U.S. health officials said on Thursday there are now 530 confirmed and probable cases and seven deaths from severe lung-related illnesses tied to vaping, and there are no signs that the outbreak is easing.

That's up from 380 cases reported a week ago. Three-fourths of the cases are male, and two-thirds are between the ages of 18 and 34.

The U.S. Food and Drug Administration is now investigating more than 150 products and substances and said it has activated its criminal investigations arm to explore the supply chain of vaping products and identify the cause of the outbreak. No individual vapers will be targeted, Mitch Zeller, director of the FDA's Center for Tobacco Products.

Zeller said no single substance or compound, including THC or Vitamin E acetate, has been linked to all of the cases so far.

Seven people have died from vaping-related illness, the Centers for Disease Control and Prevention (CDC) said. The deaths were reported in California (2), Illinois, Indiana, Kansas, Minnesota, and Oregon.

Illinois has reported an 8th death related to the outbreak, state epidemiologist Dr. Jennifer Layden said on a conference call with reporters. The CDC has not yet confirmed that death.

"We do expect others," Dr. Anne Schuchat, principal deputy director of the CDC, told reporters, referring to the number of deaths.

Layden said Illinois has now reported 69 cases, up from 52 a week ago, and the state continues to get reports of new cases daily.

Schuchat said no e-cigarette or vaping product, substance, additive or brand has been consistently identified in all of the cases, nor has any one product or substance been conclusively linked to lung injury in patients.

She repeated the CDC's advice that people should quit vaping if they can. Those who continue should monitor themselves for symptoms such as breathing issues, dry cough or chest pain, and in some cases diarrhea, vomiting and fever, and not hesitate to seek help from their doctors.

For people who use nicotine-containing e-cigarettes as a way to quit smoking cigarettes, she urged people not to return to cigarette smoking. Instead, she urged people to consider counseling or using FDA-approved smoking cessation products.

"The e-cigarette and vaping-related lung injuries are serious. People are dying. We ask you to take these recommendations seriously," she said.