Fragrance is any mixture of oils or chemicals that gives a perfume or cologne its distinctive scent. Companies that produce perfumes and colognes usually purchase fragrance mixtures from fragrance houses (companies that specialize in developing fragrances). A typical product label might list dozens, or even hundreds, of individual fragrance chemicals, but they are all listed just under the generic term “fragrance.”
Fragrances can be obtained from natural sources such as flowers and herbs. They can also be synthetically manufactured. The fragrance industry has its own trade association and research institute, which sets fragrance safety standards. These groups are a major influence on the Food and Drug Administration’s decisions about which chemicals can be included in fragranced products. The trade secrets that are protected by these rules allow companies to conceal a number of chemicals known to cause health problems including cancer, reproductive toxicity, and skin allergies.
The chemistry of a perfume is complex. Almost all perfumes are mixtures of odorous substances that evaporate at different rates. A perfume’s scent can be categorized as “top notes” that evaporate most rapidly, “middle notes” or “heart notes” that evaporate over a longer period of time and are more intense, and “base notes” that evaporate the least. Manufacturers present these components as a pyramid-shaped diagram, where the top and middle notes are shown at the top of the pyramid, and the base notes are at the bottom.
A perfume’s olfactory properties are enhanced by using high-quality oils and chemicals that have been formulated to combine well. These chemicals can include a solvent such as ethanol, an odorless compound called dimethyl sulfate, and other ingredients that make the perfume stable and long-lasting. Other chemicals, such as colorants and preservatives, are used to enhance the appearance of a perfume and protect it from contamination by bacteria and other microorganisms.
Creating great fragrances is as much an art as a science. A perfumer has to decide how much of each component to use, and he or she must balance the desired intensity and longevity of a perfume with its cost. The olfactory system of the human body is very sensitive, so the perfumer must ensure that the scent does not overpower the wearer or irritate the skin.
Chemicals found in some fragrances can cause allergic contact dermatitis, a painful, itchy rash that can spread to other parts of the body. Because the FDA does not require that perfumes be tested for their allergens before they are sold, it is difficult to know whether a specific perfume will cause this reaction in some people. Fragrance chemicals can also pollute the environment, forming ozone and particulate pollutants in the air. The vapors from some of these chemicals can trigger asthma and other respiratory conditions, especially in children and the elderly. Essential oils are a better choice for natural, healthy fragrance. They are less expensive and do not contain the hormone-disrupting, allergy-provoking chemicals that are used to artificially scent commercial lotions and creams.