According to the Brazilian National Cancer Institute (INCA), cancer is the second leading cause of death in Brazil, behind only cardiovascular diseases. Between 2023 and 2025, an estimated 704,000 new cases are expected annually. If this growth trend continues, federal spending on hospital and outpatient procedures within the Unified Health System (SUS) for oncology patients could reach BRL 7.84 billion by 2040. The disease’s etiology involves genetic, environmental, and epigenetic factors, comprising the exposome concept, which considers the totality of environmental exposures throughout life and their cumulative impact on chronic diseases like cancer. A key exposure route to hazardous chemicals is daily cosmetic use. Ingredients such as preservatives and fragrances may act as endocrine disruptors or carcinogens. In Brazil, despite regulation by ANVISA, ingredients classified by the International Agency for Research on Cancer (IARC) as toxic still appear in popular products, underscoring the need for regulatory revision focused on long-term effects and cumulative exposure.

This study aimed to identify and characterize potentially carcinogenic ingredients in cosmetics marketed in Brazil, evaluate their classification according to IARC, and discuss their relevance within the exposome framework, intending to support preventive regulatory strategies in the SUS.

This study collected and analyzed 400 cosmetic products available in Brazil. Ingredients listed on labels were cataloged and matched to IARC classifications: Group 1 (carcinogenic to humans), Group 2A (probably carcinogenic), and Group 2B (possibly carcinogenic). Ingredients without IARC classification were noted to identify toxicity data gaps. The analysis included qualitative evaluation of labeling consistency and detection of potentially masked substances. Results were discussed in the exposome context to assess cumulative risk and regulatory impact.

Among 1,112 ingredients identified, only 29 had IARC classifications: 3 carcinogenic (Group 1), 1 probably carcinogenic (Group 2A), and 2 possibly carcinogenic (Group 2B). Alarmingly, 959 ingredients (over 80%) lacked IARC classification, revealing large knowledge gaps on toxicity. Noteworthy compounds included oxybenzone, parabens, and triclosan, often linked to hormonal disruption and increased cancer risk. Labeling inconsistencies, masked substances, and lack of clear bans on toxic compounds were found.

Findings highlight the urgent need for prevention strategies based on the exposome, requiring stricter regulation, transparent labeling, and safer ingredient substitution. This urgency is supported by prior research showing pesticide-exposed workers without PPE had reduced DNA repair gene expression and CHIP mutations linked to a 27-fold higher risk of bone marrow neoplasms. Additionally, recent (2024) studies showed ammonia-based hair bleach products activated the neoplastic STING gene pathway, causing bone marrow cancer-like changes in 20% of exposed mice. This study is part of the TÓXICOS project, which will expand to food and hygiene/cleaning products, applying a Bayesian algorithm to reclassify risks and share data on an open digital platform, supporting regulatory and preventive actions within SUS.