Dermal Disposition of Triazine in Cutting Fluid Mixtures

Abstract

Triazine is often added as a biocide/preservative to cutting fluids formulations that are used in the metal machine industry. Workers involved in metal machining are not only exposed to components in these cutting fluids, but also to biocides such as triazine that have been implicated in occupational irritant dermatitis. Very little is known about how these cutting fluids and their ingredients influence the dermal disposition of triazine. The purpose of this study was to assess 14C‐triazine membrane transport when topically applied to inert silastic membranes and porcine skin in an in vitro flow‐through diffusion cell system as aqueous mineral oil (MO) or aqueous polyethylene glycol (PEG) mixtures. 14C‐triazine mixtures were formulated with three commonly used cutting fluid additives; namely, 0% or 5% linear alkylbenzene sulfonate (LAS), 0% or 5% triethanolamine (TEA), and 0% or 5% sulfurized ricinoleic acid (SRA). Triazine partitioning from the formulation into the stratum corneum (SC) was reduced significantly by the presence of LAS, while SRA significantly reduced the pH of the formulation. Triazine absorption ranged from 2.2% to 3.9% dose in porcine skin and 12.6% to 18.6% dose in silastic membranes. In silastic membranes, the complete mixture reduced triazine absorption significantly in MO‐based mixtures, while in PEG‐based mixtures triazine absorption and apparent permeability were significantly increased. In porcine skin, triazine permeability was significantly increased for both MO‐ and PEG‐based complete mixtures with a trend towards greater triazine absorption in more complex PEG‐based mixtures. Interestingly, SRA + TEA significantly increased triazine permeability absorption in MO‐ and PEG‐based mixtures, but this interaction appears to be more additive than synergistic. Although the physicochemical experiments suggest otherwise, triazine readily permeates a homogenous lipid membrane such as the SC, while triazine permeability was significantly enhanced by the complete mixture, especially in PEG‐based mixtures.