Four of the nine outlets visited last week as part of a Waikato DHB operation sold synthetic cannabinoid products to a volunteer aged under 18.
The four dairy owners and employees face enforcement action after selling the products. A fifth outlet faces enforcement action after a staff member sold tobacco to the underage volunteer.
Waikato District Health Board's Population Health staff visited nine retail premises in Hamilton last week during a controlled purchase operation which was part of Operation Dairy, a combined Police and Population Health initiative to curb the use of synthetic cannabinoid products.
The premises were identified last month, during education visits under Operation Dairy, as continuing to sell synthetic cannabinoid products despite community pressure.
The excuses from the people who sold to the underage volunteer ranged from being "distracted" to "having a bad morning".
One of the outlets was also a Lotto retailer. NZ Lotteries has demanded all its independent retailers stop selling party pills and synthetic cannabis by July 1, or risk losing their Lotto products.
Population Health advisor Nick Young said staff at four of the premises visited followed correct procedure and refused to sell to the 17-year-old volunteer who was briefed to give his correct age when asked. The retailers whose staff complied with the legislation will be notified of their employees' performance.
Reports on the five dairy employees and owners who sold synthetic cannabinoid products - and in one case cigarettes - to the volunteer will be sent to the Ministry of Health in Wellington.
The result for the sellers could range from a warning to a District Court prosecution.
Mr Young was disappointed at the level of non-compliance, especially since the education visits had been carried out within the last month.
He said it might be that retailers, conscious of the impending law changes that could see the products removed from shelves this month, were trying to unload stock without taking care to comply with the age limit restriction.
Hamilton Labour MP Sue Moroney said her party wants The Government to adopt the Psychoactive Substances Bill under urgency.
Peter Dunne's bill would see synthetic cannabis either severely restricted or completely pulled from the shelves when the legislation is passed.
Ms Moroney said the Bill had its second reading last week and that it still had committee stages and a third reading to go.