Switching to biodegradable plastics can actually leak more toxic heavy metals into the soil than using old-school plastic.
March 19, 2026
Original Paper
Unveiling the ”green paradox” of biodegradable microplastics: Global patterns, chemical mobilization mechanisms, and management implications for soil heavy metals
SSRN · 6439405
The Takeaway
While regular plastic is physically inert, biodegradable plastic acts as an active 'chemical mobilizer.' As it breaks down, it triggers soil acidification and chemical reactions that 'unlock' legacy heavy metals already in the ground, turning them into bioavailable poisons that traditional plastic would have left undisturbed.
From the abstract
Globally, substituting biodegradable plastics (BMPs) for conventional non‐biodegradable plastics (NBMPs) has been promoted as a key strategy to address plastic pollution. However, the impact of this material transition on the geochemical equilibrium of legacy heavy metals (HMs) in soils and associated ecological risks remains unclear. Using a global dataset, we systematically compared the effects of NBMPs and BMPs on soil HM bioavailability, chemical speciation, and microbial ecological function