There was no bioactivity data in the dashboard for 6-hydroxyhexanoic acid, the end hydrolysis product of PCL and an endogenous metabolite. Given that PCL continuously releases 6hydroxyhexanoic acid as it degrades, the contribution of this compound to the observed toxicity cannot be ruled out (Microtox assay EC50 = 120 µM). However, degradation into oligomers precedes monomers, likely limiting any significant formation of 6-hydroxyhexanoic acid within the timescale of our experiments. This point is supported by the chemical analyses, which did not detect it.