What are the Sources and Contributors to Arsenic Readings?

Wondering where arsenic could be coming from? You may be surprised to learn the answer. Abraxas Labs dives into the story behind arsenic


Common sources of arsenic exposure in humans can include primarily ingestion of food containing arsenic, well water contaminated by bedrock containing arsenic, mining, and various sources of industrial pollution. Meat, fish, and poultry account for 80% of dietary arsenic intake. Fish, bivalve shellfish, and algae also contain arsenic in the form of arsenobetaine and arsenocholine, sometimes referred to as “fish arsenic” which is an organic form of arsenic. Fish arsenic or organic arsenic has low toxicity to humans and is rapidly excreted in urine [1], as compared to its inorganic counterpart.

This is not true for all sea-based products, however. For example, one form of seaweed, hijiki, reportedly contains high levels of inorganic arsenic [2]. Inorganic arsenic is more toxic in humans than the organic forms of arsenic [2]. While we are still compiling the data from other clients on similar sample types, we do not yet have sufficiently large enough dataset to perform statistical analysis on the samples pertaining to various potential sources for growers (i.e. heavy metals contents in nutrients). However, commenting on our qualitative observations from the samples tested at Abraxas Labs, we have noticed increased readings of heavy metals content found in client samples submitted by clients who use sea kelp as a nutritional additive. Namely, levels of arsenic, cadmium, and lead appear to have positive association with the use of sea-based products.

While inorganic arsenic is a more toxic form of arsenic in humans, Oklahoma Medical Marijuana Authority (OMMA) and the current State regulations, require analytical laboratories that test medical cannabis for transfer or sale of the product to report arsenic as total arsenic. In other words, the current regulations make no differentiation between, or calls for speciation and determination of, the arsenic source; all sources of arsenic in the final product tested add towards the failure threshold of 0.2 ppm.


  1. Agency for Toxic Substances and Disease Registry (2016). "Addendum to the Toxicological
    Profile for Arsenic." Atlanta, GA USA. https://www.atsdr.cdc.gov/toxprofiles/Arsenic_addendum.pdf
  2. Rose, M., et al., “Arsenic in seaweed--forms, concentration and dietary exposure”. Food Chem Toxicol, 2007. 45(7): p. 1263-7.
  3. Tracy Punshon, Brian P. Jackson, Andrew A. Meharg, Todd Warczack, Kirk Scheckel, Mary Lou Guerinot, “Understanding arsenic dynamics in agronomic systems to predict and prevent uptake by crop plants”. Sci Total Environ. 2017 Mar 1; 581-582: p. 209–220
  4. L. L. Yu, R. C. Stanoyevitch and R. Zeisler, Anal. Methods, 2017, DOI: 10.1039/C7AY01111C