Developments in microbiological risk assessment models for drinking water--a short review

Area of Science:

• Environmental microbiology
• Water quality assessment
• Public health

Background:

• Microbiological risk assessment (MRA) is an emerging method for predicting infection risks from waterborne pathogens in drinking water.
• Current MRA models face limitations in accurately calculating pathogen exposures due to data constraints on pathogen density in consumed water volumes.

Purpose of the Study:

• To review the appropriateness of current MRA models for pathogen exposure via drinking water.
• To identify essential information needed for advancing MRA model development.

Main Methods:

• Review of existing MRA models and pathogen exposure data.
• Analysis of pathogen dispersal patterns in drinking water at relevant consumption volumes.
• Evaluation of current assumptions on pathogen distribution (random vs. clustered).

Main Results:

• Pathogen density data are often derived from large water samples, not representative of individual daily consumption volumes.
• Microorganisms, including pathogens, exhibit clustering, leading to uneven exposure doses for consumers.
• Current models, assuming random dispersal, misestimate risks for pathogens with varying infectiousness (e.g., rotavirus, Cryptosporidium parvum).

Conclusions:

• Accurate MRA requires understanding pathogen dispersal at the individual consumption level.
• Further research is needed on how water treatment processes affect pathogen clustering.
• Large-scale pilot plant studies are recommended to gather crucial data for improving MRA models and ensuring drinking water safety.