At least 30 Belgian companies are still legally allowed to pump chemical waste, including PFAS, into the Westerschelde estuary which separates the Netherlands from Flanders, local broadcaster Omroep Zeeland said on Monday.

The companies are being allowed to dump the dangerous chemicals under a transition agreement which runs until 2024.

The Dutch government said two weeks ago that it is sharpening up the rules for dumping PFAS following a report from public health institute RIVM.

That research showed PFAS concentrations exceeded the official threshold in over half of the samples of drinking water taken from Dutch rivers. For drinking water from groundwater, this was the case for 1 in 10 measurements.

An analysis by the Flemish environment agency VMM showed that 66 companies had a licence to discharge PFAS into the Westerschelde, but the permits for 27 of them were tightened up in June, Omroep Zeeland said.

In May, the RIVM warned people who go fishing as a hobby to sharply reduce their consumption of fish, shrimp, oysters and mussels caught in the estuary because of chemical pollution.

Fish and shellfish caught in the estuary can contain eight to 10 times the amount of PFAS found in similar products sold in the shops, the RIVM said.

PFAS (per- and polyfluoroalkyl chemicals) are widely used, long lasting chemicals, valued for their ability to repel oil and water and which have been linked to health risks in humans and animals.

In particular, PFAS are thought to have a role in liver damage, thyroid disease, decreased fertility, high cholesterol, obesity, hormone suppression and cancer.