Urine Test Revealed Arsenic Level 56 Ug. Recommendations?

I would like to learn more about arsenic poisoning. My arsenic level from a 24-hour urine sample was 56ug. The reference range was 0-50. I would not normally be concerned about a lab result that was only modestly high, but in this case, I am. I realize that the main source of arsenic is in the water supply. But I have been using only distilled water for drinking and food preparation for the last 2 years. Thus the arsenic did not come from my water in the last 2 years. Prior to that, I spent many years in an institution, where I was repeatedly told that the water quality was very poor. Also, I understand that with many heavy metals and toxins, blood and urine levels do not give an adequate portrayal of body burden. Many of these toxins are rapidly moved out of the blood and into tissues such as the brain.
Given the above scenario, what are your thoughts? Also, does a urine porphyrin profile give a better picture of toxicity? Thank you