Can tap water be radioactive?

Last July, a radioactive substance was detected in the tap water of France’s Ile-de-France region and along the Loire river: tritium. So do the French need to worry?

Tritium is a radioactive isotope of hydrogen. It is naturally found in our environment, albeit in very small concentrations. In total, our planet holds around 3.5 kg of natural tritium. Still, the vast majority of this substance is produced by man as a result of the processes in nuclear power plants and research centres.

The water used to cool nuclear reactors is loaded with tritium, then flushed into the rivers to be diluted. Now, the Association for Radioactivity Monitoring in Western France (ACRO) has reported that the water in some areas of France shows tritium contamination. The highest levels, 23.2 becquerels per litre (Bq/l), were found in the town of Châtellerault. Still, it’s evidently far from breaching the threshold set by French quality standards - 100 Bq/l.

Given the lack of research available on the effects of long-term exposure to low levels of tritium, the French Commission for Independent Research and Information about Radiation (CRIIRAD) has nonetheless ordered that this threshold be lowered to 10 Bq/l. As for the International Commission on Radiological Protection (ICRP), they recommend continuing research into the issue. One thing is sure, though – very high doses of tritium can cause cancer and mutations.