Elementary, my dear Watson – Br Bromine

By now, you should be getting quite familiar with some of the fascinating titbits of information it’s possible to unearth (pun intended) about elements.

In previous articles, we’ve explored the development of the Periodic Table (a.k.a. the Periodic Table of the Elements), and examined the elements Hydrogen, Carbon, and Mercury.

This time, for the fifth in this series, I’m going to take a closer look at the only other element which can be found in the liquid state at room temperature. Two others come fairly close, these being caesium and gallium, but they are not actually liquid, just very soft. The element which truly is a liquid is Bromine.

Figure 1: Bromine and the Periodic Table of the Elements
Modified from 2012rc, licensed under CC BY 3.0

As you’ll see from the Periodic Table above, bromine lies in Group 17. These are the halogens. They include fluorine (F), chlorine (Cl), iodine (I), astatine (At) and the synthetic radioactive element tennessine (Ts).

The ’hal’ in halogen comes from the Greek word for salt. They all react with sodium to produce sodium salts (halides), of which sodium chloride (common table salt, sometimes called halite) is the one you’ll be most familiar with.

The elements in this group are a toxic and reactive bunch and they are non-metals (well, mostly). When we get to the heavier ones, the game changes a bit, but there’s chemistry for you. Always throwing out interesting morsels.

Astatine, bromine’s cousin, is not really a very well-known element at all. For one thing, it is the rarest naturally occurring element in the Earth’s crust at just 3×10−20 ppm. However, although it’s ‘naturally’ occurring, this is simply as the decay product of heavier elements. A sample of pure astatine has never actually been isolated but, technically, it will be a solid at room temperature and, technically, it should behave very much like iodine. It’s an extremely radioactive element though, and the half-life of its most stable isotope is a mere 8 hours.

Tennessine is even odder, and despite living in the same group as bromine, is a metal. It’s a synthetic element, again highly radioactive. With an atomic number of 117, it’s the second-heaviest known element.

Group 17 elements have seven electrons in their outermost shell which means they are short of only one electron to fill it. This makes them very reactive indeed. The halogens really ain’t picky—they’ll grab electrons from wherever they can, so will happily react with both metals and non-metals. Due to this keen reactivity, the halogens are not found as ‘native’ elements on Earth but in combination with other elements, as compounds.

When they are isolated into their elemental form, the halogens are so reactive that they form bonds in pairs—never existing as single atoms. This means that all of them, bromine included, exist in elemental form as diatomic molecules. That ‘diatomic’ simply means that each molecule of the element comprises two atoms, bonded together. Other elements do this as well (e.g. O2, H2, Cl2). For bromine, these diatomic molecules are liquid, Br2.

Whilst we’re on the subject of reactivity, @upset posted this video about our last element, mercury, reacting with aluminium, and someone commented that this is why it is absolutely banned on all aircraft, even in checked luggage. Bromine simply gives a sly grin at this point and simply says “hold my beer!

Although a liquid at room temperature, bromine won’t stay that way for long if you crack open a bottle. The deep reddish-brown, rather sinister-looking, oily liquid has a high vapour pressure (an indication of its propensity to evaporate) so it is volatile. It readily converts to a gaseous state.

Figure 2: A sealed glass sphere containing bromine
W. Oelen, licensed under CC BY-SA 3.0.

You can see this above, with the liquid at the bottom of the sealed sphere and in little globules around the inner surface, and the fumes filling the space completely. The profuse fumes given off are a little heavier than air (it’s fascinating to watch the vapour roll across a table and drop to the floor), and are a characteristic orangey-brown, with a sharp, pungent, almost bleach-like odour.

This volatility poses something of a challenge because, since its molecules are small, bromine leaks out of screw-topped storage bottles with ease. For this very reason, it is often stored in sealed glass ampoules—it takes something like this to contain it. There’s an obvious disadvantage here as you need to break the container to access it. Once broken into shards of glass, you cannot store any leftover bromine.

It is not a hugely abundant element, something like the 50th most common in Earth’s crust, found at about 2.4 parts per million (ppm). You can contrast this with mercury, which we looked at last time, at only 0.08 ppm. But, in seawater, it is more concentrated, as the 35th most abundant element, typically found at around 65 ppm. Astonishingly, this concentration rises to around 4,500-5,000 ppm in the surface layers of Israel’s Dead Sea, the richest source on earth.

For once, this element is not one of those which was identified by our old friend Lavoisier. Bromine was actually isolated by two chemists independently, but around the same time, so they share the credit.

Figure 3: The discoverers of bromine, Löwig and Balard
Public Domain

In 1925, at Heidelberg University in Germany, chemistry student Carl Jacob Löwig isolated the element whilst performing experiments on mineral salts from a salt spring in his hometown of Bad Kreuznach. Löwig was asked by his professor to isolate more of this strange substance so that it could be examined more thoroughly. However, just a few months later, before Löwig had completed this task, the French chemist Antoine Jérôme Balard recognised a previously unknown element that he isolated from a concentrated residue of seawater, left over from the manufacture of sea salt at Montpellier.

In fact, these two men pipped to the post an extremely well known and well-respected chemist with this discovery. Justus Freiherr von Liebig (he of the Liebig condenser) had been sent a sample of salty spring water from Bad Kreuznach by a salt manufacturer in 1925, requesting that the water be analysed. Liebig did so and after his experiments was left with a dark reddish-brown liquid. However, rather than recognise this as a new element, he simply assumed that it was a compound of iodine and chlorine. As I said earlier, there’s chemistry for you.

It was the French Academy of Sciences who suggested that Balard give this substance the name ‘bromine’ (he had originally called it muride). This name derives from the Greek βρῶμος, which means foul smelling. Because of this, bromine has been given the symbol Br.

Bromine’s atomic number is 35 which, as we’ve seen with other elements means that each bromine atom has 35 protons in its nucleus. We’ve seen that elements often exist with more than one isotope (where the numbers of protons found in the atom’s nucleus remains the same, but the number of neutrons differ). Bromine is no exception, and has thirty-one of them: 67Br, 68Br, 69Br, 70Br, 71Br, 72Br, 73Br, 74Br, 75Br, 76Br, 77Br, 78Br, 79Br, 80Br, 81Br, 82Br, 83Br, 84Br, 85Br, 86Br, 87Br, 88Br, 89Br, 90Br, 91Br, 92Br, 93Br, 94Br, 95Br, 96Br and finally, 97Br.

Of these, only two are stable, naturally occurring isotopes, 79Br (with 35 protons, 44 neutrons) which accounts for about 51% of all bromine on Earth, and 81Br (with 35 protons, 46 neutrons) which makes up the other 49%.

So, what is interesting about this rather smelly element?

At one point, the largest bromine plant of its kind in the world was the Octel Chemical Factory at Amlwch, which was established in the early 1950s on the island of Anglesey in North Wales. This plant extracted bromine from the surrounding seawater, drawing in some three hundred thousand gallons of seawater every minute, initially to create brominated anti-knock additives for the petroleum industry but later diversifying into other bromine products. The plant could produce one ton of bromine from twenty-two thousand tons of seawater. Although documented in a rather poignant Urbex video, little now remains of this horribly vandalised historic site, which remained in operation until 2004, especially since demolition work commenced in 2019.

Figure 4: What’s left of the former Octel Chemical Works site, Amlwch
Peter Whatley, licensed under CC BY-SA 2.0

Rather than from seawater, bromine is now extracted on an industrial scale from salt lakes, some of which are unusually rich in the element. The primary extraction sites are located in the USA (the world’s largest overall producer of bromine products), in China (which is also the world’s largest bromine consumer), and at the Dead Sea, which boasts the highest concentrations of bromine in the world. Here, both Israel (the world’s second largest producer, and the largest producer of elemental bromine) and Jordan have constructed massive solar evaporation ponds and mineral extraction plants at its southern tip to exploit this.

This is all well and good but, once extracted, it needs to be moved to where it will actually be used. As we’ve already seen, bromine is a highly reactive element. It’s a strong oxidising agent (it grabs electrons readily from other elements). Because of this, it reacts vigorously, a.k.a. scarily enthusiastically, with a range of other materials. These include reducing agents (elements which can donate electrons). It also reacts strongly with many organic materials, including the tissues from which the human body is composed. It will cheerfully attack some plastics and rubber.

Whilst dry, bromine isn’t terribly reactive with most metals. The exceptions are aluminium, titanium, mercury and the alkali metals (with which it reacts violently). The problem comes as bromine is hygroscopic, so rapidly absorbs water from the atmosphere. This drastically increases its reactivity, meaning that few metals are actually resistant to moist bromine.

Although bromine itself cannot ignite and burn, that doesn’t mean fires are not another potential problem. The heat generated by reactions can be enough to kick off combustion in other materials nearby.

Figure 5: Hazard pictograms for elemental bromine
Public Domain

In my view, somewhat modestly, bromine is labelled as toxic, corrosive, and harmful to the environment. This makes both handling and transportation a serious logistical challenge. It can be shipped only when extraordinarily tight safety measures are in place. These are covered in the ‘Recommendations on the Transport of Dangerous Goods’, a.k.a. the UN Orange Book.

From the ICL plants in Israel, specially constructed large lead-lined tanks (22 ton, so very large!) are used to transport it. These have to undergo regular rigorous checks and inspections, oh, and just in case… specially trained teams of professionals have been set up worldwide to deal with emergencies. They will likely need to contend with hazards from both the gaseous and liquid phases of any spill simultaneously, as well as subsequent reactions, so special protective (gas tight) suits, masks and respirators have been devised… just in case. Bromine really is a scary element.

Although bromine as an element was unknown in past times, its compounds have found a variety of uses. Some of the most interesting to me are organic compounds of bromine which produce beautifully coloured dyestuffs.

Figure 6: Bromine compounds of Tyrian purple
SharpieType301, 2023

Known as Tyrian purple, and by the names Royal and Imperial purple, this was actually a mixture of compounds. These included the purple-blue 6-bromoindigo, with the formulae C16H9BrN2O2 and the red-purple 6,6′-dibromoindigo, with the formulae (BrC6H3C(O)CNH)2.

This deep reddish-purple substance was a highly prized natural dye, extremely valuable to a series of Mediterranean cultures in antiquity, including the Minoans, Phoenicians, Canaanites, Hebrews, Greeks, Carthaginians, and Romans.

This dye was valued more highly than gold (it was actually worth more by weight than any other material that was traded at the time). A pound in weight of pre-dyed wool (which held just a tiny proportion of the actual dye) would set back the buyer to the tune of a pound’s weight in gold!

For this reason, ‘the purple’ was specifically used to indicate high rank, prestige, wealth, and power. Its immense value meant its use was restricted (sometimes by rigorously enforced legislation, such as the Sumptuariae Leges of Rome), being reserved primarily for royal garments, although it was used for other ceremonial or ritual robes.

The splendid silken shroud in which Charlemagne (the ‘father of Europe’) was wrapped was richly decorated with gold thread, but the gloriously coloured silk was dyed in Tyrian purple. It’s glorious hues and opulence are respected to this day. Within the Roman Catholic Church, cardinals are still referred to as ‘wearers of the purple’.

Tyrian purple was produced from the mucus secreted by several, now rare, species of medium-sized predatory sea snails, native to the eastern Mediterranean. They belong to the Muricidae (Murex) family, e.g. Bolinus brandaris, Hexaplex trunculus, Stramonita haemostoma and a few other species. Since these creatures often lived in relatively deep waters, they were caught in baited traps, similar to lobster pots.

Figure 7: Murex shells, one species of shellfish which are the source of Tyrian purple
16:9clue, licensed under CC BY 2.0

To produce even a small amount of the precious dye took a veritable mountain of these shellfish. Discarded shells built up vast mounds. At one site alone, near Sidon, the spoil heap stood a hundred and thirty feet in height. The historian Béatrice Caseau calculated that:

10,000 shellfish would produce 1 gram of dyestuff, and that would only dye the hem of a garment in a deep colour

Making the dye was neither a simple nor a pleasant process, taking around ten days to complete… and it required rather a strong stomach.

Firstly, the snails had to be collected—backbreaking work. Then, the hard shells have to be broken open, allowing access to the flesh. They are tough beggars, so if you’ve ever shucked oysters (which are bivalves so much more straightforward) you’ll appreciate the sheer effort of this laborious drudgery.

Then, the hypobranchial glands (the small glands which produce the sticky mucus) must be separated from the flesh. This gland lies under the mantle just behind the rectum. It forms part of the excretory system of molluscs, but the snails also secrete this mucus when harmed.

Processing must be carried out in fairly close proximity to where the snails are harvested, as they need to be alive and fresh when the mucus is collected. It starts to degrade the moment the snail leaves the water. Indeed, writing during the first century AD, Pliny comments that “the fresher the extract, the more powerful the dye”.

When extracted from the snail’s flesh (the majority of which will be left behind and, unless discarded, continue to rot), the gland is whitish-grey, and exudes a small quantity of milky, colourless liquid, the mucus. However, as this dries, it gradually starts to oxidise (perhaps putrefy might be a better term?), turning first yellowish-green, then turning blueish, and finally to purple.

This step to extract the gland isn’t really practical for the smaller shells, so these would be crushed, along with their shells, and the mixture allowed to sit and steep for several days to extract the required chemicals. I’m quite pleased to say that I can only imagine how fragrant this practice must have been, but writers such as Aristotle, Vitruvius, and Pliny the Elder described the production of Tyrian purple (a complex process, details of which were closely guarded for millennia). They speak of the ‘hideous stench’ from vats of decomposing shellfish. It’s been said that the process was so offensive that if, after marriage, a man became a dyer, his wife was allowed to divorce him!

At this stage, the extracted glands, unless used immediately to dye fabrics must be carefully cleaned and stored. As an aside, technically, the required mucous secretions can be ‘milked’ from the snails. This, however, despite being rather kinder to the snails, simply isn’t practical since the substantial quantities required to make a usable amount of dye make this alternative prohibitive in both time and expense.

The next phase is to produce a purified pigmentation. The chemistry, while not understood as such in antiquity, is complex. The ancients worked empirically, but biochemical, enzymatic, and photochemical reactions all play a part, as do reduction and oxidation reactions. This makes the process painstakingly slow, but eventually a concentrate of the active component of the dye is achieved, and any grit and contaminants which could damage the fibres to which it is applied are removed.

They dyeing process was also laborious, and cloth was dyed ‘in the wool’, that is hanks of raw wool were dyed before being spun into yarn and woven into a fabric (rather than dying a completed garment) as this produces a more even and permanent colour.

The precise process for this (and it is likely that there was more than just one) was a closely guarded secret, sadly one which had long been lost. But in 1998, one successful method was rediscovered by a retired engineer, John Edmonds, who performed practical experiments incorporating information from old manuscripts. There’s a nice, if slightly irritating video of Tony Robinson, from his series ‘The Worst Jobs in History‘, showing him ‘helping’ Edmonds with this unenviable task. The juicy bits start at c.40 minutes in.

Interestingly, the colours produced by the dye varied, dependent on the species (or mixture of species) of sea snail used. They ranged from the deepest purple, through an indigo-blue, to mauve, pinks, and a rich, dark red. The most highly prized shade was a ‘blackish, coagulated blood’ colour, which sounds, er, delightful, but I guess tastes do change. It is now thought that fabric would have been twice dyed to achieve this precious colour, using two different species of snail.

Figure 8: Colours produced with the sea snail dye
Wikimedia Commons, licensed under CC BY-SA 4.0

The great expense of Tyrian purple wasn’t only down the challenges of production, though. The pigment’s fame, costliness, and desirability also, in part, rested on the fact that, unlike other natural dyestuffs, the colours produced didn’t fade in sunlight. Instead, they intensified, and became brighter.

The earliest identified use of ‘the purple’ comes from Thera (Santorini) and Rhodes, where pigments in wall paintings have been chemically identified as Tyrian purple. Amazingly, these pigments date to around 1,700 BC. Similarly, in textiles, fragments of Iron Age fabrics (dating to c.1,000 BC) dyed with Tyrian purple have been recovered from King Solomon Copper Mines in the Timna Valley in Israel. Even today, having lasted for millennia, their colour is beautifully rich and vibrant.

Tyrian purple’s use at the time of King David and King Solomon, and the reverence in which it was held cannot be underestimated. There is even reference to the dye in the Bible:

Solomon the King
Made himself a palanquin:
He made its pillars of silver,
Its support of gold,
Its seat of purple,
Its interior paved with love.

Although we don’t make much use of Tyrian purple today, other organobromines (organic compounds which comprise carbon and bromine atoms) still find a number of uses, including in synthetic dyestuffs, particularly azo dyes.

Although most azo dyes are non-brominated, incorporating bromine in them can make them more stable and longer-lasting. A downside to this is their toxicity, through both brominated and non-brominated have been flagged as carcinogenic and/or mutagenic.

A rather more direct form of harm came with the use of a simple aromatic halogenated organic compound, xylyl bromide C6H4(CH3)(CH2Br), during WWI. Despite the Hague Conventions of 1899 and 1907 which explicitly prohibited the use of “poison or poisoned weapons” in warfare, this was the fiendish brainchild of German chemist Karl von Tappen, an idea which essentially began Germany’s chemical weapons programme.

In January 1915, the first significant gas attack took place during the Battle of Humin-Bolimów when, for the first time, German forces fired some 18,000 so-called ‘T-shells’ (T-Granate, tear gas shells) on Russian positions west of Warsaw. Thankfully, the bitterly cold winter temperatures meant that the chemical did not disperse as anticipated (in effect, it froze). The attack, whilst awful, did not deliver the desired result—Russian forces were not rendered hors de combat.

The toxicity of bromine-based compounds is without question. This means that they have found some uses as pesticides, fumigants, and biocides. It might surprise you, it sure did me, to know that 1-Bromo-3-chloro-5,5-dimethylhydantoin (BCDMH) has been used not only in sanitising systems for pools and hot tubs to kill off harmful bacteria, viruses, and fungi…. but in the purification of drinking water!

Organobromines have also been exploited in a limited number of pharmaceuticals. They’ve been used as vasodilators, to treat vascular disorders (e.g. migraine, Raynaud’s disease and some forms of dementia). It was sold as part of the antiseptic mercurochrome, which you may remember from in the article about mercury (the compound being merbromin, C20H8Br2HgNa2O6).

Another application was to treat severe insomnia. The drug in this case is the sedative brotizolam. If the end of that particular name jangles a few uneasy bells, that’s because it’s not unrelated to a central nervous system depressant we’ve heard quite a lot about in the past few years.

Organobromine compounds are also used as indicators, mainly for scientific and medical applications (e.g. bromothymol blue to measure near-neutral pH, and others). But by far the widest use comes in use as fire-retardants, indeed brominated retardants are the current largest industrial use for bromine.

As you take a look around yourself, including at whatever device you are using to read this article, you’ll doubtless find organobromines in many of the materials you see. They can be found most frequently in plastics, and in electrical and electronic equipment, but also in textiles, furniture foam, and in thermal insulation for the construction industry.

Although there are a number of other types, the two most commonly encountered are the polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDDs). Similar chemicals are also used in halon fire extinguishers. The use of organobromine fire-retardants is on the increase, but this is not without some concerns as they are known to be hormone disrupters and can have a harmful impact on the central nervous system. That said, would you prefer to die in a fire?

But bromine hasn’t only been exploited commercially in the form of organic compounds. Inorganic compounds (those which do not include carbon) have also been well utilised.

The first commercially viable photographic process was the daguerreotype, named after one of the forerunners of modern photography, Louis-Jacques-Mandé Daguerre. Before I tell you more about him, I’d like to take a small detour to mention a local lad who set the stage for Daguerre’s work.

This is Thomas Wedgwood, who some have called ‘the first photographer’. Thomas, son of the great Josiah Wedgwood, was born at Etruria Hall, not far from where I write. This family home was built alongside the newly constructed Trent and Mersey Canal where Josiah also built a village for the workers at his Etruria Works factory.

Thomas enjoyed a privileged childhood which allowed him to indulge his love of art, and experiment with capturing images formed using a camera obscura onto paper or white leather coated with a light-sensitive chemical, silver nitrate.

He was known to have been working on this in the 1790s. By 1802, the great British chemist and inventor Sir Humphry Davy, with whom young Thomas collaborated in this work, wrote an article in the Journal of the Royal Institution crediting the young man with this discovery.

Figure 9: Davy’s article in the Journal of the Royal Institution
Wellcome Collection, Public Domain

Although he lived to see this, Thomas, never a strong man, died in 1805 aged just 34. Unfortunately, he had not been able to ‘fix’ his captured images. Unless stored in total darkness, they gradually darkened to the point where all detail was lost. Who knows what he might have achieved, had he survived.

It took until the 1830s for Louis Daguerre to refine a process (originally developed by his somewhat overlooked ‘partner’, Nicéphore Niépce) whereby an image could be ‘fixed’ to permanency, by immersing the photographic plate in a hot, saturated solution of sodium chloride (common salt).

His ‘daguerréotypes’ relied on fumes of iodine to producing a photosensitive surface coating of silver iodide on the silvered copper plate, sensitising the plate to light. The one-off images this produced were sharp, accurate, and allowed for fine detail to be captured, as can be seen in his ‘View of the Boulevard du Temple’, a street in Paris, below.

Figure 10: Daguerre’s 1838 ‘View of the Boulevard du Temple’
Louis Daguerre, Public Domain

He announced his discovery in January of 1839. Although a major milestone, Daguerre was all too aware that exposures of some twenty minutes to half-an-hour in extremely bright sunshine was required—alright for still-life images perhaps, but not practical for portraiture.

In consequence photography might have languished, until in December of 1839, Paul Beck Goddard and Robert Cornelius first introduced bromine into the daguerreotype process in the USA, producing more sensitive plates which speeded up exposure times.

Meanwhile, John Frederick Goddard of London (a coincidence in surnames if ever there was one) was following a similar path. By the autumn of 1840, he published his method (using bromine with iodine) in the Literary Gazette, commenting that it was now possible to take pictures in subdued light.

Between the two Goddards, by including bromine into Daguerre’s original process, now images could be captured in just minutes, even seconds. The history of photography took off and silver bromide is still a chemical commonly used in film photography.

Sodium bromide was also used in medicines in the 1800s and early 1900s (as were the bromides of potassium, calcium, strontium, lithium, and ammonium). The bromides were found to be natural sedatives and anticonvulsants, so were used to reduce seizures, in a potential remedy for epilepsy (it is still used as a veterinary drug in this respect).

Interestingly, there’s another side effect, which led to an urban myth still in circulation to this day. This is that their use has a marked effect on the libido, causing users to become temporarily impotent. The story goes that the British Army deliberately added potassium bromide to tea (and sometimes food) served to soldiers and PoWs during WWI, possibly into WWII and beyond.

This legend is well-known, not only in the UK, but around the world. In Poland, coffee was said to be thus doctored, for the French, it was rumoured that soldiers were issued adulterated wine.

Although it has been firmly debunked, this was said to greatly reduce ‘problems’ which stemmed from the frustration of unfulfilled sexual urges. To be quite honest, the thought of drinking a salty cuppa rather puts me off my stride, but Spike Milligan makes his views pretty clear in one of the seven autobiographical books he wrote, this one Rommel? Gunner Who?, when he says:

“…the only way to stop a British soldier feeling randy is to load bromide into a 300lb shell and fire it at him from the waist down.”

Figure 11: 1945, Queue for a brew at a NAAFI Mobile Canteen
IWMCollections, Public Domain

In offerings from the NAAFI van or no, when it comes to motor vehicles, bromine’s compounds did find some verified, if rather concerning uses.

In the 1920s, Pb(C2H5)4, a lead compound (tetraethyllead or TEL) was first added to petrol to improve the performance and fuel economy of motor vehicles. Coincidentally, TEL was actually first synthesised in 1853 by someone we’ve met earlier in this piece, the man who was one of the joint discoverers of bromine, German chemist Carl Jacob Löwig. Small world, eh?

Anyway, leaded fuels did indeed improve engine performance and reduce knock (over to you here, petrol-heads, please don’t ask me to explain this!), but the downside was that deposits of lead and lead oxide built up inside the hot engine, eventually obstructing it. Not ideal.

To get around this, another molecule, the bromine-based 1,2-dibromoethane, was added to the petrol. This lead scavenger reacted with the lead, effectively ‘soaking up’ the problem before it became a crisis. Great, eh?

Actually no. The reaction produces volatile compounds, lead(II) chloride (PbCl2) and lead(II) bromide (PbBr2). Whist this gets rid of the problem in the engine, these are flushed out in exhaust fumes, thus depositing large quantities of lead into the atmosphere. Whilst this wasn’t exactly great news for adults, the effects of lead poisoning on children were deemed much more problematic, leading to a push to phase out leaded petrol. As the use of tetraethyllead dropped (leaded petrol hasn’t been available from petrol stations in the UK since 1st January 2000), other anti-knock solutions were introduced. However, some of these pose their own problems.

Brominated chemicals have made their way into our food and drinks. Small quantities of potassium bromate (KBrO3) were, at one time, added to wheat flour to improve its baking qualities. Now banned in the UK as a possible human carcinogen, it’s still in use in bread and other baked goods the USA.

As an emulsifier, brominated vegetable oil (BVO) encourages the suspension of one liquid, e.g. oily citrus flavourings, in water-based foodstuffs. It used to be widespread in popular soft drinks, such as Pepsi, Coca-Cola, and Fanta. However, BVO is said to have been “linked to major organ system damage, birth defects, growth problems, schizophrenia, and hearing loss”. Lovely, isn’t it? Again, now banned in the UK, it is still used in the USA and Canada, and can be found in something like seventy-five carbonated soft drinks. Oh, and excess consumption can lead to a rather unpleasant condition called bromism so, boys and girls, please don’t try this at home.

I’ll leave you with a final thought which relates to this element. Until fairly recently, it was thought that bromine, whilst present in small quantities in the human body, performed no known biological role in humans or other mammals. But, about ten years ago it was discovered that bromine actually is essential to the formation of basement membranes. These are thin, flexible, sheet-like matrices which provide support for cells and tissues (a bit like biomolecular scaffolding). These membranes also play an important role in cell signalling.

As you’ll recognise from this jolly tale, the ‘science’, as we’ve been told so vehemently to believe in recent times, is always quite indisputably settled.

© SharpieType301 2023