Washington will start random testing for illegal pesticides in pot, becoming the first state to carry out such tests.

In an agreement announced Thursday, the state Liquor and Cannabis Board (LCB) and the Department of Agriculture (WSDA) will cooperate on testing about 900 samples a year.

“This is a significant milestone on the road toward consumer protection,” said Steve Fuller, WSDA policy adviser.

Some in the industry have been calling for the WSDA, with its experience in crop oversight, to take a larger role in pesticide testing. “I think it makes perfect sense,” said Ian Eisenberg, owner of Uncle Ike’s, Seattle’s top-selling pot shop.

When asked what took so long, LCB Director Rick Garza said the agency has been moving from one challenge to the next since voters authorized in 2012 state-regulated production and sales of a substance still considered an illegal drug by the federal government.

Whether local bans on legal pot, banking obstacles or problems with state-certified testing labs, Garza said, “every three to six months” a new challenge seems to arise.

“Ironically,” he said, no one seemed to push for pot pesticide-testing in medical marijuana, approved by Washington voters in 1998, until recreational weed became legal.

Pesticides became a growing concern earlier this year when the LCB issued violations to two growers after tips led to tests that found illegal pesticides on their plants. Around the same time, Colorado regulators recalled a spate of legal pot products for suspected illegal pesticides.

No Washington consumers have complained about pesticides making them ill, said Justin Nordhorn, the LCB’s enforcement chief.

But some medical experts, regulators and lawmakers have expressed concern.

Washington has a long list of approved pesticides, which have been tested for safety in the food industry.

The state has not required pesticide testing because it’s expensive and complicated.

Under the new deal, the LCB will spend $1.1 million for the necessary equipment and staffing.

Expected to start in January, new testing at the WSDA Chemical and Hop Laboratory in Yakima will focus on unapproved or illegal pesticides. Tests will be complaint-based as well as random, Nordhorn said.

Pesticides are commonly used on crops. And toxicologists often say “dose makes the poison,” meaning the amount is often more important than the mere presence of a pesticide.

A tiny trace of an unapproved pesticide shouldn’t automatically disqualify a product, the LCB decided, because it could have drifted to a pot farm from a nearby fruit orchard.

In emergency rules approved earlier this year, the LCB adopted “action” or unacceptable levels for unapproved pesticides based on levels set by the Oregon Health Authority.

The WSDA believes some of the Oregon levels are too high and has suggested changes for the LCB’s permanent rules, said Erik Johansen, a WSDA policy assistant. But Johansen said he understood why the LCB, needing some guidance for emergency rules, reached for the Oregon levels.

The LCB turned to the Agriculture Department for random tests rather than private labs, Garza said, because it was more comfortable with the state agency. Some private labs have been criticized for their practices, he noted.

Despite the new tests, King County Councilmember Jeanne Kohl-Welles said she’ll continue to consider her proposal to have county officials purchase pot at stores for pesticide testing.

“I think state regulation that’s uniform works better for the industry,” Garza said, but added that he didn’t see any problems with county testing to ensure safe products.