Natural animal musks have long been used as fragrances in beauty products, but because they are expensive to produce, scientists have developed synthetic chemicals to replace them. These synthetic compounds include nitro and non-nitro benzenes, indans and tetralins. Musk xylene, musk ketone and musk ambrette are three of the most commonly used synthetic nitro musk compounds. They are produced and used throughout the world in such scented products as detergents, soaps, lotions and perfumes. In 1988, an estimated 7,000 tons of musks were produced worldwide.Very little scientific research has been done on synthetic musk fragrances in the environment.
Much of what research has been conducted is from Germany, and the subset of those studies that are available have shown that musks, and especially nitro musks, biodegrade very slowly, if not as slowly as PCBs and some of the other extremely persistent organic pollutants. Nitro musks have been shown to accumulate in fat and have been found in surface and wastewater, freshwater fish, shellfish and in human fat, blood and breast milk.No studies have determined nitro musks' toxicity to humans, but musk compounds have been shown to cause cancer in laboratory rodents. Studies have also demonstrated significant transfer of nitro musks from mother to developing rodent fetuses and infants through blood and mothers' milk.
To test the hypothesis that nitro musks may have entered subjects' blood through skin application of beauty products, one German study tested nitro musk levels in all the scented health and beauty products used at least three to four times a week by study participants with elevated blood nitro musk levels. The study found that high nitro musk levels in frequently used products were correlated with higher blood levels in subjects who reported using these products. All of the people with elevated nitro musk levels in this study were female, suggesting the possibility that women may be more highly exposed than men to nitro musks through their use of scented health and beauty products.
Few nationwide bans and restrictions on nitro musks have been imposed because musks have only recently been identified in humans and in the environment and because little toxicity data is available on nitro musks.However, some nations have taken steps to reduce exposures. For example, Japan has completely banned musk xylene; the United States in 1979 forbade companies from using musk xylene in cosmetic products that may be ingested; and the German detergent industry voluntarily removed musk xylene from production in 1993.
Some individual companies also report that they are beginning to phase nitro musks out of their products. For example, The Body Shop states on its website that it currently sells products containing musk xylene, musk ketone and polycyclic musk, but that new products are being developed without these ingredients to replace existing products. Because nitro musk contamination is a relatively newly understood phenomenon, no benchmarks or "safe" levels have been set for human exposure.
The creation of this class of musks was largely prompted through the need for eliminating the nitro functional group from nitro-musks due to their photochemical reactivity and their instability in alkaline medium. This shown to be possible through the discovery of ambral, a non-nitro aromatic musk, which promoted research in the development of nitro-free musks. This led to the eventual discovery of phantolide, so named due to its commercialization by Givaudan without initial knowledge of it chemical structure (elucidated 4 years later). While poorer in smell strength, the performance and stability of this compound class in harsh detergents led to its common use, which spurred further development of other polycyclic musks including Galaxolide.
Nitrolide has been developed to offer perfumers a safe ingredients with the qualities of the Nitro Musks , this is in fact a substitute for Musk Ambrette which has been totally banned from all formulations. Musk Ambrette with its unique odour cannot be directly replaced by any other musk, whatsoever. Nitrolide is a complex mixture and comes close to being a substitute for that.