Improving Risk Assessment of Color Additives in Medical Device Polymers

Many polymeric medical device materials contain color additives which could lead to adverse health effects. The potential health risk of color additives may be assessed by comparing the amount of color additive released over time to levels deemed to be safe based on available toxicity data. We propose a conservative model for exposure that requires only the diffusion coefficient of the additive in the polymer matrix, D, to be specified. The model is applied here using a model polymer (poly(ether-block-amide), PEBAX 2533) and color additive (quinizarin blue) system. Sorption experiments performed in an aqueous dispersion of quinizarin blue (QB) into neat PEBAX yielded a diffusivity D = 4.8 × 10-10 cm2s-1, and solubility S = 0.32 wt. %. Based on these measurements, we validated the model by comparing predictions to the leaching profile of QB from a PEBAX matrix into physiologically representative media. By considering the release of QB from PEBAX matrices over time and computationally estimating toxicity, we demonstrate that a significant enhancement in the size of device that would give rise to toxicological concern can be achieved. These findings suggest that an initial screening-level risk assessment of color additives and other potentially toxic compounds found in device polymers can be improved.