The Right Chemistry: Beads that slurp water are amazing, and sometimes dangerous

Super-absorbent polymers were a wonderful invention, but don’t let kids shoot them out of guns for online clout.

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Throughout my career, I have performed numerous chemical demonstrations for all sorts of audiences. While these certainly have an entertainment value, my goal has always been to use “chemical magic” as an educational vehicle. One of my favourite demos is “vanishing water” by pouring water into a supposedly empty polystyrene cup and then turning the cup upside down to show that the water has disappeared. This is then emphasized by thrusting a pencil though the cup and spinning it around, eliciting oohs and ahhhs.

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I then proceed to replace the magic with science and describe how the seemingly empty cup actually had a chemical at the bottom with an incredible ability to absorb water. Turning the cup upside down and giving it a little shake dumps out the gel that formed when the sodium polyacrylate crystals absorbed the water. At this point, it is time for a little history lesson.

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Back in the 1960s, scientists at the U.S. Department of Agriculture were working on developing methods to allow soil to retain more water. As anyone who has ever thickened a sauce with flour knows, starch can absorb water. Could modifying the structure of starch enhance its water absorbing capacity, they wondered? Success came when a polymer of acrylonitrile was attached to the starch molecule creating a novel substance that absorbed some 300 times its weight in water. Imaginatively, the term “Super Slurper” was coined for the material.

As is generally the case, a new discovery sparks attempts at improvement. Before long, scientists at the Dow Chemical Company found that a polymer of sodium polyacrylate, especially if the long polymer chains were attached to each other by cross-links, was able to absorb even more water and had no need to be attached to molecules of starch. This spawned a giant industry that by the 1970s was producing super-absorbent polymers for use in diapers, adult incontinence and feminine hygiene products, wound dressings, fuel filters and coatings to help seeds germinate quickly.

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The little packets at the bottom of packaged meat trays that absorb excess moisture make use of the same technology. Another clever application was in the drying of books and documents exposed to water. Polyacrylates compressed into sheets placed between pages dried them quickly before mould set in. And then toy producers jumped on the bandwagon.

Expandable water toys became all the rage. When sodium polyacrylate was combined with polyvinyl acetate and ethylene vinyl acetate, the resulting material could be moulded into shapes that ranged from dinosaurs to gremlins. When immersed in water, these would grow to many times their size, much to the amusement of children. Allowed to dry, they would shrink back to their original dimensions and the activity could be repeated.

That was where my story usually stopped. But now the yarn has become more complicated with the appearance of an element of danger in the form of “water beads” made of sodium polyacrylate. These are tiny balls that when submerged in water swell to the size of a marble or even a golf ball. They are sold in sets that contain thousands of coloured beads and are advertised as toys that promote sensory and motor skills, colour recognition, and counting skills. Quite a stretch for these squishy balls. They are also marketed as decorative items to fill flower vases at receptions, sometimes with glow-in-the-dark colours. Toxicity is not the issue here, sodium polyacrylate is remarkably non-toxic. Concern is about children swallowing the beads that can then expand in the gut and cause obstruction, leading to calamity. Unfortunately, this isn’t only a theoretical concern.

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The beads come with warnings that they are a choking hazard and are only suitable for children older than three. But unfortunately, they can look like candy to their younger siblings. There have been at least two infant deaths attributed to swallowing a bead, and several cases that required surgery to remove the expanded balls. While manufacturers have recalled the specific brands that caused these tragedies, there are many other varieties on the market.

And now there is a controversy about one of these, Orbeez. It isn’t about swallowing the beads because they supposedly only reach a diameter of 7 mm in the intestine, which according to the company cannot cause an obstruction. In this case, the issue is about the “Orbeez Challenge” that has gained traction on TikTok, the social media platform that has promoted other lunacies like basting a chicken in Nyquil, swallowing Tide pods, taking Benadryl until it causes hallucinations, and eating a corn cob attached to a rotating power drill.

The challenge that has alarmed police forces is all about encouraging people to shoot expanded Orbeez balls at people and animals out of what are known as “gel blaster guns.” These guns are sold as fun toys for children to engage in “safe” gunfights. I am not partial to children playing with any kind of gun, but these blasters are powerful enough to produce quite a sting if someone is hit, and the balls can cause significant eye damage, which is why they are sold with protective goggles.

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A small ball is shot out of a toy gun by a child
A child shoots a toy Orbeez gun as he plays with his little brother. Photo by Mike Hensen /The London Free Press files

The Orbeez Challenge encourages taking aim at passersby and cars with gel guns. There have already been reports of people getting hurt. The makers of Orbeez of course do not support this activity and do not sell the guns, but these and their “ammunition” are readily available from a host of companies. The guns are sometimes made to be replicas of real weapons, which is another problem. And the claim that the gel balls fragment into tiny particles that disappear when they dry is false. The fragments may become nearly invisible, but that is because they shatter into microplastics that pollute the environment.

Pollution due to super-absorbent materials is not restricted to water beads. Polyacrylates are not biodegradable and all the disposable diapers ending up in landfills constitute a problem. There is extensive research to come up with biodegradable alternatives based, for example, on polysaccharides from shellfish or agricultural waste. Sort of coming full circle from the original Super Slurper.

More than improvement of consumer items is at stake. Super-absorbent materials formulated into pills can be impregnated with drugs that are then released at a controlled rate. This is of great importance when it comes to increasing the efficacy and reducing the side-effects of chemotherapeutic drugs. Clearly, there are issues with some of the applications of super-absorbent polymers and next time I do my “Super Slurper” demo I will certainly bring up the various water bead problems.

Let’s, though, not throw the baby out with the bathwater. But you certainly do not want to throw any water beads into the baby’s bath as seen in some TikTok videos.

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Joe Schwarcz is director of McGill University’s Office for Science & Society (mcgill.ca/oss). He hosts The Dr. Joe Show on CJAD Radio 800 AM every Sunday from 3 to 4 p.m.

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