Investigators said they found traces of the toxic chemical Agent Orange in and around Camp Carroll, a U.S. military facility in South Korea.
A team of local and U.S. specialists found traces of 2,4,5-T, a key component of cancer-causing defoliant in five groundwater wells tested at the base in Chilgok, the team said Friday.
The levels of contamination were below what the World Health Organization permits for drinkable water, officials said.
Investigators said they also found a high level of volatile organic compounds, exceeding 900 times guidelines permit for drinking water, which could pose a risk to human health.
Team members said they will be take action to stop people who live near the base from drinking the water until further studies can locate the exact source of the contamination.