It is important to understand the presence of arsenic in natural products. Natural Calm magnesium comes from deep in the ocean and like any substance from the earth or water, contains trace amounts of inorganic arsenic.
Arsenic is an element found in nature and in man-made products, including some pesticides. As a result, we ingest arsenic every day. All water – including treated municipal water – contains arsenic. Soils also contain arsenic and common plant foods are a source.
Two tsp of Natural Calm has less than 1 microgram of inorganic arsenic.
In comparison, a serving of long grain brown rice from Whole Foods has about 10 x that amount. (See http://www.consumerreports.org/cro/magazine/2012/11/arsenic-in-your-food/index.htm)
Most Canadians’ “daily intake of inorganic arsenic from food would be 10.5 µg (micrograms). This contrasts with an intake of <7.5 µg (micrograms) of principally the pentavalent inorganic arsenic species in drinking water.” (From http://healthycanadians.gc.ca/publications/healthy-living-vie-saine/water-arsenic-eau/index-eng.php?page=6#a5.2)
From food and water combined, you are likely getting about 20x the amount of arsenic you would ingest from a normal daily dose of Natural Calm (which is 1-2 tsp.)