Evaluation of a Proportional Response Addition Approach to Mixture Risk Assessment and Predictive Toxicology Using...

Area of Science:

• Toxicology
• Environmental Chemistry
• Risk Assessment

Background:

• Chemical mixtures pose complex toxicological challenges.
• Predictive models are crucial for assessing mixture risks.
• Trihalomethanes (THMs) are common environmental contaminants.

Purpose of the Study:

• To evaluate the Proportional Response Addition (Prop-RA) model.
• To assess Prop-RA's predictive accuracy for binary THM mixtures.
• To analyze hepatotoxicity data from THM exposure.

Main Methods:

• Statistical analysis of toxicity data for four THMs and their binary combinations.
• Application of the Prop-RA model using component fractions and dose-response data.
• Evaluation of 160 unique prediction scenarios.

Main Results:

• Prop-RA predictions showed statistically significant departures in seven out of 160 evaluations.
• Deviations included predictions higher (1.3-1.4 fold) and lower (2.6-3.8 fold) than observed responses.
• The model performed best when chemical effective dose ranges overlapped.

Conclusions:

• Prop-RA is a viable model for predicting toxicity of chemical mixtures, including those with unknown modes of action.
• The model's accuracy is supported by its performance with THM mixtures.
• Prop-RA is applicable to mixtures affecting the same organ system.