Skin Permeation of Solutes from Metalworking Fluids to Build Prediction Models and Test A Partition Theory

Area of Science:

• Occupational Health and Safety
• Environmental Chemistry
• Analytical Chemistry

Background:

• Chemical solute permeation through skin poses significant health risks.
• Occupational skin exposure is a concern in industries like metalworking.
• Simulating complex exposure scenarios is crucial for risk assessment.

Purpose of the Study:

• To evaluate the skin permeation of chemical solutes using a membrane-coated fiber (MCF) approach.
• To develop and test models for predicting solute partitioning in various metalworking fluid formulations.
• To assess the validity of partition theory under simulated occupational skin exposure conditions.

Main Methods:

• Utilized membrane-coated fiber (MCF) solid-phase membrane extraction (SPME) to simulate skin permeation.
• Investigated partition coefficients for 37 solutes across 90 treatment combinations mimicking metalworking fluids.
• Applied and compared linear free-energy relationship (LFER) models, including extensions accounting for experimental conditions.

Main Results:

• A single LFER model was insufficient; extended models improved solute partitioning predictions.
• The Expanded Nested-Solute-Concentration LFER model showed benefits over the Expanded Crossed-Factors LFER model via cross-validation.
• Partition theory was not supported under the complex, realistic experimental conditions.

Conclusions:

• Advanced LFER models can enhance predictions of solute partitioning in complex formulations.
• Cross-validation is essential to accurately assess predictive power in such models.
• The tested partition theory is inadequate for simulating occupational skin exposure in metalworking environments.