The Massachusetts Cannabis Control Commission released a sweeping set of draft marijuana testing regulations Thursday, proposing a comprehensive framework governing laboratory operations, contaminant limits, product sampling, testing accuracy and the handling of marijuana that fails safety testing.
The proposed regulations, designated 935 CMR 503.000, were released during the commission’s October 22 public meeting as part of a 50-page materials packet. The new regulatory section would consolidate testing requirements for both recreational and medical marijuana while establishing detailed standards for independent testing laboratories, including procedures intended to ensure accurate and consistent results.
Among the most significant provisions are separate heavy metal limits for products intended to be inhaled versus ingested, additional safeguards against laboratory data manipulation, restrictions on retesting failed products and a maximum of two remediation attempts before contaminated marijuana must be destroyed.
The proposal also establishes detailed requirements for cannabinoid testing, pesticide screening, residual solvents, moisture levels, microbial contaminants and the reporting of laboratory results.
New Testing Limits for Heavy Metals and Other Contaminants
One notable component of the draft establishes different heavy metal testing thresholds depending on how marijuana products are intended to be consumed.
For products intended for inhalation or other non-ingestion uses, the proposed maximum concentrations are 200 micrograms per kilogram for arsenic, 200 for cadmium, 500 for lead and 100 for mercury. Products intended for ingestion would have higher allowable concentrations of 1,500 micrograms per kilogram for arsenic, 500 for cadmium, 1,000 for lead and 1,500 for mercury.
The commission’s Testing Regulatory Working Group also recommends a corresponding labeling requirement for marijuana that meets the ingestion-specific thresholds. Such products would carry a warning stating: “THIS PRODUCT HAS BEEN EVALUATED FOR IMPURITIES BASED ON ORAL CONSUMPTION ONLY. DO NOT INHALE THIS PRODUCT.” That labeling proposal has been recommended for consideration by a separate regulatory working group.
The draft also establishes pesticide testing requirements covering nine named pesticides and plant growth regulators, including bifenthrin, imidacloprid, myclobutanil and bifenazate. Laboratories would be required to use testing methods capable of detecting these substances at concentrations of 10 parts per billion or lower, with a detected prohibited residue resulting in a failed test.
For mycotoxins, which are toxic substances produced by certain fungi, the proposal establishes a combined threshold of less than 20 micrograms per kilogram for the five specified compounds, including four aflatoxins and ochratoxin A.
THC Potency, Terpenes and Laboratory Accuracy
The proposed regulations would establish detailed performance standards for measuring cannabinoids, including THC, THCA, CBD, CBDA, CBN and delta-8 THC. Testing methods would need to distinguish delta-9 THC from delta-8 THC and demonstrate accuracy within 90% to 110% of known reference concentrations, with relative standard deviations not exceeding 10%.
Single-serving marijuana products would also be subject to a potency variance of no greater than 10% above or below the applicable stated amount.
The proposal includes terpene testing requirements covering at least five compounds: alpha-pinene, beta-myrcene, D-limonene, terpinolene and beta-caryophyllene. Laboratories making quantitative determinations would have to meet established accuracy and precision standards, although commissioners have not yet finalized which products must undergo particular terpene tests.
Other provisions address residual solvents, including specific limits for propane, n-butane and isobutane. For inhalable products, the proposed limits are 2,100 parts per million for propane and 800 parts per million each for n-butane and isobutane, compared with 5,000 parts per million for each substance in non-inhalation products.
The draft would prohibit the use of dichloromethane and trichloroethylene as production solvents while retaining testing thresholds for detecting their residues.
Moisture, Mold and Product Inspection Requirements
The regulations establish specific moisture and water activity thresholds intended to address conditions that can contribute to microbial growth.
Dried marijuana flower and pre-rolls would be required to have water activity no higher than 0.65 and moisture content no greater than 15%. Solid edible products would be subject to a water activity limit of 0.85.
Laboratories would also need to visually examine at least 20 grams of representative marijuana samples for foreign organic material, including visible mold, mildew and other fungal growth. The draft requires photographs of samples during inspection and states that no such contaminants may be detected in the examined material.
For applicable products, laboratories would conduct vitamin E acetate screening. A detection would trigger a noncompliant finding and require notification to regulators within 72 hours, although the draft separately specifies that the screening requirement does not establish a numerical regulatory action limit.
Stronger Oversight of Testing Laboratories
A substantial portion of the draft addresses laboratory operations and the reliability of testing results.
Independent testing laboratories would be required to maintain documented quality management systems, validated or verified testing methods, detailed equipment calibration records and competency assessments for employees. Personnel performing laboratory activities would need to demonstrate initial competency and undergo reassessment at least annually.
Laboratories would also be required to participate in blind proficiency testing at least once annually for applicable testing categories. The commission could conduct additional unannounced comparisons between laboratories to evaluate whether different facilities produce consistent analytical results.
The proposal includes explicit restrictions on manipulating laboratory data. Manual alteration of chromatographic or mass spectrometric data would generally be prohibited unless necessary to correct a documented processing error or address a demonstrated equipment or software issue. Any authorized correction would require scientific justification, preservation of the original data and documented internal review.
Laboratories would have to preserve original testing records, electronic audit trails and related documentation for at least five years. The requirements are intended to make it possible to reconstruct how individual testing results were generated and identify changes made after the original analysis.
New Requirements for Samples and Reporting Results
The proposed framework establishes minimum sample quantities of 30 grams for marijuana flower and 10 grams for other materials submitted for regulatory testing.
For dried flower, testing samples would come from strain-specific post-harvest batches limited to 15 pounds. Fresh-frozen flower testing samples could represent up to 60 pounds of material, with separate provisions allowing seed-to-sale tracking packages of up to 120 pounds.
Laboratories would generally be required to retain portions of tested samples for at least 30 days, allowing additional examinations or investigations when necessary.
The draft also requires all testing results, including failures and results obtained before remediation or reanalysis, to be reported and uploaded to the state’s seed-to-sale tracking system within 72 hours of completing the required testing. A product that subsequently passes testing would not erase the record of its earlier failure.
Certificates of analysis would need to identify the laboratory, sample, testing methods, measured concentrations, applicable detection limits, employees responsible for testing and whether the product was previously subjected to sanitization or remediation.
The proposal also specifies that testing results remain valid for one year. Marijuana products with expired test results could not be sold or otherwise distributed until successfully retested.
Restrictions on Retesting and Remediating Failed Marijuana
The proposed regulations establish detailed procedures for marijuana that fails regulatory compliance testing.
Products failing certain tests, including microbial contamination, residual solvents, moisture levels or foreign organic material, could potentially be repurposed into other authorized marijuana products. However, the resulting products would have to pass all applicable testing requirements before being sold.
Remediation would be allowed for certain failures involving microbial contaminants, mycotoxins, heavy metals, residual solvents and moisture levels, although edible products would be excluded from remediation.
Businesses would be limited to two remediation attempts. After each attempt, the entire production batch would have to be held for at least five calendar days before a new sample could be submitted for full-panel testing.
Any marijuana that fails testing following a second remediation attempt and subsequent reanalysis would have to be destroyed.
The draft takes a stricter approach to pesticide contamination. Marijuana products that fail testing for prohibited pesticide residues or plant growth regulators could not be repurposed, reanalyzed or remediated. Such failures would also be reported to the Massachusetts Department of Agricultural Resources.
The commission has not yet finalized its general rules governing reanalysis of failed samples, identifying that issue as a policy question requiring further discussion.
Additional Decisions Expected November 12
Despite the extensive proposed framework, several provisions remain subject to additional decisions. The draft identifies unresolved questions involving which product categories must undergo specific testing panels, the scope of microbial testing requirements and procedures for reanalysis following failed results.
The Testing Regulatory Working Group also recommends retiring the commission’s existing testing protocol and rescinding two administrative orders once the new regulations are formally adopted and implemented. Corresponding amendments would be made to existing recreational and medical marijuana regulations.
The changes are part of the commission’s implementation of Chapter 65 of the Acts of 2026, which established a broader modernization process for Massachusetts marijuana regulations.
Commissioners are scheduled to discuss the draft regulations and outstanding policy questions at their next public meeting on November 12. A formal public comment process is expected to begin in January 2027, with additional testing-related regulatory changes under consideration for spring 2027.
The regulations remain proposals and have not taken effect. The draft also leaves the implementation date unspecified, meaning the commission must complete further review and rulemaking before the new framework becomes enforceable.
