The extent of tebuconazole leaching from unpainted and painted softwood

Abstract

Exposure to water and high air humidity may affect the preservation of wood products as many preservatives are water-soluble and thus likely to leach. In this study, depletion of a common fungicide, tebuconazole (TAZ), from treated wood was investigated using a C-labeled tracer. The wood species and treatment technique were chosen to be representative of products such as windows and doors; specifically, ponderosa pine was dip treated with a solvent-based, metal-free formulation. The impact of different aqueous settings including high air humidity, and either simulated continuous or intermittent rain was evaluated over a period of two months. Along with the exposure type, the effect of end-grain sealing on TAZ loss was explored. Despite the exposure of treated wood to laboratory-simulated harsh environmental conditions, more than 60% of the originally sorbed TAZ remained in the wood under all scenarios. While high air humidity did not lead to TAZ depletion, simulated continuous rain led to a TAZ leaching mainly from the end grain. TAZ leaching was found to be higher for unpainted wood, where up to 40% of the originally sorbed TAZ was prone to depletion from an end grain. End-grain sealing with water-based primer and paint led to a substantial two-fold reduction of TAZ leaching. Unexpectedly, wood exposure to intermittent rain caused additional TAZ loss that could not be explained only by water leaching.

Characterization of the diffusion of organic fungicides with amine oxides in white pine and white spruce

“…For propiconazole, the mass loss was more linear over time, resulting in a greater mass at any given conditioning duration. This observation agrees with other workers, which showed that the loss of triazoles (like propiconazole) through evaporation and leaching is similar every week until stabilization (Woo 2010; Kukowski et al 2017;Kukowski et al 2018Kukowski et al , 2019. Coors et al (2014) also found that PBC, a degradation product of IPBC, leaches much faster than propiconazole.…”

“…These results could however be considered in good agreement with the white pine studied in this publication, as leaching is reduced by the sealed longitudinal pathways which would otherwise be a main route for the loss of propiconazole (Haloni and Vergnaud 1997). The paint also reduces the leaching by slowing down the exchanges of water (Kukowski et al 2018).…”