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.

https://en.wikipedia.org/wiki/Boll_Weevil_Eradication_Progra...