The chlorine we use to clean water can accidentally turn normal chemicals into new ones that are 10 million times more toxic.
March 26, 2026
Original Paper
Coupling vs Cleavage: Elucidating the Transformation Pathways and Enhanced Ecological Risks of Nonylphenols during Chlorination
SSRN · 6459673
The Takeaway
Standard water treatment processes meant to kill bacteria can cause 'aromatic coupling,' where common pollutants from soaps and plastics are fused into new, highly lethal structures. These newly created toxins are far more dangerous than the original chemicals and are currently not detected by standard safety protocols.
From the abstract
While chlorination is a cornerstone of wastewater disinfection, its potential to inadvertently transform endocrine-disrupting nonylphenols (NPs) into more hazardous products remains poorly understood. In this study, we integrated non-targeted screening with density functional theory (DFT) calculations to systematically elucidate the time-dependent transformation pathways and toxicity evolution of two representative NPs (NP36 and NP112) during chlorination. Our findings reveal a distinct, multi-s