Unveiling the Hidden Dangers of Safrole: Carcinogenic Effects and Potential Exposure Routes


Safrole, a colorless or slightly yellow liquid, is an organic compound commonly found in various plants and essential oils. It is known for its aromatic properties and is often used in the production of fragrances, soaps, and traditional medicines. However, what many people may not be aware of is that safrole has been linked to cancer development.

Unveiling the Hidden Dangers of Safrole Carcinogenic Effects and Potential Exposure Routes
Carcinogenic Effects and Potential Exposure Routes

Safrole and Carcinogenic Studies

Several authoritative institutions have conducted extensive research on the carcinogenic properties of safrole. The International Agency for Research on Cancer (IARC) classified safrole as a Group 2B carcinogen, suggesting that it is possibly carcinogenic to humans. A study published in the Journal of the National Cancer Institute demonstrated that safrole exposure led to the development of liver and lung tumors in rats.

According to research by the U.S. Food and Drug Administration (FDA), safrole has been shown to cause liver cancer. Adding 0.04% to 1% safrole to the diet of mice for 150 days to 2 years can induce liver cancer in these mice. The process by which safrole is metabolized into an active carcinogen is now relatively clear: safrole is first metabolized into a phenylethanol form in mice, then activated into an acetate or sulfate, becoming the final carcinogen. If safrole combines with oxidants, it can generate epoxysafrole, which has even stronger carcinogenic activity.

In the United States, the use of safrole as a food additive is no longer permitted. Recently, an expert committee of the European Union decided to further reduce the allowable dosage of safrole within the EU to reduce its harm to humans. The International Codex Committee on Food Additives is initiating the development of the “Guidelines for the Use of Flavourings,” which stipulates that the maximum limit of safrole in food and beverages is 1 milligram per kilogram.

Cancer Associations

Safrole has been associated with various types of cancer, primarily affecting the liver and lungs. Animal studies have shown a strong link between safrole exposure and the occurrence of hepatocellular carcinoma (liver cancer) and lung adenocarcinoma. Additionally, some research suggests that safrole may also be associated with other cancers, such as colorectal and pancreatic cancer, although further studies are needed to confirm these findings.

Carcinogenic Mechanism

The exact mechanism by which safrole induces cancer is not yet fully understood. However, research indicates that safrole is metabolized in the body to form a toxic intermediate called 1′-hydroxysafrole. This intermediate can react with cellular macromolecules, such as DNA, leading to the formation of DNA adducts. These adducts can disrupt normal DNA replication and repair processes, potentially leading to mutations and cancer development.

Potential Exposure Routes

Safrole can be encountered through various sources in our daily lives:

Essential Oils
Essential Oils
  • 1.Dietary Sources: Safrole is naturally present in certain plants, such as sassafras, black pepper, and star anise. Consumption of these plants or products derived from them can lead to safrole exposure.
  • 2.Essential Oils: Many essential oils, including sassafras oil, contain safrole. Inhaling or using these oils in aromatherapy can result in exposure.
  • 3.Traditional Medicines: Some traditional herbal remedies contain safrole, and their consumption can lead to its intake.
  • 4.Environmental Sources: Safrole can be released into the environment through industrial processes, waste disposal, and combustion of certain materials. Inhalation of contaminated air or ingestion of contaminated water can be potential exposure routes.


Safrole, a compound found in various plants and essential oils, has raised concerns due to its potential carcinogenic effects. Research conducted by authoritative institutions suggests a link between safrole exposure and the development of liver and lung cancers. The exact mechanisms by which safrole induces cancer involve the formation of DNA adducts and subsequent genetic mutations. Safrole can be encountered through dietary sources, essential oils, traditional medicines, and environmental exposure. It is crucial to be aware of these potential exposure routes and take necessary precautions to minimize the risk of safrole-related cancers. Further research is needed to fully understand the extent of safrole’s carcinogenic properties and develop effective preventive measures.

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