Simulated Gastrointestinal Dissolution of Synthetic Vitreous Fibers: A Preliminary Study Using USP Apparatus 4

Owens Corning is committed to advancing fiber safety science through the development of ethical, in-vitro test methods aligning with global regulatory standards. By expanding toxicity assessments beyond traditional lung solubility to include gastrointestinal dissolution, we aim to pioneer innovative approaches to facilitate alternatives to regulatory-required in-vivo testing while enhancing our understanding of potential exposure pathways.

This talk explores a novel application of pharmaceutical dissolution technology—specifically the USP Apparatus 4—in evaluating the gastrointestinal (GI) behavior of synthetic vitreous fibers (SVFs). Traditionally employed in lung bio-persistence studies, the USP-4 system was reconfigured from a closed-loop to an open-loop setup to simulate digestive tract conditions. This pilot study considers the feasibility of this approach and characterizes the dissolution behavior of three commercially available fibers: glass wool, mineral wool, and alkaline earth silicate (AES) “superwool.”

Fibers were exposed sequentially to both simulated gastric fluid (low pH) and intestinal fluid (neutral pH) to mimic physiological conditions. The open-loop setup enabled continuous flow and collection of eluates for compositional analysis via standalone optical emission spectroscopy. Key findings revealed that mineral wool fibers exhibited significant dissolution in the gastric mimic, with reduced solubility in the intestinal mimic. In contrast, both glass wool and AES fibers showed minimal dissolution across both fluid types, suggesting greater chemical stability under simulated GI conditions.

This work demonstrates the value of cross-industry technology transfer, leveraging pharmaceutical dissolution tools to advance toxicological method development in materials science. The successful adaptation of USP Apparatus 4 for GI simulation opens new avenues for evaluating bio-accessibility and informing risk assessments of non-traditional materials.