• Radioactive substance tritium found near nuclear sites in US
• 48 nuclear power sites contaminated
•Tritium enters groundwater aquifers
Investigations undertaken by the US Nuclear Regulatory Commission have found tritium leaked through corroded pipes into the ground.
The Washington Post reported the substance, a radioactive form of hydrogen, had concentrations at some sites exceeding the federal drinking water standard.
At three sites, two in Illinois and one in Minnesota, leaks were also found to have contaminated drinking wells near homes.
At a fourth site, in New Jersey, tritium had leaked into an aquifer and the discharge canal off Barnegat Bay.
According to officials, the tritium leaks had not shown any signs of health threat, even at hundreds of times over the legal limit.