Watch: Sulfonic acid spill covers Brazil river in thick white foam
Sulfonic acid, which can cause serious harm to humans, has leaked into the Rio Seco in Brazil, police footage shows.
The acid, which is used to produce household cleaning materials, leaked after a truck crashed in Joinville on Monday (29 January).
Police have since declared a local state of emergency.
A treatment station has now been closed by officials in a bid to prevent the intake of contaminated water, potentially affecting access to drinking water.
Videos shared on social media show people stockpiling bottled water.
