PORTLAND — While Denver has recalled 19 pot products in as many weeks over pesticide issues, no such recalls have affected Washington state in 18 months that pot sales have been legal.

The Seattle Times reports that no products were recalled after Washington officials fined two marijuana growers and suspended the licenses of two others for using unapproved pesticides.

Experts say it’s difficult to determine whether consumers should be worried about that.

Although there’s abundant research on pesticides on food, there’s little information about the effects of heating and inhaling such chemicals. The federal prohibition on marijuana has prevented that research.

Oregon State University professor and National Pesticide Information Center Director Dave Stone says people should keep in mind that experts just don’t know whether there is cause for concern over pesticides in marijuana.