Many consumers don't realize the hidden dangers lurking in product fragrances. This is because, in the U.S. as in many other countries, manufacturers don't have to specify on product labels exactly what ingredients a fragrance contains. With many 'fragrances' now comprising complicated mixtures of hundreds of ingredients, and the U.S. Food & Drug Administration (FDA) not requiring safety tests of cosmetic products, this makes the exact composition of a 'fragrance' a black box of many different, untested chemicals.In the worst cases, some of the chemical cocktails listed on product labels merely as a 'fragrance' have been linked to allergies, skin reactions, hormone disruptions, birth defects and even cancer.This problem isn't confined to just a few products, since about 95% of 3,000 the different fragrance ingredients now used consist of low cost synthetic compounds derived from petroleum.Phthalates, or phthalate esters, are a top hazard in fragrance mixtures. These are a group of chemical compounds that are mainly added to plastics to increase their flexibility. Certain phthalate esters are also used in the manufacture of nail polishes, paint, adhesives and perfumes. In 2004, a joint Swedish-Danish research team found a strong link between allergies in children and the phthalates; this study was later published in The Journal of Environmental Health Perspectives. Subsequent studies have also linked phthalates with birth defects, toxicity and damage to adult reproductive, adrenal, liver, and kidney organs. Although some manufacturers have removed these chemicals from their products, a recent study conducted by the Environmental Working Group found phthalates in nearly three-quarters of 72 name-brand products tested.Artificial musks can also cause unintended side effects. These chemicals remain popular, however, since the price of natural musk, which is derived mainly from a gland of the male musk deer, has become prohibitively expensive. Of the three primary types of synthetic musk (nitromusk, polycyclic musk and macrocyclic musk), nitromusk is particularly dangerous as it has been linked to reproductive and fertility problems in women at high levels of exposure. Because of this, the EU has banned the usage of some nitromusks in cosmetics and personal care products, but in the United States, musk chemicals remain unregulated, and safe levels of exposure have not yet been set. Many synthetic fragrance components are considered allergens and can both cause asthma and trigger asthma attacks. But when the Environmental Working Group conducted a survey in 2005 of U.S. cosmetic industry ingredient reviews, it found that for about one third of all ingredients, allergen and sensitizer determinations were made inadequately.In contrast, natural fragrance ingredients such as essential oils are obtained entirely from plants. When properly prepared, they have not been associated with significant adverse reactions. However, natural ingredients tend to be more expensive than synthetic chemicals, resulting in fewer skin care product manufacturers using them.