It’s a timeless lesson that applies whether you’re considering going permanently barefoot, growing dinosaurs out of DNA harvested from Jurassic amber or, apparently, making ice cream out of snow.
Ice cream made from snow is having a moment online, with cooking blogs, celebrities like Reese Witherspoon and social media influencers singing the praises of “snow cream.”
One recipe calls for combining milk, sugar, vanilla extract, sea salt and eight cups of fresh snow. Another, even shorter recipe says to mix snow, vanilla extract and sweetened condensed milk together in a bowl.
In a post on TikTok that went viral late last week, actor Reese Witherspoon demonstrated how to make her “snow salt chococinno” recipe by adding chocolate syrup, salted caramel sauce and cold brew to snow from her backyard.
But scientists say you might want to pause before digging into a bowl of snow ice cream.
‘Snow is anything but pure’
Krystopher Chutko is an assistant professor and chair of the environment and society and hydrology programs at the University of Saskatchewan who specializes in hydrometeorology. He also happens to have experience eating snow.
“I was up in the very Far North of Canada working on some glaciers, and we always hear commercials, especially beer commercials, talking about glacier-fresh water,” he told CTVNews.ca in a phone interview on Monday.
“So I collected some glacial ice, melted it down and drank it, and it tasted terrible. It was not fresh water. It was very, very dusty.”
Chutko said it’s common for snow to have an unpleasant flavour because it collects dust, soot and other particulate matter on its way down to earth, and continues to gather sediment as it, too, settles on the ground.
“Snow is anything but pure,” he said.
The particles — and sometimes even microorganisms — that cling to snow not only taste unpleasant, but some of them can make you sick. What is in your snow will vary depending on where you live and where you gather it from, with city snow more likely to capture pollutants in the air, and snow under trees more likely to contain traces of what Chutko referred to as animal “deposits.”
Factories and other industrial sites upwind can also contribute to snow pollution, and the same acids present in acid rain — like sulfuric and nitric acid — can also be concentrated in snow.
“The atmosphere itself is not clean. It’s constantly filled with stuff, whether it be smoke particles from fires, could be dust from anything, could be salt if you’re close to a coastal area,” Chutko said, “and there are plenty of living organisms that thrive in snow, and as soon as it comes out of the atmosphere and accumulates on the ground, those things are going to populate it.”
According to a 2022 report published by Western University, the porousness of snowflakes makes them “superabsorbent for a wide range of pollutants,” including vehicular exhaust particulate matter, persistent organic pollutants (POPs), trace metals and chlorides from road salts.
“POPs are some of the most dangerous pollutants because they remain active, lasting for several years within their environments before finally degrading into other chemical forms,” writes the report’s author, Ubong Eduok. “Most POPs are carcinogens. Some of them may alter the nervous systems, leading to chronic health conditions. POPs can also affect reproductive health and disrupt the immune system.”
Some sources online have suggested the solution to the problem of snow pollution involves waiting several hours into a snowfall event before gathering snow, since the snow that falls first will “scrub” pollution from the atmosphere, leaving it cleaner for the snow falling later.
However, Chutko is skeptical.
“I don’t think there’s anything to suggest that that’s true, because the snow at the beginning of a storm is created in the same way that the snow at the end of a storm is created,” he said, explaining that all snow is impure by definition, due to the way it forms.
The ice crystals that form snow are made when water vapour in the air goes straight from a gaseous state to a solid state. For water vapour to achieve this transformation, the air needs to be very cold — at least -40 C — and there needs to be a tiny particle or foreign substance for the crystal to form around. This is called the ice nucleus.
“Every snowflake has, at its core, some form of impurity,” he said. “Whether it’s at the beginning of a snowfall or at the end of a snowfall or in the middle of a snowfall, every flake is going to have some form of impurity in it.”
If you still want to try it…
Nevertheless, Chutko said the concentration of contaminants in snow is probably not high enough to cause acute illness from a small amount. Therefore, he’s not against trying it once in a while.
“I would not make it part of my diet,” he said. “It’s a fun one-off thing, but I would definitely not make a habit of it. There would certainly be long-term effects.”
If you’re determined to try this weird TikTok food trend despite knowing the risks, and you want to use the best snow you can find, Chutko said it’s best to avoid snow that hasn’t freshly fallen.
“I wouldn’t collect any snow that fell earlier than, say, today,” he said. “I wouldn’t collect anything that accumulated under a tree. I would probably avoid doing it in the city. Try to get out into the rural area around the city, preferably with no significant pollutant sources up-wind.”
And in the words of the late American musician Frank Zappa, “don’t eat the yellow snow.”