What I got by reading the paper: loose tumeric powder and polished tumeric root are the main "culprits" because they are contaminated with Lead Chromate (chemical used in paintings for yellow color.)
If you're using branded/packaged tumeric powder, or natural unpolished tumeric root, you're still good as a tumeric consumer in South Asia (though the paper differentiates branded vs packaged tumeric in Table 2, but does not explicitly explain the difference.)
Also, Patna in Bihar is the major source of Lead-adulterated tumeric (in the forms mentioned above) in India, and any exports of tumeric to other places from Patna could be harmful. Lead contamination in Guwahati, Assam is mostly found in imported tumeric from Patna.