Students at the University of New Haven are developing a DNA test that could detect contaminants in medical marijuana. Dr. Heather Coyle, a forensic botanist and associate professor at UNH, said patients using pot for medicinal purposes could be harmed by contaminants that they can't see.

Coyle said, "We are looking at marijuana samples that could potentially be contaminated with mold, fungi, bacteria, or other viruses, and we're considering the impact on cancer patients that are immuno-compromised. What would be the effect?"

While it's not clear how tainted marijuana could affect patients, Coyle said a recent study by an independent testing lab found that pesticide residue on cannabis is transferred to inhaled marijuana smoke. The UNH test could be ready by next summer to meet demands for a faster, easier test as more states legalize medical marijuana. Currently, Connecticut, 19 other states, and Washington, D.C. allow medical marijuana with a prescription.

WNPR's Lucy Nalpathanchil's spoke with with Dr. Coyle.

Lucy Nalpathanchil: It sounds like legalizing medical marijuana by some states has now created a new testing industry. Can you tell us about the work you and your students are doing?

Dr. Heather Coyle: Yes, we're looking at marijuana samples that could potentially be contaminated with mold, fungi, bacteria or other viruses. Right now there isn't a lot of information about contaminants but we have noticed in drug samples from previous types of studies that mold is definitely present on some of them and we're considering the impact on cancer patients for example that are immuno-compromised and what the effect would be on them experiencing these other types of contaminates on the marijuana they should be smoking.

Connecticut is one of the more recent states that have approved medical marijuana and are still going through the process of who can dispense it, but are there other tests on the market that other states have been using?

Other states have legalized medical marijuana use, even though the federal government has not. In those states, many of them require a minimum of at least some kind of idea of what the THC content is, but I'm not aware of any except one group in California that recently looked at pesticide contaminants in marijuana, and found they could be potentially toxic.

How soon before your test will be ready for the market?

We have one that's available, in place, now that we tested. That will allow us to tell the difference between standard cannabis marijuana and synthetic herbal blends that have THC added. We have in development and hope to have ready by end of summer 2014 an additional one that will tell us what types of fungi, what types of mold, what types of bacteria -- things like E. coli and salmonella -- that could be present in marijuana.

As a private university, we have a research interest in developing technology, and would likely publish this, and make it publicly available, so that whoever the state contracts to do quality control testing would be able to use that, or implement it at the private testing facility.This is something we envision would be done at the state level if they contract with a supplier for medical marijuana.

A private testing lab also could also use this, if private citizens have a question about materials they purchased, and could then send it to a private lab for testing of contaminants. If, for example, it tasted funny, they didn't experience the effect anticipated, or even had an allergic reaction, they could do independent testing as well, which is pretty standard in forensic science -- to have state and government labs, and also private labs.

Is the work you and your students are doing pretty unique compared to other programs around the country?

It certainly is, because we are a forensic science program, so we are allowed by law to use drug samples in small quantities for training purposes and for research and development. In that sense we are unique. There are many universities across the US that do biological testing but they don't necessarily work with drug substances so we have special precautions in place that allow us to do that.