What happens when a sample fails a safety screen?

It’s common knowledge that dispensaries are required to perform a number of safety screens on their products before they can hit the shelves. But what happens to a batch of flower or product when a sample fails?

By Alexandra Gomes — October 7, 2020

Safety screens are, without a doubt, the most important work we do here at the lab. Cannabis can contain impurities like microbiological contaminants that, when consumed in large volumes, can wreak havoc on human health.

The cannabis itself, however, remains full of potential medicinal benefits which means a good number of cannabis consumers are immunocompromised patients treating symptoms like chronic pain and inflammation. These patients would be particularly susceptible to even a tiny bit of mold hiding in a nug.

This is why preventing contaminated products from ever reaching the consumer is such a vital part of what we do. In Massachusetts, all cannabis and cannabis products are required to be screened for the following:

  • Heavy Metals

MCR Labs has prevented over 2 million units that had some sort of impurity detected from hitting the shelves and entering the hands of consumers since November 2018, when the recreational market first opened. That’s a lot of product that dispensaries were required to destroy or remediate based on failed tests. So what actually happens to a sample when it receives a negative hit on a safety screen?

The Testing Process

Let’s start from the beginning of the whole testing process. The samples sent in for testing are representative of batches grown or manufactured by licensed cultivators, producers, and dispensaries. For example, one sample is screened for every 10 pound batch of flower in a harvest.

If the sample is flagged for testing above the acceptable limits for a contaminant, the operators have two options. The first is a simple retest, which requires no modifications to the original batch. However, the operators must receive two passing test results from not only the lab who originally tested the sample, but a secondary lab as well.


The second option is remediation, for which operators have several different courses of action. There are a few different ways to treat harvested flower, or the operator could choose to turn the flower into oil. After a batch is remediated, it will need to pass a full set of safety screens.

If the batch can not pass a safety screen, even after remediation, the operator must submit plans to the state’s Cannabis Control Commission on how they plan to destroy the batch and remedy the source of the contamination at their facility. The only safety screen failure that automatically requires operators to destroy their batch is the pesticides screen.

We hope this article was able to shed a little light on the whole testing process and how MCR, dispensaries, and the state work together to ensure consumers and patients have access to safe products and medicine. Do you have more questions? Feel free to send them our way via info@mcrlabs.com.

You can read up more on the state’s testing requirements here or here.

Originally published at https://mcrlabs.com on October 7, 2020.



MCR Labs is an independent cannabis testing & research laboratory located in Framingham, Massachusetts devoted to cannabis safety and education.

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MCR Labs

MCR Labs is an independent cannabis testing & research laboratory located in Framingham, Massachusetts devoted to cannabis safety and education.