California officials are warning people not to eat the Mexican cactus known as nopales sold at certain stores over concerns they may be tainted with unapproved pesticides.

The Department of Public Health said Wednesday that routine samples last month found contaminated nopal cactus pads at six markets and distribution centers across the state.

Products packaged under the names Mexpogroup Fresh Produce, Aramburo or Los Tres Huastecos should be thrown away. Officials say most tainted nopales have been removed from store shelves and destroyed. But it is possible that some may have been sold to other retail locations in California, Nevada and Oregon.

No illnesses have been reported. Officials warn the pesticides can potentially cause poisoning, neurotoxicity and permanent nerve damage.