Setting microbiological water quality standards for sea bathing--a critical evaluation

Area of Science:

• Environmental Health
• Risk Assessment
• Microbiology

Background:

• The World Health Organization (WHO) developed draft guidelines for safe recreational water environments.
• Current microbiological standards are based on a risk assessment using a dose-response model from randomized controlled trials.

Purpose of the Study:

• To evaluate the accuracy of the WHO's proposed microbiological standards for recreational water quality.
• To identify potential overestimations of health risks in the WHO's risk assessment model.

Main Methods:

• Analysis of the dose-response model used in the WHO risk assessment.
• Identification of potential biases and statistical analysis issues in the underlying randomized controlled trials.
• Evaluation of the WHO risk assessment's consideration of uncertainty, variability, and model sensitivity.

Main Results:

• The WHO's proposed microbiological standards may overestimate the required water quality for public health protection.
• Biases and statistical problems in the trials likely led to an overestimation of risks in the dose-response model.
• The WHO risk assessment did not adequately address uncertainty, variability, or sensitivity to assumptions.

Conclusions:

• Revised microbiological standards for recreational water environments are needed.
• Improving WHO standards requires extending risk assessments to include uncertainty and variability.
• Incorporating a revised dose-response model can lead to more accurate public health protection standards.