Doctor warns of cannabis health risks
By Jenn Watt
Local doctor Nell Thomas said she’s receiving an increasing number of inquiries from patients about marijuana now that it's legal for recreational use in Canada, but the increased access has not corresponded with increased education on the risks involved. It led her to craft a paper on the topic that is to be distributed via harm reduction emails and alerts, shared with the mental health office, and given to other health professionals.
“By saying nothing, we [doctors] are telling the world it’s OK to smoke cannabis. I don’t think I’m comfortable with that,” said Dr. Thomas during an interview in July.
Her paper, “Cannabis Risks and Harms the Public Should Know,” is an essay written in a conversational tone, bringing together the research she has done on marijuana use. She said not enough research has been done on the drug and that so far, scientifically verified benefits have been found for only a handful of uses.
Cannabis was legalized for recreational use by the Canadian government in October of 2018 in order to quash the illegal market, encouraging consumers to buy from regulated industry that will ensure the safety of the product and proper labelling, and to restrict use for those under 19.
“Unfortunately, legalization may be generating the sentiment that it [cannabis] is neither addictive nor risky, and has not, as yet, halted the burgeoning cannabis business and easily obtainable illegal supply that is now marketed in more creative and enticing ways,” the essay states. “... In my role as a health educator and advocate, I feel compelled to present the potentially serious adverse effects of short- or long-term cannabis use.”
The essay lists potential negative health implications including memory and cognitive impairments; driving while impaired; cardiovascular damage; respiratory damage; interference with other medical treatments; depression and anxiety; psychosis; digestive issues; harm to unborn babies and infants when used by pregnant or nursing women; accidental ingestion by pets and small children; and addiction.
The cannabis available today is often much stronger than what was available to baby boomers 50 years ago. “Whereas, for the ‘Woodstock Generation,’ the average marijuana cigarette contained approximately 10 mg of THC [the psychoactive component of cannabis], a joint today contains 60 to 150 mg of THC,” Dr. Thomas wrote.
Although she doesn’t prescribe marijuana for her patients, she said some of them have been referred to doctors who do (she said it’s not technically called prescribing, but rather is an agreement or contract between doctor and patient due to lack of “verified, published research that supports marijuana as a medical treatment”). After trying it, she said “the vast majority have opted out.”
“I’ve also had a couple of patients whose blood pressure went up, whose heart rates went up, who were very compromised in their physical endurance because of the use and were uncomfortable using it because of that,” she said. Her paper details some potential effects, including a sudden heart rate increase between 20 and 100 per cent in inexperienced users. It can also increase or decrease blood pressure, cause dizziness or loss of consciousness.
“I have a patient, he was prescribed cannabis for his chronic back pain from a physician and he comes in and he says, ‘that scared the [heck] out of me,’” Dr. Thomas recalled. “He said, ‘I actually couldn’t get off the couch for three hours. I just lay there. I couldn’t move.’ So you’ve got respiratory depression as well. It will suppress your respiratory drive. It’s not a benign substance.”
According to her essay, smoking marijuana is particularly dangerous, with “the amount of tar in marijuana … three times higher than in tobacco, and one third more of it lands in the respiratory tract.” Illegal pot may also include a fungus contamination that can lead to lung and sinus infections.
There are particular dangers for young people, starting in the womb.
“Cannabis use by pregnant women nearly doubles rates of premature birth, low birth weight and admittance to neonatal intensive care unit,” the paper states.
Accidentally consuming pot is another risk, especially as Canada is set to legalize edibles, which often take candy form. In particular, small children and pets are at risk of exposure, as Dr. Thomas learned in February of 2018 with her Australian shepherd, Jack.
Her dogs had gone out for a run around the property she owns with her husband before dinner, and were sleeping in front of the television when she got home. When they got up to greet her, Jack was stumbling, unable to sit, and recoiled from her touch. Alarmed, the couple called the vet in Peterborough, since it was after hours.
“We raced like the wind to Peterborough,” she said. “I was so scared because I thought he’d gotten into anti-freeze.”
When the vet tested the dog’s urine, it was determined that Jack had THC poisoning, which Dr. Thomas believes came from the dog finding a joint while running out on the lake, around the fishing huts.
Minden Animal Hospital owner and veterinarian Dr. Jenn Morrow confirmed that marijuana can be life-threatening to pets. “Pets may ingest the substance or can become intoxicated with smoke blown in their faces or by second-hand exposure,” she said via email.
“We have always seen marijuana toxicities, here is a potential we may see more now that it’s legalized,” she said.
If you think your pet has consumed pot, the best thing to do is get them to a vet right away and be honest about your suspicion. “Clinical signs can mimic many other things, so focusing treatment on the cause is important and doesn’t waste time and resources on looking for other causes of clinical signs,” she said.
The best way to prevent THC poisoning is to keep any marijuana locked away and to watch out for symptoms such as “lethargy, somnolence, stumbling, vomiting, tremors, dripping urine.” Pot can cause “seizures, low heart rate and low body temperature” in pets.
Harm reduction approach
Public health advocates take a harm reduction approach to cannabis legalization, which they point out provides tools useful in controlling the drug’s usage, its quality and better educating those who do choose to partake.
Megan Deyman, co-ordinator of the Haliburton, Kawartha Lakes, Northumberland Drug Strategy, said legalization provides “controls on: availability (e.g. hours of sale) and accessibility (e.g. minimum age requirements), promotion and advertising restrictions, packaging and labelling requirements, and targeted education and health promotion.”
In an effort to reduce associated risks, the local health unit supports the Lower Risk Cannabis Use Guidelines created by the Centre for Addiction and Mental Health, which include choosing lower THC products; only using cannabis occasionally; delaying use for as long as possible; avoiding use when pregnant or breastfeeding; not using synthetic varieties; never driving or operating machinery while using; and never mixing cannabis with alcohol or other drugs.
Legalization ensures those who do choose to ingest cannabis know what they’re getting, which improves safety, said Catherine MacDonald, substances and harm reduction co-ordinator with the Haliburton, Kawartha, Pine Ridge District Health Unit.
“For example, packaging is regulated and must contain specific information on THC levels, allowing people to determine the strength and strain of the products they are purchasing. With the illicit market, there are concerns about the potency, effects and potential contamination of the products. With illegal cannabis, there is no way of knowing what you are getting,” she wrote in an email.
Statistics show that Canadians’ usage following legalization increased in the first quarter of 2019, particularly in the 45-64 age demographic, she said.
“This age group also makes up half of all new users,” she wrote. “The rate of use for young people has remained stable. More people are now purchasing cannabis from legal sources. And daily use has remained stable while occasional use has increased.”
MacDonald said there are some people who find therapeutic benefit from using marijuana, but the science isn’t yet in.
“There is some research and anecdotal evidence to suggest cannabis is effective in relieving symptoms such as pain, inflammation, anxiety, stress, nausea/vomiting and appetite loss. However, there is not enough strong or credible evidence to either support or refute the health claims of cannabis use. A very important aspect of cannabis legalization is that it will allow for meaningful, scientific research into cannabis use to see if it does offer health benefits,” she said.
Deyman said legalization has created an opportunity for more study of the drug, something Dr. Thomas’s essay also explores.
“A lot of research to date has focused on the risks and harms of cannabis use, but there is also some evidence examining the potential therapeutic uses for cannabis or its component chemicals (cannabinoids), as well as harm reduction approaches that utilize cannabis as an alternative to other illicit or diverted substances,” Deyman said in an email. “While the current, available evidence cannot fully support or refute the potential therapeutic uses of cannabis, legalization does allow for opportunity to do more research into this in a more controlled, safer environment.”
Dr. Thomas said she’s open-minded about potential uses for cannabis. “This is one of the benefits of having legalized cannabis, that is, that we can use the tax revenues to support much more rigorous science. And this is for public safety.” Currently, she said there are three conditions that cannabis is demonstrated scientifically to work for: chemotherapy-induced nausea and vomiting; nerve pain and spasticity in patients with multiple sclerosis and severe pain; and refractory pain in palliative patients and refractory nerve pain.
Despite her concerns about marijuana usage, Dr. Thomas said she’s not naive to the realities of her patients’ lives and the fact that many use pot recreationally and because they are looking for relief from an ailment.
She said she hopes her paper will provide people with a solid foundation to make decisions about their health, better understanding the risks and taking precautions, such as buying their pot legally, never driving while high, keeping drugs locked away from children and pets, and delaying use until well after age 19.
“Judging isn’t going to get anybody to the goal that we want, which is to keep people safe and keep people healthy,” she said.
Read Dr. Thomas's essay below or click this link.