Rice is easy to solve by just buying California grown. They have the lowest regional levels in the world and I expect the variance amongst those growers to not have significant impact.
IIRC, This was previously (recently) discussed wrt rice sold (or given) to Haiti. Because that rice came from the Confederate States, it has more arsenic.
IIRC2, don't buy rice from land formerly used to grow cotton. Because calcium arsenate was used to kill the boll weevil.
Specifically, rice seems to contain a good deal of arsenic (https://www.consumerreports.org/cro/magazine/2015/01/how-muc...) and I've been interested for a while in trying to find some that has the least, as I eat a lot of rice.