Arsenic was used as an early insecticide against boll weevels in cotton fields and for various pests in other crops.

Rice plants pull that arsenic out of the soil when grown on land where arsenic was used in the past.

https://www.wired.com/2012/06/arsenic-pesticides-in-our-food...

I'm an Indian who eats Palakkad (place) Matta with unpolished husk. Should I mitigate my risk by eating polished rice or move to millets, which need less water? Seems my rice is not cultivated in an arsenic hotspot. Should I worry when groundwater depletion gets worse?

https://www.researchgate.net/figure/Map-shows-worldwide-arse... https://www.researchgate.net/figure/Rice-harvested-areas-at-...

Using the 100 ppb arsenic level as a baseline, and using selenium as a model for daily requirements and toxicity since we don't have one for arsenic, that seems to suggest that up to half a kilo per day of rice should be well-tolerated? Assuming I math-ed it correctly.

There is insufficient data to build an authoritative model of dietary arsenic requirements AFAIK. It is a necessary micronutrient in animal biology and evidence suggests it is similar to selenium in requirement magnitude and toxicity profile, so it is sometimes treated as comparable in the literature. Obviously, it is a rough cut since this was extrapolated from animal models -- we don't have good human models -- but in principle the RDA should be well-tolerated by definition and these levels are endemic in some parts of the world.

Figure if this was really a problem the Japanese would be front and center. Like you’d at least hear something from the nation that eats 10x as much rice as me

http://archive.today/SuFE5

TLDR:

“The analysis also showed that brown rice contained more arsenic than white rice.”

“…the levels varied depending on where the rice was grown. The highest concentrations were found in arborio rice from Italy and white and brown rices from the southeastern United States.

Sushi, jasmine and other types of white rice from California, as well as jasmine rice from Thailand and basmati rice from India, had the lowest levels.”

No mention in the article of whether there are differences in conventional and organic products (I would imagine not, if this is a groundwater problem?).

Also of note:

"Though the findings were not published in a peer-reviewed journal, they jibe with past research, said Dojin Ryu, a professor of food toxicology at the University of Missouri. Rice and rice products are typically the most concentrated food sources of inorganic arsenic, according to the F.D.A."