Anne Hardie

Putting staff in control of a quad bike or tractor has its risks any day of the week with the most reliable drivers. Add cannabis into someone’s system even up to two days before they take charge of machinery or any job where safety is concerned, then there’s the risk of impairment because it changes their perception and how they judge distance.

If cannabis is legalised, employers will need to have policies for a zero tolerance of drugs in safety-sensitive roles to ensure safety in the workplace, The Drug Detection Agency (TDDA) chief executive Kirk Hardy warns.

Smoking a joint up to two days before work can cause impairment that will affect cognitive function such as distance and perception which are crucial factors for staff employed for many jobs in the dairy industry.

‘A lot of it comes down to education and managers need the right training to identify drug use, even at the onset when people are being employed.’

Next year the public gets to vote on whether to legalise the personal use of recreational cannabis. At this stage the draft legislation would allow cannabis consumption, sale and purchase for recreational use to be legal for those over 20 years old and only consumed at home or on licensed premises. It would legalise raw cannabis and a small amount of home cultivation, plus edibles, lotions and cannabis resin.

Many agriculture industry employers already test for drugs through urine or saliva, though the latter only tests positive for THC (tetrahydrocannabinol – the principal psychoactive constituent of cannabis) if the person has taken the drug in the previous three to four hours. The problem, Hardy says, is the carryover effect of cannabis on cognitive function and the fact today’s cannabis is up to 10 times stronger than the drug in the 80s, 90s or even 2000.

He refers to the aviation industry’s research when cannabis had a mere 3% THC, which conducted a series of simulated tests on pilots who were given controlled amounts of cannabis and then had their performance measured.

“They all made mistakes that would have caused casualties. So they sent them home and the next day they did the same test. Everyone felt as good as gold, but some were making grave errors 24 hours later. It’s called the carryover effect.

“That was when cannabis was 3% THC and now it’s 15-27% THC. I don’t like to call it cannabis anymore, but high-potency THC.”

Cannabis isn’t as simple as smoking a joint anymore either, he says, with edibles now on the market and vaping which can use cannabis with the turpenes stripped from it which are the aromatic oils that give cannabis its trademark aroma, meaning anyone around them is unaware it is cannabis. BHO (butane hash oil) concentrates can have up to 95% potency which he says is still called a cannabis product.

The only way for employers to ensure safety in the workplace and cover liability, culpability and even the subsidiary duties of directors, is zero tolerance, he says.

“They can’t afford to have someone jeopardising themselves as well as others. A lot of it comes down to education and managers need the right training to identify drug use, even at the onset when people are being employed.”

Even with a robust drug and alcohol policy in place, he says employers today still get 5% to 6% of staff testing positive for drugs.

The gold standard test for drugs is the urine test and he says any positive test must be confirmed in a laboratory. It means drug testing must also be robust to ensure it is not allowing someone to stay on a worksite when they are not safe.

Hardy says one of the debates is around employees who don’t feel high shouldn’t have to have a urine test, but the research shows they could still be a risk.

  • More? See NZ Dairy Exporter magazine, June 2019