The methylation of inorganic arsenic to monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) have been generally considered to be the major pathway for inorganic arsenic biotransformation and detoxification in humans. Yet, when arsenate/arsenite is injected into the Callithrix jacchus (marmoset) monkey or the chimpanzee, monomethylarsonic acid and dimethylarsinic acid were not found in the urine. But there may also be some polymorphisms in humans.
Methylation of inorganic arsenic in different mammalian species and population groups., , Sci Prog, 1999, Volume 82 ( Pt 1), p.69-88, (1999)
Enzymatic methylation of arsenic compounds. III. The marmoset and tamarin, but not the rhesus, monkeys are deficient in methyltransferases that methylate inorganic arsenic., , Toxicol Appl Pharmacol, 1996 Sep, Volume 140, Issue 1, p.77-84, (1996)