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Odour, Odour: what artificial air-fresheners could be doing

Linda B. Buck and Richard Axel were awarded the Nobel Prize in Medicine and Physiology in 2004 for their research into understanding the science behind the perception of the sense of smell. Their work led to the subsequent discovery of more than 1,000 different genes responsible for appreciating different types of odour, though some of these remain dormant in many people.

My wife strongly believes that in my case 999 of them don’t work, except for the one responsible for the smell of coffee.

Such statements make me philosophical. Does she understand that the perception of smell of a stray dog is 10 million times more astute than that of the most intelligent human on earth?

Despite the fact that I cannot differentiate burnt toast from incense sticks at 10 feet, I am pretty sure there is a change in the perception of smell, from the consumer’s perspective. Today, enter any room and chances are that you would smell lavender, vanilla, rose or some exotic wild flower, depending on the owner’s taste and budget. From the stinking toilets and dark closets, the technology of good smell has travelled out to boardrooms and car interiors. The naphthalene-balls of yesteryear have given way to sophisticated air-fresheners.

Air-fresheners come in different shapes and sizes, from solid cakes to liquid dispensers, from aerosol cans to battery-powered canisters; the business of good smell has invaded every nook and corner of our life. With an estimated $8 billion annual worldwide sales, the air freshener market is growing every year.

The underlying technology is simply brilliant. An air freshener is not just a perfume. The fragrance needs to remain suspended in the air so that the stale smell is kept away long enough. To do that, scientists had to piggyback the fragrance on top a molecule, one that is easy to aerosolise and at the same time remain suspended for a long period without getting precipitated or blown away.

‘Phthalates’ (pronounced tha-lates) were first introduced as an additive to plastics to make it more plastic, replacing the pungent camphor, which was used till 1920. Phthalates quickly became popular. Their use increased from plastic wrappers to toys, from packaging materials to cosmetics, and they became an integral part of human society.

Human exposure to phthalates is so ubiquitous that it took years of research to confirm that they are toxic to us, but when they did, the data were disturbing. Phthalates tend to suppress androgenic hormones, alter growth and development and cause neuro-endocrine disturbance; we call them gender-benders. Growing kids happen to be the most susceptible group.

Over the years the data became stronger and in 2008, under pressure from the Environmental Working Group (EWG), the U.S. Congress banned six different phthalates from children’s toys and cosmetics.

The Natural Resource Defense Council (NRDC) last year randomly tested 14 commonly available brands of air-fresheners in the U.S. market. Twelve of them contained high levels of phthalates. Surprisingly, none of them listed phthalates as a constituent of their product. This subsequent uproar resulted in the withdrawal of these brands from the U.S. market.

But that is just the tip of the iceberg. One way to keep the fragrance float in air is to add small amounts of terpene, acetone, toluene and dicholoro-benzene. They reliably do their job, keeping your olfactory nerves happy — but they do something more.

Terpenes react to ozone and create pungent formaldehyde, which notoriously causes broncho-spasm (ask any medical student going to the anatomy dissection hall), acetone is toxic to blood and heart (read the warning on the nail polish remover container) while toluene targets the central nervous system. 1-4 dichloro-benzene is known to cause bronchial asthma and decreased lung function. The very fact that these molecules remain suspended for long after you press that nozzle makes the toxicity more profound for the poor consumer.

From the office to the car, from home to restaurant, waiting halls to rest rooms, the fragrance, tagged by the phthalates and company, follow you wherever you go, in effect forcing you to inhale the chemicals for far longer than you can imagine or your kids can tolerate.

If you are one of those who are finicky about bad odour, here is a piece of advice before you press that nozzle. There is an economically viable and technologically simple solution available to get rid of the problem of bad smell. Open the window and let the fresh air and sunshine in.

I have tried it; it works very well for me — even with that single functioning gene.

tinynair@gmail.com

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Printable version | Apr 7, 2020 4:14:46 AM | https://www.thehindu.com/opinion/open-page/odour-odour-what-artificial-airfresheners-could-be-doing/article6555814.ece

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