BBC News reported that Health Minister Edwina Hart ordered the investigation into concerns over the Hanson Cement plant at Padeswood.
A response team has been set up by Public Health Wales, which wants any responses by 11 June.
Hanson has previously said there are no health risks at the site, but said it would welcome any study.
Irish building materials group CRH is working on a number of potential purchases, chief executive Myles Lee said in a newspaper interview.
