Also, there are papers on PubMed, that describe that younger people and children do not show obvious signs of arsenic poisoning or intake. Skin reactions are absent for them, because they excrete the arsenic faster than older people.

Given that you are young, your body may be handling this better than say if you were 40 or 50.

Arsenic is a fairly common contaminant in our environment and occurs naturally in foods and water. (foods may be contaminated by arsenical pesticides). It is just that arsenic does not get the media attention that mercury (fish) and lead (from paint, and car exhaust) does. I think one is more likely to get arsenic issues than lead (unless you eat old paint, or use leaded paint).

There is another issue too. A urine test only shows what is coming out.
But it does not show what is in your blood. When my son had his tests for lead (for ADHD) it was a blood test that was used.
Some heavy metals are stored in the body. Mercury is stored in fat and bone, and so is lead. So I think other tests should be done as well.

http://www.labtestsonline.org/unders...lead/test.html

http://www.labtestsonline.org/unders...cury/test.html
urine tests do not show all types of mercury.

http://www.atsdr.cdc.gov/csem/arseni...valuation.html
This paper says urinary tests for arsenic are more useful than blood work.