Refilling bottles: why it may not be as simple as you thought

Two years or so ago most of us had given relatively little thought to single-use plastics. We bought things, we used things, we put the packaging in the bin. Possibly the recycling bin. Hopefully the right recycling bin. And we thought no more about it.

Then Blue Planet II aired on BBC One, specifically episode 7, and suddenly everyone was obsessed with where all this plastic was ending up. Rightly so, since it was clearly ending up in the wrong places, and causing all sorts of havoc in the process.

People started buying reusable cups, eschewing plastic straws and demanding the option of loose fruit and vegetables in supermarkets. Wooden disposable cutlery, oven-cook food containers, and bamboo straws became increasingly common.

And people started to ask more questions about refilling containers. Why do I need a new bottle each time I buy more shampoo or washing up liquid or ketchup, they asked. Why can’t we just refill the bottle? For that matter, couldn’t I take a container to the shop and just… fill it up?

Infinity Foods allow customers to refill containers.

Shops started to offer exactly that. One such place was Infinity Foods, based in Brighton in the UK. Actually, they’d always taken a strong line when it came to recycling and reducing waste, and had been offering refills of some products for years.

Where this gets interesting from a chemistry point of view is a Facebook post they made at the beginning of this month. It said, from the 1st of November, “your empty bottle can only be refilled with the same contents as was originally intended. This includes different brands and fragrances.”

Naturally this spawned lots of comments, many suggesting the change was “daft” and saying things like “I bet it is major corporations not wanting us to reuse the bottle.

Infinity Foods argued that they were tightening up their policy in order to comply with legislation, specifically the Classification, Labelling and packaging of substances and mixtures (CLP) Regulation (EC) No 1272/2008 and others.

This post, and the comments, got me thinking. I’m old enough, just, to remember the days when random glass bottles were routinely filled with random substances. You wandered into the garage (it was always the garage) and there’d be something pink, or blue, or green, or yellow in a bottle. And it might have a hand-written label, and it might not, and even if it did, the label wasn’t guaranteed to actually be representative of the contents. The “open it and sniff” method of identification was common. The really brave might take their chances with tasting. Home-brew wine might well be next to the lawnmower fuel, and if they got mixed up, well, it probably wouldn’t be fatal.


Bottles may be single-use, but they’ve also been designed to be as safe as possible.

You know, I’m not sure we ought to be keen to go back to that, even if it does save plastic. Sealed bottles with hard-to-remove child safety caps, nozzles that only dispense small amounts (making it difficult if not impossible to drink the contents, by accident or otherwise) and accurate ingredients lists are, well, they’re safe.

And we’ve all grown used to them. Which means that now, if I pick up a bottle, I expect the label to tell me what’s in it. I trust the label. If I went to someone else’s house and found a bottle of, say, something that looked like washing up liquid by the sink, I’d assume it was what the label said it was. I wouldn’t even think to check.

You might think, well, so what? You fill a bottle, you know what’s in it. It’s up to you. But what about all the other people that might come into contact with that bottle, having no idea of its origins? What if a visitor has an allergy to a particular ingredient? They look at the label, check it doesn’t contain that ingredient, and use it. Only, someone has refilled that bottle with something else, and maybe that something else does contain the thing they’re allergic to.

Even simpler, someone goes to a shop that sells refills, fills a hair conditioner bottle with fabric softener and doesn’t think to label it. They know what it is, right? They leave it in the kitchen, someone else picks up that bottle, and takes it into the shower. They get it in their eyes and… maybe it causes real harm.

Toilet cleaner must never be mixed with toilet bleach.

Then there are the very real hazards associated with mixing chemicals. One that always worries me is the confusion between toilet cleaner and toilet bleach. Many people have no idea what the difference is. The bottles even look quite similar. But they are not the same substance. Toilet cleaner is usually a strong acid, often hydrochloric acid, while toilet bleach contains sodium hypochlorite, NaClO. Mixing the two is a very bad idea, because the chemical reaction that occurs produces chlorine gas, which is particularly hazardous in a small, enclosed space such as a bathroom.

Okay, fine, toilet bleach and cleaner, noted, check. Is anyone selling those as refills anyway? Probably not. (Seriously, though, if you finish one bottle, make sure you don’t mix them in the toilet bowl as you open the next.)

But it may not be as straightforward as that. Have you ever used a citrus-scented cleaning product? They can be quite acidic. Combine them with bleach and, yep, same problem. What if someone refilled a container that contained traces of a bleach cleaner with one that was acidic, not realising? Not only would it be harmful to them, it could also be harmful for other people around them, including employees, especially if they suffer from a respiratory condition such as asthma.

There are risks associated with the type of container, too. Some plastics aren’t suitable to hold certain substances. Infinity Foods themselves pointed out that some people were trying to find drinking water bottles and plastic milk bottles with cleaning products. These types of bottles are usually made of high-density polyethylene (HDPE). This type of plastic is a good barrier for water, but not oily substances and solvents. Cleaning products could weaken the plastic, resulting in a leak which would be messy at best, dangerous at worst. That’s before we even think about the (un)suitability of the cap.

The type of plastic used to make water bottles isn’t suitable to hold oily substances.

Plus, think of the poor salesperson. How are they supposed to judge, in a shop, whether a particular bottle is safe for a particular product? I wouldn’t feel at all confident about that decision myself. It’s not even always easy to identify which plastic a bottle is made of, and that’s before you even start to consider the potential risks of mixing substances.

In fact, the more you think about it, the more Infinity Foods’ policy makes sense. If you say that you can only refill a bottle with the exact same substance it originally contained, and you insist that the labels have to match, well, that’s easy to check. It’s easy to be sure it’s safe. Yes, it might mean buying a bottle you wouldn’t have otherwise bought, but if you’re going to reuse it, at least it’s just the one bottle.

These concerns all arise from wanting to make sure the world is a safer and healthy place. We do need to cut down on single-use plastics, but taking risks with people’s health to do so surely misses the point.

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Glow sticks or sparklers: which is riskier?

by Unknown artist,print,(circa 1605)

Remember, remember the 5th of November… (Image by Unknown artist, circa 1605)

It’s fireworks night in the UK – the day when we celebrate a small group of terrorists nearly managing to blow up the Houses of Parliament in 1605 by, er, setting fire to stuff. No, it makes perfect sense, honestly, because…. look, it’s fun, all right?

Anyway, logical or not, Brits light fireworks on this day to mark the occasion. Fireworks, of course, are dangerous things, and there’s been more than one petition to ban their sale to members of the general public because of safety concerns. It hasn’t happened yet, but public firework displays, rather than private ones at home, are more and more popular.

Which brings me to this snippet from a letter a friend of mine recently received.


In case you can’t read it, it says:

“NO SPARKLERS PLEASE – with so many children runni[ng] around, we believe it is too dangerous fro children to be [words missing] lighted sparklers around.
Last year we had a few incidents of children drinking the [words missing] glowsticks – please advise against this.”

Now there are some words missing here, but it’s fairly clear that sparklers are prohibited at this event, and it seems to be suggesting that children have managed to get into, and swallow, the contents of glowsticks. But they, by contrast, haven’t been banned. Indeed, parents are merely being asked to “advise” against it.


Does this seem like an appropriate response? Well, let’s see…

1024px-sparklers_moving_slow_shutter_speedWhat are these things? Let’s begin with sparklers. They’re hand-held fireworks, usually made of a stiff metal wire, about 20 cm long, the end of which is dipped in a thick mixture of metallic particles, fuel and an oxidising agent. The metal particles are most commonly magnesium and/or iron. The fuel usually involves charcoal, and the oxidiser is likely to be potassium nitrate. Sometimes metal salts are also added to produce pretty colours.

Sparklers are designed to burn hot and fast. The chemical-dipped end can reach temperatures between 1000-1600 oC, but the bit you hold doesn’t have time to heat up before the firework goes out (although gloves are still recommended). The sparks, likewise, are extremely hot but burn out in seconds. This makes sparklers relatively safe, if they’re held well way from the face and body, and if the hot end isn’t touched.

If. Every year there are injuries. Sparkler injuries aren’t recorded separately from other firework injuries in the UK, but the data we do have suggest we might be looking at a few thousand A&E admissions each year, and probably a lot more minor injuries which are treated at home.

Sparklers are most dangerous once they've gone out.

Sparklers are most dangerous after they’ve gone out.

The biggest danger comes from people, usually children, picking up ‘spent’ sparklers. The burny end takes a long time to cool down, but once the sparkles are finished and it’s stopped glowing it’s impossible to judge how hot it is just by looking.

The burns caused by picking up hot sparklers are undoubtedly very, very nasty, but they’re also relatively easy to avoid. Supply buckets of cold water, and drill everyone to put their spent sparklers into the buckets as soon as they go out. Hazard minimised. Well, assuming everyone follows instructions of course, which isn’t always a given. Other risks are people getting poked with hot sparkers – which can be avoided by insisting sparkler-users stand in a line, facing the same way, with plenty of space in front of them – and people lighting several sparklers at once and getting a flare. Again, fairly easily avoided in a public setting, where you can threaten and nag everyone about safety and keep an eye on what they’re doing.

Although I do understand the instinct to simply ban the potentially-dangerous thing, and thus remove the risk, the idea does worry me a little bit. I was born in the 70s and I grew up with fire. I remember the coal truck delivering coal to us and our neighbours. I was taught how to light a match at an early age, and cautioned not to play with them (and then I did, obviously, because in those days it was usual for kids to spend hours and hours entirely unsupervised – but fortunately I emerged unscathed). Pretty much everyone kept a supply of candles in a drawer, in case the lights went out. And bonfires were a semi-regular event – this being long before garden waste collections.

These days things are very different. It’s not unusual to meet a child who, by age 11, has never lit a match. If their home oven and hob are electric, they may never have seen a flame outside of yearly birthday cake candles. But so what? You may be thinking. Aren’t fewer burns and house fires a good thing?

Of course they are, but people who’ve never dealt with fire tend to panic when faced with it. If the only flame you’ve ever met is a birthday cake candle, your instinct might well be to blow when faced with something bigger. This can be disastrous – it can make the fire worse, and it can spread hot embers to other nearby flammable items.

I’m personally of the opinion that children ought to be taught to handle fire safely, how to safely extinguish a small fire, when to call in the experts, and not to disintegrate into hysterics the presence of anything warmer than a cup of tea. Sparklers, I think, can be part of that. Particularly if they’re used in a well-supervised setting, with plenty of safety measures and guidance on-hand. (As opposed to, say, picking them up for the first time at university with some drunk mates, setting fire to half a dozen at once and immediately dropping them.)

Now. Onto glowsticks. They’re pretty neat, aren’t they? We’ve already established that I’m quite old, and I remember these appearing in shops for the first time, sometime in the very early 90s, and being utterly mesmerised by that eerie, cold light.


Diphenyl oxalate (trademark name Cyalume)

They work thanks to two chemicals. Usually, these are hydrogen peroxide (H2O2 – also used to bleach hair, as a general disinfectant, and as the subject of a well-known punny joke involving two scientists in a bar) and another solution containing a phenyl oxalate ester and a fluorescent dye.

These two solutions are separated, with the hydrogen peroxide in a thin-walled, sealed glass vial which is floating in the mixture of ester and dye solution. The whole thing is then sealed in a tough, plastic coating. When you bend the glowstick the glass breaks, the chemicals mix, and a series of chemical reactions happen which ultimately produce light.

How Light Sticks work (from - click image for more)

How Light Sticks work (from – click image for more)

Which is all very well. Certainly nice and safe, you’d think. Glowsticks don’t get hot. The chemicals are all sealed in a tube. What could go wrong?

I thought that too, once. Until I gave some glowsticks to some teenagers and they, being teenagers, immediately ripped them apart. You see, it’s actually not that difficult to break the outer plastic coating, particularly on those thin glow sticks that are often used to make bracelets and necklaces. Scissors will do it easily, and teeth will also work, with a bit of determination.

How dangerous is that? Well… it’s almost impossible to get into a glowstick without activating it (the glass vial will break), so it’s less the reactants we need to worry about, more the products.

And those are? Firstly, carbon dioxide, which is no big deal. We breathe that in and out all the time. Then there’s some activated fluorescent dye. Now, these vary by colour and by manufacturer, but as a general rule they’re not something anyone should be drinking. Some fluorescent dyes are known to cause adverse reactions such as nausea and vomiting, and if someone turns out to be allergic to the dye the consequences could be serious. This is fairly unlikely, but still.

Another product of the chemical reactions is phenol, which is potentially very nasty stuff, and definitely not something anyone should be getting on their skin if they can avoid it, let alone drinking.

Inside every activated glowstick are fragments of broken glass.

Inside every activated glowstick are fragments of broken glass.

And then, of course, let’s not forget the broken glass. Inside every activated glowstick are fragments of broken glass – it’s how they’re designed to work. If you break the plastic coating, that glass is exposed. If someone drinks the solution inside a glow stick they could, potentially, swallow that glass. Do I need to spell out the fact that this would be a Bad Thing™?

The thing with hazards is that, sometimes, something that’s obviously risky actually ends up being pretty safe. Because people take care over it. They put safety precautions in place. They write risk assessments. They think.

Whereas something that everyone assumes is safe can actually be more dangerous, precisely because no one thinks about it. How many people know that glowsticks contain broken glass, for instance? Probably not the writer of that letter back there, else they might have used stronger language than “please advise against this.”

So glowsticks or sparklers? Personally, I’d have both. Light on a dark night, after all, is endlessly fascinating. But I’d make sure the sparkler users had buckets of water, cordons and someone to supervise. And glowstick users also ought to be supervised (at least by their parents), warned in the strongest terms not to attempt to break the plastic, and all efforts should be made to ensure that the pretty glowy things don’t fall into the hands of a child still young enough to immediately stuff everything into his or her mouth.

The most important thing about managing risks is not to eliminate every potentially hazardous thing, but rather to understand and plan for the dangers.

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