This article was first published in聽
Can a 鈥渇ragrance-free鈥� product have a smell? Absolutely. Can an 鈥渦nscented鈥� product contain any ingredients that have a smell? Yes. It鈥檚 all a matter of semantics, although there are no universally recognized definitions here.
Unscented products are formulated to have no smell but can contain ingredients that have a smell, but the smell has been neutralized by 鈥渕asking鈥� components. A fragrance-free product cannot contain any ingredients that have been added to impart a smell, but may contain ingredients that have a scent but are not added because of their scent. For example, if a cream is made with an oil that has a smell, it can still be labelled as fragrance-free because the purpose of the oil is to act as an emollient, not as a scent. But it could not be labelled unscented. However, if a product is formulated with lavender, for example, but some chemical such as cyclodextrin is added to mask the smell, the product can be labelled as 鈥渦nscented.鈥�
This type of terminology is important to understand because someone who is allergic to lavender can still be allergic to a product in which the smell is masked, but they may not realize that the allergen is present because of the unscented designation.
In general, fragrances are added to make a consumer product more appealing and can be categorized as 鈥渆ssential oils,鈥� as 鈥渘atural鈥� or as 鈥渟ynthetic.鈥� Essential oils are complex mixtures that are isolated from plant sources. Natural fragrance molecules are single molecular entities derived from a natural source. Geraniol, extracted from roses, would be a natural fragrance. But geraniol synthesized in the lab would be a synthetic fragrance even though it is exactly the same substance. You can also have fragrances that are synthetic molecules not found in nature at all.
Fragrances in consumer products can be made up of literally hundreds of components, both natural and synthetic. The individual compounds do not have to be listed by name on labels. Unfortunately, some of these can cause adverse reactions in people, especially if they already suffer from some sort of respiratory problem. They can also react with ambient compounds in the air to generate secondary pollutants. For example, limonene and pinene, used to impart lemony or pine odours to cleaning agents or air fresheners, can react with indoor ozone to produce formaldehyde, glycol ethers or hydroxyl radicals, all of which are irritants. Most people, of course, are not at risk, but asthmatics can be.
Sometimes fragrances serve a purpose other than just to impart a pleasant smell. When infants are bathed in fragranced bath products, there is an increase in infant-mother engagement. Somehow the scent reinforces the infant-mother bond. There鈥檚 another possible benefit. In one study, infants bathed with fragrant products spent less time crying before falling asleep and experienced deeper sleep than babies bathed with unscented products.
On the other hand, it is also possible for babies to develop allergic reactions to fragrances. Over the years, the fragrance molecules most likely to cause allergic reactions have been identified and are not used in baby products. That, though, doesn鈥檛 eliminate all concerns, such as that of the issue of phthalates.
Phthalates are used to extend the longevity of a fragrance by slowing down the evaporation of volatile components. But they can also be found in fragrance-free and unscented products because they are also effective solvents that can help ingredients mix well.
So, what is the problem? Phthalates are 鈥渆ndocrine disruptors,鈥� meaning that they can interfere with the action of hormones, potentially causing health problems. They are not unique in this capacity; we are regularly accosted by hundreds of endocrine disruptors both synthetic and natural. Still, if phthalates can be avoided, so much the better. With personal-care products, the only way to be sure of their absence is if the label says 鈥減hthalate-free.鈥�
Now let鈥檚 flip to the other side of the smell coin 鈥� instead of adding smells, how to get rid of them. Bad smells are not rare. Pet odours, the stench of garbage, halitosis, body odour, bathroom aroma, mildew fragrance and numerous others annoy us on a regular basis. There are several options in the battle against them. Odour can be masked by a more powerful one, which is essentially what floral-scented air fresheners do. Sort of like masking a small noise with a large bang. But smelly molecules can also be removed from the air in several ways.
Air purifiers pass air through activated carbon filters that can bind smelly compounds. Chemical reactions can also be used. Fish odour on the hands is due to chemicals called amines that smell because they are volatile. But if reacted with citric acid, they form salts that do not become airborne, which is why washing hands with lemon juice eliminates fishy aromas. Fragrant molecules in the air can also be destroyed by means of a chemical reaction. Ozone generators produce ozone gas, a very strong oxidizing agent, meaning that it has the ability to strip electrons from molecules. Since electrons are the glue that hold the atoms in a molecule together, ozone can eliminate smells. Ozone generators are commonly used after a fire to get rid of the smell of smoke but should not be used when people are around because ozone can also disrupt molecules in the body.
Certain enzymes produced by bacteria can also chew up smelly compounds. Most pet odour eliminators are bacterial concoctions. Molecules can also be removed from the air by interacting with other volatile substances in such a way that the resulting complex of molecules is no longer volatile and drops to the ground. Cyclodextrin, the active ingredient in products like Febreze, is a large cyclic molecule that forms a pocket in which other molecules of the appropriate size are entrapped. The cyclodextrin-smelly molecule complex drops out of the air because of the increase in mass.
Some essential oils from plants also can interact with volatile compounds in this fashion and many smell 鈥渘eutralizers鈥� are based on this principle. But there is more to essential oils. Some can bind to receptors in our nose without triggering any action, but in the process block other molecules from interacting with the receptor. Sort of like the wrong key that fits the lock and cannot unlock it but can prevent the right key from fitting in. There has been a great deal of research trying to find essential oils to block specific smells, with some success. Unfortunately, the information is proprietary, and companies will not reveal exactly what oils they use. This is the technology apparently used in products like 鈥淧oo-Pourri鈥� that claims to eliminate offensive toilet smells. A few drops in the bowl, and you can sit and relax. Probably works better than a burning match.
