https://www.symmetrymagazine.o…our-own-particle-detector
says
"... Radon is a naturally occurring radioactive element, but it exists in such low concentrations in the air that it is less radioactive than peanut butter. ..."
http://fusrapmaywood.com/factsheet/radenv.html
claims
"...
Food contribues an average of 20 mrem/year, mostly from potassium-40, carbon-14, hydrogen-3, radium-226, and thorium-232.
- Beer= 390 pCi/liter
- Tap Water= 20 pCi/liter
- Milk= 1,400 pCi/liter
- Salad Oil= 4,900 pCi/liter
- Whiskey= 1,200 pCi/liter
- Brazil Nuts= 14 pCi/g
- Bananas= 3 pCi/g
- Flour= 0.14 pCi/g
- Peanuts 8 Peanut Butter= 0.12 pCi/g
- Tea= 0.40 pCi/g
..."
This means, to me, that controls need doing. Water alone, wire alone, in Cloud Chamber. Just to see.