The World Health Organization's (WHO) cancer research agency has delivered a damning report on powdered mineral talc, calling it "probably" cancer-causing to humans, mainly because of powders being unknowingly contaminated with asbestos.
The International Agency for Research on Cancer (IARC) classified the naturally occurring talc as "probably carcinogenic to humans (Group 2A)" based on "limited evidence" of ovarian cancer, "sufficient evidence" of experimental animals developing cancers and "strong mechanistic evidence" of carcinogenic properties found in human cells.
It supports the findings of a large study published in May, which found that applying talc to female genitals was associated with a greater risk of ovarian cancer.
"There were numerous studies that consistently showed an increase in the incidence of ovarian cancer in humans self-reporting the use of body powder in the perineal region," the IARC report noted. "Although the evaluation focused on talc not containing asbestos, contamination of talc with asbestos could not be excluded in most of the studies of exposed humans.
"An increased rate of ovarian cancer was also observed in studies looking at occupational exposure of women exposed to talc in the pulp and paper industry," the report continued.
The agency found a higher rate of malignant neoplasms in female rats (adrenal medulla and lung cancers) and both benign and malignant neoplasms in males (adrenal medulla). In addition to this, talc's impact on cells revealed strong evidence it induced chronic inflammation and altered cell growth and death.
This comes just a month after Johnson & Johnson agreed to pay US$700 million in a massive class-action suit that accused the company of deceiving customers about the safety of its famous baby powder and other talc products. An investigation had found that J&J's products had been contaminated with trace amounts of carcinogenic asbestos.
However, IARC's report highlights its limitations – the findings relied on self-reporting and observation, not testing, and the agency admits it was unable to state definitively that talc causes cancer.
"In addition, biases in how talc use was reported in the epidemiological studies could not be ruled out with reasonable confidence," the statement cautioned. "As a result, a causal role for talc could not be fully established."
A naturally occurring mineral made up of magnesium, silicon, oxygen and hydrogen, talc has been used in skincare products since the 1800s. While not every product contains asbestos, the two minerals often form close together, making it challenging to mine for just talc. What's more, talc deposits often house the most toxic asbestos – such as tremolite or anthophyllite – which are more carcinogenic than chrysotile, which makes up 95% of asbestos found in the US.
"Raw material talc is obtained from mines that may also contain asbestos and related minerals," the Food and Drug Administration (FDA) noted in 2020. "Removal of asbestos by purification of talc ores is extremely difficult."
Also difficult is testing talc products for personal use, and scientific studies so far have returned mixed results regarding cancer risks.
"Until more information is available, people who are concerned about possible links between talcum powder and cancer may choose to avoid or limit their use of consumer products that contain it," suggests the American Cancer Society.
The study was published in the journal The Lancelet Oncology.
