Glyphosate

Roundup active · N-(phosphonomethyl)glycine

CAUTION, The single most contested classification in this set: IARC calls it a probable human carcinogen (Group 2A); the EU, EPA, and WHO/FAO did not classify it as carcinogenic. Residue has been measured on non-organic cotton tampons and gauze at low ppb. Both camps are real, we name both.

What it is

The most widely used herbicide on earth, the active ingredient in Roundup. On cotton it is often sprayed directly on the crop at harvest as a drying agent, which is when residue binds to the fiber.

In this product: None. It is an agricultural residue carried into non-organic cotton products, not an added ingredient.

Dose & route, what actually matters

Detected on raw cotton and finished cotton products at parts-per-billion. The mucosal route raises the question of absorption, but the measured residue is low and the human-cancer evidence is the part experts genuinely disagree on. Organic cotton avoids the spraying entirely.

EUROPEAN UNION

Not classified as carcinogenic under EU harmonized CLP; the EU re-approved glyphosate after EFSA's review diverged from IARC (EFSA included industry data IARC could not).

UNITED STATES

EPA classifies it 'not likely to be carcinogenic to humans at relevant doses' (under active litigation). No residue limit specific to menstrual products.

The evidence

IARC classified glyphosate as 'probably carcinogenic to humans' (Group 2A) in March 2015, citing limited human evidence, sufficient animal evidence, and strong genotoxicity evidence.

regulatory · 2015 · source

A University of La Plata (Argentina) analysis reported glyphosate and/or its metabolite AMPA in the large majority of cotton hygiene products tested, including tampons, pads, and sterile gauze, at low-ppb levels.

review · 2015 · source

California Prop 65: Listed under California Prop 65 as a carcinogen (based on the IARC 2A classification); the listing has been litigated.

How to avoid it

Choose certified organic cotton products. Organic cotton is grown without glyphosate and is not desiccated with it at harvest, which is where most fiber residue comes from.

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.