‘Among the most toxic in the world’: Hamilton couple survive brush with airborne aquarium toxin

Then his husband started coughing.

“I thought, well, great. So we’re both getting sick.”

Then it was his four dogs: shaking and vomiting, abnormally lethargic, spaced out.

“All of this put together,” the Hamilton man said of the roughly half-hour stretch April 13, “it was like, something is up.”

And something was.

But while most people might stand around confused if they and their pets suddenly fell ill, Evans’ mind went back to a story he said he’d read years earlier about a Quebec woman who was hospitalized after being exposed to a deadly toxin while cleaning out her fish tank.

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• Dec 31, 1969
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• Dec 31, 1969
• Comments

That afternoon, Evans was engaged in the same activity, standing over his emptied aquarium with a jug of vinegar in hand.

The avid aquarium hobbyist had wanted to give his saltwater tank a deep clean for weeks due to nagging algae issues. An arduous process, it required him to scoop up his eclectic collection of fish and corals, transfer them to a local fish store in plastic bags, go home, scrape off any lingering marine life stuck to the tank glass and then empty the tank completely.

“The idea was to take everything out of the aquarium and start from scratch to get rid of the algae outbreak,” he said. “That’s why I used vinegar, because I really wanted to give it a complete reset, which takes time.”

Instead, he and his husband ended up in an intensive care unit, their four dogs at a Mississauga vet and their home professionally decontaminated, due to a rare exposure to a marine life toxin that’s considered one of the world’s deadliest.

Called palytoxin, the poison is found in soft, colourful corals like palythoas and zoanthids, which release potent chemicals as a defence mechanism when under threat. Exposure through skin or inhalation — in humans or animals — can result in chest pain, respiratory distress, fluid in the lungs, rashes, vomiting, seizures and even death, with the onset of those symptoms ranging from a few minutes to several hours.

In Evans’ case, it was roughly three hours.

He said he poured vinegar into his tank at about 6 p.m. While he believed it was empty, still concealed within the aquarium’s sand bed were a handful of palythoas, which, after interacting with the vinegar, started to bubble and spew out particles of its odourless poison into the air.

By 9 p.m., Evans came down with what he called bronchitis-like symptoms, including a heavy chest. Within a half-hour, his husband, Chris Stewart, followed suit with convulsions and trouble breathing. His dogs set off the final alarm bell shortly thereafter, with the four of them shaking and one having difficulty holding up her head.

“I immediately thought back to that story because it was the only explanation,” Evans said of the Quebec woman, Melissa Tremblay, who in 2019 fell seriously ill after transferring her collection of zoanthids to a larger home aquarium.

“We have a carbon monoxide detector and it wasn’t going off, so that story was the only thing that came to mind. And it saved me, because otherwise I wouldn’t have known what was wrong.”

Evans is speaking out after his traumatic experience to spread awareness about certain corals which, while esthetically beautiful and sold legally, could be the difference between life and death if not treated properly.

“We’re experienced hobbyists, we were aware they had toxins, we knew about best practices and it still happened,” he said. “I didn’t ever think there was even a potential for those toxins to become airborne, and although it’s so rare, people should still be aware it can happen.”

Indeed, cases of palytoxin poising are incredibly rare, with only about one reported per year in Ontario, according to the Ontario Poison Centre (OPC).

“We very rarely get calls about these exposures,” said Dr. Margaret Thompson, medical director of the OPC, adding she couldn’t comment on Evans’ toxin case due to privacy reasons.

Corals like palythoas and zoanthids, commonly referred to as “palys” or “zoas,” are living animals capable of quickly expanding into large colonies. Aquatic hobbyists revere them for their endless variety of eccentric colours and patterns. “Beautiful, vibrant, just like flowers,” said Evans, who’s bought more than 40 different types of palys and zoas in the past decade. Quite often, the corals are sold at aquatic or pet shops alongside saltwater fish, making it easy to build an in-home marine oasis in one go.

“Within the tank itself, (the coral) wouldn’t be toxic, but as soon as you remove it and put it in the air, it releases particular toxins as a defence mechanism,” Thompson explained. “They should be kept under water at all times. If you’re cleaning or disbanding your tank, you should use enclosed plastic bags and basically scoop the coral into it while it’s still underwater, that way the toxin doesn’t become airborne or get on your hands.”

But even the keenest of eyes can miss a nickel-sized palythoa.

“One of the things palythoas can do and that they’re very good at is pulling in on itself so it looks like a lump of rock or piece of sand,” said Michael J. Risk, a coral expert and longtime McMaster University geology professor.

It’s a tendency that links back to the coral’s roots in the deep sea, where they have become fierce, aggressive chemical competitors capable of overtaking massive swaths of reefs.

Risk said to imagine looking at a single dandelion in your backyard. “You turn away for five minutes, look back, and that one dandelion has spread to five more dandelions. That’s palythoas. They spread at a rate that’s 10 times faster than other corals.”

“There are parts of the Caribbean where there are just huge sheets of palythoas — they’ve taken over everything because their toxin is so effective,” he added. “And if they’re harsh enough to kill competitors in the marine environment, they’re sure going to do a job on humans.”

While human exposure to palytoxin is “very, very rare,” Risk said all it takes for corals to release lethal chemicals is a threat.

“So something like vinegar. The minute it touches one of these little barbs on a palythoa, all of the coral’s cells will instantly discharge toxins that dissolve into the air if there’s no water in the tank.”

Once aerated, the toxins can consume an entire household, leaving humans and pets equally at risk to fall dangerously ill, Risk said.

Consider Evans’ husband, Chris, who wasn’t near the tank while it was being cleaned.

“He was upstairs, but for some reason it hit him harder than me, even though I was directly over the toxins,” Evans said. He noted Chris’ condition deteriorated so quickly the vet clinic they dropped their dogs off at called 911 to get him to hospital. “In the waiting room at the vet he was shaking and convulsing. The vet actually brought out oxygen for him until paramedics arrived.”

Evans himself was put on oxygen within “10 to 15 minutes” of reaching Credit Valley Hospital in Mississauga, which was close to the only vet they could find that night. He and Chris remained in the hospital’s cardiac ICU until April 16. Their dogs were released to Chris’ sister a day earlier. It would take another week for the couple and their pets to return home, which had to be professionally decontaminated under the direction of the OPC.

The OPC didn’t have an answer when asked why these corals, given their potential lethality, are still legal and sold at local stores. Neither did Risk, who believes they’re unsafe for domestic use.

“I personally feel they’re too dangerous to be sold and placed in a home aquarium, and I think the international transport and sale of these things should be outlawed because they’re among the most toxic in the world,” he said.

Of the dozens of palys and zoas Evans has purchased over the past decade, he said none of them came with a disclaimer warning about their toxicity or defensive reactions.

“As an experienced hobbyist, I already knew they were toxic, but I didn’t know those toxins could become airborne,” he said. “Maybe it’s a sign in the store or a message on the coral (packaging), but just something that explains how these toxins can be discharged would make people more aware.”