Scientists have discovered that blue-green algal blooms can produce a light flurry of a potent toxin into the surrounding air. While the toxin is widely known to be found in water, this is the first time it’s been identified in the air around pond water. The risk to human health and animals is unclear, but the researchers argue it does highlight that toxic algal blooms may be even more perilous than previously appreciated.
When a body of water turns a strange green or blueish color, it's often due to an algal bloom. They occur when a water system is exposed to too many nutrients, often through fertilizer run-off, allowing the excessive growth of microscopic algae or cyanobacteria in water. Algal blooms are bad news for other wildlife as the profusion of microbes deprives the wider water system of oxygen, leading to fish die-offs. On top of this, many species of microscopic algae or cyanobacteria produce nasty toxins, acting as a further threat to marine life. One of these chemicals is algal toxin anatoxin-a (ATX), more commonly known as “Very Fast Death Factor,” which is produced by an array of cyanobacteria found in harmful algal blooms.
ATX is a neurotoxin that has been responsible for many cases of deaths among livestock, wildlife, and pets that have drunk from the contaminated water. Water containing ATX can also poison humans, although it’s not been definitively linked to any deaths.
Now, a new study indicates that ATX may be able to become airborne too. In the journal Lake and Reservoir Management, scientists explain that they detected airborne ATX close to a small pond experiencing a harmful algal bloom on Nantucket Island, Massachusetts. The researchers note that the observation was made on a foggy day in September 2019, after a windy night, suggesting the toxin was likely blown up from the water’s surface by the strong wind and then held there by the thick fog.
It's unclear how common airborne ATX is — it may be that the researchers simply stumbled across the ideal but rare conditions for this phenomenon to occur. Nevertheless, they do say that this observation highlights a new potential human health exposure and needs to be investigated further.
"ATX is one of the more dangerous cyanotoxins produced by harmful algal blooms, which are becoming more predominant in lakes and ponds worldwide due to global warming and climate change," Dr James Sutherland, lead study author at the Nantucket Land Council, said in a statement.
"People often recreate around these lakes and ponds with algal blooms without any awareness of the potential problems," explains Sutherland. "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."