Alcoholic drinks are a leading cause of cancer and should carry a warning about that risk on their labels, the U.S. surgeon general said Friday.

Alcohol is a factor in nearly 100,000 newly diagnosed cancers each year and roughly 20,000 deaths from the disease, U.S. Surgeon General Vivek Murthy said in an advisory intended to focus the public’s attention on the health risk. By comparison, traffic accidents tied to drinking kill about 13,500 Americans each year.

“Alcohol consumption is the third leading preventable cause of cancer in the United States, after tobacco and obesity,” the 22-page advisory said. “While scientific evidence for this connection has been growing over the past four decades, less than half of Americans recognize it as a risk factor for cancer.”

Labels on bottles and cans of alcoholic beverages already warn about drinking while pregnant. They also warn about drinking before driving or operating other machinery. In California, the voter-approved Proposition 65 also requires businesses that serve or sell alcoholic beverages to provide a warning about health risks, including cancer.

Any decision to update or expand the label would require congressional approval, an uncertain prospect. Murthy was appointed by President Biden, who has a little more than two weeks left in office. President-elect Donald Trump has picked Janette Nesheiwat, an executive at a New York-based chain of urgent care clinics, as his nominee for surgeon general.

Executives in the beer, wine and spirits industry said Friday that the scientific data linking alcohol to cancer are mixed.

Amanda Berger, senior vice president at the Distilled Spirits Council, noted that a recent report by the National Academies of Sciences, Engineering, and Medicine found that alcohol was associated with a higher risk of breast cancer but did not find such associations with other types of cancer.

That report also concluded that moderate alcohol consumption is associated with lower risks of all-cause mortality and cardiovascular disease, compared with never consuming alcohol.

“The current health warning on alcohol products has long informed consumers about the potential risks of the consumption of alcohol,” Berger said. “Many lifestyle choices carry potential risks, and it is the federal government’s role to determine any proposed changes to the warning statements based on the entire body of scientific research.”

The surgeon general’s advisory said that cancers of the colorectum, esophagus, liver, mouth, throat and larynx are all tied to drinking, as is breast cancer in women. The risk of developing breast, mouth or throat cancers may increase with less than one drink per day, it said.

Yet more than half of Americans are unaware that their drinking behavior affects their cancer risk. A survey by the American Institute for Cancer Research found that 89% of Americans recognized that smoking causes cancer and 53% knew that obesity was a risk factor, but only 45% realized that alcohol could cause cancer as well.

Nearly half of alcohol-related cancers in the U.S. are breast cancers in women, according to a study published by the American Cancer Society. About 1 in every 6 female breast cancers is due to alcohol, and the disease accounts for about 60% of all alcohol-related cancer deaths in women.

As a result, drinking is a bigger cancer risk for women than men. In 2019, about 54,330 women were diagnosed with a cancer that resulted from drinking, as were roughly 42,400 men. About 60% of alcohol-related cancer deaths in women are due to breast cancer, while liver cancer and colorectal cancer are responsible for about 54% of alcohol-related cancer deaths in men.

For women who consume less than one drink a week, the absolute risk of developing an alcohol-related cancer is 16.5%. Having one drink per day increases that risk to 19%, and having two drinks each day raises it to 21.8%, according to the advisory.

For men, drinking once a week is tied to a 10% absolute risk of an alcohol-related cancer. That risk rises to 11.4% by having one drink per day, and to 13.1% by having two drinks per day, the advisory says.

The World Health Organization’s International Agency for Research on Cancer says alcohol is a Group 1 carcinogen, putting it in the company of tobacco, asbestos and ultraviolet radiation. The U.S. National Toxicology Program declared in 2000 that alcohol causes cancer in humans, and organizations including the Centers for Disease Control and Prevention, the National Cancer Institute, the American Cancer Society and the American Assn. for Cancer Research agree that at least seven kinds of cancer are related to drinking.

There is also evidence to suggest that drinking contributes to skin, prostate, pancreatic and stomach cancers, though more research is needed, the surgeon general’s advisory says.

Scientists first linked alcohol consumption to certain cancers nearly 50 years ago, and the evidence showing that drinking is a risk factor for at least seven types of cancer has grown since then, the advisory says.

For instance, an observational study of 28 million people in 195 countries and territories found that the more alcohol a person consumed, the higher their risk of cancer. A study involving more than 1 million women found that those who had up to 1 drink per day were 10% more likely to get breast cancer compared with those who abstained. Likewise, a study with 36,000 people found that those who consumed about a drink per day were 40% more likely to develop mouth cancer than people who didn’t drink.

Laboratory experiments have shown how alcohol leads to cancer.

When alcohol is metabolized in the body, it breaks down into a chemical called acetaldehyde that can attach itself to DNA. The resulting damage can trigger the uncontrolled cell growth that leads to cancer.

Drinking also creates unstable molecules called reactive oxygen species that can interfere with DNA, proteins and essential fats. They also increase inflammation, which makes the body more hospitable to cancer.

There is also evidence that alcohol fuels breast cancers by affecting levels of estrogen and other hormones, and that other kinds of carcinogens — such as those found in tobacco smoke — are more easily absorbed in the body when they are dissolved in alcohol.

The companies selling alcoholic beverages say they have long urged consumers to drink the beverages safely.

“The U.S. beer industry has been a champion of responsible consumption for decades,” a spokesperson for the Beer Institute said Friday. “We encourage adults of legal drinking age to make choices that best fit their personal circumstances, and if they choose to drink, to consume alcohol beverages in moderation.”

Dr. Laura Catena, a winemaker and physician, said that she would “welcome any kind of alert or communication from the surgeon general about the cancer risks of heavy alcohol drinking,” but that it shouldn’t go beyond the established science.

The American Assn. for Cancer Research says alcohol use is responsible for 5.4% of all cancer cases in the U.S. That makes it a bigger risk factor than exposure to UV radiation, poor diet, and infections from pathogens like hepatitis and the human papillomavirus. (For comparison, 19.3% of U.S. cancers are attributable to smoking, according to the association.)

Studies suggest that people who cut back on alcohol or eliminate it can reduce their risk of these cancers by 8%, and reduce their overall cancer risk by 4%.

The Dietary Guidelines for Americans from the U.S. Departments of Agriculture and Health and Human Services say there is no health reason for nondrinkers to start consuming alcohol. Those who do drink can minimize their risk by limiting their intake to no more than one drink per day for women and no more than two drinks per day for men.

A 5-ounce glass of wine, 12-ounce bottle of beer or 1.5-ounce tumbler of distilled spirits count as a single drink.

The surgeon general’s advisory says about 83% of alcohol-related cancer deaths occur in people who exceed those limits. But that means 17% of deaths were in people who engaged in moderate drinking.