Arsenic is a category one (the highest level) carcinogen. Most of the arsenic in the American diet comes from animal products; it is fed to factory farmed animals to kill intestinal parasites. Chicken probably has the most arsenic. But fish may also not be safe in this regard. In fact, arsenic is used a biomarker for total fish and seafood intake (see also here).
One seaweed species, hijiki (also commonly spelled hiziki), absorbs so much arsenic from the sea water that it is not safe to eat. Rice grown in water logged soil can absorb arsenic found naturally in the environment, and it concentrates in the bran; US rice may have lower arsenic levels. The common Ayurvdeic medicine triphala has been found to be commonly contaminated with arsenic, lead, and mercury (see also here, here).
See also the related blog post: Dr. Oz, apple juice, and arsenic: chicken may have 10 times more
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