Emergency efforts to contain a benzene leak from a tanker were completed Sunday, local authorities said.
The tanker, carrying 28.66 tonnes of the highly hazardous crude material, plunged into the Fenhe River, a tributary of the Yellow River, in Xinjiang County, Yuncheng city, Wednesday.
Four dozen belts of activated carbon were placed in three counties downstream to absorb the pollutants, the local government said.
Benzene is a colorless compound used to manufacture plastics. It is known to damage blood production in humans. The accident occurred about 100 kilometers from the mouth into the Yellow River.
The local government said that water quality tests had showed the area was free of benzene.
Two people in the truck were killed in the accident.