Styrene

Vinyl benzene

CAUTION, IARC upgraded styrene to probable human carcinogen (Group 2A) in 2018, and a peer-reviewed 2020 survey found it in menstrual pads, with scented pads carrying about ten times the aromatic VOCs of unscented. Present at trace levels, so a calibrated caution.

What it is

An industrial chemical used to make polystyrene, synthetic rubber, and resins. It off-gasses as a volatile organic compound and can show up as a trace residual in synthetic fibers, adhesives, and fragrance.

In this product: None intended. It appears as a trace VOC residual, more in scented pads than unscented.

Dose & route, what actually matters

The exposure is low (tens of nanograms per gram) but sits against highly permeable tissue during long wear. The clearest lever the data shows is simple: scented pads carry far more of it than unscented, so the scent is the avoidable variable.

EUROPEAN UNION

Classified Carc. 2 (suspected human carcinogen) under EU CLP.

UNITED STATES

The US National Toxicology Program lists styrene as 'reasonably anticipated to be a human carcinogen.' No menstrual-product limit.

The evidence

IARC upgraded styrene from Group 2B to Group 2A (probably carcinogenic to humans) in 2018, citing a cohort of 73,000+ reinforced-plastics workers.

regulatory · 2018 · source

A peer-reviewed survey of feminine hygiene products found styrene among VOCs in menstrual pads, with scented pads containing roughly 10x the aromatic VOC levels of unscented (Lin et al., Environment International, 2020).

human · 2020 · source

California Prop 65: Listed under California Prop 65 as a carcinogen.

How to avoid it

Skip scented pads and liners, which carry far higher VOC levels. Unscented and organic-cotton options measured substantially lower.

Editorial analysis of publicly available regulatory and peer-reviewed sources. Not medical advice. We name our evidence and link it, including when an ingredient is fine.