Formulation effect on the dermal bioavailability of isothiazolone biocide

Area of Science:

• Toxicology
• Dermatology
• Materials Science

Background:

• The dose-response relationship is fundamental in toxicology, stating toxic effects increase with material dose.
• Isothiazolone biocides, like Kathon LX, are known to induce cutaneous contact allergy.
• Previous research established a dose-response for isothiazolone-induced allergy.

Purpose of the Study:

• To determine and demonstrate differences in toxicological risk from aqueous biocide formulations with and without polymers.
• To evaluate how formulation matrices affect biocide delivery to skin and subsequent allergy risk.

Main Methods:

• Established dose-response relationships for isothiazolone biocides.
• Compared biocide skin absorption from aqueous solutions, oil-in-water emulsions, and polymeric emulsions/paints.
• Assessed risk based on delivered biocide dose to target tissue.

Main Results:

• Polymeric formulations (emulsions/paints) significantly reduce the dose of biocide delivered to the skin compared to non-polymeric formulations.
• A lower delivered dose of biocide from polymeric matrices leads to a reduced risk of cutaneous contact allergy.
• The formulation matrix is a critical factor influencing biocide bioavailability and associated risk.

Conclusions:

• The formulation matrix critically impacts biocide delivery and toxicological risk.
• Risk assessments and safe use levels for biocides must account for formulation-dependent dose differences.
• Polymeric formulations offer a strategy to mitigate the risk of contact allergy from isothiazolone biocides.