Customs Restrictions on Agarwood

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I am having a hard time figuring out US Customs restrictions on agarwood chips. The USDA seems to regulate them under CITES II. It also seems to require treatment of some sort, either chemical or irradiation, on import. How in the world does someone go on holiday and bring agarwood chips back into the US without having to expose the chips to destructive chemicals or radiation? How does one avoid fines? Is there a difference if the chips are for personal use or for sale? Thanks.