1. What is Galaxolide?
1.1 Definition and other names
Galaxolide, also known as Abbalide, Pearlide, Astrolide, or Musk 50, is a synthetic musk with a woody, floral, musky, and sweet scent. It was first synthesized in 1965 by International Flavours & Fragrance (IFF). Its chemical structure is characterized by a complex combination of stereoisomeric isomers. It belongs to the family of musky polycyclic aromatic hydrocarbons, which are frequently used to add a musky touch to cosmetic and personal care products, such as perfumes, detergents, and fabric softeners.
1.2 Uses of Galaxolide in industry
Galaxolide is primarily used for its fragrance. Thanks to its high stability and resistance to oxidation, it can be used in a wide variety of products, from high-end perfumes to fabric softeners. Its popularity in the fragrance industry stems from its ability to mimic the natural scent of musk, a fragrance prized for centuries. Galaxolide can be found in high concentrations in luxury perfumes, but it is also used in lower concentrations in cleaning products and detergents.
2. Chemical properties of Galaxolide
2.1 Molecular Structure
Galaxolide, with the chemical name 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta[g]benzopyran (HHCB), is a mixture of several isomers. It has a molecular formula of C18H26O and a molecular weight of 258.4 g/mol. Its structure contains chiral centers at carbons 4 and 7, generating four different stereoisomers: (4R,7R), (4R,7S), (4S,7S), and (4S,7R). The (4S,7R) and (4S,7S) isomers are known to be the most potent in terms of odor, with extremely low odor thresholds, on the order of 1 ng/L.
2.2 Physical Properties
At room temperature, Galaxolide is a viscous liquid. Its melting point is -20°C and its boiling point is estimated at approximately 330°C. These properties make it a stable and long-lasting ingredient in many cosmetic and industrial formulations.
3. Laboratory analysis of Galaxolide
3.1 Common analysis methods
Galaxolide is typically analyzed using gas chromatography-mass spectrometry (GC-MS) . This method is particularly well-suited for detecting volatile compounds like Galaxolide, thanks to its ability to identify and quantify molecules based on their fragmentation spectra. Samples for this type of analysis are often collected in XAD-2 tubes, a medium designed to capture volatile molecules in air.
3.2 GC-MS Screening
The HS-GC-MS (Headspace Gas Chromatography-Mass Spectrometry) screening test is a highly effective method for analyzing volatile compounds such as Galaxolide. Samples are collected in sealed, inert vials to prevent contamination. The limit of quantification (LOQ) depends on the compound being analyzed and generally ranges from 0.1 to 10 mg/L. This technique provides accurate data for assessing the concentration of Galaxolide in environmental matrices or finished products.
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4. Environmental and health impacts of Galaxolide
4.1 Environmental Effects
Galaxolide has been extensively studied for its environmental . With an octanol-water partition coefficient (log Kow) of approximately 5.5, it exhibits a high affinity for fats, facilitating its bioaccumulation in the tissues of aquatic organisms. However, according to the European Union, although Galaxolide is classified as "very toxic to aquatic life," it does not meet all the criteria to be classified as a PBT (Persistent, Bioaccumulative, and Toxic) substance. Nevertheless, US authorities, such as the EPA, consider it moderately persistent and bioaccumulative, with high toxicity to aquatic organisms.
4.2 Presence in the environment
Studies have shown that Galaxolide can be detected in many environmental compartments, including rivers, lakes, sediments, and fish. In the Great Lakes, research has revealed that Galaxolide concentrations are increasing in sediments, doubling every 8 to 16 years. This potential bioaccumulation raises concerns about its long-term impact on aquatic ecosystems.
5. Regulations and safety of Galaxolide
5.1 European Regulations
In Europe, Galaxolide has been extensively studied by the Scientific Committee on Consumer Safety (SCCS), which concluded that it can be used without restriction in cosmetic products. EU REACH regulations impose strict obligations regarding risk assessments related to the production and import of Galaxolide.
5.2 US Regulations
In the United States, Galaxolide is currently being evaluated by the Environmental Protection Agency (EPA) under the Priority Program for Chemical Risk Assessments (PPRA) of the Toxic Substances Control Act (TSCA). In 2019, the EPA designated Galaxolide as one of 20 priority chemicals to be assessed for its environmental and health risks.
6. Impact of Galaxolide on human health
6.1 Biomonitoring studies
Galaxolide has been detected in human biomonitoring studies, with levels measured in breast milk, blood plasma, and adipose tissue samples. Although its presence has been widely documented, research shows that galaxolide is neither toxic, irritating, nor a skin sensitizer. Studies conducted by international regulatory bodies have found very few cases of allergic reactions.
6.2 Conclusion of health studies
Despite the widespread presence of Galaxolide in human tissues, European and American authorities consider current exposure levels to be safe for human health. The Scientific Committee on Consumer Safety (SCCS) has confirmed that Galaxolide can be used without restriction in consumer products.
Conclusion
Galaxolide is a key molecule in the fragrance industry, thanks to its musky scent and unique chemical properties. While its environmental effects raise concerns about bioaccumulation, regulatory authorities consider it safe for use in cosmetic and household products. Analyzing Galaxolide using techniques such as GC-MS allows for close monitoring of its impact and ensures its compliance with current regulations.
