In Canada, natural tritium levels vary between 0.2 and 1.4 Bq/L, depending on geographical location and other factors.

Unfortunately, few measurements of natural tritium in precipitation were made before atmospheric contamination occurred.

This quantity can be compared against the permanent inventory of natural tritium, which is 3.5 kg (1.2x1018 Bq; UNSCEAR, 2000; Guétat et al., 2008).

A small fraction of natural tritium is produced in the Earth’s crust during neutron capture from traces of lithium-6 contained in the rock.