Take a look at the Periodic Table. Which out of all those elements is mankind’s oldest friend, the simple substance that gives life to the most complex matter in the universe, life itself? Oxygen, and there it stands at the top of Group XVI, head of the family of elements known as the chalcogens. The further down that family you go from oxygen however, the more distant the relative, and the less helpful.

Known since ancient times, oxygen’s neighbor, sulfur, is the layman’s go-to element for a noseful of bad times. Referred to in the Bible as brimstone, sulfur is the smell of hell, not just because of its bouquet of bad eggs, but for its association with areas of seismic activity, where the underworld met the surface world; volcanoes, geysers, mud pots, the broiling active heat of the living Earth. The ready availability of pure sulfur in nature led to ancient man to find sulfur had beneficial uses, such as in balms and fumigation, when mixed with other substances. It doesn’t take much however, to provoke plain old sulfur in making life worse for people.

Sulfur, when combined with the most abundant element of all, hydrogen, creates hydrogen sulfide, the worst smell any of use might encounter in the course of a lifetime, be it in the form of sewer gas, or swamp gas, or the smell of a tower block of waste collecting in the depths of a ventilation shaft. If sulfur gives off the smell of bad eggs, then hydrogen sulfide is bad eggs gone bad, rotten, rotting and rotted eggs, the ultimate in evil egginess. And, unless you are a professional chemical engineer, you won’t know how lucky you are if hydrogen sulfide is the worst smell you ever experience. 

The next element down from sulfur is selenium. Oxygen doesn’t smell (or at least not if you’re an earthly life form), and sulfur smells pretty bad. But selenium, good old selenium, sold by the jar in health food shops?

SeleniumCredit: Wikimedia Commons/Pumbaa

If you’ve ever opened a jar of selenium supplements and inhaled, you’ll know how bad ‘good for you’ can get. Essential to human life, albeit in amounts so small that eating the occasional brazil nut will keep you going just fine, selenium repairs body cells, and what the nose dislikes is much appreciated by the liver and the thyroid. Garlic is a good source of selenium; indeed selenomethionine, the digestible organic form of selenium, gives garlic its ‘distinctive’ odor. Selenium is not only good for insides, but our outsides too, in the form of selenium sulfide, an active ingredient in anti-dandruff shampoo. Selenium is important to us in many ways; without it we are vulnerable to disease, and prone to stunted growth and reproductive problems; modern life would grind to a halt without the selenium used in photocopiers; our very future may depend on technologies using selenium-coated solar panels. This is not to say the future stinks, but we might need to take a deep breath.

Man is not the only species to use selenium to its advantage. Skunks deploy selenium, in the SkunkCredit: Wikimedia Commons/Public Domainform of butanethiol, as part of their infamous defense against anything a skunk takes a dislike to, as cat and dog owners discover to their cost when their pet pads into their bedroom after a night’s wanderings. Noted in the Guinness Book of Records for its terrible smell, the compound butanethiol is also found in stink bombs. But what smells worse than a skunk? How about several skunks? This brings us to the organic solvent known as selenophenol. Older readers may recall plain old phenol as the antiseptic ingredient in carbolic soap, but adding selenium turns the invigorating smell of phenol into selenophenol, once described as “six skunks wrapped up in rubber inner tubes and set ablaze,” giving off a “metaphysical stench.” A careless chemist working with selenophenol in 1908 reported intense itching blisters
on contact with the skin and a smell “nauseating beyond description.”

And if you think that’s bad, try a snifter of hydrogen selenide, a tiny amount of which can wipe out your sense of smell for five or six hours and leave the nasal membranes irritated for up to two weeks. Or give selenium dioxide a try, with its alluring aroma of decomposing horseradish, or if you prefer something stronger, how about carbon diselenide, first synthesized by a research team in Germany in 1936, the smell of which escaped the laboratory, with the nearest village evacuated? These are ordinary chemical compounds respectable scientists swear never to work with, such is their nasal notoriety. But the worst is still to come.

Tellurium is a metallic element rarer than gold, a fact for which we should give thanks, as TelluriumCredit: Wikimedia Commons/Pumbaaselenium is a breath of fresh air in the Periodic Table compared to tellurium. Not only does tellurium smell bad, but it can also make you smell bad. According to the Royal Society of Chemistry of Great Britain, the simple act of exposure to half a microgram of tellurium is enough to give you the foulest garlic breath imaginable for up to thirty hours. Experiments on volunteers demonstrated consuming just 0.0015 grams of tellurium retained an unpleasant smell about them for the next eight months.

This is because as soon as any form or amount of tellurium makes contact with the human body, it metabolizes the tellurium into an organotelluride known as dimethyl telluride, secreted by the body through the breath, sweat and, to put it politely, the ‘usual outlets’ (although another unfortunate side effect of tellurium ingestion is constipation).

How bad is it to reek of dimethyl telluride? In a 2013 edition of Scientific American, a science journalist quoted the great chemist, and founder of quantum chemistry, Linus Pauling, who described the difficulties of working with tellurium to biologist Matt Meselson. Common hydrogen is a bad influence on its elemental fellows, as Pauling explained to Meselson in that although hydrogen sulfide smelled terrible, it was nothing compared to hydrogen selenide, and yet even hydrogen selenide wasn’t nearly as awful as hydrogen telluride, a smell beyond the scale of description.

Holding his noseCredit: Wikimedia Commons/Wellcome ImagesExposure to tellurium, Pauling continued, had led some chemists to develop the dreaded ‘tellurium breath’, a devastating form of halitosis which can last for months, and in extreme cases, lead the afflicted chemist to commit suicide, such is the social exclusion rendered by the dreadful, uncontrollable odor their bodies emitted. Dimethyl telluride possesses a smell so noxious, so potent, that even the objects you touch give off foul odors for days afterwards. Worse still, if you drown your sorrows at your status as a social pariah, the alcohol converts the dimethyl telluride into ethyl telluride which, unimaginably, stinks even worse.

Due to all this unpleasantness, we still know relatively little about the potential uses of tellurium, as so few people will experiment with the element, despite its discovery in 1793 (in Transylvania, of all places) predating selenium (discovered by Swedish chemist Jons J Berzelius in 1817). Of the more approachable compounds, tellurium dioxide is an anti-corrosive, while tellurium suboxide is part of the production process of compact discs and DVDs and cadmium telluride goes into the manufacture of solar cells.

As for the rest of the chalcogens, you needn’t fret about their smell; polonium is highly radioactive and lethal in microscopic doses, and so is rarely stocked by health food stores, while the last member of the group, livermorium, is only observable on an atom-by-atom basis by scientists ready to work fast, given its radioactivity is such it disintegrates within milliseconds of its synthesized creation in nuclear laboratories. Just remember if a science teacher calls you tellurium-breath, you need to stock up on the breath mints.