Priorities and Challenges in Methodology for Human Health Risk Assessment from Combined Exposure to Multiple...

Area of Science:

• Environmental Health
• Toxicology
• Risk Assessment

Background:

• Combined exposure to multiple chemicals poses complex challenges for human health risk assessment.
• Current methods often rely on simplified assumptions, necessitating more refined approaches.

Purpose of the Study:

• To review key elements and challenges in assessing human health effects from combined chemical exposures.
• To propose a decision-making scheme for risk assessment of chemical mixtures.
• To identify areas for scientific advancement in mixture toxicology.

Main Methods:

• Review of existing knowledge and tools for chemical mixture risk assessment.
• Proposal of a tiered decision-making scheme, starting with the hazard index (HI).
• Description of sequential or parallel assessment options (RPI/MOET, mRPI/nMOET, Option 3, MAF) based on data availability and complexity.

Main Results:

• The hazard index (HI) serves as a starting point for component-based risk assessments.
• Specific risk assessment options are detailed for prospective and retrospective analyses, including consideration of population groups.
• A mixture assessment factor (MAF) is proposed for data-poor situations.

Conclusions:

• A structured, tiered approach enhances the assessment of human health risks from combined chemical exposures.
• Further scientific developments in New Approach Methodologies (NAMs) and integrated approaches will improve mixture risk assessment.
• The proposed scheme aids risk assessors in navigating complex chemical mixture evaluations.