Nonylphenol ethoxylate (NPE)

What it is

Nonylphenol ethoxylate (NPE) is a nonionic surfactant made by reacting nonylphenol with ethylene oxide. It is a workhorse detergent and wetting agent that was used across household and industrial cleaners for decades because it is cheap and effective at cutting oily soils.

Where it appears in car care

NPE shows up in older or value-oriented cleaning formulations, including some glass and all-purpose cleaners, as the surfactant that provides detergency and sheeting. Newer formulas increasingly substitute alcohol ethoxylates or alkyl polyglucosides because those have a cleaner environmental profile.

Why it is flagged

The environmental record is the issue. NPE and its degradation product nonylphenol are toxic to aquatic organisms and are persistent and endocrine-active in the environment. The European Union restricts nonylphenol ethoxylates in detergents, and EPA's Safer Choice program steers formulators away from the class. In a wipe-off glass cleaner, residue reaches wastewater through cloth laundering, so the aquatic-toxicity flag is the relevant environmental pathway even at low product concentration.