Saturday July 12, 2013 (foodconsumer.org) -- Prior research has already shown an association between consumption of drinking water with high levels of inorganic arsenic in a dose of 500 ug/L or higher and elevated risk of type 2 diabetes mellitus.  A new study has now found that even much lower levels of arsenic in drinking water (lower than 100 ug/L) can increase the risk.

The case-control study analyzed data from 141 cases of diabetes mellitus who were identified in the  prospective San Luis Valley Diabetes Study between 1984 and 1998 and 488 controls who were randomly sampled from 936 participants who were free of diabetes mellitus at baseline.

The study found an increase in the arsenic level in drinking water by 15 ug/L was associated with 27% increased risk for developing type 2 diabetes mellitus after adjustment for ethnicity and age, body mass index and physical activity.

The study concluded "Exposure to low-level inorganic arsenic in drinking water is associated with increased risk for type II DM (diabetes mellitus) in this population based on a comprehensive lifetime exposure assessment."

Katherine A. James from University of Colorado, Denver in Aurora, CO, United States and colleagues conducted the study and reported the findings in the journal Environmental Research.

Arsenic in apple juice and cancer risk

The U.S. Environmental Protection Agency (EPA) has set the arsenic limit for drinking water at 10 ppb or ug/L even though any dose lower han 10 ppb can still pose a small risk of cancer.

A document released in 2011 by the U.S. Food and Drug Administration shows that some apple juices produced from Turkey and United States and tested by the agency contained more than 10 ug/L arsenic. 

Another document released on the website of the FDA also assesses the risk of life-time exposure to arsenic which says that life-time exposure to 10 ppb arsenic in apple juice can lead to the development of 8 cancers per 1 million people.

The FDA released a statement on July 12, 2013 on its website showing that  the agency tested 94 apple juice samples and found 95% have arsenic below 10 ppb and 100% samples have inorganic arsenic below 10 ppb.  Inorganic arsenic is the form of arsenic that can cause cancer.  It should be noted that organic arsenic may be decomposed in vivo to release the toxic inorganic arsenic.

Drinking water (and apple juice) is not the only source of arsenic.  Rice from the U.S. and chicken meat have been found high in arsenic.  Arsenic chemicals have been used for the production of chicken to boost their growth.  Some chicken producers have discontinued using arsenic based antiparasitic drugs now.  Also outdoor wood products like decks and fences are often treated with arsenic to preserve the material.

Apple juice is often used by young children.  It is not a good idea to let young children drink apple juice not only because of potential contamination with arsenic, but also organic acids that can damage their teeth.

It should be noted that arsenic in drinking water below 10 ppb (EPA standard) can also pose a small cancer risk, according to an FDA document, for instance, life-time exposure to 5 ppb arsenic in apple juice can cause 5 cancers per 1 million people.  To eliminate the risk, tap water filters can be used to remove arsenic in drinking water.

Arsenic and other toxic metals like cadmium can raise oxidative oxidants or produce free radicals.  Antioxidants or detoxifying agents including S-adenosyl-methionine, lipoic acid, glutathione, selenium, zinc, N-acetylcysteine (NAC), methionine, cysteine, alpha-tocopherol, and ascorbic acid are known to mitigate the toxicity of arsenic and other toxic metals. (reporting by Jimmy Downs)