Waikato District Health Board says dairy owners in Hamilton may be selling synthetic cannabinoids to minors in an effort to clear their stock before the drugs become illegal.
The Psychoactive Substances Bill. which would regulate cannabinoids not already controlled by other legislation, is currently before Parliament.
Five Hamilton dairy owners and employees are to be penalised for selling cannabinoid and tobacco products to teenagers on Wednesday.
DHB smokefree enforcement office Nick Young says the non-compliance may be evidence of dairies trying to sell excess stock before it's banned.
Mr Young says dairy staff may also be selling smaller portions of the stock, at a reduced price, to clear it quickly.
Associate Health Minister Todd McClay wants the new law enacted before September.