Fragrance is a mixture of chemicals that give personal care, cleaning and other products their distinctive smell. It is estimated that there are more than 3,500 fragrance chemicals, many of which are linked to health problems such as allergies and asthma. Many fragrance ingredients are also hazardous to the environment. A glance at the label of almost any household or personal care product will reveal that it contains one or more perfume chemicals.
Perfume is a liquid mixture used to emit a pleasant smell, usually from fragrant essential oils and synthetic aroma compounds. It can be applied to the skin as perfume, cologne or aftershave, or it can be incorporated into other cosmetic products such as shampoo, lotions and hair sprays. Almost all perfumes are mixtures, and they can be loosely grouped according to their structure into five main groups: perfume, cologne, toilette water, eau de parfum (EdP) and eau de cologne. Each group contains perfumes of varying concentrations of aromatic compounds.
During the 19th century, commercially synthesised fragrance materials allowed perfumers to create scents that were not possible with natural aromatics alone. These are known as the “modern” fragrances. These modern perfumes are the basis of the current fragrance industry and include a wide range of scents from a variety of sources.
Most fine perfumes are composed of three structural elements: a top note, a middle note and a base note. A top note is the refreshing, volatile odour perceived immediately after application; middle notes are the dominant aromatics that emerge as the top notes fade; and base notes are the scents that remain longest, becoming more intense over time. A perfume can contain as few as 100 ingredients and as many as 1,000, depending on its complexity and intensity.
The odours of a perfume can be further classified by family, such as floral, woody or oriental, with each group being a combination of one or more scent families. A general rule of thumb is that the more a perfume is reminiscent of a specific flower, the more it belongs to the floral group.
A natural scent’s smell will vary depending on its source, which will influence the perfumer’s choice of raw materials. Because of this, perfumers often blend different scents to achieve a desired odour. A natural odour’s quality can also be influenced by the time of year it is harvested and the extraction method.
Perfume oils are generally diluted with solvents such as ethanol, alcohol and fractionated coconut oil. The amount of fragrance left behind on the body is called sillage and can vary from person to person.
A perfume may be labelled as “natural” or “synthetic”. However, in some countries, such as the United States, manufacturers are not required to disclose on the product label whether a fragrance is natural or synthetic. This practice is a loophole that allows companies to maintain their trade secrets and hide potentially harmful chemicals from consumers. The international perfume association and the Research Institute for Fragrance Materials set voluntary standards for disclosure of fragrance ingredients.