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Of the 10 Americans who have mysteriously died during their trips to the Dominican Republic in the last year, nine showed symptoms commonly associated with methanol poisoning.

Now, both Dominican authorities and the FBI are looking into a counterfeit alcohol as the possible culprit, officials confirmed to VICE News.

The nine victims died from either pulmonary edema, the medical term for fluid in the lungs, or of a heart attack. At least four of them had drunk an alcoholic beverage at resorts in Punta Cana, Santo Domingo and La Romana shortly before their deaths, according to loved ones.

In addition to the recent deaths, a number of other tourists, including 47 of the 114 Jimmy Buffet fans visiting the Caribbean island for a group trip, said they became sick during their stay at a resort on the island.

“I think what the authorities are investigating is what we in science call a credible hypothesis at this point,” said LeeAnn Jaykus, a food microbiologist at North Carolina State University. “If it were the right chemicals, it could result in many of the symptoms we’ve seen in many of the victims who have died.”

During a normal distillation process, alcohol producers perform a series of steps to isolate ethanol, the form of alcohol that’s safe to drink, from more toxic compounds. But without regulation, those producers might cut corners to reduce costs, which can be deadly.

One of the byproducts of fermentation, methanol, gets people just as drunk as normal alcohol — but lethally damages the liver, the optic nerve, and neurological and respiratory systems. Oftentimes, once the consumer starts to notice they don’t feel right, it’s too late to reverse the effects.

"It’s actually quite dangerous."

Improper distillation can also leave traces of other poisonous compounds like formaldehyde; chloroform; formic acid, which is used in the processing of leather and other textiles; and acetone, found commonly in nail polish remover, according to Nathan Lents, a biology expert at John Jay College of Criminal Justice.

“When you distill alcohol in an unregulated way, it’s actually quite dangerous,” Lents said.

A spokesperson with the U.S. Embassy in the Dominican Republic told VICE News that “there will be no new information concerning the toxicology reports until the investigation is completed.” The FBI also declined to comment on any updates concerning the investigation.

Not the first time

Over in Mexico, more than 150 U.S. tourists reported passing out and vomiting shortly after consuming small amounts of alcohol at various resorts in Cancun, Los Cabos, Playa del Carmen, and other cities between December 2017 and February 2018.

Shortly afterward, local police seized a total of 19,700 gallons of bootleg liquor from black-market tequila operations throughout the country, although it’s unclear if the tourists’ illnesses were related. Of the gallons seized, 235 were found to contain lethal amounts of methanol.

A number of countries have also seen deaths from counterfeit alcohol in recent years, according to a 2018 report from the International Alliance for Responsible Drinking. Last year, 141 people in Indonesia died from drinking a tainted batch of local moonshine called “oplosan.” And in 2016, more than 70 people died in Russia after consuming a bath tincture commonly used by counterfeiters as a low-cost alcohol substitute.

In the Dominican Republic, the International Alliance for Responsible Drinking reported that illicit alcohol makes up 29% of all alcohol in the nation. The report also found that distilled spirits make up 69% of the Dominican Republic’s black market for alcohol and estimated estimates bootleggers cost the country $262 million in revenue every year.

But the Dominican Republic’s Minister of Tourism Javier Garcia has insisted the island “a tranquil, peaceful destination and the safest in the region.”

“In the last five years, the Dominican Republic has welcomed almost 30 million people, evidencing the large preference of visitors as well as the safety levels of the destination,” Garcia said during a press conference earlier this month. “This also demonstrates these cases are isolated and regrettable. We ask the National Police to speed up as fast as possible the investigation into these cases.”

Other theories

As far back as February, Patrick Quade started noticing an uptick in tourists reporting that they too became ill at various resorts in the Dominican Republic to his open source website, IWasPoisoned.com. Now, he’s catalogued more than 1,000 cases.

“As a comparison, we received 10 reports in total in all of 2018 for the Dominican Republic,” Quade said.

The State Department, however, told NBC News that officials haven't seen an "uptick in the number of U.S. citizen deaths reported."

The Minister of Tourism of the Dominican Republic Francisco Javier García, holds a copy of an online article in a local paper saying the U.S. State Department considers recent reports on tourists' deaths to be exaggerated, at the Ministry of Tourism office in Santo Domingo, Dominican Republic, Friday, June 21, 2019. (AP Photo/Tatiana Fernandez)

Since the site started in 2009, Quade has used IWasPoisoned.com to successfully pinpoint harmful bacterial outbreaks around the world, including the 2015 E. coli outbreak at Chipotle restaurants, before they became widely reported epidemics. Both NPR and the New York Times noted that public health officials in more than 46 states have adopted the site as a tool to detect signs of potential food and drink related issues.

“In a case like this, media attention often makes more people aware that there is a place to report, and what we are seeing are real cases, that previously went unreported,” Quade said.

Quaid said that a significant number of IWasPoisoned.com users who reported being sick in 2019 suspected the spraying of insecticides as the root of their illness. But both Quade and Jaykus didn’t think that reason was plausible.

“Insecticide can make you sick, but you’d really need like massive doses of it,” Jaykus said. “It was a little mystifying to me as to how anyone could be getting that high a dose just by spraying the stuff around.”

Earlier this week, CNN also reported that more than a dozen people they interviewed say they got sick during their trip to the Dominican Republic after they smelled a powerful, chemical odor in their resort hotel rooms. They all also suffered from a number of strange symptoms including stomach cramps, nauceousness, uncontrollable drooling, and burning of the nose and throat immediately after noticing the scent.

The New York Post, The Cut, and local stations in Texas and South Carolina, have all published stories from tourists who say they became ill during their visits to the Dominican Republic.

Detecting fake booze

As alcohol prices fluctuate around the world for any number of reasons, so does the interest in illegitimate spirits. In countries like the U.K., for example, fake booze started entering the market after the introduction of minimum pricing laws, which were meant to combat binge drinking culture, last year.

According to Safeproof.org, many bootleggers typically package and sell their products in emptied bottles of cheap alcohol and pass them off as authentic and safely processed liquors to distributors.

But consumers can take a number of steps to avoid or even detect counterfeit alcohol.

One way, according to Lents, is to avoid cheaper liquors, particularly clear ones like gin and vodka. He said those types are easier to replicate because nearly all liquors, when distilled, come out clear. Counterfeiters then don’t have to worry about mimicking signature colors or consistencies in spirits like whiskey.

“These liquors are also the ones that tend to be mixed,” Lents said. “Think about your vodka sodas or your vodka and gin and tonics. This typically helps mask any funny flavors and smells that some counterfeit liquors have.”

Counterfeit liquors usually smell sweeter than regular alcohol thanks to the presence of methanol, chloroform, and acetone. Lents said people shouldn't be afraid to ask their bartender if they can take a whiff from the bottle they’re drinking from.

Consumers — or concerned bars and resorts selling alcohol — can also set a small amount on fire first. Ethanol, the part of alcohol that’s safe to drink, will burn blue, while methanol can burn green or orange, according to Lents.

“Anything that doesn’t burn blue is cause for concern,” Lents said.

“Or just stick with beer,” he added. “You don’t see a lot of this stuff popping up with beer at all. And just in case, stick with beers that you know and are familiar with.”