Effects of four synthetic musks on the life cycle of the harpacticoid copepod Nitocra spinipes

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.

Fragrance materials affect life history parameters and gene expression in Daphnia magna: An emerging issue for freshwater ecosystems

A chronic toxicity test (21 d exposure) with the model organism Daphnia magna was performed to study the single-compound and combined effects of four fragrance materials (FMs), including musk xylene (MX), Celestolide™ (ADBI), Galaxolide™ (HHCB), and ethylene brassylate (MT). Furthermore, the transcriptional responses of ten target genes related to detoxification, molting and reproduction (DHR96, P-gp, CYP360A8, GST, CYP314, EcRb, Vtg, CAT, GPX, and GCLC) were determined by performing a quantitative real-time polymerase chain reaction (qRT‒PCR) after juvenile D. magna was exposed for 48 h. The results showed that MX, ADBI and HHCB affected development and reproduction after chronic exposure at a concentration of 10 μg L^-1. Conversely, MT did not affect reproduction, growth or molting during the 21 d exposure. In juvenile D. magna, gene expression was significantly altered by ADBI (DHR96, CYP260A8, and GCLC) and MX (DHR96, CYP360A8, EcRb, Vtg, CYP314, and GCLC) but not by HHCB. These results suggest that compared to biochemical measures, conventional biological endpoints provide more informative data regarding the effects of this FM. Compared to single substances in the chronic test, the mixture of the four FMs showed effects at lower concentrations and increased gene expression for EcRb and CYP314 during juvenile exposure, indicating a possible additive or synergistic effect of the four FMs compared to single compound exposure.

Long-term effects of neonicotinoids on reproduction and offspring development in the copepod Acartia tonsa

Neonicotinoids (NEOs) are neurotoxic pesticides acting as nicotinic acetylcholine receptor agonists. NEOs' efficacy against pest insects has favoured their spreading use in agriculture, but their proven effectiveness against non-target insects in terrestrial and aquatic ecosystems also raised concern over their environmental impact. Crustaceans were often studied for the impacts of NEOs due to their economic values and nervous' system similarity with insects. However, most studies on crustaceans focused on acute effects or exposure of early-life stages, while long-term effects were seldom explored. The present study aimed to assess the potential long-term effects of four commercially available NEOs on the reproduction and offspring of the calanoid copepod Acartia tonsa, a key species in the food webs of several coastal and estuarine environments. NEOs were confirmed as potent interferents of copepod reproduction. The first-generation compound acetamiprid significantly inhibited egg production and hatching ratio at 10 ng L-1, while larval survival and development were affected at 81 ng L-1. Similarly, the first-generation compound thiacloprid significantly inhibited the hatching ratio and larval development at 9 ng L-1, while it did not affect egg production and larval survival. Second-generation compounds were less toxic than acetamiprid and thiacloprid: clothianidin affected significantly only larval development of the offspring at 62 ng L-1, while thiamethoxam was not toxic at both the tested concentrations (8 ng L-1 and 84 ng L-1). These data evidenced that effects on copepods may occur at concentrations below the chronic aquatic life benchmarks reported by USEPA for acetamiprid (2100 ng L-1) and thiacloprid (970 ng L-1), suggesting that long-term effects of NEOs have been underestimated. A comparison with environmental concentrations evidenced that NEO-mediated effects on copepods are more liable in coastal areas receiving discharge from wastewater treatment plants or diffuse inputs from agricultural land during pesticide application periods.

Derivation of predicted no effect concentration and ecological risk assessment of polycyclic musks tonalide and galaxolide in sediment

Polycyclic musks (PMs) have drawn increased attention in recent years because of their persistence, bioaccumulation and toxicity. As two typical PMs contaminants, tonalide (AHTN) and galaxolide (HHCB) are widely detected in sediment worldwide. Acute and chronic toxicity data of AHTN and HHCB to freshwater and seawater organisms in water and sediments are collected and screened. The predicted no effect concentrations (PNEC_sediment) for AHTN and HHCB is derived according to the equilibrium partitioning method recommended by the EU technical guidance document (TGD) and the species sensitivity distribution (SSD) method based on the measured sediment toxicity data. The concentration levels of AHTN and HHCB are investigated and evaluated in freshwater and seawater sediments. Results show the difference between native and non-native freshwater species is not statistically significant. AHTN is more toxic to freshwater and seawater organisms than HHCB, and seawater organisms are more sensitive to 2 musks than freshwater organisms. The chronic PNEC_sediment values of AHTN and HHCB are 194.48 and 416.47 ng/g in freshwater sediment, 88.93 and 128.34 ng/g in seawater sediment respectively. The AHTN and HHCB linear correlation analysis exhibited a strong positive linear correlation in both domestic (R²=0.9054) and foreign (R² = 0.9645) sediment. Preliminary risk assessment shows that the risks posed by AHTN and HHCB in sediment based on individual or combined concentrations of two musks are at medium to high levels in some regions. Further risk assessment results indicate that, for HHCB, 1.72% of foreign freshwater sediment may pose an ecological risk to 5% species; for AHTN, 8.06% of foreign freshwater sediment and 1.02% of domestic freshwater sediment may pose an ecological risk to 5% species, and 5.86% of seawater sediment may pose an ecological risk to 5% species. The above results indicate that there are some negligible risks in domestic and foreign sediments posed by these two musks, we should continue to pay attention to the toxic effects and pollution level of both musks in environment.

Application of a biological multilevel response approach in the copepod Acartia tonsa for toxicity testing of three oil Water Accommodated Fractions

Copepods play a critical role in the marine food webs, being a food source for marine organisms. In this study, we investigated the toxic effects of Water Accommodated Fractions (WAFs) from three types of oil: Naphthenic North Sea crude oil (NNS), Intermediate Fuel Oil (IFO 180) and a commercial Marine Gas Oil (MGO). The WAFs were prepared at 10 °C and 30 PSU (practical salinity unit), and tested on the marine copepod Acartia tonsa at different endpoints and at different levels of biological organization. We determined the median lethal concentrations after 96 h (LC50) and reproduction capabilities were calculated in adult females following seven days of exposure to sublethal WAF doses. The total lipid content was measured in reproductive females using Nile red lipophilic dye after 96 h of WAF exposure. We also measured the transcription levels of genes involved in antioxidant response and xenobiotic biotransformation after short exposure for 48 h. High doses (7% WAF) of MGO affected survival, percentage of fecund females, egg hatching success, and total lipid content. The IFO 180 WAF affected, at medium (20%) and high (40%) doses, the number of fecund females, mortality and produced significant effects on gene expression levels. In conclusion, toxicity assays showed that the WAFs prepared from refined oils were more toxic than crude oil WAF to Acartia tonsa.

Making Sense of Life-History Effects of the Antidepressant Citalopram in the Copepod Nitocra spinipes Using a Bioenergetics Model

The global consumption of human antidepressants has steadily increased over the last years. The most widely prescribed antidepressants are the selective serotonin reuptake inhibitors (SSRIs), which have been linked to various life-history effects in nontarget organisms. We investigated the effects of the SSRI citalopram hydrobromide on the life history of the copepod Nitocra spinipes. Slight but significant developmental delay effects were observed at nominal concentrations of 0.1 and 1 µg/L, with stronger effects occurring at measured concentrations of 178 µg/L and above. At 77 µg/L and above, a significant increase in adult body length and offspring production/brood was found, although the time between brood releases remained unaffected. The pre-adult surviving fraction was significantly reduced (by 44%) at 765 µg/L. For a mechanistic evaluation of these observations, we used a bioenergetics model for N. spinipes based on the dynamic energy budget theory. Toxicokinetic and toxicodynamic submodels were used to dynamically simulate the chemical uptake and elimination, as well as dose-response relationships for hypothetical physiological modes of action and survival over time. Although none of the commonly invoked physiological modes of action, acting on assimilation, maintenance, growth, or offspring production, could explain the observed combination of effects, a newly proposed physiological mode of action acting on the process of maturation delivered correct predictions in terms of each effect's direction. The model fits could be further improved by allowing for a gentler concentration-effect slope and by adding an auxiliary physiological mode of action acting on the reproduction efficiency. The quantitative explanations provided in the present study offer a starting point for exploratory simulation studies investigating the effects of SSRIs at higher ecological levels. Environ Toxicol Chem 2021;40:1928-1939. © 2021 SETAC.

Fragrance materials (FMs) affect the larval development of the copepod Acartia tonsa: An emerging issue for marine ecosystems

Fragrance materials (FMs) are used in a variety of detergents and cosmetics, including household and personal care products. Despite their widespread use and the growing evidence of their occurrence in surface waters worldwide, very little is known about their toxicity towards marine species, including a key component of the marine food webs such as copepods. Thus, we investigated the toxicity of six of the more long-lasting and stable commercial fragrances, including Amyl Salicylate (AMY), Oranger Crystals (ORA), Hexyl Salicylate (HEX), Ambrofix (AMB), Peonile (PEO), and Benzyl Salicylate (BZS), to assess their ability to impair the larval development of the calanoid copepod Acartia tonsa. FMs inhibited the development of A. tonsa significantly at concentrations by far lower than the effect-concentrations reported in the literature for aquatic species. The more toxic FMs were HEX (EC₅₀ = 57 ng L^-1), AMY (EC₅₀ = 131 ng L^-1) and ORA (EC₅₀ = 766 ng L^-1), while the other three compounds exerted toxic effects at concentrations higher than 1000 ng L^-1 (LOEC at 1000 ng L^-1 for PEO and BZS, and at 10,000 ng L^-1 for AMB). Early life-stage mortality was unaffected by FMs at all the tested concentrations. A comparison with water concentrations of FMs reported in the literature confirmed that FMs, especially HEX and AMY, may act as contaminants of potential concern in many aquatic habitats, including urban areas and remote and polar environments.

Effects of the Fragrance Galaxolide on the Biomarker Responses of the Clam Ruditapes philippinarum

The musk fragrance Galaxolide® (HHCB) is widely used in personal care and household products. Its large use leads to a continuous release of the compound into aquatic environments. Although some studies on the presence of HHCB in ecosystems and biota have been conducted, limited data about its effects on organism biomarkers are available. This study aimed at investigating both cellular and biochemical effects of HHCB in the clam Ruditapes philippinarum. Mussels were exposed for 7, 14 and 21 days to 100 ng/L and 500 ng/L of HHCB in seawater, and the effects on haemocyte parameters and antioxidant enzyme activities in the gills and digestive gland were evaluated. In addition, the neurotoxic potential of HHCB and its capacity to cause oxidative damage to proteins were assessed. Overall, our results demonstrated that exposure to HHCB was able to induce changes in biomarker responses of mussels, mainly at the cellular level.

Galaxolide and tonalide modulate neuroendocrine activity in marine species from two taxonomic groups

Galaxolide (HHCB) and tonalide (AHTN) are polycyclic musk compounds (PMCs) used in household and personal care products that have been included on the list as emerging contaminants of environmental concern due to their ubiquity in aquatic and terrestrial environments. There still exists a dearth of information on the neurotoxicity and endocrine disrupting effects of these contaminants, especially for marine and estuarine species. Here, we assessed the neuroendocrine effects of HHCB and AHTN using adult clams, Ruditapes philippinarum, and yolk-sac larvae of sheepshead minnow, Cyprinodon variegatus. The clams were treated with concentrations (0.005-50 μg/L) of each compound for 21 days. Meanwhile, sheepshead minnow larvae were exposed to 0.5, 5 and 50 μg/L of HHCB and AHTN for 3 days. Enzyme activities related to neurotoxicity (acetylcholinesterase - AChE), neuroendocrine function (cyclooxygenase - COX), and energy reserves (total lipids - TL) were assessed in R. philippinarum. Gene expression levels of cyp19 and vtg1 were measured in C. variegatus using qPCR. Our results indicated induction of AChE and COX in the clams exposed to HHCB while AHTN exposure significantly inhibited AChE and COX. Gene expression of cyp19 and vtg1 in yolk-sac C. variegatus larvae exposed to 50 μg/L AHTN was significantly downregulated versus the control. The results of this study demonstrate that HHCB and AHTN might pose neurotoxic and endocrine disrupting effects in coastal ecosystems.

Effects and Risk Assessment of the Polycyclic Musk Compounds Galaxolide® and Tonalide® on Marine Microalgae, Invertebrates, and Fish

The current research investigated the potential environmental risk of the polycyclic musk compounds, Galaxolide® (HHCB) and Tonalide® (AHTN), in the marine environments. These substances are lipophilic, bioaccumulated, and potentially biomagnified in aquatic organisms. To understand the toxicity of HHCB and AHTN, acute toxicity tests were performed by exposing marine microalgae (Phaeodactylum tricornutum, Tretraselmis chuii, and Isochrysis galbana), crustaceans (Artemia franciscana), echinoderms (Paracentrotus lividus), bivalves (Mytilus galloprovincialis), fish (Sparus aurata), and a candidate freshwater microalga (Raphidocelis subcapitata) to environmentally relevant concentrations (0.005–5 µg/L) following standardized protocols (US EPA, Environment Canada and OECD). P. tricornutum and I. galbana were sensitive to both substances and for P. tricornutum exposed to HHCB and AHTN, the IC10 values (the inhibition concentration at which 10% microalgae growth inhibition was observed) were 0.127 and 0.002 µg/L, respectively, while IC10 values calculated for I. galbana were 5.22 µg/L (a little higher than the highest concentration) and 0.328 µg/L, for HHCB and AHTN, respectively. Significant (p < 0.01) concentration dependent responses were measured in P. lividus and M. galloprovincialis larvae developments, as well as S. aurata mortality tested with HHCB. The effect of HHCB on P. lividus larvae development was the most sensitive endpoint recorded, producing an EC50 value (the effect concentration at which 50% effect was observed) of 4.063 µg/L. Considering the risk quotients both substances seem to represent high environmental risk to P. tricornutum and M. galloprovincialis in marine environments.

Potential of environmental concentrations of the musks galaxolide and tonalide to induce oxidative stress and genotoxicity in the marine environment

Polycyclic musk compounds have been identified in environmental matrices (water, sediment and air) and in biological tissues in the last decade, yet only minimal attention has been paid to their chronic toxicity in the marine environment. In the present research, the clams Ruditapes philippinarum were exposed to 0.005, 0.05, 0.5, 5 and 50 μg/L of the fragrances Galaxolide® (HHCB) and Tonalide® (AHTN) for 21 days. A battery of biomarkers related with xenobiotics biotransformation (EROD and GST), oxidative stress (GPx, GR and LPO) and genotoxicity (DNA damage) were measured in digestive gland tissues. HHCB and AHTN significantly (p < 0.05) induced EROD and GST enzymatic activities at environmental concentrations. Both fragrances also induced GPx activity. All concentrations of both compounds induced an increase of LPO and DNA damage on day 21. Although these substances have been reported as not acutely toxic, this study shows that they might induce oxidative stress and genotoxicity in marine organisms.

Algal toxicity, accumulation and metabolic pathways of galaxolide

Galaxolide (HHCB) is known to be persistent during wastewater treatment and has raised increasing concern due to its high detection frequency in the environment and potentially negative effects. However, little information is available on the degradation of HHCB by algae, the degradation mechanisms and the toxicity of HHCB on algae. In the present study, HHCB was found to be toxic to Navicula sp. and Scenedesmus quadricauda, with a 3 d EC₅₀ of 0.050 and 0.336 mg L^-1, respectively. Both microalgae showed high removal efficiency (72.9-100%) for HHCB. S. quadricauda showed a more satisfactory effect in the bioremediation of HHCB than Navicula sp. A total of four metabolites were found in the biotransformation processes of HHCB, and its possible metabolic pathways were proposed. Hydroxylation, methoxylation, methylation, ketonization, demethylation, and oxaloacetate conjunction contributed to the metabolism of HHCB in algal cells.

Development of aquatic life criteria for tonalide (AHTN) and the ecological risk assessment

AHTN (tonalide) is a polycyclic musk that is widely used as fragrance additive in numerous consumer products. AHTN is of great worldwide concern owing to its adverse effects on aquatic organisms and frequent detection in both domestic and foreign aquatic environments. Therefore, derivation of the aquatic life criteria for AHTN exposure is urgently needed. In this work, AHTN toxicity data for eight Chinese native freshwater organisms were used to derive a criterion maximum concentration of 59.39 μg/L and a criterion continuous concentration of 22.43 μg/L using United States Environmental Protection Agency guidelines. Toxicity tests showed that the annelid L. hoffmeisteri and the amphibian R. nigromaculata were the least and most sensitive species to AHTN, respectively. The sensitivity of the planktonic crustacean D. magna to AHTN obviously differed from that of the benthic crustacean M. nipponense. The AHTN and HHCB correlation analysis exhibited a strong positive linear correlation (R² = 0.8622) in water. The ecological risk assessment showed that AHTN and HHCB posed a higher risk in foreign surface waters than Chinese waters, but a lower risk in foreign wastewater treatment plant effluent than in China. The ecological risks of AHTN and HHCB in most surveyed water bodies of various countries were at acceptable levels, with a few exceptions.

Enzymatic cascade biosynthesis reaction of musky macrolactones from fatty acids

Musky macrolactones are an important group of compounds used in high-valued perfumery. An enzymatic cascade reaction including cytochrome P450 hydroxylase and lipase was explored to biosynthesize musky macrolactones. Firstly, fatty acids were hydroxylated by P450 hydroxylase to produce the corresponding ω-hydroxy fatty acids. Then ω-hydroxy fatty acids were lactonized by lipase. ω-Hydroxy fatty acids can difficultly be synthesized by traditional chemical methods, and the production of these compounds were key constraint factors during the whole reaction. To obtain enough precursors of macrolactones, an efficient production of ω-hydroxy fatty acids was explored. A mutant of P450 BM3 from Bacillus megaterium was used as terminal hydroxylases. To improve the yield of ω-hydroxy fatty acids, the coenzyme regeneration system and auxiliary organic solvent were optimized. The conversion using the P450 BM3 mutant under the biphase system was up to 42% towards ω-hydroxy pentadecanoic acid and 98% towards ω-hydroxy palmitic acid. The results reveal that the musky macrolactones, exaltolide and silvanone supra, could be synthesized in the hydroxylation-lactonization cascade reaction. Finally, 81 mg of exaltolide was obtained from 242 mg pentadecanoic acid, and 199 mg of silvanone supra from 256 mg palmitic acid.

Avoidance behaviour of the shrimp Palaemon varians regarding a contaminant gradient of galaxolide and tonalide in seawater

The musk fragrances galaxolide (HHCB) and tonalide (AHTN) are compounds of emerging concern that have been found in various environmental compartments. The present study addressed the ability of HHCB and AHTN to elicit the avoidance response in the estuarine shrimp Palaemon varians and to predict the population immediate decline (PID) of P. varians when exposed to HHCB and AHTN by integrating both avoidance (non-forced exposure) and lethality (forced exposure) responses. The avoidance response was tested in a non-forced multi-compartmented static system, in which the shrimps could move freely among the compartments with different concentrations. The shrimps (n = 3 shrimps per compartment/concentration; 18 shrimps per system) were exposed to a gradient (0, 0.005, 0.05, 0.5, 5 and 50 μg/L) of both substances and their positions were checked at every 20 min for a 3 h period. The results from 24-h forced exposure showed no dose-response relationship and the highest percentage mortality was 17% for HHCB at 0.005 and 0.5 μg/L. In the 3-h non-forced exposure to a gradient of HHCB and AHTN, significant concentration-dependent spatial avoidance was observed for both substances. The shrimps avoided the lowest concentration of HHCB and AHTN (0.005 μg/L) by 15% and 16%. The avoidance increased significantly (p < 0.005) to a 61% and 57%, respectively, for the highest concentration (50 μg/L). The population immediate decline was driven by the avoidance behaviour of the shrimps rather than mortality. These results indicated that the aversiveness of HHCB and AHTN might have serious consequences for habitat selection processes by organisms.

Deriving aquatic life criteria for galaxolide (HHCB) and ecological risk assessment

The polycyclic musk galaxolide (HHCB) is widely used as fragrances in personal care products (PCPs) and has been detected in various environmental media. There is an urgent need to derive aquatic life criteria (ALC) of HHCB for the protection of aquatic organisms. Toxicity tests with 8 Chinese resident aquatic organisms from 3 phyla and 8 families were conducted, and three methods were used for deriving the ALC. A criterion maximum concentration (CMC) of 8.33 μg/L and a criterion continuous concentration (CCC) of 2.20 μg/L were derived according to the USEPA guidelines. The acute predicted no effect concentrations (PNECs) values derived by log-normal species sensitivity distribution (SSD) and log-logistic SSD method were 77.41 and 66.47 μg/L, respectively. In addition, a significant sensitivity difference was observed between the planktonic crustacean and benthic crustacean, and there was no significant difference (p > 0.05) among SSDs based on resident and non-resident species. A comparison of chronic SSDs between HHCB, tonalide (AHTN) and musk ketone (MK) showed that nitro musk (MK) was more toxic to aquatic organisms than polycyclic musks (HHCB and AHTN). Finally, an assessment of risk to aquatic organisms in surface waters and effluents of wastewater treatment plants (WWTPs) worldwide showed that potential risk may exist at several locations. HHCB concentrations in 4.08 and 46.17% of the WWTP effluents in China and 1.71 and 16.13% of the WWTP effluents in other countries exceed the hazard concentration for 5% and 1% aquatic species.

Insights into the sediment toxicity of personal care products to freshwater oligochaete worms using Fourier transform infrared spectroscopy

Personal care products (PCPs) are ubiquitous in the environment due to their wide use in daily life. However, there are insufficient sediment toxicity data of PCPs under ecologically relevant conditions. Here we used Fourier transform infrared spectroscopy (FTIR) to investigate the sediment toxicity of triclosan (TCS) and galaxolide (HHCB) to two freshwater benthic macroinvertebrates, Limnodrilus hoffmeisteri and Branchiura sowerbyi, in microcosms containing a diverse biological community. Exposure to 8 µg TCS/g and 100 µg HHCB/g dry weight (dw) sediment induced significant biochemical alterations in the L. hoffmeisteri tissue. 8 µg TCS/g primarily affected proteins and nucleic acid while 100 µg HHCB/g mainly affected proteins and lipids of L. hoffmeisteri. However, 0.8 µg TCS/g and 30 µg HHCB/g did not cause significant subcellular toxicity to L. hoffmeisteri. In contrast, exposure of B. sowerbyi to 30 µg HHCB/g led to significant biochemical changes, including proteins, polysaccharides and lipids. Therefore, B. sowerbyi was more sensitive to sediment-associated HHCB than L. hoffmeisteri. Such effects were significantly enhanced when the HHCB concentration increased to 100 µg/g dw where death of B. sowerbyi occurred. These results demonstrate the application of FTIR spectroscopy to sediment toxicity testing of chemicals to benthic invertebrates with biochemical alterations as endpoints that are more sensitive than standard toxic endpoints (e.g., survival and growth).

Fate and effects of sediment-associated polycyclic musk HHCB in subtropical freshwater microcosms

Galaxolide (HHCB) is used as a fragrance ingredient in household and personal care products, and has been ubiquitously detected in the environment. Here we investigated the fate of HHCB in subtropical freshwater microcosms, and evaluated effects of sediment-associated HHCB on a biological community consisting of algae, Daphnia, benthic macroinvertebrates and bacteria. The concentrations of sediment-associated HHCB did not change significantly during a 28 days exposure period, but HHCB accumulated in worms with biota-sediment accumulation-factor (BSAF) values in the range of 0.29-0.66 for Branchiura sowerbyi and 0.94-2.11 for Limnodrilus hoffmeisteri. There was no significant effects of HHCB (30 μg/g dry weight (dw) sediment) on chlorophyll-a content, sediment bacterial community composition, and survival and growth of benthic macroinvertebrates. However, the presence of benthic macroinvertebrates altered the sediment bacterial community structure relative to microcosms without introduced organisms. The findings of this study suggest that a single high-dose of HHCB, over 28 days, at environmentally relevant concentrations would not impose direct toxicological risks to aquatic organisms such as benthic macroinvertebrates.

Effect of polycyclic musk compounds on aquatic organisms: A critical literature review supplemented by own data

Synthetic musk compounds are extensively used in personal care and cosmetic products around the world. Because they are not completely removed in sewage treatment plants, they eventually end up in aquatic environments. The aim of this review was to summarize published information on effects of polycyclic musks on aquatic organisms and to discuss whether the experimental design of toxicological studies involving these substances could influence the results obtained. With the exception of one study run in a flow-through system, all published toxicological studies on synthetic polycyclic musks have been conducted in semi-static or even static systems. Based upon data in the literature and our own results, we conclude that in toxicological tests with semi-static set-ups, concentrations of polycyclic musks decrease with time between bath exchanges, and, as a result, tested organisms are not being exposed to stable concentrations but rather to concentration pulses. The duration and character of these pulses are influenced mainly by aeration of experimental baths, as polycyclic musks have a tendency to volatilize from water baths. Under semi-static conditions, tested organisms may be subjected to lower concentration of the tested substance for relatively long periods. Those levels may even fall below the limits of quantification. During these periods, some level of detoxification and/or elimination (depuration) of the toxicant may reduce toxic effect of the previous exposures. Consequently, toxicity of polycyclic musk substances for aquatic organisms obtained under these conditions may be underestimated. Based upon existing data in the literature, therefore, it is very difficult to correctly estimate risk of polycyclic musks to aquatic organisms.

Assessment of the ecotoxicity of urban estuarine sediment using benthic and pelagic copepod bioassays

Urban estuarine sediments are sinks to a range of contaminants of anthropogenic origin, and a key challenge is to characterize the risk of these compounds to receiving environments. In this study, the toxicity of urban estuarine sediments was tested using acute and chronic bioassays in the benthic harpacticoid Quinquelaophonte sp., and in the planktonic calanoid Gladioferens pectinatus, two New Zealand copepod species. The sediment samples from the estuary tributary sites significantly impacted reproduction in Quinquelaophonte sp. However, results from one of the estuary sites were not significantly different to those from the tributaries sites, suggesting that chemicals other than trace metals, polycyclic aromatic hydrocarbons and ammonia may be the causative stressors. Sediment elutriate samples had significant effects on reproductive endpoints in G. pectinatus, and on the induction of DNA damage in cells, as shown by the comet assay. The results indicate that sediment contamination at the Ahuriri Estuary has the potential to impact biological processes of benthic and pelagic organisms. The approach used provides a standardized methodology to assess the toxicity of estuarine sediments.

Multibiomarker Responses of Juvenile Stages of Zebrafish (Danio rerio) to Subchronic Exposure to Polycyclic Musk Tonalide

Synthetic polycyclic musks, widely used as additives in personal care products, are present in both biotic and abiotic matrices of the aquatic environment at concentrations of ng/l to µg/l. Although they are determined at comparatively low concentrations, these levels are biologically relevant and pose a significant growing risk as stressors to aquatic organisms. The purpose of our study was to evaluate the effects of 28-day-long exposure to polycyclic musk tonalide in zebrafish juvenile stages (Danio rerio) using selected biomarkers. Environmentally relevant concentrations of tonalide caused significant changes in selected enzyme activities in the experimental groups exposed to the highest concentrations. The activity of glutathione S-transferase and lipid peroxidation increased significantly (p < 0.05) after exposure to the highest concentration (50,000 ng/l) compared with the control. A similar trend was observed in catalase activity; there was a significant increase (p < 0.05) after exposure to two highest concentrations of tonalide (5000 and 50,000 ng/l). In addition, a statistically significant decrease (p < 0.05) in glutathione reductase activity was found in the lowest test concentration of tonalide (50 ng/l). None of the tested concentrations resulted in histopathological changes in liver, kidney, skin, or gill. Furthermore, no effects on body weight, body length, specific growth rate, and behavior were observed. Our results showed that tonalide exposure induced profound changes in the activities of antioxidant and detoxifying enzymes, such changes representing an adaptive response of the fish organism to tonalide toxicity.

Testing lagoonal sediments with early life stages of the copepod Acartia tonsa (Dana): An approach to assess sediment toxicity in the Venice Lagoon

The early-life stages of development of the calanoid copepod Acartia tonsa from egg to copepodite I is proposed as an endpoint for assessing sediment toxicity by exposing newly released eggs directly onto the sediment-water interface. A preliminary study of 5 sediment samples collected in the lagoon of Venice highlighted that the larval development rate (LDR) and the early-life stages (ELS) mortality endpoints with A. tonsa are more sensitive than the standard amphipod mortality test; moreover LDR resulted in a more reliable endpoint than ELS mortality, due to the interference of the sediment with the recovery of unhatched eggs and dead larvae. The LDR data collected in a definitive study of 48 sediment samples from the Venice Lagoon has been analysed together with the preliminary data to evaluate the statistical performances of the bioassay (among replicate variance and minimum significant difference between samples and control) and to investigate the possible correlation with sediment chemistry and physical properties. The results showed that statistical performances of the LDR test with A. tonsa correspond with the outcomes of other tests applied to the sediment-water interface (Strongylocentrotus purpuratus embryotoxicity test), sediments (Neanthes arenaceodentata survival and growth test) and porewater (S. purpuratus); the LDR endpoint did, however, show a slightly higher variance as compared with other tests used in the Lagoon of Venice, such as 10-d amphipod lethality test and larval development with sea urchin and bivalves embryos. Sediment toxicity data highlighted the high sensitivity and the clear ability of the larval development to discriminate among sediments characterized by different levels of contamination. The data of the definitive study evidenced that inhibition of the larval development was not affected by grain-size and the organic carbon content of the sediment; in contrast, a strong correlation between inhibition of the larval development and the sediment concentrations of some metals (Cu, Hg, Pb, Zn), acid-volatile sulphides (AVS), polychlorinated biphenyls (PCBs) and polynuclear aromatic hydrocarbons (PAHs) was found. No correlation was found with DDTs, hexachlorobenzene and organotin compounds.

Photo-induced oxidative damage to dissolved free amino acids by the photosensitizer polycyclic musk tonalide: Transformation kinetics and mechanisms

Residue from the polycyclic musks (PCMs) in household and personal care products may harm human beings through skin exposure. To understand the health effects of PCMs when exposed to sunlight at molecular level, both experimental and computational methods were employed to investigate the photosensitized oxidation performance of 19 natural amino acids, the most basic unit of life. Results showed that a typical PCM, tonalide, acts as a photosensitizer to significantly increase photo-induced oxidative damage to amino acids. Both common and exceptional transformation pathways occurred during the photosensitization damage of amino acids. Experimental tests further identified the different mechanisms involved. The common transformation pathway occurred through the electron transfer from α amino-group of amino acids, accompanying with the formation of O₂^•-. This pathway was controlled by the electronic density of N atom in α amino-group. The exceptional transformation pathway was identified only for five amino acids, mainly due to the reactions with reactive oxygen species, e.g. ¹O₂ and excited triplet state molecules. Additionally, tonalide photo-induced transformation products could further accelerate the photosensitization of all amino acids with the common pathway. This study may support the protection of human health, and suggests the possible need to further restrict polycyclic musks use.

Test procedures for measuring the (sub)chronic effects of chemicals on the freshwater cyclopoid Eucyclops serrulatus

The purpose of this study has been to describe test procedures for measuring the (sub)chronic effects of chemicals on the freshwater cyclopoid Eucyclops serrulatus. To this end we have adapted the setting of the standard full life-cycle protocol of the marine harpacticoid A. tenuiremis to E. serrulatus. We have tested the effects of 4 different diets, two temperatures and two rearing volumes on the survival, development, reproduction and population growth rates of this species. Our results have highlighted that full life-cycle tests can be run using 2 mL-glass vials, a diet consisting of a mixture of living cells of Chlorella sorokiniana and Scenedesmus quadricauda, at either 25 °C (test duration: 42 days) or 18 °C (test duration: 51 days). However, the best performance in terms of survival, development, reproducibility and population growth rates with this species was obtained at 18 °C, albeit with significantly longer test duration. Subchronic tests in 2 mL-glass vials with the mixture microalgal diet at both temperatures are available options if considered appropriate for the objectives of a given study. In particular, developmental tests from nauplius to copepodid may profitably be performed in about 11 days at 18 °C and in 6 days at 25 °C. Under the same test conditions, subchronic tests from copepodid to adult may be run in 19 days at 18 °C and in 16 days at 25 °C.

Temperature and food quantity effects on the harpacticoid copepod Nitocra spinipes: Combining in vivo bioassays with population modeling

The harpacticoid copepod Nitocra spinipes has become a popular model species for toxicity testing over the past few decades. However, the combined influence of temperature and food shortage, two climate change-related stressors, has never been assessed in this species. Consequently, effects of three temperatures (15, 20 and 25°C) and six food regimes (between 0 and 5 × 10⁵ algal cells/mL) on the life cycle of N. spinipes were examined in this study. Similarly to other copepod species, development times and brood sizes decreased with rising temperatures. Mortality was lowest in the 20°C temperature setup, indicating a close-by temperature optimum for this species. Decreasing food concentrations led to increased development times, higher mortality and a reduction in brood size. A sex ratio shift toward more females per male was observed for increasing temperatures, while no significant relationship with food concentration was found. Temperature and food functions for each endpoint were integrated into an existing individual-based population model for N. spinipes which in the future may serve as an extrapolation tool in environmental risk assessment. The model was able to accurately reproduce the experimental data in subsequent verification simulations. We suggest that temperature, food shortage, and potentially other climate change-related stressors should be considered in environmental risk assessment of chemicals to account for non-optimal exposure conditions that may occur in the field. Furthermore, we advocate combining in vivo bioassays with population modeling as a cost effective higher tier approach to assess such considerations.

Potential of the small cyclopoid copepod Paracyclopina nana as an invertebrate model for ecotoxicity testing

Aquatic invertebrates contribute significantly to environmental impact assessment of contaminants in aquatic ecosystems. Much effort has been made to identify viable and ecologically relevant invertebrate test organisms to meet rigorous regulatory requirements. Copepods, which are ecologically important and widely distributed in aquatic organisms, offer a huge opportunity as test organisms for aquatic toxicity testing. They have a major role not only in the transfer of energy in aquatic food chains, but also as a medium of transfer of aquatic pollutants across the tropic levels. In this regard, a supratidal and benthic harpacticoid copepod Tigriopus japonicus Mori (order Harpacticoida) has shown promising characteristics as a test organism in the field of ecotoxicology. Because there is a need to standardize a battery of test organisms from species in different phylogenetic and critical ecosystem positions, it is important to identify another unrelated planktonic species for wider application and comparison. In this regard, the cyclopoid copepod Paracyclopina nana Smirnov (order Cyclopoida) has emerged as a potential test organism to meet such requirements. Like T. japonicus, it has a number of features that make it a candidate worth consideration in such efforts. Recently, the genomics of P. nana has been unraveled. Data on biochemical and molecular responses of P. nana against exposure to environmental chemicals and other stressors have been collected. Recently, sequences and expression profiles of a number of genes in P. nana encoding for heat shock proteins, xenobiotic-metabolizing enzymes, and antioxidants have been reported. These genes serve as potential biomarkers in biomonitoring of environmental pollutants. Moreover, the application of gene expression techniques and the use of its whole transcriptome have allowed evaluation of transcriptional changes in P. nana with the ultimate aim of understanding the mechanisms of action of environmental stressors. Whole-animal bioassays and gene expression studies indicate that P. nana may serve as an excellent tool to evaluate the impact of diverse disturbances in the marine environment. With a better understanding of toxicological mechanisms, ecotoxicologists will be able to understand defense mechanisms against toxicants in copepods. In this review, we illustrate the potential of P. nana as an alternative as well as a complementary invertebrate model organism for risk assessment of aquatic pollutants.

Ecotoxicity and genotoxicity of cadmium in different marine trophic levels

Cadmium ecotoxicity and genotoxicity was assessed in three representative species of different trophic levels of marine ecosystems - the calanoid copepod Acartia tonsa, the decapod shrimp, Palaemon varians and the pleuronectiform fish Solea senegalensis. Ecotoxicity endpoints assessed in this study were adult survival, hatching success and larval development ratio (LDR) for A. tonsa, survival of the first larval stage (zoea I) and post-larvae of P. varians, egg and larvae survival, as well as the presence of malformations in the larval stage of S. senegalensis. In vivo genotoxicity was assessed on adult A. tonsa, the larval and postlarval stage of P. varians and newly hatched larvae of S. senegalensis using the comet assay. Results showed that the highest sensitivity to cadmium is displayed by A. tonsa, with the most sensitive endpoint being the LDR of nauplii to copepodites. Sole eggs displayed the highest tolerance to cadmium compared to the other endpoints evaluated for all tested species. Recorded cadmium toxicity was (by increasing order): S. senegalensis eggs < P. varians post-larvae < P. varians zoea I < S. senegalensis larvae < A. tonsa eggs < A. tonsa LDR. DNA damage to all species exposed to cadmium increased with increasing concentrations. Overall, understanding cadmium chemical speciation is paramount to reliably evaluate the effects of this metal in marine ecosystems. Cadmium is genotoxic to all three species tested and therefore may differentially impact individuals and populations of marine taxa. As A. tonsa was the most sensitive species and occupies a lower trophic level, it is likely that cadmium contamination may trigger bottom-up cascading effects in marine trophic interactions.

Effects of dietary exposure of polycyclic musk HHCB on the metamorphosis of Xenopus laevis

The compound 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-[γ]-2-benzopyrane (HHCB; galaxolide, Chemical Abstracts Service number 1222-05-5) is a synthetic musk used extensively as a fragrance in many consumer products and classified as an emerging pollutant. The ecotoxicological information available for HHCB addresses exposure via water, but this compound is frequently adsorbed into particulate matter. The goal of the present study was to assess the effects of dietary exposure to several environmentally relevant HHCB concentrations adsorbed in food during Xenopus laevis metamorphosis. The authors sought to determine if such exposure to this synthetic musk resulted in histological changes in the thyroid gland in conjunction with changes in development (staging, timing to metamorphosis), body weight, and length. Developmental acceleration on day 14, together with hypertrophy of the thyroid follicular epithelium in tadpoles, suggested a possible agonistic effect of HHCB, which would have been compensated after metamorphosis by regulatory mechanisms to maintain homeostasis. Further research into the potential thyroid-related mechanisms of action of HHCB should be conducted. Environ Toxicol Chem 2016;35:1428-1435. © 2015 SETAC.

Ultrasound-assisted dispersive liquid-liquid microextraction for the determination of synthetic musk fragrances in aqueous matrices by gas chromatography-mass spectrometry

A rapid and simple method for the simultaneous determination of twelve synthetic musks in water samples, using ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) was successfully developed. The influence of seven factors (volume of the extraction solvent and disperser solvent, sample volume, extraction time, ionic strength, type of extraction and disperser solvent) affecting the UA-DLLME extraction efficiency was investigated using a screening design. The significant factors were selected and optimised employing a central composite design: 80 μL of chloroform, 880 μL of acetonitrile, 6 mL of sample volume, 3.5% (wt) of NaCl and 2 min of extraction time. Under the optimised conditions, this methodology was successfully validated for the analysis of 12 synthetic musk compounds in different aqueous samples (tap, sea and river water, effluent and influent wastewater). The proposed method showed enrichment factors between 101 and 115 depending on the analyte, limits of detection in the range of 0.004-54 ng L(-1) and good repeatability (most relative standard deviation values below 10%). No significant matrix effects were found, since recoveries ranged between 71% and 118%. Finally, the method was satisfactorily applied to the analysis of five different aqueous samples. Results demonstrated the existence of a larger amount of synthetic musks in wastewaters than in other water samples (average concentrations of 2800 ng L(-1) in influent and 850 ng L(-1) in effluent). Galaxolide, tonalide and exaltolide were the compounds most detected.

Environmentally relevant concentrations of galaxolide (HHCB) and tonalide (AHTN) induced oxidative and genetic damage in Dreissena polymorpha

Synthetic musk compounds (SMCs) are extensively used as fragrances in several personal care products and have been recognized as emerging aquatic pollutants. Among SMCs, galaxolide (HHCB) and tonalide (AHTN) are extensively used and have been measured in aquatic ecosystems worldwide. However, their potential risk to organisms remains largely unknown. The aim of this study was to investigate whether 21-day exposures to HHCB and AHTN concentrations frequently measured in aquatic ecosystems can induce oxidative and genetic damage in Dreissena polymorpha. The lipid peroxidation (LPO) and protein carbonyl content (PCC) were measured as oxidative stress indexes, while the DNA precipitation assay and the micronucleus test (MN test) were applied to investigate genetic injuries. HHCB induced significant increases in LPO and PCC levels, while AHTN enhanced only protein carbonylation. Moreover, significant increases in DNA strand breaks were caused by exposure to the highest concentrations of HHCB and AHTN tested in the present study, but no fixed genetic damage was observed.

Experimental and predicted acute toxicity of antibacterial compounds and their mixtures using the luminescent bacterium Vibrio fischeri

This article investigates the bioluminescence inhibition effects of the antimicrobials triclocarban, triclosan and its metabolite methyl triclosan, using the marine bacterium Vibrio fischeri as the test organism (Microtox©). The concentration response analysis was performed for the three individual substances and for a mixture in which the three compounds were mixed in a ratio of the IC50 of the individual components (equitoxic ratio). Toxicity values (the median inhibitory concentration value, in mg L(-1)) in the decreasing order of sensitivity were triclosan (0.73)>triclocarban (0.91)>methyl-triclosan (1.76). The comparison of the experimental data with those obtained by using Quantitative Structure-Activity Relationship (QSAR) equations indicated that triclosan and triclocarban act as polar narcotic compounds towards V. fischeri, whereas methyl-triclosan acts as a narcotic (baseline toxicity). The toxicity of the mixture was measured experimentally and predicted by two models (CA: concentration addition; IA: independent action). The results showed that the observed mixture toxicity (IC50=0.23 mg L(-1)) had no significant differences from those predicted by both CA and IA models.

The occurrence and fate of chemicals of emerging concern in coastal urban rivers receiving discharge of treated municipal wastewater effluent

To inform future monitoring and assessment of chemicals of emerging concern (CECs) in coastal urban watersheds, the occurrence and fate of more than 60 pharmaceuticals and personal care products (PPCPs), commercial/household chemicals, current-use pesticides, and hormones were characterized in 2 effluent-dominated rivers in southern California (USA). Water samples were collected during 2 low-flow events at locations above and below the discharge points of water reclamation plants (WRPs) and analyzed using gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry. Approximately 50% of targeted CECs were detectable at stations downstream from WRPs, compared with <31% and <10% at the reference stations above the WRPs. Concentrations of chlorinated phosphate flame retardants were highest among the CECs tested, with mean total aggregate concentrations of tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), and tris(1,3-dichloro-2-propyl) phosphate (TDCPP) of 3400 ng/L and 2400 ng/L for the 2 rivers. Maximum in-stream concentrations of pyrethroids (bifenthrin and permethrin), diclofenac, and galaxolide exceeded risk-based thresholds established for monitoring of CECs in effluent-dominated receiving waters. In contrast, maximum concentrations of PPCPs commonly detected in treated wastewater (e.g., acetaminophen, N,N,diethyl-meta-toluamide [DEET], and gemfibrozil) were less than 10% of established thresholds. Attenuation of target CECs was not observed downstream of WRP discharge until dilution by seawater occurred in the tidal zone, partly because of the short hydraulic residence times in these highly channelized systems (<3 d). In addition to confirming CECs for future in-stream monitoring, these results suggest that conservative mass transport is an important boundary condition for assessment of the input, fate, and effects of CECs in estuaries at the bottom of these watersheds.

Comparison of embryo toxicity using two classes of aquatic vertebrates

Toxicity tests of musk ketone (MK) and tetrabromobisphenol-A (TBBPA) on embryos were conducted in two amphibian species, Xenopus (Silurana) tropicalis and the Swedish native species Rana arvalis. TBBPA was also tested on fish embryos of Danio rerio. All species were tested in similar experimental setup. Musk ketone caused decreased heart rates at concentrations from 10 and 100 μg/L in R. arvalis and X. tropicalis, respectively. TBBPA caused effects at 1000 μg/L in all three species. The responses were comparable between all three species which supports the relevance for using data from non-native species in national risk assessment.

Investigation of Galaxolide degradation products generated under oxidative and irradiation processes by liquid chromatography/hybrid quadrupole time-of-flight mass spectrometry and comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry

RATIONALE

Polycyclic musks have become a concern due to their bioaccumulation potential and ecotoxicological effects. The HHCB transformation product (TP) (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta[γ]-2-benzopyran; HHCB-lactone) is the most stable intermediate generated and it is frequently detected in river waters. The aim of this work was the identification of relevant TPs generated from UV irradiation and ozone treatments.

METHODS

Identification of HHCB TPs was carried out by liquid chromatography/hybrid quadrupole time-of-flight mass spectrometry (LC/ESI-QTOF-MS) and two-dimensional gas chromatography/electron impact time-of-flight mass spectrometry (GC×GC-EI-TOF-MS). With LC/ESI-QTOF-MS, TPs were characterized by means of mass accuracy in both full-scan and MS/MS modes through information-dependent acquisition (IDA) and direct injection on-column. With stir bar sorptive extraction (SBSE)-GC×GC-EI-TOF-MS, identification was based on the enhanced separation capacity and screening of unknowns through the acquisition of full-range mass spectra.

RESULTS

The effectiveness of these complementary techniques allowed a detailed evaluation of the main TPs. Eighteen TPs were elucidated based on mass accuracy, in both full-scan and MS/MS modes using LC/ESI-QTOF-MS with mass errors below 5 ppm and 10 ppm (mostly), respectively. Most of the TPs had not been analytically identified in previous studies. Separation of the enantiomeric species (R) and (S) of HHCB-lactone, and the identification of other relevant TPs, was performed using SBSE-GC×GC-EI-TOF-MS.

CONCLUSIONS

LC/ESI-QTOF-MS and GC×GC-EI-TOF-MS analysis provides the best alternative for TP identification of chemicals of concern, which have a wide range of polarities and isobaric compounds. A prediction of PBT (persistence, bioaccumulation and toxicity) using the PBT Profiler program suggested a classification of 'very persistent' and 'very toxic' for most of the TPs identified.

Occurrences and potential risks of 16 fragrances in five German sewage treatment plants and their receiving waters

Fragrances are used in a wide array of everyday products and enter the aquatic environment via wastewater. While several musk compounds have been studied in detail, little is known about the occurrence and fate of other fragrances. We selected 16 fragrance compounds and scrutinized their presence in Bavarian sewage treatment plants (STP) influents and effluents and discussed their ecological risks for the receiving surface waters. Moreover, we followed their concentrations along the path in one STP by corresponding time-related water sampling and derived the respective elimination rates in the purification process. Six fragrance substances (OTNE, HHCB, lilial, acetyl cedrene, menthol, and, in some grab samples, also methyl-dihydrojasmonate) could be detected in the effluents of the investigated sewage treatment plants. The other fragrances under scrutiny were only found in the inflow and were eliminated in the purification process. Only OTNE and HHCB were found in the receiving surface waters of the STP in congruent concentrations, which exceeded the preliminary derived environmental thresholds by a factor of 1.15 and 1.12, respectively, indicating potential risks. OTNE was also detected in similar concentration ranges as HHCB in muscles and livers of fish from surface waters and from ponds that are supplied with purified wastewater. The findings show that some fragrance compounds undergo high elimination rates, whereas others-not only musks-are present in receiving surface water and biota and may present a risk to local aquatic biota. Hence, our results suggest that the fate and potential effects of fragrance compounds in the aquatic environment deserve more attention.

Improved understanding of key elements governing the toxicity of energy ash eluates

Ash from incinerated waste consists mainly of a complex mixture of metals and other inorganic elements and should be classified based on its inherent hazardous effects according to EUs Waste Framework Directive. In a previous study, we classified eight eluates from ash materials from Swedish incineration plants, both chemically and ecotoxicologically (using bacteria, algae, crustacean and fish). Based on measured concentrations in the eluates together with literature acute toxicity data on the crustacean Nitocra spinipes we identified six elements (i.e. Zn, Cu, Pb, Al, K and Ca) potentially responsible for the observed ecotoxicity. However, comparing the used test methods with N. spinipes, the acute test was relatively insensitive to the eluates, whereas the (sub)chronic test (i.e. a partial life cycle test, investigating larval development ratio) was very sensitive. The overall aim of this follow-up study was to verify if the pinpointed elements could be responsible for the observed (sub)chronic toxicity of the eluates. Individual effect levels (i.e. NOEC values) for these six elements were therefore generated using the (sub)chronic test. Our results show that for six of the eight eluates, the observed ecotoxicity can be explained by individual elements not classified as ecotoxic (Al, K and Ca) according to chemical legislation. These elements will not be considered using summation models on elements classified as ecotoxic in solid material for the classification of H-14, but will have significant implications using ecotoxicological test methods for this purpose.

Antioxidant enzyme activities and lipid peroxidation in earthworm Eisenia fetida exposed to 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta-γ-2-benzopyran

Polycyclic musks have been indicated to cause lethal and sublethal effects on exposed biota. However, knowledge about the effect of polycyclic musks on the antioxidant defense system in earthworms is vague. In this work, the activities of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and malondialdehyde (MDA) exposed to 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta-γ-2-benzopyran (HHCB) were systematically investigated. The investigation shows that their activities are closely related to the exposed dose and time of HHCB. For SOD and CAT, the activities increased monotonically with increased exposed dose of HHCB, which indicates a dose-dependent change pattern. POD exhibited its peak activity in 0.0157 μg cm(-2) HHCB treatment and decreased at higher concentrations. These two changing patterns were complementary, which reveals the cooperation of enzymes in response to oxidative stress. MDA content in earthworms was basically unaffected with a 1-day exposure and significantly increased after 2-day and 3-day exposures, correlating with changes in the activities of SOD and CAT when the concentration of HHCB was high. It was also found that the sensitivity of Eisenia fetida to HHCB increased over time. These results may support the theoretical hypothesis that oxidative stress is an important component for the response of earthworms to the toxicity of HHCB in environment. Among the studied enzymes, SOD and CAT appeared to be the most responsive biomarkers of oxidative stress caused by HHCB. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2012.

Multilevel ecotoxicity assessment of polycyclic musk in the earthworm Eisenia fetida using traditional and molecular endpoints

The ecotoxicity assessment of galaxolide (HHCB) and tonalide (AHTN) was investigated in the earthworm Eisenia fetida using traditional and novel molecular endpoints. The median lethal concentration (LC(50)) for 7-day and 14-day exposures was 573.2 and 436.3 μg g(-1) for AHTN, and 489.0 and 392.4 μg g(-1) for HHCB, respectively. There was no observed significant effect on the growth rate of E. fetida after a 28-day exposure except that at the highest concentration (100 μg g(-1)) of AHTN and HHCB, whereas a significant decrease of cocoon production was found in earthworms exposed to 50 and 100 μg g(-1). To assess molecular-level effect, the expression of encoding antioxidant enzymes and stress protein genes were investigated upon sublethal exposures using the quantitative real time PCR assay. The expression level of SOD, CAT and calreticulin genes was up-regulated significantly, while the level of annetocin (ANN) and Hsp70 gene expression was down-regulated in E. fetida. Importantly, the level of ANN expression had a significant positive correlation with the reproduction rate of earthworms. Furthermore, the lowest observed effect concentration (LOECs) of ANN expression level was 3 μg g(-1) for AHTN and 10 μg g(-1) for HHCB, suggesting that ANN gene expression can serve as a more sensitive indicator of exposure to AHTN and HHCB than traditional endpoints such as cocoon production. The transcriptional responses of these genes may provide early warning molecular biomarkers for identifying contaminant exposure, and the data obtained from this study will contribute to better understand the toxicological effect of AHTN and HHCB.

Effects of the polycyclic ketone tonalide (AHTN) on some cell viability parameters and transcription of P450 and immunoregulatory genes in rainbow trout RTG-2 cells

To assess the potential effects of environmental pollutants belonging to the musk fragrances group in the physiology of aquatic animal species, in this work we treated rainbow trout RTG-2 cells with the polycyclic ketone tonalide (AHTN) at dilutions ranging from 3.5 to 500 ng/ml. The following parameters were monitored: intracellular ATP concentration (energy production), mitochondrial membrane potential (early apoptosis marker), cell viability (vital staining with DFP), quantitative expression of genes coding for the cytochrome P450 detoxifying enzymes CYP1A1 and CYP3A27, and of genes coding for the immunoregulatory peptides IL-1β, IL-8, TNFα, Cox-2 and TGF-β. Obtained results showed that incubation with tonalide induced in RTG-2 cells no effects on cell viability, a slight increase of mitochondrial membrane potential activity, and a significant increase in intracellular ATP concentration. However, dramatic effects were observed in transcription levels of some tested genes, with upregulation levels of 300 and 600 times measured for TGF-β and TNFα, respectively and of 150 times for the CYP3A27 gene. Our results show for the first time the potent effects exerted by tonalide on immunoregulatory genes of RTG-2 cells and also indicate that the measured sensitivity of RTG-2 towards tonalide was in the same range of that currently available using chemical methods. A possible use of the panel of genes we employed as a tool for the monitoring of musk fragrances in biological samples is discussed.

A short life-cycle test with the epibenthic copepod Nitocra spinipes for sediment toxicity assessment

A new short life-cycle test methodology is presented to evaluate sublethal effects of contaminated sediments to the harpacticoid copepod species Nitocra spinipes. The method combines a 4-d survival-gravidity test with a 7-d development test. For water-only Cu exposures, the sensitivity of the development test endpoints were compared with tests using nonexposed gravid females to initiate the 7-d development test phase, and also with a multiple generation test comprising three successive phases: 9-d development; 21-d survival-gravidity; second-generation 9-d development. The results indicated that the development endpoints were the most sensitive, with median effective concentration (EC50) values of 95 µg Cu/L for nauplii/gravid female and 101 µg Cu/L copepodites/gravid female endpoints, followed by the gravidity (144 µg Cu/L) and survival (347 µg Cu/L). The sensitivity of the short life-cycle test endpoints was similar to the multiple-generation test endpoints, and the shorter test had less variability in controls. The multiple-generation test showed a large amount of stimulation of reproduction and development at Cu concentrations of 50 to 100 µg/L. The suitability of the short life-cycle test for assessing sediment toxicity was demonstrated using Cu-spiked and naturally contaminated whole sediments. Although the small nauplii were more difficult to isolate from sediments, the small amounts of sediments used for the tests and the large effects of the contaminated sediments on nauplii and copepodite numbers resulted in significant differences to controls. For sediment exposures, the sensitivity of the endpoints was in the order development > gravidity > survival. The short life-cycle test was demonstrated to detect, within 11 d of exposure, similar levels of effects on reproduction and development to those detected using a 39-d multiple-generation exposure.

Acute toxicity, biochemical and gene expression responses of the earthworm Eisenia fetida exposed to polycyclic musks

AHTN (Tonalide) and HHCB (galaxolide) are recognized as ubiquitous contaminants in soil and have potential adverse impacts on soil organisms. The aim of this study is to investigate the effects of AHTN and HHCB on the earthworm (Eisenia fetida) as an important soil animal with attention to the acute toxicity, biochemical and transcriptional changes of representative antioxidant enzymatic (SOD, CAT) and stress-response gene (Hsp70). The 48 h-LC(50) value was 20.76 μg cm(-2) for AHTN and 11.87 μg cm(-2) for HHCB respectively in the acute lethal studies. The time-dependent elevation in the level of malondialdehyde (MDA) suggests that reactive oxygen species (ROS)-induced cellular oxidative injury of E. fetida might be one of the main toxic effects of AHTN and HHCB. SOD and CAT were both up-regulated at low exposure dose (0.6 μg cm(-2) AHTN and 0.3 μg cm(-2) HHCB) during 48 h testing period, which protected earthworms from oxidative stresses. However, the down-regulation of SOD and CAT after 48 h exposure to high dose contaminants might be caused by the extreme oxidative stress levels (maximum up-regulation 1.70-fold and 1.40-fold for MDA levels at 6.0 μg cm(-2) AHTN and 3.0 μg cm(-2) HHCB compared to the controls, respectively). The Hsp70 gene expression did not show variation during 48 h, except that it had a significant down-regulation (P<0.05) after 48 h of exposure to high doses of contaminants. These results showed that the dermal contact of AHTN and HHCB could result in pronounced biochemical and physiological responses to earthworms, and the transcriptional level changes in antioxidant genes could be potential molecular biomarkers for the stress of the pollutants.

Ecotoxicological responses of the earthworm Eisenia fetida exposed to soil contaminated with HHCB

Although polycyclic musks have been shown to cause lethal and sub-lethal effects on organisms, their biochemical toxicity to earthworms is not well understood. In the current study, we investigated the responses of antioxidant systems and lipid peroxidation after exposing Eisenia fetida to soil contaminated with 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta-γ-2-benzopyran (HHCB). Significant increase in lipid peroxidation level was observed on day 14 at two high concentrations, 50 and 100 mg kg(-1). Among antioxidant enzymes, the primary response to chronic HHCB exposure can be attributed to superoxide dismutase (SOD) and catalase (CAT). Of the two enzymes, SOD exhibited more sensitive response to HHCB stress. In addition, these two enzymes could have a combined effect on fighting damage by reactive oxygen species, evidenced by a marked relationship between lipid peroxidation and enzyme activity. On the other hand, dose-dependent inhibition of peroxidase (POD) activity has been observed throughout the test. The results suggest that the variations in investigated parameters of E. fetida could be used as responsive biomarkers for oxidative stress caused by HHCB in a soil environment.

A review of personal care products in the aquatic environment: environmental concentrations and toxicity

Considerable research has been conducted examining occurrence and effects of human use pharmaceuticals in the aquatic environment; however, relatively little research has been conducted examining personal care products although they are found more often and in higher concentrations than pharmaceuticals. Personal care products are continually released into the aquatic environment and are biologically active and persistent. This article examines the acute and chronic toxicity data available for personal care products and highlights areas of concern. Toxicity and environmental data were synergized to develop a preliminary hazard assessment in which only triclosan and triclocarban presented any hazard. However, numerous PCPs including triclosan, paraben preservatives, and UV filters have evidence suggesting endocrine effects in aquatic organisms and thus need to be investigated and incorporated in definitive risk assessments. Additional data pertaining to environmental concentrations of UV filters and parabens, in vivo toxicity data for parabens, and potential for bioaccumulation of PCPs needs to obtained to develop definitive aquatic risk assessments.

Interaction of Galaxolide® with the human and trout estrogen receptor-α

Synthetic musks have been detected in sewage effluents, surface waters, and fish tissues where the polycyclic musk compound, HHCB (Galaxolide®) is the dominant compound in those matrices. In the present study, the Galaxolide® formulation was tested in the yeast estrogenicity screening (YES) assay, and also tested in in vitro and in vivo teleost systems to determine whether it interacts with the estrogen receptor as either an agonist or antagonist. In those tests, Galaxolide® did not act as an estrogen agonist, however there was strong evidence of antagonistic activity as Galaxolide® inhibited the estrogenic activity of 17β-estradiol (E2). In the YES assay based on a recombinant strain of yeast containing the human estrogen receptor (i.e. hERα), Galaxolide® inhibited the effects of E2 in a dose-dependent manner (IC50=1.63×10(-5)M). In a luciferase reporter gene assay based on the rainbow trout estrogen receptor (i.e. rtER) transfected into a rainbow trout gonadal (RTG-2) cell line, the IC50 for the antagonistic effect of Galaxolide® was 2.79×10(-9)M. In an in vivo assay based on modulation of vitellogenin in rainbow trout, Galaxolide® i.p. injected into trout at a dose of 3.64mg/kg caused inhibition of E2-induced vitellogenin production. That dose is within the range of concentrations of Galaxolide® that have been detected in tissues of fish from contaminated locations.

Aquatic hazard assessment for pharmaceuticals, personal care products, and endocrine-disrupting compounds from biosolids-amended land

Reuse of biosolids on agricultural land is a common practice. Following the application of biosolids to land, contaminants in the biosolids have the potential to migrate offsite via surface runoff and/or leaching and pose a hazard to aquatic ecosystems. The aim of this screening-level assessment study was to determine the relative hazard posed to aquatic ecosystems by pharmaceuticals, personal care products, and endocrine-disrupting compounds (EDCs) that have been detected and quantified in biosolids. This involved estimating maximum possible runoff water concentrations of compounds, using an equilibrium partitioning approach and then comparing these with the lowest available aquatic toxicity data, using the hazard quotient (HQ) approach. A total of 45 pharmaceuticals, personal care products, and EDCs have been detected in biosolids. Ten of these compounds (tonalide, galaxolide, 17β-estradiol, 17α-ethinylestradiol, ciprofloxacin, doxycycline, norfloxacin, ofloxacin, triclosan, and triclocarban) posed a high (HQ >1.0) hazard to aquatic ecosystems relative to the other compounds. This hazard assessment indicated that further research into potential offsite migration and deleterious effects on aquatic ecosystems is warranted for the 10 organic contaminants identified, and possibly for chemicals with similar physicochemical and toxicological properties, in biosolids-amended soils. Because many antibiotic compounds (e.g., ciprofloxacin, norfloxacin, and ofloxacin) have ionic properties, the methods used may have overestimated their predicted aqueous concentrations and hazard. Further research that includes site-specific variables, e.g., dilution factors in waterways, rain intensity, slope of land, degradation, and the use of management strategies such as buffer zones, is likely to decrease the hazard posed by these high hazard compounds.

Comparison of six sewage effluents treated with different treatment technologies--population level responses in the harpacticoid copepod Nitocra spinipes

Since conventional treatment technologies may fail in removing many micro-pollutants, there is currently a focus on the potential of additional treatment technologies for improved sewage treatment. The aim of the present study was to evaluate six different effluents from Henriksdal Sewage Treatment Plant in Stockholm, Sweden. The effluents were; conventionally treated effluent (chemical phosphorous removal in combination with an activated sludge process, including biological nitrogen removal and a sand filter), with additional treatments individually added to the conventional treatment; active carbon filtration, ozonation at 5 mg l(-1), ozonation at 15 mg l(-1), ozonation at 5 mg l(-1)+moving bed biofilm reactor and irradiation with ultraviolet radiation+hydrogen peroxide. The evaluation was done by characterizing and comparing the effluents using a Lefkovitch matrix model based on a life cycle test with the harpacticoid copepod Nitocra spinipes, combined with analysis of juvenile development and survival over time. The conventionally treated effluent resulted in the most negative effects, leading to the conclusion that all additional treatments in the present study created effluents with less negative impacts on the copepod populations. The ozone treatments with the low dose treatment in particular, resulted in the overall least negative effects. Moving bed biofilm reactor combined with ozone did not improve the quality of the effluent in the sense that slightly more negative effects on the population abundance were seen for this treatment technology compared to ozonation alone. The active carbon treatment had more negative effects than the ozone treatments, most of which could possibly be explained by removal of essential metal ions. The effluent which was treated with ultraviolet radiation+hydrogen peroxide resulted in few developmental and survival effects over time, but still showed negative effects on the population level. Matrix population modeling proved a useful tool for biologically characterizing and comparing the effluents. Basing the assessment either on the individual level data (development and survival over time or total reproductive output) or the population level data (lambda values and projected population abundances) would not have resulted in the same conclusions as combining both analyses. The juvenile development and survival over time allowed for closer monitoring of the important molting process, whereas the population modeling provided an integrated measure of potential effects at the population level. If the dilution of the effluent in the recipient is considered, the biological effects recorded in the present study were not of substantial significance for the copepod populations, regardless of treatment technology.

Biodegradation of pharmaceutical and personal care products

Medical treatments and personal hygiene lead to the steady release of pharmaceutical and personal care products (PPCPs) into the environment. Some of these PPCPs have been shown to have detrimental environmental effects and could potentially impact human health. Understanding the biological transformation of PPCPs is essential for accurately determining their ultimate environmental fate, conducting accurate risk assessments, and improving PPCP removal. We summarize the current literature concerning the biological transformation of PPCPs in wastewater treatment plants, the environment, and by pure cultures of bacterial isolates. Although some PPCPs, such as ibuprofen, are readily degraded under most studied conditions, others, such as carbamazepine, tend to be recalcitrant. This variation in the biodegradability of PPCPs can be attributed to structural differences, because PPCPs are classified by application, not chemical structure. The degradation pathways of octylphenol by Sphingomonas sp. strain PWE1, ibuprofen by Sphingomonas sp. strain Ibu-2, and DEET by Pseudomonas putida DTB are discussed in more detail.