The news about the tragic deaths of several American tourists in the Dominican Republic in May has created an outcry and a media frenzy. As of June 30, there were at least nine deaths with similar circumstances in the past few months. The FBI and Dominican authorities are investigating, and one theory is that alcohol was the cause of these deaths.

The FBI has reportedly taken samples of alcohol for testing, and the hotels where some tourists died have removed alcohol from the minibars in the hotel rooms. But the concerns are growing, and Sen. Chuck Schumer, D-N.Y., on June 30 recommended that the Bureau of Alcohol, Tobacco, Firearms and Explosives and the Centers for Disease Control and Prevention should aid the ongoing investigation.

Many may find it puzzling that alcohol, particularly adulterated or counterfeit alcohol, could have caused these deaths. But some experts seem to agree that the symptoms and circumstances fit the indicators of deaths caused by adulterated alcohol.

As a professor of public health, I need to note that research now shows that no amount of alcohol is considered safe in terms of your health, and that alcohol is linked to many cancers and heart disease and is also a key contributor to traffic crashes, violence and suicide. Even so, counterfeit or illegally made alcohol brings a new level of risk, as it is not monitored for safety and may include added ingredients, such as methanol, known to be extremely harmful to health.

Thanks to rigorous regulation of alcohol, Americans may not see or hear much about counterfeit alcohol in the U.S., but in many other parts of the world counterfeit or “illegal” alcohol is more common and a growing public health concernWorld Health Organization estimates.

Counterfeit or illegal alcohol is part of a larger category described as “unrecorded” alcohol because it is not recorded in official statistics and not monitored for quality or for taxation. The that 25% of the alcohol consumed worldwide is unrecorded.

Counterfeit alcohol is typically meant to resemble legitimate alcohol, such as finer wines and expensive spirits, in terms of its look, taste and packaging. But there are also other types of alcohol that are typically considered illegal, such as “moonshine” or “bootleg” alcohol, or simply alcohol that is made under less rigorous processes and that have added ingredients to make the alcohol faster or cheaper.

One of the key aspects of counterfeit or illegal alcohol is that producers distill the alcohol more cheaply and quickly using dangerous shortcuts in the process, such as adding water and methanol, also known as methyl alcohol, which is highly toxic. Methanol is not intended for human consumption and can cause liver damage, blindness and death if consumed. Earlier this year, toxic alcohol killed at least 154 people in India because it was tainted with methanol.

Interpol, the International Criminal Police Organization, says counterfeit alcohol is a top concern globally. In 2018, during one operation, it reported that “16,000 (metric tons) and 33 million liters of potentially dangerous fake food and drink was seized worth an estimated $117 million.” In Europe, wine and spirits are in the top five sectors for lost sales.

Counterfeit wine is becoming more common and now represents a billion-dollar market. In China, for example, counterfeit wine is so common it has been referred to as an epidemic, especially in terms of finer wines.

Even though lost revenue is a big concern for law enforcement and businesses, travel advisories for Americans traveling abroad are sometimes issued because of the risk posed by tainted alcohol. One was issued in 2017 to a resort in Mexico. Similarly, in June there was a notification that 23 people died and 10 patients were undergoing treatment for alcohol tainted with methanol in Nigeria.

The reality is that counterfeit or toxic alcohol is common in many places of the world, even in places you may not expect. So the next time you travel abroad and reach for an alcoholic beverage, particularly a finer wine or spirit, take a second look at that bottle.

The travel experts at the U.S. Overseas Security Advisory Council made a list of tips for alcohol consumption while abroad. In particular, they recommend to tourists traveling abroad:

Don’t drink homemade or counterfeit “booze.”

Don’t overdo it.

Don’t compete with locals and their brew.

Don’t let your drink out of sight.

Also, there are some tips for spotting fake alcohol by the Trading Standards Institute in the U.K. It is key to remember to pay attention to the place, price, packaging and product, the group says. Most importantly, if the alcohol tastes or smells bad, don’t drink it.

The medical and public health community is growing more concerned about the dangerous effects of alcohol, as new research shows there is no safe amount of alcohol. That said, if you choose to drink, especially while abroad, make sure the alcohol you drink is the real thing, and keep it shaken or stirred, but not poisoned.

Monica H. Swahn is a professor of epidemiology and public health at Georgia State University. This was written for The Conversation, a nonprofit news service.