A Toxin From Blue-Green Algae Can Go Airborne, Study Finds

A potent toxin released by algae blooms has the potential to become airborne, recent research suggests. In what’s said to be a first, the study found traces of the toxin in the air near pond water in Massachusetts. Though it’s unclear whether this and similar toxins are harmful to people and animals when airborne, the scientists warn that the discovery is definitely worrying.

Algae blooms and the toxins they produce have become an increasingly common problem. These blooms are showing up more often and more intensely than they did decades ago, often in lakes or freshwater sources, and when they do, they can cause mass poisonings and die-offs in the local ecosystem. People and their pets exposed to these toxins aren’t safe, either—dogs dying after swimming in or ingesting algae-contaminated freshwater has sadly become an annual event.

One particularly scary toxin is called anatoxin-a (ATX), also known by its edgier name, “Very Fast Death Factor.” ATX is produced by species of blue-green algae—a group of bacteria that survive through photosynthesis, like plants (the blue-green refers to the color they usually display in massive numbers). ATX is known to have killed birds, dogs, and other animals since its discovery in the 1960s; it’s also suspected of having poisoned people. In humans, it’s been linked to blurred vision, dizziness, headache, and gastrointestinal symptoms like vomiting and diarrhea.

Though ATX has never been observed to go airborne, the researchers behind this new study theorized that it could happen under the right conditions. Their study, published in Lake and Reservoir Management Friday, seems to show that it can.

In the summer of 2019, they periodically visited Capaum Pond, found on the tiny island of Nantucket off Massachusetts. When an algae bloom appeared, they collected samples of pond water as well as air nearby, using a prototype device that collected air through a glass fiber filter. They consistently found ATX in the water throughout the summer. And during a trip in mid-September, they found the toxin in the air as well.

“This study is the first to report ATX captured on glass fiber filters adjacent to a waterbody experiencing a [harmful algae bloom],” the study authors wrote.

Other algae-related toxins have been shown to become airborne as well, but there’s a lot left unknown about how this process would work with ATX. It could have gotten suspended inside water droplets, for instance, or the bacteria producing it could have become airborne themselves. The researchers think that heavy winds the night before their collection played a part, while the fog that happened the next day might have helped it stay afloat as long as it did.

It’s unclear how much of a health risk airborne ATX might be to animals and humans. Though dangerous, ATX is produced in high amounts less often than other toxins associated with blue-green algae (one likely reason is that it degrades easily in the environment). And aside from one documented cluster of cases in France, it hasn’t been shown to harm people frequently. But since climate change will only make these blooms more frequent and harder to combat, any potential added risks from ATX and other toxins have to be studied now, the researchers say, adding that the general public should be warned about the possible dangers of these toxins.

“People often recreate around these lakes and ponds with algal blooms without any awareness of the potential problems,” said study author, James Sutherland, an environmental scientist with the Nantucket Land Council, in a statement released by the study’s publisher. “Direct contact or inhalation of these cyanotoxins can present health risks for individuals, and we have reported a potential human health exposure not previously examined.”