Nitro musks, nitro musk amino metabolites and polycyclic musks in sewage sludges. Quantitative determination by HRGC-ion-trap-MS/MS and mass spectral characterization of the amino metabolites

Nitro- and polycyclic musks were quantified in sewage sludge samples from different catchment areas using high-resolution gas chromatography (HRGC) and ion-trap MS/MS. Collision induced dissociation (CID) turned out to be a useful tool for quantification of the analytes. Negative chemical ionization (NCI) quadrupole MS in the selected ion mode (SIM) showed similar sensitivities compared to ion trap MS/MS. Among the nitro musks, musk ketone (MK) and musk xylene (MX) were the main compounds in predominantly domestic sewage sludges, found at low microgram/kg dry matter (d.m.) whereas polycyclic musks were present in domestic as well as in industrial sludges up to 12 mg/kg d.m. Galaxolide (HHCB) and Tonalide (AHTN) were the major polycyclic musks found in the sludges. Amino metabolites of the nitro musks, amino musk xylene (AMA), amino musk moskene (AMM) and amino musk ketone (AMK) were detected for the first time in sewage sludges, and reached partly higher concentrations compared to the parent compounds.     

Environmental risk assessment of musk ketone and musk xylene in the Netherlands in accordance with the EU-TGD

An environmental risk assessment has been carried out for musk ketone and musk xylene according to the EU Technical Guidance Document for Environmental Risk Assessment for New and Existing Substances [1]. Musk ketone and musk xylene are used in fragrances for cosmetics and household products. For the fragrance industry these are important fragrance ingredients because of their excellent substantivity as well as for their unique smell, which determines largely the odor of a product.

The initial environmental risk assessment is based on information provided by the fragrance industry as represented in the Netherlands by its association NEA, by the Research Institute for Fragrance Materials (RIFM) and data reported in the international open literature. The risk assessment includes an evaluation of the risks for aquatic organisms in surface water and sediment and for soil organisms in soil after application of sewage sludge. Secondary poisoning of fish-eating birds and mammals is considered as well. For each compartment the Predicted Environmental Concentration (PEC) is compared to the Predicted No Effect Concentration (PNEC) to obtain PEC/PNEC ratios. Since monitoring data are available in water, sediment and fish, similar ratios are obtained with measured concentrations instead of the predicted ones.

For both substances, PEC/PNEC ratios are at or below 0.1 for organisms in the aquatic environment, including sediment organisms. PEC/PNEC ratios for fish-eating predators are 0.01. Ratios based on monitoring data are below 0.01 for all of these organisms. For soil organisms the PEC/PNEC ratio is 0.5 for musk ketone and 1.3 for musk xylene. Although in the Netherlands (as well as in some other European countries), sewage sludge presently finds no application as fertilizer on agricultural soil, the aim of environmental policy is to upgrade the sludge quality to enable future applications on agricultural and grassland. The reliability of the predicted soil concentrations can be greatly improved by obtaining experimental data on fate and behaviour of musk ketone and musk xylene in digested sludge and soil.

The risk assessment provides reassurance for the aquatic compartment while pointing the way for obtaining aditional data for the soil compartment.     

Nitromusk compounds in San Francisco Bay sediments

Synthetic nitromusk fragrances are used in a wide variety of consumer products and can enter aquatic environments through wastewater effluent. Although nitromusks are known to be hydrophobic, little attention has been paid to their behavior in sediments. A sediment extraction method using sonication was developed and used to analyze samples from San Francisco Bay. Both musk xylene (MX) and musk ketone (MK) were found at low levels, with mean concentrations of 0.034 and 0.038ngg(-1), respectively. The highest concentrations were found in the southernmost region of the Bay. Samples were also analyzed from a nearby tidal channel fed by a wastewater treatment plant outfall. At this location both musk xylene and musk ketone were found at higher concentrations of 0.13-0.24ngg(-1) MX and 1.08-2.74ngg(-1) MK. A metabolite of musk xylene was also found at levels up to 4.08ngg(-1), suggesting that these metabolites may play an important role in the fate of nitromusk compounds. Concentrations of all three compounds were highest at the earliest of four sampling dates, and a geographic survey of sediments along the tidal channel showed that concentrations decreased rapidly with distance from the outfall and were close to background before the channel reached the Bay.     

Blood concentrations of polycyclic musks in healthy young adults

Knowledge on the concentration of polycyclic musk fragrance compounds in human blood is sparse. This study examined the concentrations of six polycyclic musks in blood samples from healthy volunteers. Blood was taken from hundred healthy students of the Medical University of Vienna. The lipophilic fraction was extracted and after purification analyzed by GC-MS. Study participants also completed a questionnaire on the use of cosmetics, about nutrition and other life-style aspects. Two compounds -- galaxolide and tonalide -- were identified in higher percentages of the blood plasma samples. Maximum plasma levels over 100 ng/l were also only found for galaxolide (4100 ng/l) and tonalide (800 ng/l). Women showed significantly higher levels than men. In a statistical multivariate approach only use of body lotion and age were predictive of positive galaxolide concentrations. For tonalide no significant predictor could be found. The findings mirror the replacement of nitro musk fragrances by polycyclic musks, mainly galaxolide. The high concentrations of galaxolide in human blood raise concern since few toxicological data are available.     

Persistent organic pollutants, brominated flame retardants and synthetic musks in fish from remote alpine lakes in Switzerland

Remote alpine lakes do not receive any direct aquatic inputs from anthropogenic activities. Therefore, these ecosystems may receive persistent organic compounds (POPs) by direct atmospheric deposition, only. Consequently, fish dwelling in these ecosystems represent an excellent indicator for the long-term atmospheric input of bioaccumulating and persistent contaminants. In the present study, fish from seven remote alpine lakes, located between 2062 and 2637 m above sea level in south eastern Switzerland (Grisons), were investigated. Lipid-based fish tissue concentrations of pesticides including dichlorodiphenyltrichloroethane (DDT) and its transformation products (2,4'-DDT, 4,4'-DDT, 2,4'-dichlorodiphenyldichloroethane (DDD), 4,4'-DDD, 2,4'-dichlorodiphenyldichloroethene (DDE), 4,4'-DDE), as well as dieldrin, heptachlor exo-epoxide (HPEX), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCH), polychlorinated biphenyls (PCB), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F), and polybrominated diphenyl ethers (PBDE) were measured. In addition, seven synthetic musk compounds (Crysolide (ADBI), Phantolide (AHMI), Fixolide (AHTN), Traseolide (ATII), Galaxolide (HHCB), musk ketone (MK), and musk xylene (MX)) were determined. Concentrations of PCB, PCDD/F, and PBDE were in the same range as in fish from the major lakes situated in the Swiss plateau, indicating mainly atmospheric input of these persistent compounds. In contrast, concentrations of synthetic musks which are used as fragrances in laundry detergents and cosmetic products were distinctly lower than concentrations in fish from Swiss plateau lakes which receive inputs from waste water treatment plants.     

Occurrence of polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls pollution in sediments from the Haihe River and Dagu Drainage River in Tianjin City, China

The pollution status of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in the sediments of Haihe River, which is the most polluted among the seven largest basins in China, Dagu Drainage River flowing through a chemical industry zone, and two other rivers flowing into Bohai Sea in Tianjin City, China were investigated. The concentrations of PCDD/Fs and PCBs in the sediments from the mainstream of Haihe River were 1.3-26pgI-TEQg(-1) dry weight (dw) and 0.07-0.54pgTEQg(-1)dw, respectively. Heavy PCDD/Fs and PCBs pollution, with 1264pgI-TEQg(-1)dw and 21pgTEQg(-1)dw, was found in sediment from Dagu Drainage River. The congener profiles of PCDD/Fs indicated that the principal contamination source was the production of pentachlorophenol (PCP) or PCP-Na in this area. The correlation between PCDD/Fs or PCBs and total organic matter (TOM) showed that PCDD/Fs or PCBs were independent on TOM.     

Synthetic musk fragrances in trout from Danish fish farms and human milk

Synthetic musk compounds used in detergents and cosmetics include nitro and polycyclic musk compounds. These compounds are discharged after use via domestic wastewater and sewage treatment plants to the aquatic environment. Quantitative detection of nitro musk and polycyclic musk compounds by GC/HRMS in Danish farmed trout and human milk from primiparous mothers are reported. The polycyclic musk, HHCB, dominated the synthetic musk compounds found in trout samples from 1999 with a median concentration of 5.0microg/kg fresh weight (n.d.-52.6microg/kg fresh weight) and in trout samples collected in 2003 and 2004 with a median concentration of 1.2microg/kg fresh weight (n.d.-28.0microg/kg fresh weight). It was also found that the concentration of musk xylene in trout sampled at the same fish farms decreased considerably from a median concentration of 5.1microg/kg fresh weight in 1992 to a median of 0.5microg/kg fresh weight in 1999 and to a median less than the detection limit (0.23microg/kg fresh weight) in 2003. HHCB also dominated in Danish human milk samples collected in 1999 with a median concentration of 147microg/kg fat (38.0-422microg/kg fat). Human dietary intake assessment and body burden calculations on data from 1999 indicate that the main source of exposure to human cannot be attributed to the consumption of farmed trout.     

Concentrations of synthetic musk compounds in personal care and sanitation products and human exposure profiles through dermal application

Synthetic musks, such as 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN) and 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-gamma-2-benzopyran (HHCB), musk ketone (MK) and musk xylene (MX), are used as an alternative for natural musk. Due to their widespread use, these synthetic compounds turned up in different environmental compartments, such as wastewater, human and animal tissues. Yet, little is known about their distribution and occurrence in personal care and household products, information needed in order to evaluate the different human exposure routes. This paper gives an overview of the synthetic musk levels in six different product categories: body lotions, perfumes, deodorants, hair care products, shower products and sanitation products. Especially body lotions, perfumes and deodorants contained high levels of synthetic musks. Maximum concentrations of HHCB, AHTN, MX and MK were 22 mg g(-1), 8 mg g(-1), 26 microg g(-1) and 0.5 microg g(-1), respectively. By combining these results with the average usage of consumer products, low-, medium- and high-exposure profiles through dermal application could be estimated. HHCB was the highest contributor to the total amount of synthetic musks in every exposure profile (18-23 700 microg d(-1)). Exposure to MK and MX did not increase substantially (10-20-fold) between low- and high-exposure profiles, indicating that these compounds cover a less broad range. In comparison, exposure to HHCB and AHTN increased up to 10 000 fold between low- and high-exposure.     

Distribution and ecological risk of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in surface sediments from the Bizerte lagoon,Tunisia

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were determined in 18 surface sediment samples collected from Bizerte lagoon, Tunisia. The total concentrations of ten PCBs (∑PCBs) and of four OCPs (∑OCPs) in the sediments from this area ranged from 0.8 to 14.6 ng g^?1 dw (average value, 3.9 ng g^?1 dw) and from 1.1 to 14.0 ng g^?1 dw (average value, 3.3 ng g^?1 dw), respectively. Among the OCPs, the range of concentrations of dichlorodiphenyltrichloroethane and its metabolites (DDTs) and hexachlorobenzene (HCB) were 0.3–11.5 ng g^?1 dw (1.9 ng g^?1 dw) and 0.6–2.5 ng g^?1 dw (1.4 ng g^?1 dw), respectively. Compositional analyses of the POPs indicated that PCB 153, 138 and 180 were the predominant congeners accounting for 60 % of the total PCBs. In addition, p,p′-DDT was found to be the dominant DDTs, demonstrating recent inputs in the environment. Compared with some other regions of the world, the Bizerte lagoon exhibited low levels of PCBs and moderate levels of HCB and DDTs. The high ratios ΣPCBs/ΣDDTs indicated predominant industrial versus agricultural activities in this area. According to the established guidelines for sediment quality, the risk of adverse biological effects from such levels of OCPs and PCBs, as recorded at most of the study sites, was insignificant. However, the higher concentrations in stations S1 and S3 could cause biological damage.     

Determination of coplanar and ortho substituted PCBs in some sewage sludges of Switzerland using HRGC/ECD and HRGC/MSD

The three most toxic coplanar PCB congeners PCB 77, 126 and 169 as well as 7 mono-and di-ortho-PCBs (PCB 28, 52, 101, 118, 153, 138, 180) were measured in 19 sewage sludges. Concentrations of the coplanar PCBs ranged between 231–5050 ng/kg dw for PCB 77, 43–1511 ng/kg dw for PCB 126 and 29–273 ng/kg dw for PCB 169. Comparable results were obtained with mass selective detection in the single ion monitoring mode (MSD-SIM) except for PCB 169, where MSD-SIM was less sensitive than ECD. The sum of the 7 mono-and di-ortho-PCBs, which are routinely measured as representatives of the PCB fraction, reached levels between 43–550 μg/kg dw and agreed well with results previously obtained in our laboratory. Based on our data, a selective accumulation of the coplanar PCBs could not be observed. Sludges that received industrial effluents clearly showed higher PCB levels than rural ones. Finally, calculation of TEQ equivalents of the coplanar PCBs in the sewage sludges revealed that, based on application rates normally used in Switzerland, the contribution of the sludges to soil pollution seems to be of minor importance.     

Inputs and distributions of synthetic musk fragrances in an estuarine and coastal environment; a case study

Synthetic musks are ubiquitous contaminants in the environment. Compartmental distributions (dissolved, suspended particle associated and sedimentary) of the compounds throughout an axial estuarine transect and in coastal waters are reported. High concentrations of Galaxolide^® (HHCB) and Tonalide^® (AHTN) (987-2098 ng/L and 55-159 ng/L, respectively) were encountered in final effluent samples from sewage treatment plants (STPs) discharging into the Tamar and Plym Estuaries (UK), with lower concentrations of Celestolide^® (ADBI) (4-13 ng/L), Phantolide^® (AHMI) (6-9 ng/L), musk xylene (MX) (4-7 ng/L) and musk ketone (MK) (18-30 ng/L). Rapid dilution from the outfalls is demonstrated with resulting concentrations of HHCB spanning from 5 to 30 ng/L and those for AHTN from 3 to 15 ng/L. The other musks were generally not detected in the estuarine and coastal waters. The suspended particulate matter (SPM) and sedimentary profiles and compositions (HHCB:AHTN ratios) generally reflect the distribution in the water column with highest concentrations adjacent to sewage outfalls.     

Dioxins, PCBs, metals, metalloids, pesticides and antimicrobial residues in wild and farmed Australian southern bluefin tuna (Thunnus maccoyii)

Data concerning the concentration of dioxins (PCDD/PCDFs), polychlorinated biphenyls (PCBs), metals, metalloids, pesticides and antimicrobials residues are reported for the edible portion of Australian wild and farmed southern bluefin tuna (Thunnus maccoyii). In 2004 wild caught (n=5) and farmed (n=26) southern bluefin tuna (SBT) were collected. The mean concentration of total mercury on a fresh weight (fw) basis was 0.34 mg/kg in wild SBT and 0.31 mg/kg in farmed SBT. Concentrations of dioxins (PCDD/PCDFs) and polychlorinated biphenyls (PCBs) found in wild SBT were extremely low. The mean concentration (fw) of the sum of PCDD/PCDFs and the dioxin-like PCBs was 0.27 pg TEQ/g in wild SBT and 0.61 pg TEQ/g in farmed SBT. Mean PCB total concentration (fw basis) was 0.47 ng/g in wild SBT and 6.60 ng/g in farmed SBT. No detectable residues of any pesticide or antimicrobial compounds were found. All residues detected were within regulatory limits set by the Japanese Competent Authority, the Ministry of Health, Labour and Welfare (MHLW) and the Australian Competent Authority, Food Standards Australia New Zealand (FSANZ). The need for harmonisation of international product integrity procedures for bluefin tunas in international trade is highlighted.     

Levels,congener profile and inventory of polychlorinated biphenyls in sediment from the Songhua River in the vicinity of cement plant,China: a case study

This study investigated the contamination levels, homologue, and congener profiles and evaluated the residue inventory of polychlorinated biphenyls (PCBs) in sediment of the Songhua River in the vicinity of cement plant. The total concentration of detected 35 PCB congeners ranged from 1.12 to 2.19 ng/g dry weight (dw) in sediment, with a mean value of 1.56 ng/g dw, and the concentration of PCBs decreased in the following order: the downstream?>?cement plant?>?upstream. The results of total organic carbon (TOC)-normalized PCB concentrations indicate that the sediments have low potential ecological risk in this area. The study results on homologue and congener of PCBs show that the emissions from cement production could be the major sources of PCBs in sediment, and the low-chlorinated PCBs will be exchanged among air, water, and sediment with increasing temperature during summer and flow to downstream with water during the wet season. The spatial density and total burden of PCBs in the surface sediments were 17.2 ng/cm² and 1.2 kg, respectively. To our knowledge, this study is the first to explore the pollution characteristics of unintentionally produced PCB emissions from cement industry by means of monitoring sediment samples.     

Concentrations and assessment of exposure to siloxanes and synthetic musks in personal care products from China

We investigated the concentrations and profiles of 15 siloxanes (four cyclic siloxanes, D₄-D₇; 11 linear siloxanes, L₄-L₁₄), four synthetic musks (two polycyclic musks, HHCB and AHTN; two nitro musks, MX and MK), and HHCB-lactone, in 158 personal care products marketed in China. Siloxanes were detected in 88% of the samples analyzed, at concentrations as high as 52.6 mg g⁻¹; Linear siloxanes were the predominant compounds. Among synthetic musks, more than 80% of the samples contained at least one of these compounds, and their total concentrations were as high as 1.02 mg g⁻¹. HHCB was the predominant musk in all of the samples analyzed, on average, accounting for 52% of the total musk concentrations. Based on the median concentrations of siloxanes and musks and the average daily usage amounts of consumer products, dermal exposure rates in adults were calculated to be 3.69 and 3.38 mg d⁻¹ for siloxanes and musks, respectively.     

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.     

水体中酮硝基麝香的臭氧氧化降解研究

采用臭氧氧化水体中的酮硝基麝香,考察pH、H2O2等因素对降解程度的影响,结果表明提高初始pH能加快酮硝基麝香的氧化降解,当pH为12时,反应时间1 h,酮硝基麝香几乎完全去除,浓度为2 mol/L和5 mol/L的H2O2存在有利于O3分解生成·OH自由基,使得酮硝基麝香的氧化降解速率加快,当H2O2浓度超过5 mol/L,H2O2会成为·OH的清除剂,降低·OH利用率;无论O3单独作用和O3/H2O2协同作用,酮硝基麝香降解符合准一级动力学规律;酮硝基麝香氧化降解产物包括甲酸、二乙酸和硝酸根等,其中硝基从苯环上脱落降低了硝基麝香对环境的风险.     

Contamination of human milk in Middle Hesse, Germany--a cross-sectional study on the changing levels of chlorinated pesticides, PCB congeners and recent levels of nitro musks

Human milk samples from women in Middle Hesse, Germany were chemically analyzed for contamination levels of alpha-, beta- and gamma-HCH, HCB, p,p'-DDE and p,p'-DDT as well as the PCB-congeners no. 28, 31, 49, 52, 101, 118, 138, 153, 156, 170 and 180. Changes in concentrations of these compounds in human milk over an extended time period were studied by comparing samples from 1984/85, 1990/91 and 1995. In addition, concentrations of the nitro-aromatic compounds musk xylene and musk ketone were determined in the 1995 samples. The study showed statistically highly significant (p<0.001) reductions in levels of beta- and gamma-HCH, HCB, p,p'-DDE and p,p'-DDT, in human milk from 1995 compared to samples from 1984/85. A weakly significant reduction (p<0.05) of alpha-HCH was also observed. For low-chlorinated PCB congeners, on the other hand, a highly significant increase of PCB no. 28 was detected and concentrations of congeners no. 31, 49 and 52 remained unchanged. Concentrations of the high-chlorinated congeners no. 101, 138, 153 and 180 dropped (highly significant). A highly significant reduction of PCB no. 118 and 156 occurred between 1990/91 and 1995, but a highly significant increase was found for no. 170. Lower levels of hydrocarbon contamination of human milk samples from 1995 than were found in samples from 1984/85 and 1990/91 can be seen to result partially from voluntary reductions, but primarily reflect restrictive environmental legislation in the Federal Republic of Germany. Mean concentrations of musk xylene and musk ketone in samples from 1995 were 41 microg/kg and 10 microg/kg milk fat, respectively.     

Transformation products and reaction kinetics of fragrances in advanced wastewater treatment with ozone

The reaction of the fragrance compounds 4,6,6,7,8,8-hexamethyl-1,3,4,7-tetrahydrocyclopenta[g]isochromene (HHCB), 1-(3,5,5,6,8,8-hexamethyl-6,7-dihydronaphthalen-2-yl)ethanone (AHTN), 1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene (musk xylene/MX), 1-(4-tert-butyl-2,6-dimethyl-3,5-dinitrophenyl)ethanone (musk ketone/MK), and 1-(2,3,8,8-tetramethyl-1,3,4,5,6,7-hexahydronaphthalen-2-yl)ethanone (OTNE) with ozone in tap water as well as waste water treatment plant (WWTP) effluents is described. Several transformation products are characterized by means of gas chromatography coupled to mass spectrometry. One transformation product (HHCB-Lactone) was confirmed by means of a true standard. Musk xylene and musk ketone do not react with ozone under the conditions used in this study. AHTN and HHCB reacted slowly to a multitude of transformation products, while OTNE reacted quickly to several stable transformation products. The reaction constants and half lives are used to predict removal efficiencies for full scale reactors.     

PCDDs, PCDFs, PCBs and DDE in edible marine species from the Adriatic Sea

Edible marine species from several areas of the Adriatic sea were analyzed for their content in persistent organic pollutants (POPs), such as polychlorinated dibenzodioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), and pp'-DDE (dichlorodiphenyldichloroethylene), a metabolite of the organochlorine pesticide dichlorodiphenyltrichloroethane (DDT). On the whole, PCDD/F contamination levels were low. In general, I-TEQ findings were greater for those species at higher levels in the trophic web (mackerel > red mullet > anchovy). Contamination levels were within 0.23 and 1.07 pg TEQ/g fw (fresh weight) in the aforesaid species, while all remaining species exhibited contamination levels ranging from approximately 0.07 to 0.25 pg TEQ/g fw. Besides, TEQ cumulative findings in species from the northern area were in general greater than those from the central and southern areas. PCB cumulative findings in the samples also revealed a detectable difference in contamination levels in species obtained from the northern, central, and southern sampling sites, between 7.6 and 177, 2.3 and 157, and 4.5 and 94 ng/g fw, respectively. The greatest PCB concentrations were found in mackerel (94-177 ng/g fw). Finally, DDE concentration levels varied from 0.7 to 32.4 ng/g fw. The highest levels of contamination were found in mackerel, red mullet and anchovy (17.7-32.4 ng/g fw, 8.1-9.8 ng/g fw, and 6.4-11.9 ng/g fw, respectively).