Global distribution and ecological risk assessment of synthetic musks in the environment

Synthetic musks, as an alternative product of natural musks, are widely used in almost all fragrances of consumer products, such as perfumes, cosmetics and detergents. During the past few decades, the production of synthetic musks has been increasing year by year, subsequently followed by large concern about their adverse effects on ecosystems and human beings. Until now, several studies have reviewed the latest development of analytical methods of synthetic musks in biological samples and cosmetics products, while there is still lack of a systematic analysis of their global distribution in different environmental media. Thus, this review summarizes the occurrence of synthetic musks in the environment including biota around the world and explores their global distribution patterns. The results show that galaxolide (HHCB), tonalide (AHTN), musk xylene (MX) and musk ketone (MK) are generally the most frequently detected synthetic musks in different samples with HHCB and AHTN being predominant. Higher concentrations of HHCB and AHTN are normally found in western countries compared to Asian countries, indicating more consumptions of these musks in western countries. The persistence, bioaccumulation and toxicity (PBT) of synthetic musks (mainly for polycyclic musks and nitro musks) are also discussed. The risk quotients (RQs) of HHCB, AHTN, MX and MK in most waters and sediments are below 0.1, reflecting a low risk to aqueous and sediment-dwelling species. In some sites, e.g., close to STPs, high risks (RQs>1) are characterized. Currently, limited data are available for macrocyclic musks and alicyclic musks in terms of either occurrence or PBT properties. More studies with an expanded scope of chemical type, geographical distribution and (synergic) toxicological effects especially from a long-term point of view are needed.