Anti-odour finishes for activewear usually contain an antimicrobial substance. That brings them under pesticide or biocide rules, not only textile rules, and the wording of your claims decides which obligations apply. Claims such as "antibacterial" or "kills 99.9% of germs" are the kind of wording that causes most problems.

United States

Under FIFRA, the US EPA regulates antimicrobial pesticides. The treated articles exemption in 40 CFR 152.25(a) covers an article treated to protect the article itself, if the pesticide is registered for that use. EPA's PR Notice 2000-1 explains that claims to inhibit odours in the treated article itself, such as "resists odors" or "treated to resist bacterial odors", can fall within the exemption. Claims about germs, bacteria harmful to people, or health protection are public health claims, and the product would need registration. EPA also explains that terms like "antimicrobial" need clear qualification, and that the claim should be no more prominent than other features.

European Union

In the EU, the Biocidal Products Regulation, Regulation (EU) No 528/2012, covers treated articles. A garment treated with a biocidal product may only be placed on the market if the active substances are approved for that use, and if a biocidal property is claimed, the article must be labelled with information set out in the Regulation, such as the name of the active substances.

What to ask the mill

Ask for the name of the active substance, its US registration status for textile use, its EU approval status for the relevant product type, and the wording the supplier says is permitted. Keep this in writing.

Durability

If you say the odour resistance lasts, you need evidence. Wash garments with a named procedure such as ISO 6330 and have them tested after the claimed number of washes by a suitable laboratory method.

Wording

Keep claims about the garment, for example "treated to resist odours", and remove references to germs, bacteria on skin or health. Check the label, hang tag and product page say the same thing.

If you sell into other markets, check their rules separately, and review the wording whenever the mill changes the finish or its supplier, since approvals are tied to specific active substances and uses.