP risks were up to 6 orders of magnitude higher than MAC risks for the inhalation route of exposure for all scenarios. Both inhalation and ingestion QMRA simulations support that while drinking, showering, and garden hosing with RHRW may present the highest risks, car washing and clothes washing could constitute appropriate uses of RHRW for all populations, and toilet flushing and consumption of lettuce irrigation with RHRW would be appropriate for non- immune-compromised populations. Highlights: A QMRA of opportunistic pathogens was undertaken for roof-harvested rainwater. Drinking water, showering, and garden hosing presented the greatest risks. Drinking untreated rainwater is not recommended for children or immune-compromised. Car and clothes washing appear to be appropriate uses of rainwater. Toilet flushing is appropriate for non-immune-compromised populations.