Separate “notable seizures” of rainbow fentanyl in the Portland area spurred federal authorities to issue a warning Friday about the brightly colored clumps of the synthetic opioid that look like sidewalk chalk.

Multnomah County announced in mid-August that deputies had seized about 4 ounces of multi-colored fentanyl powder from a safe in a Northeast Portland apartment.

Earlier this week, Tigard police said officers found 5.5 grams of rainbow fentanyl chunks (about two-tenths of an ounce) during a search of a man who had been reported by witnesses on top of a car and screaming on Aug. 10.

Rainbow fentanyl has been seized elsewhere in the form of pills that resemble candy, federal officials said.

They said anyone who encounters any form of fentanyl shouldn’t touch it and should call 911 immediately.

“We urge all Oregonians to be on the lookout for fentanyl in our community and respect the highly toxic nature of this substance,” said Steve Mygrant, the lead drug prosecutor in Oregon’s U.S. Attorney’s Office.

The Portland office of the U.S. Drug Enforcement Administration is seizing record amounts of fentanyl, said Jacob D. Galvan, the acting special agent in charge of the agency’s office in Seattle.

Fentanyl is 80 to 100 times more potent than morphine and 30 to 50 times more potent than heroin.

About 107,000 people died in drug overdoses across the U.S. last year — with synthetic opioids, mostly fentanyl, accounting for more than three-quarters of the deaths, according to the federal Centers for Disease Control and Prevention.

For help: Call the Lines for Life substance abuse helpline at 1-800-923-4357 or go to www.linesforlife.org. Phone support is available 24 hours a day, seven days a week. You can also text “RecoveryNow” to 839863 between 8 a.m. and 11 p.m. daily.

— Margaret Haberman; mhaberman@oregonian.com; 503-799-6551