Maine cannabis testing requirements

Required tests

• Potency
• Pesticides
• Residual solvents
• Heavy metals
• Microbials
• Mycotoxins
• Water activity
• Foreign matter
• Homogeneity

ISO/IEC 17025 accreditation

Required within a set period. The Maine CDC certifies labs and OCP licenses them. A lab whose ISO/IEC 17025 application has been accepted can get provisional certification for 12 months, and must be accredited before it expires or stop testing (18-691 CMR ch. 5, §2).

Notes

• Mandatory testing applies to the adult-use program only. Adult-use rules: 18-691 CMR ch. 40 (Testing of Adult Use Cannabis) and ch. 5 (Certification of Cannabis Testing Facilities), both effective November 2024. Statute: 28-B MRSA §602.
• Adult-use panel: filth and foreign material; residual solvents (only for products made with solvents); pesticides; metals (cadmium, lead, arsenic, mercury); total yeast and mold; microbes (total aerobic bacteria, coliforms, Enterobacteriaceae, STEC, Salmonella); THC potency, homogeneity and cannabinoid profile; water activity.
• Mycotoxins (aflatoxins B1, B2, G1, G2 and ochratoxin A, combined under 20 µg/kg) must be tested when a batch that failed yeast and mold testing is retested (ch. 5).
• Water activity: at most 0.65 Aw for dried flower and 0.85 Aw for shelf-stable solid and semi-solid edibles.
• Pesticides are tested on dried flower, trim and concentrates, not on finished products. Products made from inputs that already passed may skip some contaminant tests.
• P.L. 2025, ch. 764 (emergency law, effective April 19, 2026): edibles made from concentrate that passed all contaminant testing need only potency, cannabinoid and homogeneity testing (OCP guidance, April 28, 2026).
• In flux: OCP proposed amendments to ch. 5 and ch. 40 (edible testing, potency retests, sampling SOP). The comment period closed August 14, 2026.
• Medical: OCP says medical cannabis is not subject to mandatory contaminant testing or inventory tracking. Labelled potency or contaminant claims must be verified by a licensed lab, and OCP can test products during investigations. LD 1847, which would have required testing, died on April 29, 2026.