Environmental experts have started a review into whether land from the former Hauxton Chemical Works in Cambridgeshire is safe and ready to be built on.
Planning permission for 380 new homes was granted for the site in 2010 on condition that it is not still contaminated.
The plan to build homes at Hauxton has been very controversial, with local residents expressing concerns that the measures taken to clean up the waste ground have dispersed chemicals into the air, causing them breathing and health problems. They have also expressed fears that building on the site could allow toxins buried deep in the earth to escape into the water supply.
Tests on the area's groundwater have been taken at Hauxton since the clean up on the site finished last November. South Cambridgeshire District Council say that every precaution will be taken to ensure the area is safe and uncontaminated.