We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Airborne microplastics as evolving contaminant carriers: atmospheric weathering, transformation pathways, and the Trojan horse hypothesis
Summary
This review of 113 studies finds that microplastics floating in the air don't just sit there unchanged—sun, oxygen, and weathering actually break them down and make them better at absorbing and carrying other toxic chemicals, like a "Trojan horse" that sneaks pollutants into your body. Since these particles have already been found in human brain tissue, and almost everyone breathes urban air containing them, this matters because current safety assessments may be underestimating the real risks by treating microplastics as harmless, unchanging specks rather than evolving contaminant carriers.
Atmospheric microplastics represent a rapidly emerging environmental threat, yet their dynamic behavior remains poorly understood. This study synthesizes 113 publications to reveal that airborne microplastics undergo continuous transformation through atmospheric weathering, fundamentally altering their toxicological properties. The analysis introduces the atmospheric microplastic transformation and exposure framework (AMTEF), demonstrating how weathering processes such as photodegradation, oxidation, and fragmentation progressively enhance particle reactivity and contaminant-carrying capacity. Critically, only approximately 1.77% of existing studies examine this "Trojan horse" effect, despite its central role in health risks. The research proposes the evolving toxicity paradigm (ETP), which reconceptualizes microplastic hazards as dynamic rather than static, driven by surface amplification, contaminant concentration, synergistic interactions, and size-dependent transformation. Recent evidence of microplastic bioaccumulation in the human brain tissue (Nihart et al., Nat Med 31:1114-1119, 2025) further underscores the urgency of understanding transformation-driven toxicity pathways. This paradigm shift from inert particles to active vectors demands transformation-aware risk assessment protocols. The findings reveal that current toxicological models substantially underestimate exposure risks by ignoring atmospheric evolution, with implications for the 99% of humans who breathe urban air containing these evolving contaminants.