Sassafras is banned as a food additive in the United States because it contains safrole, a compound that causes liver cancer in laboratory animals. The FDA prohibited sassafras bark and safrole from food products after studies showed that safrole, which makes up roughly 80% of sassafras root bark oil, produced liver tumors in rats and mice. It remains one of the very few times the FDA has restricted a naturally occurring food ingredient based on cancer risk.
What the FDA Actually Banned
The FDA removed safrole from the list of approved food additives in 1960, ending its long history as the signature flavor in root beer. In the 1970s, the agency went further and specifically banned sassafras bark itself, which people had been using to brew sassafras tea for generations. The distinction matters: the FDA didn’t just ban the isolated chemical. It banned the whole bark because safrole is so concentrated in it that there’s no practical way to consume the bark without also consuming safrole.
This was an unusual move. The FDA has rarely pulled a naturally occurring food from the market over a toxic compound found in it. Plenty of common foods contain trace amounts of harmful chemicals, but sassafras bark had safrole as its dominant component, not a trace one.
How Safrole Causes Cancer
Safrole itself isn’t the direct problem. Your liver metabolizes safrole into a more dangerous compound called 1′-hydroxysafrole, which turned out to be a stronger carcinogen than safrole itself. This metabolite gets further converted into an unstable sulfate derivative that reacts directly with DNA, binding to it and forming what scientists call DNA adducts. These adducts are essentially chemical damage to your genetic code, and they can trigger the mutations that lead to cancer.
In animal studies, this process reliably produced liver tumors. Researchers found safrole-DNA adducts in the livers of rats, mice, chickens, turkeys, and, critically, humans. The International Agency for Research on Cancer (IARC) classifies safrole as Group 2B, meaning “possibly carcinogenic to humans.” That’s not the highest risk category, but the DNA damage mechanism has been confirmed across multiple species, including ours.
The strongest human evidence comes from studies of people who chew betel quid, a preparation common in parts of Asia that can contain up to 15 milligrams of safrole per gram. Researchers have found safrole-like DNA adducts in oral cancers and liver cancers from betel quid users, and these users have elevated rates of oral cancer. This isn’t a perfect parallel to drinking sassafras tea, but it demonstrates that safrole’s cancer-causing mechanism operates in human tissue, not just in rodent models.
What About Sassafras Tea?
Homemade sassafras tea, brewed from the root bark, delivers a meaningful dose of safrole. In sufficient amounts, safrole causes genotoxicity (damage to DNA), oxidative stress, and cellular damage, all precursors to cancer development. The FDA’s ban covers commercial sale of sassafras bark for tea, though the plant grows wild across the eastern United States and people still forage it.
The risk from a single cup is not the same as the risk from habitual use. But unlike many food safety questions where the dose is vanishingly small, sassafras root bark is roughly 80% safrole by oil content. That’s not a trace contaminant you’d need laboratory instruments to detect. It’s the primary chemical in the product.
Why Filé Powder Is Still Legal
If you’ve eaten gumbo in Louisiana, you’ve likely had filé powder, a seasoning made from dried, ground sassafras leaves. This is perfectly legal, and the reason is straightforward: sassafras leaves contain negligible or even undetectable amounts of safrole. The problematic compound is concentrated in the root bark and its oil, not in the leaves. So the FDA’s ban targets bark, root, and oil products while leaving the leaf-based seasoning alone. It’s the same plant, but the part you use makes all the difference.
The Drug Connection
Sassafras faces a second layer of regulation beyond food safety. Safrole is a precursor chemical for manufacturing MDMA (ecstasy), and the Drug Enforcement Administration lists it as a List I controlled chemical. This means bulk purchases of sassafras oil trigger the same regulatory scrutiny as other drug precursor chemicals. The DEA specifically warns that safrole and sassafras oil are used in illicit MDMA production, which adds law enforcement interest to what would otherwise be purely a food safety issue.
How Root Beer Survived the Ban
Root beer existed for decades before the ban with sassafras as its defining ingredient. After 1960, manufacturers had two options: switch to artificial sassafras flavoring or use a specially processed safrole-free sassafras extract. Federal regulations spell out exactly how that extract must be made. The root bark is extracted with dilute alcohol, concentrated through vacuum distillation, then diluted with water. The oily fraction, where safrole lives, is discarded. The remaining aqueous extract must be completely safrole-free.
Most modern root beers rely on artificial flavoring or this purified extract, supplemented with a mix of other botanicals: vanilla, wintergreen, black cherry bark, licorice root, sarsaparilla, anise, cinnamon, sweet birch, and others. The flavor profile people associate with root beer today is a composite that no longer depends on sassafras in any meaningful way.
How Other Countries Handle Safrole
The European Union takes a different approach. Rather than banning sassafras outright, EU regulations set maximum safrole concentrations in food: 1 part per million in most foods and beverages, 2 ppm in alcoholic drinks up to 25% alcohol, and 5 ppm in stronger spirits. Foods containing nutmeg or mace, which naturally contain small amounts of safrole, get a higher limit of 15 ppm. This reflects the reality that safrole appears in trace amounts across many common spices, including nutmeg and cinnamon, and that low-level exposure is essentially unavoidable in a normal diet.
The practical difference is that Europe permits foods with trace safrole while the U.S. treats safrole as a zero-tolerance additive. Neither approach suggests sassafras root bark tea is safe. Both regulatory systems recognize safrole as a carcinogenic risk; they simply draw the line in different places for incidental exposure.