The World Health Organization (WHO) has classified talc, a natural mineral used in cosmetics and body powders, as a product “probably carcinogenic” to humans. International Agency for Research on Cancer (IARC), The WHO body responsible for identifying the carcinogenic potential of substances has concluded, after studying the available scientific evidence, that this mineral may have the capacity to cause cancer in the population. Specifically, it places it at level 2A, the second highest level within its identification pyramid of dangers: this means that, although there is limited evidence that it can cause tumors in humans (specifically, ovarian tumors), there is sufficient certainty that it causes cancer in experimental animals and there is also “strong mechanistic evidence”. This means that talc “exhibits key characteristics of carcinogens in human cells and experimental systems”, explains the IARC in a statement. The WHO cancer agency has also identified acrylonitrilea compound used in the textile sector and for consumer plastics, as “carcinogenic” for humans.
Talc is a mineral that is mined in many parts of the world. According to IARC, in addition to occupational exposure to this product (during its extraction or processing), the general population can come into contact with this substance through the use of cosmetics or body powders that contain this mineral, such as makeup or deodorants. And although it is less studied, it can also be present in food, medicines and other consumer products. The WHO cancer agency also expresses its concern about the contamination of talc with asbestos (a substance similar to asbestos and considered a dangerous carcinogen: although it is difficult to measure, it assures, this risk “can lead to the exposure of workers and the general population to asbestos, for example, through makeup and body powders contaminated with talc.”
Thirty international experts have “exhaustively” reviewed the available scientific literature and concluded that talc is “probably carcinogenic to humans (Group 2A).” This means that the level of certainty about its carcinogenic potential is the same as that about the effects of eating red meat or working night shifts. “LGroup 2A classification “It is the second highest level of certainty that a substance may cause cancer. There were numerous studies that consistently showed an increased incidence of ovarian cancer in humans who reported the use of body powders in the perineal region. Although the evaluation focused on talc that did not contain asbestos, in most studies conducted in exposed humans, contamination of the talc with asbestos could not be excluded,” explains the IARC.
The scientists note that an increased rate of ovarian cancer was also observed in studies looking at occupational exposure among women working in the pulp and paper industry. “However, confounding by simultaneous exposure to asbestos could not be excluded, and the increased rate was based on a small number of ovarian cancers in these occupational studies,” the experts who analysed the risk level admit.
In animal models, talc treatment also caused an increased incidence of adrenal and lung cancer in female rats; in male rats, a combination of benign and malignant tumours (in the adrenal medulla) were also recorded. Based on evidence of mechanisms typical of cancer-causing compounds, IARC scientists concluded that talc exhibits key characteristics of carcinogens, “including the induction of chronic inflammation and the disruption of cell proliferation, cell death or nutrient supply.”
The link between talcum powder and ovarian cancer has been under scrutiny for some time. Tens of thousands of people in the United States sued the multinational Johnson & Johnson (J&J) for the alleged presence of carcinogenic components in one of its flagship products, talcum powder sold under the Baby Powder brand. The pharmaceutical giant has always maintained that its talcum powders were safe, but the litigation reached such a scale that the company announced that, starting in 2022, it would suspend the sale of Baby Powder worldwide, after doing so in 2020 in the United States and Canada.
“This does not mean that just because someone has used talcum powder at some point, they are at risk. The risk of developing cancer will depend on the dose of exposure, the time and the form of contact with the talcum powder.”
Alejandro Pérez Fidalgo, oncologist at the Hospital Clínico de Valencia
Regarding this new IARC consideration, Joan Albanell, head of the Medical Oncology Service at the Hospital del Mar in Barcelona, points out: “The WHO review provides mechanistic and preclinical evidence that talc has a carcinogenic effect, but its definitive translation into epidemiological studies seems to be limited, at least in part, by the co-exposure to talc and asbestos in certain professions. It will be important to see how this recent classification of talc in group 2A of carcinogenic agents is translated into public health and prevention policies.”
Along the same lines, Alejandro Pérez Fidalgo, a doctor from the Oncology Service at the Hospital Clínico de Valencia and a researcher at the INCLIVA Biomedical Research Institute, makes a clarification: “That does not mean that, just because someone has used talcum powder once or even because they use it regularly, they are clearly at risk, since the risk of developing cancer will depend on the dose of exposure, time and form of contact with the talcum powder. The studies that support this classification have many biases, that is, certain confounding factors that prevent us from appreciating or predicting with complete solidity the relationship between the use of talcum powder or exposure to it and cancer.”
Regarding human studies, the scientist points out: “The two studies that support the recommendation include women who used talcum powder applied to the genital area. The application of talcum powder in this area showed a slight increase in ovarian cancer, but not significant, in a first study that included more than 100 women. 250,000 people In the United States, a second analysis of eight case-control studies, including more than 18,000 people, found that women who had used genital talcum powder had a slightly increased risk of infiltrating serous, clear cell, and serous ovarian tumors. borderline “Statistically significant. In the case of those who used talcum powder in other locations (i.e. not in the genital area), there was no increased risk of cancer.”
Pérez Fidalgo says that “it would be advisable” to avoid, as far as possible, the use of talcum powder in genital areas, especially in women. But he again calls for caution with regard to the IARC decision: “This does not mean that prior use of talcum powder will cause cancer or that prior exposure to this agent will clearly be responsible for the appearance of a tumor.”
Acrylonitrile, carcinogenic to humans
In this review of potential carcinogens, the WHO cancer agency has also placed acrylonitrile at the highest level of certainty for cancer: group 1, where there is no doubt that substances and behaviours are harmful to the body. This compound is, according to the IARC, carcinogenic to humans and the level of certainty about its ability to cause cancer is the same as that regarding smoking or solar radiation.
According to IARC, this volatile organic compound is used especially in the production of polymers (polyacrylonitrile, styrene-acrylonitrile, acrylonitrile butadiene styrene and other synthetic rubbers). These products are used in clothing fibres, carpets and other textiles, but also in plastics for consumer products, car parts and construction. Human exposure to this substance, apart from occupational exposure (during its production process), is through inhalation of cigarette smoke, since it is present in this context. Another source of exposure is air pollution.
The WHO cancer agency believes there is sufficient evidence that it causes lung cancer in humans and, although with more limited evidence, also bladder cancer. “The evidence came mainly from studies in workers who produced or used acrylonitrile. In addition, there was sufficient evidence of cancer in experimental animals and strong mechanistic evidence of key characteristics of the carcinogens in experimental systems,” the international organization concludes.
Speaking to SMC, Andrew Watterson, a researcher in Public Health at the Faculty of Health Sciences at the University of Stirling (United Kingdom), stressed that the two decisions of the IARC “are based on a careful examination of the evidence”: “These decisions mean that we need a good preventive and precautionary policy to eliminate exposure to talc, if possible, but it may be more difficult to achieve than with acrylonitrile.” Regarding this organic compound, the scientist calls for alternatives to be sought to reduce the use of this toxic substance. “Worker protection should be improved with even stricter acrylonitrile exposure standards and the risks of acrylonitrile for smokers should be highlighted again,” he said.
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