Dear Editor,
I read that the engineering students opted not to use gentian violet to dye their skin this year in light of Health Canada’s “potential cancer risk” publication earlier this year. Health Canada says they published the “potential cancer risk” in light of recent World Health Organization (WHO) updates, although the cited updates were published in 2006, 2010, and 2014 – not particularly recent. And the 2014 update was a regarding the use of gentian violet in animal feed, not even related to humans.
What is more relevant are the WHO’s International Agency for Research on Cancer (IARC) updates in 2006 and 2010. These updates reviewed three of formaldehyde’s metabolites (chemicals made when you swallow gentian violet) have been classified by IARC, specifically: formaldehyde, C.I. Basic Red 9, and Michler’s Ketone; all produced in very small amounts.
The IARC carcinogenicity scale goes from Group 1 to Group 4. Here are examples of IARC Groups:
- IARC Group 1 “carcinogenic in humans”: drinking ethanol, processed meats including bacon, ultraviolet radiation, and formaldehyde.
- Some IARC Group 2A carcinogens “probably carcinogen” based on limited evidence in humans and sufficient evidence in animals: red meat, very hot beverages (including coffee, tea, mate)
- Some IARC Group 2B carcinogens “possibly carcinogenic” based on less than sufficient animal data: gentian violet metabolites of C.I. Basic Red 9 and Michler’s Ketone, both of which are formed by intestinal flora when gentian violet is swallowed.
I know formaldehyde sounds scary but consider this: formaldehyde is produced in similarly small amounts when you drink coffee or eat fruit such as pears. Our bodies seem able to tolerate formaldehyde in these amounts. Mind you, that only applies if you swallow gentian violet. Engineering students make wish to note drinking ethanol and eating processed meats are realistically a higher cancer risk than ingesting gentian violet.
But – keep gentian violet on the skin and you don’t ingest it. Other uses for gentian violet include treatment of oral thrush (a yeast infection that can occur in infant’s mouths) and nipple thrush (a yeast infection in breastfeeding person’s nipples). I’ve used gentian violet on myself and my infant, and I knew this IARC carcinogenicity data when I used gentian violet. I would do so again if I needed to and could find gentian violet.
Sincerely,
Krista Thompson, ArtSci ’04
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