The temporary ban on the use of steel slag in construction projects is to be extended until January 2027, environment junior minister Annet Bertram told MPs during a debate on the issue on Thursday.

The ban had been due to expire in July, pending two reports to determine whether a permanent ban is needed or if the material can be used without harming the environment.

Broadcaster NOS said last week that work on the reports has not yet started, although the minister on Thursday disputed that. She did tell MPs, however, that she is in talks with the RIVM to speed up the reporting process.

Steel slag, a byproduct of the steel smelting process, has been used all over the country as a replacement for sand and gravel, particularly in roads and pathways. However, the public health institute RIVM said in a report in 2023 that it can release harmful substances when it comes into contact with rain or groundwater.

The environment inspectorate has also warned twice that steel slag can damage the environment, even when used according to current regulations. The national audit office has also called for action.