Health Risk Assessment of Toluene and Formaldehyde Based on a Short-Term Exposure Scenario: A Comparison of the...

Area of Science:

• Environmental Health
• Toxicology
• Risk Assessment

Background:

• Conventional health risk assessments inadequately address short-term chemical exposure scenarios, particularly following accidental releases.
• Existing health guidance values (HGVs), such as reference concentration (RfC) and reference dose (RfD), may not be optimal for acute exposure durations.
• Minimal Risk Levels (MRLs) are derived considering specific exposure durations, potentially offering a better fit for short-term scenarios.

Purpose of the Study:

• To evaluate the efficacy of current health risk assessment methods for short-term chemical exposures.
• To propose a more suitable risk assessment approach for hazardous chemical accidents.
• To compare the outcomes of using MRLs versus traditional RfC/RfD values in a hypothetical accident scenario.

Main Methods:

• Analyzed foundational studies for deriving RfC, RfD, and MRL values.
• Applied these HGVs to a hypothetical chemical accident scenario involving formaldehyde and toluene.
• Calculated hazard quotients (HQs) and compared the spatial extent of areas of potential concern (HQ > 1) between MRL-based and RfC/RfD-based assessments.

Main Results:

• Most HGVs were derived under conditions comparable to their intended exposure durations, with MRLs aligning well with acute exposures.
• RfC/RfD-based HQs were consistently higher than MRL-based HQs, indicating more conservative risk estimates.
• Using RfC for formaldehyde instead of MRL expanded the area of potential concern by 2.08 km², highlighting the impact of HGV selection on risk assessment outcomes.

Conclusions:

• Minimal Risk Levels (MRLs) provide a more appropriate basis for risk management decisions in short-term chemical exposure scenarios like accidents.
• The choice of health guidance values significantly influences the determination of affected areas and potential health risks for populations.
• This study offers a scientific foundation for refining exposure and risk assessment frameworks for chemical accidents and informs effective risk management strategies.