Re: Arsenic? Mercury? Formaldehyde?
It is always good to approach a modality with healthy skepticism. I am afraid you will not find double blind studies on this or many other natural health modalities due to the fact that the main supporter of studies is pharmaceutical companies. Even double blind studies can be created to have a certain outcome. Part of the reason you are likely struggling with this is our conditioning about urine in the west.
However Martha Christy in here book "Your Own Perfect Medicine" quotes many doctos who have treated multiple persons with various health issues. You can listen to a 45 min. you tube talk by her and Dr. Bertrice Barturm. There are doctors working with it and many doctors worked with it prior to 1940.
Basically urine is a "blood plasma ultrafiltrate." Scientists don't call urine, urine, but rather refer to it with the above mentioned term. Urine is sterile. The small amounts of metals and contaminents in urine serve to boost the immune system and cause them to recognize and deal with issues inside the human body. You don't drink or inject or massage all your urine, you use some of it. Dr. William Ray does provacation neutralization, where he finds a substance the body isn't dealing with well, like mercury, finds the dose creating problems, then the dose that will turn the problem off. This is similar to the small amounts of contaminants one finds in urine.
Urine contains the outer proteins of infections in the body, has hormones, polypeptides, amino acids, vitamins, minerals and if taken back into the body are readily available. They were excreted due to the fact they were not needed at the time by the blood.