Arsenic is a metal that occurs naturally in soil and rocks. As a result, arsenic can be present in food and water. Arsenic is also used in some pesticides and industries. Because arsenic is so abundant in the environment, all people have some amount of exposure to arsenic. Arsenic is found in many popular foods and drinks. Exposure to small amounts, such as those reported in brands of apple juice and rice sold in the United States, have not been associated with illness. Arsenic is also one of many chemicals found in cigarette smoke.
Arsenic can be present in different forms. A gaseous form of arsenic, called arsine, is used in some industries and can be very harmful if inhaled. Another form is inorganic arsenic, which is used in medicine and has been used in pesticides. For the typical American today, the most common source of exposure to arsenic is seafood. Fish and shellfish contain an organic form of the chemical known as arsenobetaine. Additionally, most calcium supplements are from seashells which also contain organic arsenic compounds. This form of arsenic is considered non-toxic compared to other forms of arsenic, and there are no regulatory limits on the amount of arsenic seafood can contain.
After a single seafood meal, the levels of arsenic measured in urine can be extremely high compared to ‘normal’ ranges. When measuring arsenic in urine samples, most laboratories do not distinguish between inorganic and organic arsenic. In the vast majority of cases, the high urine arsenic reported is due to organic, non-toxic, arsenic in the urine from seafood exposure.
So if you have a urine test that reports high arsenic, and you don’t have a history of recent, excessive exposure to arsenic beyond usual environmental exposure, it is doubtful that you have been poisoned by arsenic. If there is any real concern for arsenic poisoning, the urine should be tested specifically for both the organic and inorganic forms of arsenic. Even more importantly, testing should be done only after a physician determines there is a real concern for arsenic poisoning. Medical toxicologists, who specialize in the diagnosis and management of human poisoning, are available through regional poison centers to assist primary care physicians with questions regarding arsenic poisoning. The ACMT website also provides a list of medical toxicology services across the country where patients may consult directly with these specialists.
Michelle Ruha, MD FACMT