Traces of glyphosate, a pesticide linked to cancer, has been found at very high levels in menstrual products, according to a report by the Pesticide Action Network UK (Pan UK), the Women’s Environmental Network and the Pesticide Collaboration.

This is concerning, according to the authors, because chemicals absorbed through the vagina directly enter the bloodstream, bypassing the body’s detoxification systems. This means even small traces of chemicals in direct contact with the vagina could cause health risks.

The researchers tested 15 boxes of tampons from UK retailers across a range of different popular brands. Glyphosate was found in tampons in one of the boxes, at 0.004 mg/kg. The UK and EU maximum residue level for drinking water is 0.0001 mg/kg, making this 40 times higher than permitted levels of glyphosate in drinking water.