The Environmental Protection Agency has taken the first ever federal action against a system that misleads consumers about the recycled content in plastic products.

A ProPublica investigation in June showed how the plastics industry uses a controversial accounting method called mass balance to advertise plastic products as 20% or 30% recycled even if they physically contain less than 1% recycled content.

It involves a number shuffle, done only on paper, that inflates the advertised recycledness of one product by reducing the advertised recycledness of another, often less lucrative, product. Done purely for marketing, it has been criticized by environmentalists as a greenwashing tactic.

According to an EPA policy released this month, companies that want the federal government’s stamp of approval for their sustainable products can no longer use such convoluted math.