In vivo and in vitro degradation and biological toxicity studies of polyesters with varying degradation rates

The fragmentation of biodegradable plastics into "degradable particles" is an essential step during their degradation process. Investigating their in vivo degradation behaviors and toxicity differing from microplastics holds significant implications. In this study, we selected biodegradable polyesters with distinct degradation rates—polyglycolic acid (PGA) and its copolymer poly(butylene succinate-co-glycolate) (PBSG)—alongside non-biodegradable polyethylene terephthalate (PET) as a control. Using combined in vitro simulations and animal experiments, we assessed their degradation in simulated body fluid (SBF), simulated gastric fluid (SGF), simulated intestinal fluid (SIF) and toxicity effects on rat body weight and multiple organs (heart, liver, spleen, stomach, lung, kidney, colon, brain). Results showed PET exhibited negligible degradation and the highest biotoxicity. After 18 weeks, PGA demonstrated degradation rates of 53.28% (SBF), 96.35% (SGF), and 76.14% (SIF), while PBSG degraded at 7.98%, 10.28%, and 10.42%, respectively. Biodegradable plastics caused no significant toxicity at low doses. However, high doses induced weight loss, tissue necrosis and inflammation in rats. Notably, PGA—with the fastest degradation—showed the weakest physiological toxicity. These findings highlight the important relationship between the degradation rate of biodegradable plastics and their biotoxicity, and can guide the development of new materials to balance environmental benefits and minimized health risks.