Increased drug-testing in Wellington workplaces shows cannabis is the preferred drug among those testing positive.
Statistics from the New Zealand Drug Detection Agency (NZDDA) show 80 per cent of all the Wellington region's positive on-site workplace drugs tests last year were for cannabis, up from 74 per cent in 2011.
Detection of methamphetamine, or P, fell from 7 per cent to 5 per cent, and opiate detection from 12 per cent to 9 per cent.
Nationally, the number of on-site workplace drug tests increased by 31 per cent, and of those more than 6 per cent came back positive.
However, the New Zealand Drug Foundation says the data does not represent societal trends as the industries tested tend to have high numbers of young men, who figure disproportionately in drug-use statistics.
NZDDA chief executive Chris Hilson said the increase in test numbers showed employers were taking workplace safety seriously.
"Most of our testing takes place in the safety-sensitive sectors such as forestry, transport and construction . . . There's no second chance if there's any impairment from drugs and alcohol in those workplaces."
The fall in methamphetamine use could be the result of changing personal preference or reduction in supply, he said.
Drug Foundation executive director Ross Bell said overall methamphetamine use had halved in the past three years, reflecting the natural life-cycle of a drug, as well as increased police and border security busts.
- The Dominion Post