Planet Smart, a London-based biomaterials startup, has raised $1m to take on one of the biggest hidden sources of plastic pollution: the fossil-based polymers inside nappies and sanitary pads.

Those hidden plastics in hygiene products are a massive but overlooked source of microplastic pollution. PlanetSorb biodegrades within six months, leaves no microplastics, absorbs more than 1a litre per gram (up to twice as much as traditional materials), and is cost-competitive, the startup says.

The company already has three letters of intent and two purchase orders from European hygiene brands.