More vaping-linked deaths reported in U.S.

More deathslinked to e-cigarette use have been reported in the U.S., in an investigation that nowincludes up to 450 cases of serious lung illnessin 33 U.S. states and one territory, federal health officials said Friday.

A recent spike in patients reporting respiratory distress has health officials looking to vaping products, which have become popular among young people and those trying to quit smoking cigarettes, as well as cannabis users.

In the data from the U.S. Centers for Disease Control and Prevention many, but not all, of the patients reported recent use of products containing tetrahydrocannabinol, or THC, the active ingredient in cannabis. Some reported using both THC- and nicotine-containing products.

There was one death each in Illinois, Oregon and Indiana fromlung illnesses that were possibly tied to vaping, the CDC said.Health officials in Los Angeles and Minnesota have also each reported deaths. Minnesota health officials say the person was over 65 years with a history of lung problems who had vaped illicit THC products and died in August.

The CDC, the U.S. Food and Drug Administration and state partners are combining information about e-cigarette exposures, results from FDA testing of product samples, and clinical testing resultsto try to identify a cause or causes of these illnesses.

The lung illnesses areassociated with use of e-cigarette products including devices, liquids, refill podsand cartridges. The FDA is analyzing more than 120 samples of products or substances that may be causing the illness.

"The FDA is analyzing these for a broad range of chemicals, but no one substance, including vitamin E acetate, has been identified in all of the samples tested," acting FDA commissioner Dr. Ned Sharpless said in a release.

Non-infectious pneumonia

Vitamin E acetate is found in supplements and skin creams but is not an approved vaping additive.

Dr. Daniel Fox, a pulmonary and critical care physician atWakeMed Health & Hospitals in Raleigh, North Carolina, described a cluster of five cases in the state in patients that were between the ages of18 and35.

"We found a certain type of a pneumonia that was non-infectious it's called lipoid pneumonia that can occur when either oils or lipid-containing substances enter the lungs,"Fox said in a media briefing.

Dr. Daniel Croft, who treats and studies pulmonary disease at the University of Rochester, says he's seen patients with lipoid pneumonia among some who've vaped cannabis products, one of which is cannabis oil.

"When the oil is heated, it forms an aerosol and is able to travel into the lungs. From that very hot initial temperature, it can condense into the harmful droplets and stick to the walls and coat the walls," Croft told NBC News.

Doctors have cautioned peopleto stop vaping until they figure out exactly why some are falling ill withserious breathing issues.

Watch for symptoms

Health Canada said any Canadians who use vaping products should monitor themselves for symptoms of pulmonary illness (e.g., cough, shortness of breath, chest pain) andseek medical attention promptly if they have concerns about their health given the acute pulmonary illnesses in the U.S.

No cases of respiratory illness specifically linked to vaping have so far been reported in Canada, but health experts are still wary of the products.

"With new findings coming out, I'm more reluctant to say that vaping is less harmful than smoking," Robert Schwartz, of the Ontario Tobacco Research Unit, said in an interview with CBC News on Friday.

Separately onFriday, the New England Journal of Medicine published an article on a cluster of cases in Illinois and Wisconsin as well as a letter on six cases in Utah.

Epidemiologist Dr. Jennifer Layden, chief medical officer in Illinois, and her co-authorsdescribed 53 patients since July. About84 per centof them reported having used THC products in e-cigarette devices. Most were men, and half were aged 19 and under. They all had one thing in common when chest imaging was carried out: identifiablelung abnormalities.

Active infection, such asbacterial contamination from e-cigarette fluids, does not appear to explain what doctors see in patients, but "acute toxic lung injury does seem to fit," a journal editorial said.

Laydentold reporters the earliest case was reported in mid April.