By Roger Chriss, PNN Columnist

An outbreak of vaping-associated pulmonary illness is getting national attention. Over 800 people have been sickened and 12 have died.

The CDC reported last week that vaping products containing tetrahydrocannabinol (THC) -- the psychoactive compound in marijuana – were involved in 77 percent of the illnesses. Several states responded with bans on vaping products and health alerts on vaping THC.

What do we know about the risks of vaping?

Vaping THC is so new that there is very little research. An animal study on vaping THC was published earlier this year. Performed on male and female rats, the study found that “repeated THC vapor inhalation in adolescent rats results in lasting consequences observable in adulthood."

Specifically, both sexes became tolerant to THC and male rats ate more. Interestingly, THC use did not change oxycodone self-administration in either sex, but increased fentanyl self-administration in female rats. There is no mention of lung effects.

While vaping with e-cigarettes is relatively new, inhaling THC via cannabis smoking is old. And there is an extensive literature on multiple harms.

A recent study of nearly 9,000 people found that regular cannabis use was significantly associated with greater risk of respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD) and pneumonia. The study used blood work to confirm use and had a control group, making its results more reliable than a simple population survey.

According to the National Institute on Drug Use, cannabis smoke contains multiple carcinogens and inhalation causes lung inflammation, increased airway resistance and hyperinflated lungs, a symptom of COPD

Josh Bloom at the American Council of Science and Health writes that the solubility and boiling point of THC and CBD in cannabis vaping products may play a role in the lung illnesses.

But complicating matters is the presence of other subtsances in vaping liquids and in the devices themselves. A newly published study in Scientific Reports on aerosols in tank-style e-cigarettes found levels of chromium, lead and nickel, all known carcinogens, in excess of OSHA permissible exposure limits.

Most cases of vaping-associated pulmonary illness involve illicit products. But one fatal case in Oregon involved someone who bought vaping products at two state-licensed cannabis dispensaries.

Some vaping illnesses involve people who report no use of THC products at all, though investigators are finding that these self-reports are not necessarily accurate. According to STAT News, eight patients in Wisconsin initially said they didn’t use THC products, but were later found to have used the drug.

In other words, we may not know what people were really vaping. Given that vaping THC is federally illegal and only marginally regulated in states where cannabis is legal, investigating the role of THC in the vaping outbreak is challenging.

But the emerging risks have led states like Washington to ban all flavored vaping products. And the FDA has asked the DEA to pursue criminal charges against anyone who sells illicit vaping products.

For patients who use cannabis products for pain relief, there are better alternatives than vaping. The Arthritis Foundation recently released new guidelines that recommend CBD oils and tinctures that can be taken orally.

It is not clear what this means for the cannabis industry. But Joe Tierney, known as the "Gentleman Toker,” told the Washingtonian that he would be shutting down his cannabis website.

“I don’t feel good about the industry any longer,” Tierney said. “I don’t think it’s safe to consume cannabis anywhere after all of my travels.”

Sorting out the risks of THC vaping will take time. At present there is only circumstantial evidence and intriguing ideas. It is possible that THC is one of several different causes or is just guilty by association. Beyond that, we have the unknowns of vaping itself, which may be too novel for anyone to fully understand the risks.

Roger Chriss lives with Ehlers Danlos syndrome and is a proud member of the Ehlers-Danlos Society. Roger is a technical consultant in Washington state, where he specializes in mathematics and research.

The information in this column is for informational purposes only and represents the author’s opinions alone. It does not inherently express or reflect the views, opinions and/or positions of Pain News Network.