Occurrence and transport of synthetic musks in paired maternal blood, umbilical cord blood, and breast milk

A critical review of distribution, toxicological effects, current analytical methods and future prospects of synthetic musks in aquatic environments

Synthetic musks (SMs) have gained widespread utilization in daily consumer products, leading to their widespread dissemination in aquatic environments through various pathways. Over the past few decades, the production of SMs has consistently risen, prompting significant concern over their potential adverse impacts on ecosystems and human health. Although several studies have focused on the development of analytical techniques for detecting SMs in biological samples and cosmetic products, a comprehensive evaluation of their global distribution in diverse aquatic media and biological matrices remains lacking. This review aims to provide an up-to-date overview of the occurrence of SMs in both aquatic and various biological matrices, investigating their worldwide distribution trends, assessing their ecological toxicity, and comparing different methodologies for processing and analysis of SMs. The findings underscore the prevalence of polycyclic musks as predominant SMs, with consumption of various products in different countries leading to contrasting distribution of contaminants. Furthermore, the migration of SMs from sediments to the water phase is investigated, indicating the role of solid-phase reservoirs. Incomplete degradation of SMs in the environment could contribute to their accumulation in aquatic systems, impacting the growth and oxidative stress of aquatic organisms, and having a possibility of genotoxicity to them. Human exposure data highlight substantial risks for vulnerable populations such as pregnant women and infants. Moreover, contemporary methods for SMs analysis are presented in this review, particularly focusing on advancements made in the last five years. Finally, research enhancement and critical questions regarding the analysis of SMs are provided, offering suggestions for future research endeavors.

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.

A new bi-radical species formed during the photochemical degradation of synthetic musk tonalide in water: Study of in-situ laser flash photolysis and validation of synthesized standard sample

The ubiquitous presence of synthetic musks is causing serious concern due to the species produced from their transformation and environmental impacts. In this study, tonalide was selected as a representative synthetic musk to evaluate the transformation mechanism and pathway in water under ultraviolet (UV) irradiation. The results showed that tonalide could undergo rapid photochemical degradation through a new pivotal bi-radical, which acts as the initial active species. The bi-radicals with a typical absorption peak at 340 nm was observed by in-situ laser flash photolysis technology, and the absolute decay rate constant was obtained as 3.61 ± 0.01 × 10⁹ M^-1 s^-1 with the life-time of 83.3 ns. The photochemical degradation by-products of tonalide were also identified by high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry, and the precise structures of key by-products have been validated by our preparative synthesized standard samples confirmed by nuclear magnetic resonance. Thus, the mechanism of tonalide photochemical degradation, continuous photoenolization of the bi-radicals and followed cycloaddition reaction with O₂, was proposed as the predominant pathway. The main degradation by-product, photoenol which has a higher bioconcentration than that of tonalide, was found to form from the bi-radicals photoenolization. This study is the first work to propose a new bi-radical as the photoenol precursors during photochemical degradation of tonalide in water.

Chemoenzymatic Synthesis of the Most Pleasant Stereoisomer of Jessemal

We describe the asymmetric synthesis of the most pleasant enantiomer of Jessemal fragrance. The key steps are (i) the one-pot reduction of an α-chloro-tetrasubstituted cyclohexenone to give the chlorohydrin, catalyzed by two stereoselective redox enzymes (an ene-reductase and an alcohol dehydrogenase); (ii) the regioselective epoxide ring-opening with organocuprate or organolithium nucleophiles. Density functional theory calculations together with the Curtin–Hammett principle allowed the rationalization of the regioselectivity.

Occurrence, spatial distribution, and fate of polycyclic musks in sediments from the catchment of Chaohu Lake, China

Twenty-nine surface sediments from Chaohu Lake in China and from its six main tributaries were sampled to investigate the concentrations of two important polycyclic musks (PCMs), 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyran (galaxolide, HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (tonalide, AHTN), as well as the concentration of 4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyran-1-one (galaxolidon, HHCB-lactone), which is the main degradation product of HHCB. Except for the high concentrations of AHTN and HHCB measured in the Nanfei River (879 ng/g dw and 5,513 ng/g dw, respectively), the levels of AHTN and HHCB in the river sediments were 7.08-44.9 ng/g dw and 20.6-268 ng/g dw, respectively, which are slightly lower than those documented in various areas worldwide. The concentrations of AHTN and HHCB in the sediments of Chaohu Lake were one or two orders of magnitude lower than those in the tributary rivers and showed a clear regional distribution. The concentrations of HHCB-lactone were comparable to those of HHCB and presented a significant positive correlation with the concentrations of HHCB, suggesting that the HHCB-lactone originated directly from the degradation of HHCB in wastewater treatment plants (WWTPs) or in the natural environment. The diagnostic ratios of HHCB/AHTN and HHCB-lactone/HHCB and the enantiomeric fractions (EFs) of these PCMs showed that the direct origins of the target PCMs in the study area were municipal and industrial wastewaters discharged from adjacent cities or point sources and that the HHCB-lactone in sediment originated from the natural degradation of HHCB in the rivers and the lake. The results of the risk assessment showed that the PCMs in the watershed sediments were unlikely to pose a threat to aquatic species. However, the effluents of industrial and municipal wastewaters that are discharged into the Nanfei River should be investigated in future research.

Synthetic Musk Compounds in Human Biological Matrices: Analytical Methods and Occurrence-A Review

Extensive use of synthetic musk compounds (SMs) in numerous consumer and personal care products has resulted in direct human exposures via dermal absorption, inhalation of contaminated dust and volatilized fragrances, and oral ingestion of contaminated foods and liquids. SMs and their metabolites are lipophilic, hence commonly detected in various biological matrices such as blood, breast milk, and adipose tissue. Appropriate analytical techniques are needed to detect and quantify SMs in biological matrices to assess their potential effects on human health. Different methods to process and analyze SMs in biological matrices, including sample-pretreatment, solvent extraction, cleanup, and instrumental analysis, are presented in this review. The concentration levels of selected musk compounds in biological samples from different countries/regions are summarized. Finally, research gaps and questions pertaining to the analysis of SMs are identified and suggestions made for future research studies.

Diet, exposure to polycyclic aromatic hydrocarbons during pregnancy, and fetal growth: A comparative study of mothers and their fetuses in industrial and urban areas in Southwest Iran

The presence of polycyclic aromatic hydrocarbons (PAHs) in the fetal environment is a high-priority concern due to the fetus being more sensitive than adults to these ubiquitous xenobiotics. The aim of the present study was to compare the maternal and fetal serum levels of ΣPAHs and their effects on fetal growth in an industrial and an urban area in Southwest Iran. The industrial area was the petrochemical and gas area (PGA) of the Central District of Asaluyeh County and the urban area (UA) was the Central District of Bushehr County, Ninety-nine maternal serum (MS) and 99 cord serum (CS) samples from the PGA and 100 MS and 100 CS samples from the UA were collected during May 2018 to February 2019. The mean concentrations of ΣPAHs were significantly (p < 0.05) higher in the PGA than the UA in both MS (157.71 vs. 93.56 μg/L) and CS (155.28 vs. 93.19 μg/L) samples. Naphthalene (NAP) was the predominant PAH detected in all the studied samples. Significant negative associations were found between birth weight and anthracene (ANT) level in MS (β = -22.917, p = 0.032; weight decrement = 22.917 g for a 1 μg/L increase in ANT); head circumference and chrysene (CHR) level in MS (β = -0.206, p = 0.023; head circumference decrement = 0.206 cm for a 1 μg/L increase in CHR); and birth height and NAP level in CS (β = -0.20, p = 0.005; height decrement = 0.20 cm for a 1 μg/L increase in NAP). Maternal diet had a significant effect on the serum levels of PAHs. The results of this study showed that transmission of PAHs from mother to fetus through the cord blood is an important issue and mothers who live in industrial areas and consume PAH-containing foodstuffs, and their fetuses, are more at risk than those living in a non-industrial urban area.

A Selective and Sensitive Gas Chromatography-Tandem Mass Spectrometry Method for Quantitation of Synthetic Musks in Human Serum

BACKGROUND

Synthetic musk compounds are widely used as fragrances in many consumer products; however, information on human exposure and health effects is limited. Also, analytical methods for their quantification in biological matrices are limited.

OBJECTIVE

In this study, an integrated method was developed and validated for the analysis of selected synthetic musk compounds in human serum.

METHOD

The method is based on liquid-liquid extraction (LLE), sample clean-up by solid-phase extraction (SPE), and separation and detection by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS).

RESULTS

The method demonstrated good recoveries (86-105%) and high sensitivity, with low method detection limits (MDLs) ranging from 0.04 to 0.17 µg/L. The method was applied to the analysis of 10 synthetic musk compounds in 40 serum samples collected from Canadian women aged 20-44 years (20 individual samples collected in 2014 and 20 pooled samples collected in 2006). The most commonly detected compound was Galaxolide (HHCB), with median concentrations of 0.59 µg/L in samples collected in 2006, and 0.34 µg/L for samples collected in 2014. Musk ketone (MK) was not detected in any of the samples collected in 2006, but was detected in 60% of the samples collected in 2014 with a median concentration of 0.29 µg/L. Tonalide (AHTN) was detected in only one sample above its MDL (0.12 µg/L).

CONCLUSIONS

This is the first study in Canada to report levels of synthetic musks in human. The data generated from this study has been used in risk screening assessment by Environment and Climate Change Canada and Health Canada.

Synthetic Musks: A Class of Commercial Fragrance Additives in Personal Care Products (PCPs) Causing Concern as Emerging Contaminants

Synthetic musks (SMs) are promising fragrance additives used in personal care products (PCPs). The widespread presence of SMs in environmental media remains a serious risk because of their harmful effects. Recently, the environmental hazards of SMs have been widely reported in various environmental samples including those from coastal and marine regions. This paper provides a systematic review of SMs, including their classification, synthetic routes, analysis and occurrence in environmental samples, fate and toxicity in the environment, as well as the associated risk assessment and pollution control. Research gaps and future opportunities were also identified with the hope of raising interest in this topic.

Transplacental transfer of polycyclic aromatic hydrocarbons in paired samples of maternal serum, umbilical cord serum, and placenta in Shanghai, China

Prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) is a high-priority public health concern. However, maternal to fetal transplacental transfer of PAHs has not been systematically studied. To investigate the transplacental transfer of PAHs from mother to fetus and determine the influence of lipophilicity (octanol-water partition coefficient, K_OW) on transfer process, in the present study, we measured the concentrations of 15 PAHs in 95 paired maternal and umbilical cord serum, and placenta samples (in total 285 samples) collected in Shanghai, China. The average concentration of total PAHs was the highest in maternal serums (1290 ng g^-1 lipid), followed by umbilical cord serums (1150 ng g^-1 lipid). The value was the lowest in placenta samples (673 ng g^-1 lipid). Low molecular weight PAHs were the predominant compounds in the three matrices. Increases in fish and meat consumption did not lead to increases in maternal PAH levels, and no obvious gender differences in umbilical cord serums were observed. The widespread presence of PAHs in umbilical cord serums indicated the occurrence of transplacental transfer. The ratios of PAH concentrations in umbilical cord serum to those in maternal serum (F/M) and the concentrations in placenta to those in maternal serum (P/M) of paired samples were analyzed to characterize the transfer process of individual PAHs. Most F/M ratios on lipid basis were close to one (range: 0.79 to 1.36), which suggested that passive diffusion may control the transplacental transfer of PAHs from maternal serum to the fetal circulation. The P/M and F/M values calculated on lipid basis showed that PAHs with lower K_OW were more likely to transfer from mother to fetus via the placenta.