Thorium, among the longest-lived of radioisotopes, is widely spread around the universe; think “big bang”.
Fracking dislodges and concentrates this and other naturally-occuring radionucleotides, like uranium, radium, and radon, thereby contaminating the water.
About 0.5% to 1% of fracking fluid is composed of chemicals, silica and other propants, and even radionucleotide tracers added to help guide drilling and fracking operations.
This can amount to as much as 65,000 gallons of added toxins in 13 million gallons of water “abused” per well.