Rhoca-Gil is a type of industrial sealant produced by Rhône-Poulenc, used in the construction of tunnels to block the passage of groundwater inside.
The sealant begins as a liquid, then is injected into cavities which need to be sealed, and polymerises, causing it to harden.
Rhoca-Gil consists of two fluids, that are mixed, thinned out with water and then sprayed into cracks in the bedrock.
In 1997, fish and local cattle started dying as a result of Rhoca-Gil in its liquid form leaking into the water supply, contaminating it with acrylamide, a known carcinogen, mutagen and neurotoxin.
The main contractor, Skanska, along with Rhône-Poulenc and the Swedish Rail Administration had criminal charges brought against them.