FORMULATION EFFECT ON THE DERMAL BIOAVAILABILITY OF ISOTHIAZOLONE BIOCIDE

A central tenet of the science of toxicology is that the toxic effect of any material monotonically increases with the amount of the materia l delivered to the target tissue. This is the so-called dose-response relationship. Previous work is discussed in which a dose-response rela tionship is established for the induction and elicitation of cutaneous contact allergy from the isothiazolone biocide which is a 3 to 1 mixt ure of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazo lin-3-one. The commercial product name for this mixture is Kathon (R) LX biocide. Given a tissue dose-response, this current work determines and demonstrates a difference in risk from aqueous formulations with and without polymer. A lower delivered dose of biocide goes into the s kin from an aqueous-based polymeric emulsion or paint than from an aqu eous solution or oil-in-water emulsions without polymer. Thus, the est imate of risk, as a direct result of dose, and the determination of a safe use level of a biocide in any particular formulation matrix need to incorporate this reality.