"I read recently that Paul Bragg would save his urine every day, water fasting, and
then have it tested, and always find chemical residue...we're awash in it."
It's been close to 40 years since I read Paul Braggs book, but I recall he would put his urine in a jar and store it some where to look at it daily to see all the foreign matter that would settle at the bottom, to see what was leaving his body during the fast. He believed this stuff would end up as crystals in the joints to cause joint pain
At that time he was under a supervised fast in Switzerland because of having tuberculosis. He does mention doctors taking samples of the urine to be tested to see if too much poison is over taxing the kidneys. If so that would be an indication to end the fast. His first fast was during this time, and was for a duration of four days.
He was also down on salt.