HOW TO TRACK WEED

A new technology allows law enforcement to track legal marijuana using DNA.

DNA allows forensic investigators to see exactly where strains of marijuana originated from, taking us a step closer to effective legislation.

Marijuana may be legal in Colorado, but that doesn’t mean the US state has no illegal marijuana. A number of legal growers are illegally selling cannabis across state lines, and illegal growers can forge a paper trail to enter the legal market. It’s becoming a problem for law enforcement, which needs to combat this grey market to keep the state’s ±R18.8 trillion cannabis industry on the right side of federal compliance.

Starting this year, the state could be able to identify all above-board cannabis. Using technology previously employed to follow premium American cotton from gin to shirt, growers spray their legal plants with DNA that acts like a molecule- sized encrypted bar code. By bonding to the plant – but not changing its DNA – the tag withstands processing, and even shows up in refined products such as oils and edibles. Dispensaries and local law enforcement can then feed a tiny bit of a product into a reader, the Signify, which confirms the farm, strain, and permit number.

Biotech company Applied DNA Sciences produces the tags. ‘ Think of the DNA as a content carrier,’ says Jim Hayward, company CEO. The tags are engineered to embed up to 250 bits of identifying information in the sequence of DNA nucleotides. This allows for billions of potential DNA signatures for plants and manufacturers.

To avoid harming or affecting the plants, the tags are dissolved in water and measure in the parts per trillion, and the spray uses minimal moisture to minimise the risk of mold.

When a sample is placed in the Signify, the device uses a polymerase chain reaction ( see right) to reproduce the tags for identification. Because the contents of the tags are secure – Applied DNA employees can access only portions of them – they can’t be copied.

This means counterfeits simply can’t be made, and fewer illegal products can make it into a legal system.

The outer fins create a heat sink for the hot- cold polymerase chain reaction ( explained right) that multiplies the DNA tag.

Cannabis samples are fed into Signify’s 16 tubes. If a DNA tag is present, it will be replicated for easy identification.