# Legacy and emerging per- and polyfluoroalkyl substances in eggs of yellow-legged gulls from Southern France

William Jouanneau, Thierry Boulinier, Dorte Herzke, Vladimir A. Nikiforov, Geir W Gabrielsen, Olivier Chastel

► To cite this version:

William Jouanneau, Thierry Boulinier, Dorte Herzke, Vladimir A. Nikiforov, Geir W Gabrielsen, et al. Legacy and emerging per- and polyfluoroalkyl substances in eggs of yellow-legged gulls from Southern France. Marine Pollution Bulletin, 2025, 216, pp.117941. 10.1016/j.marpolbul.2025.117941. hal-05043906

HAL Id: hal-05043906

https://hal.science/hal-05043906v1

Submitted on 23 Apr 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
<figure><img src="image_2.png" /></figure>

# Legacy and emerging per- and polyfluoroalkyl substances in eggs of yellow-legged gulls from Southern France

William Jouanneau<sup>a,b,*</sup>, Thierry Boulinier<sup>c</sup>, Dorte Herzke<sup>d</sup>, Vladimir A. Nikiforov<sup>d</sup>, Geir W. Gabrielsen<sup>b</sup>, Olivier Chastel<sup>a</sup>

## ARTICLE INFO

Keywords:

PFAS
Avian toxicity
Seabird
Biomonitoring
Maternal transfer
Mediterranean

## ABSTRACT

More than 70 years of industrial production of per- and polyfluoroalkyl substances (PFAS) have resulted in their ubiquitous presence in the environment on a global scale, although differences in sources, transport and fate lead to variability of occurrence in the environment. Gull eggs are excellent bioindicators of environmental pollution, especially for persistent organic pollutants such as PFAS, known to bioaccumulate in organisms and to be deposited in bird eggs by maternal transfer. Using yellow-legged gull (*Larus michahellis*) eggs, we investigated the occurrence of more than 30 PFAS, including the most common chemicals (i.e., legacy PFAS) as well as their alternatives (i.e., emerging PFAS) in the Bay of Marseille, the second largest city in France. Compared to eggs from other colonies along the Mediterranean coast, those from Marseille had PFAS concentrations ranging from slightly higher to up to four times lower, suggesting that this area cannot be specifically identified as a hotspot for these compounds. We also found several emerging PFAS including 8:2 and 10:2 FTS, 7:3 FTCA or PFECHS in all collected eggs. Although the scarcity in toxicity thresholds for seabirds, especially during embryogenesis, does not enable any precise statement about the risks faced by this population, this study contributes to the effort in documenting legacy PFAS contamination on Mediterranean coasts while providing valuable novel inputs on PFAS of emerging concern. Identifying exposure in free-ranging species also participate to determine the main target for toxicity testing in wildlife.

## 1. Introduction

Poly- and perfluoroalkyl substances (PFAS) are a large class of anthropogenic chemicals first synthetized at the end of the 1940's. Increasingly produced along the second part of the 20th century for their unique amphiphilic properties making them valuable surfactants and repellents molecules, they are now used in an extensive number of industrial processes and final products (Glüge et al., 2020). PFAS and their precursors may be released in the environment at each step of their life cycle from production to disposal and can then travel long-distances via atmospheric and marine currents before entering trophic webs (Evich et al., 2022). Occurrence of PFAS in wildlife tissues has been reported in the early 2000s notably for several compounds characterized by a long carbon chain and now identified as "legacy" PFAS (e.g., perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA)), due to high

migration, bioaccumulation and persistence potentials (Giesy and Kannan, 2001; Hansen et al., 2001). This finding paved the way to numerous studies reporting PFAS occurrence and fate in the environment and biota. Soon afterwards, the widespread pollution by PFAS led relevant manufacturers to phase-out their production of PFOS and PFOA in the U.S. Additionally, PFOS, PFOA and more recently perfluorohexane sulphonic acid (PFHxS) were included in the list of persistent organic pollutants (POPs) under the Annex B of the Stockholm Convention (Schulz et al., 2020). Since the discovery of their ubiquitous nature, the toxicity of legacy PFAS has been investigated for humans and wildlife. These numerous studies identified diverse PFAS-related health effects including biochemical and immune parameters, liver and kidney diseases or cancers, as well as endpoints related to reproductive success and developmental outcomes (Ankley et al., 2021; Fenton et al., 2021).

As regulations on legacy PFAS were put into place, alternative

<footnote><sup>a</sup> Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 CNRS - La Rochelle Université, 17031 La Rochelle, France</footnote>

<footnote><sup>b</sup> Norwegian Polar Institute, Fram Centre, NO-9296 Tromsø, Norway</footnote>

<footnote><sup>c</sup> Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, Montpellier, France</footnote>

<footnote><sup>d</sup> NILU, Fram Centre, NO-9296 Tromsø, Norway</footnote>

<footnote>* Corresponding author at: Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 CNRS - La Rochelle Université, 17031 La Rochelle, France
E-mail address: w.jouanneau@gmail.com (W. Jouanneau).</footnote>
fluorinated molecules were developed. These alternatives, called "emerging PFAS", as well as short-chain homologues, precursors and degradation products of legacy PFAS are being found in the environment and wildlife tissues in recent years and are now receiving increased attention (Chen et al., 2021; Jouanneau et al., 2022; Munoz et al., 2019; Xiao, 2017). The production of these PFAS of emerging concern is ongoing although very little is known about their toxicity for humans and wildlife (Hamid et al., 2024; Mahoney et al., 2022; Wang et al., 2019). Yet, they are still seldom included in studies investigating PFAS occurrence. Indeed, documenting legacy PFAS concentrations is still of high interest to assess the effectiveness of regulations, but it is now just as essential to record the occurrence of emerging PFAS to better identify potential exposure, hotspots and dispersion patterns.

Seabirds are commonly used as bioindicators of environmental pollution (Elliott and Elliott, 2013) because they often accumulate contaminants including PFAS, although in an unequal manner in their different organs (Verreault et al., 2005). In particular, high concentrations of PFAS tend to be transferred by females into their eggs, which have therefore been identified as valuable biological samples to analyze for less abundant compounds including emerging PFAS (Jouanneau et al., 2022; Wang et al., 2021b). Nonetheless, so far, most studies aiming at measuring PFAS in seabird and their eggs have focused on legacy PFAS (Sun et al., 2023). Studies investigating PFAS of emerging concern in seabird eggs were limited to glaucous gull (*Larus hyperboreus*), common eiders (*Somateria mollissima*) and black-legged Kittiwakes (*Rissa tridactyla*) from Svalbard (Herzke et al., 2022; Jouanneau et al., 2022), Caspian terns (*Hydropropgne caspia*) and American herring gulls (*Larus smithsonianus*) from the Great Lakes of North America (Letcher et al., 2015; Su et al., 2017), black-tailed gulls (*Larus crassirostris*) from South Korea (Wang et al., 2021b), white-tailed eagles (*Halliaetus alMICILLa*) from Sweden (Haque et al., 2023) and common guillemots (*Uria aalge*) from the Baltic Sea (Gebbink et al., 2016), documenting the occurrence of several novel compounds such as perfluoroethylcyclohexane sulfonate (PFECHS), chlorinated polyfluoroalkyl ether sulfonic acid (F-53B), hexafluoropropylene oxide dimer acid (GenX), dodecafluoro-3H-4,8-dioxanonanoate (ADONA) and 7:3 FTCA. Nonetheless, numerous highly-urbanized regions were not covered by these studies, such as the Mediterranean Sea, an almost closed sea particularly vulnerable to chemical pollution (Danovaro, 2003). Legacy PFAS were however investigated on its coasts in yellow-legged gull (*Larus michahellis*) eggs, and elevated concentrations were documented in several colonies in Italy (Parolini et al., 2020) and Spain (Bertolero et al., 2015; Colomer-Vidal et al., 2022; Vicente et al., 2012). These studies reported high inter-colonies differences though, suggesting a strong spatial variation in PFAS contamination, with eggs from colonies closer to urbanized regions being the most contaminated. It is therefore essential to track emerging PFAS concentrations in Mediterranean seabirds, especially close to heavily urbanized locations suspected to be pollution hotspots.

In that framework, we investigated legacy and emerging PFAS in yellow-legged gull eggs from the Bay of Marseille, the second largest city in France and located on the coast of the Gulf of Lion, part of the Mediterranean Sea. Using the yellow-legged gull as a bioindicator of local environment, we aim at evaluating the contamination by legacy PFAS in this highly urbanized area while providing the first measurements for emerging PFAS in French wildlife.

## 2. Materials and methods

### 2.1. Study area and sampling

All sampling permits were obtained from the Direction Départementale des Territoires et de la Mer des Bouches-du-Rhône and the Parc National des Calanques, and the study was conducted according to the appropriate French regulations and protocols. Field work was conducted at the Iles du Frioul (Parc National des Calanques, Marseille,

France) in March 2021. During the peak of the egg laying period, one freshly-laid egg was collected from 30 different yellow-legged gull nests regardless of its ranking in the clutch. Egg floatability test - commonly used to estimate the incubation stage of bird eggs (Van Paassen et al., 1984) - was used to select freshly laid egg. For each egg independently, we separated albumen and yolk upon return in the laboratory at the end of the day, and kept them frozen separately until PFAS assay. As the majority of PFAS in bird eggs is found in the yolk and not in the albumen, we measured PFAS in the egg yolk only to avoid dilution in homogenized egg (Gebbink and Letcher, 2012).

### 2.2. PFAS analyses

Yolk PFAS concentrations were measured at the Norwegian Institute for Air Research (NILU) using a method from Powley et al. (2005) adjusted for egg yolk (Jouanneau et al., 2022). Briefly, sample (~0.20 g of yolk) were extracted in methanol (0.8 mL), and matrix was removed using three series of vortexing followed by 10 min of sonication baths, after what a centrifugation (10,000 rpm) what used for sedimentation. The supernatant was then cleaned using glacial acetic acid (50 µL) and ENVI-Carb 120/400 (Supelco 57.210-U; 25 mg). Internal PFAS standards (20 µL) were added at the beginning of the process of every sample, as well as recoveries (20 µL) at the end, to calculate recovery of the ¹³C labeled internal standards. We then conducted the quantification of PFAS by ultrahigh-performance liquid chromatography triple-quadrupole mass spectrometry (UHPLC - MS/MS). Chromatograms were then quantified using LCQuan software (Thermo Fischer Scientific, Waltham, USA), by applying the isotopic dilution method. An eight-point calibration curve with a concentration range from 0.02 to 10.0 pg µL⁻¹ was used. We searched a total of 34 PFAS (14 considered as emergent and 20 legacy; Table 1). All concentrations are expressed in ng g⁻¹ wet weight (ww). One blank and a standard reference material (human serum AM-S-Y-2108 INSPQ; AMAP ring test) were concurrently analyzed every sample batch to ensure analyses quality.

The limit of detection (LOD) was defined as three times the signal-to-noise ratio for the specific matrix, or in the case of detection in the blanks as the sum of the average of the blank level and 3 times standard deviation. LOD varied depending on the compounds and ranged from 0.003 to 0.25 ng g⁻¹ ww (Table 1). Only compounds detected in more than 70 % of the samples (a commonly used cutoff) were kept for comparisons to other studies. Descriptive statistics are provided for all detected PFAS (Table 1) using the R software (v. 4.4.1; R Core Team, 2024), they were estimated using the regression on order statistics method from the NADA2 package for PFAS containing non-detected (Helsel, 2011; Julian and Helsel, 2024). Values for compounds detected in less than 70 % of the samples are exclusively calculated on measurements above the LODs and therefore are only documented here for informational purposes.

## 3. Results and discussion

### 3.1. Detected PFAS in egg yolks

Among the 34 targeted compounds, PFHpS, brPFOS, linPFOS, C₈ to C₁₄ PFCAs (perfluoroalkyl carboxylic acids) and PFECHS were detected in 100 % of the eggs sampled. PFHxS (97 %), PFHxA (93 %), 8:2 FTS (87 %), 10:2 FTS (87 %) and 7:3 FTCA (87 %) were also frequently detected while PFBS (13 %), PFNS (10 %), PFDcS (3 %), PFHxA (27 %), PFHpA (27 %), 6:2 FTS (53 %) and HPFO-TeA (23 %) were only occasionally measured above LOD (Table 1).

### 3.2. Legacy PFAS in egg yolks

LinPFOS, accounting for 61 % of the ΣPFAS, was by far the dominant compound measured in egg yolk followed by PFTriA, PFTeA and PFDoA together representing 10 % of the ΣPFAS (Table 1 & Fig. 1). PFOS being
<caption>**Table 1**</caption>

List of targeted per- and polyfluoroalkyl substances (PFAS) separated into legacy and emerging compounds: their groups, abbreviations, chemical names, detection rates and limits of detection (LODs) as well as descriptive statistics (mean ± standard deviation: SD, median and range: min-max, expressed in ng g⁻¹ ww) in egg yolk of yellow-legged gulls from the Frioul Islands (Marseille, France). Those found in more than 70 % of the samples are in bold. Mean, SD and median of PFAS containing non-detected were estimated using the regression on order statistics method. Descriptive statistics of PFAS found in less than 70 % of the samples were calculated using exclusively values above LODs and are provided here for informational purposes only. A single egg was measured above LOD for PFDCS.

<table><thead><tr><th>Group</th><th>Abbreviation</th><th>Chemical name</th><th>Detection rate</th><th>Limit of detection (ng g<sup>-1</sup> ww)</th><th>Mean ± SD</th><th>Median</th><th>Min-max</th></tr></thead><tbody><tr><td rowspan="12">Legacy PFAS</td><td rowspan="3">Perfluoroalkane sulfonic acids</td><td>PFBS</td><td>perfluorobutanesulfonic acid</td><td>13.30 %</td><td>0.050</td><td>0.11 ± 0.00</td><td>0.11</td><td>0.11–0.11</td></tr><tr><td>PFPS</td><td>perfluoropentanesulfonic acid</td><td>0.00 %</td><td>0.100</td><td>–</td><td>–</td><td>–</td></tr><tr><td>PFHxS</td><td>perfluorohexanesulfonic acid</td><td>96.70 %</td><td>0.050</td><td>1.76 ± 1.39</td><td>1.33</td><td>LOD – 4.94</td></tr><tr><td rowspan="3">PFHpS</td><td>perfluoroheptanesulfonic acid</td><td>100.00 %</td><td>0.100</td><td>0.88 ± 0.55</td><td>0.80</td><td>1.19–2.67</td></tr><tr><td>brPFOS</td><td>branched perfluorooctanesulfonic acid</td><td>100.00 %</td><td>0.100</td><td>11.2 ± 7.38</td><td>9.55</td><td>1.70–31.9</td></tr><tr><td>linPFOS</td><td>linear perfluorooctanesulfonic acid</td><td>100.00 %</td><td>0.100</td><td>44.2 ± 21.9</td><td>47.2</td><td>15.4–87.3</td></tr><tr><td rowspan="9">Perfluoroalkyl carboxylic acids</td><td>PFNS</td><td>perfluorononanesulfonic acid</td><td>10.00 %</td><td>0.100</td><td>0.27 ± 0.03</td><td>0.3</td><td>0.25–0.30</td></tr><tr><td>PFDCS</td><td>perfluorodecanesulfonic acid</td><td>3.30 %</td><td>0.100</td><td>5.72 ± –</td><td>5.72</td><td>–</td></tr><tr><td>PFHxA</td><td>perfluorohexanoic acid</td><td>26.70 %</td><td>0.100</td><td>0.20 ± 0.13</td><td>0.17</td><td>0.12–0.52</td></tr><tr><td>PFHpA</td><td>perfluoroheptanoic acid</td><td>26.70 %</td><td>0.050</td><td>0.41 ± 0.29</td><td>0.3</td><td>0.19–0.91</td></tr><tr><td>PFOA</td><td>perfluorooctanoic acid</td><td>100.00 %</td><td>0.020</td><td>0.93 ± 0.51</td><td>0.72</td><td>0.29–2.63</td></tr><tr><td>PFNA</td><td>perfluorononanoic acid</td><td>100.00 %</td><td>0.100</td><td>0.98 ± 0.38</td><td>0.9</td><td>0.48–2.07</td></tr><tr><td>PFDcA</td><td>perfluorodecanoic acid</td><td>100.00 %</td><td>0.100</td><td>1.46 ± 0.54</td><td>1.3</td><td>0.67–2.44</td></tr><tr><td>PFUnA</td><td>perfluoroundecanoic acid</td><td>100.00 %</td><td>0.100</td><td>1.66 ± 0.81</td><td>1.4</td><td>0.57–4.18</td></tr><tr><td>PFDoA</td><td>perfluorododecanoic acid</td><td>100.00 %</td><td>0.100</td><td>2.00 ± 0.78</td><td>1.89</td><td>0.90–3.73</td></tr><tr><td rowspan="3">PFTriA</td><td>perfluorotridecanoic acid</td><td>100.00 %</td><td>0.100</td><td>2.78 ± 1.18</td><td>2.7</td><td>1.08–5.54</td></tr><tr><td>PFTeA</td><td>perfluorotetradecanoic acid</td><td>100.00 %</td><td>0.100</td><td>2.62 ± 1.34</td><td>2.53</td><td>0.95–6.81</td></tr><tr><td>PFHxDA</td><td>perfluorohexadecanoic acid</td><td>93.30 %</td><td>0.160</td><td>0.68 ± 0.17</td><td>0.64</td><td>LOD – 1.37</td></tr><tr><td rowspan="2">Perfluoroalkane sulfonamido substances</td><td>PFODcA</td><td>perfluorooctadecanoic acid</td><td>0.00 %</td><td>0.150</td><td>–</td><td>–</td><td>–</td></tr><tr><td>FOSA</td><td>perfluorooctane sulfonamide</td><td>0.00 %</td><td>0.100</td><td>–</td><td>–</td><td>–</td></tr><tr><td rowspan="12">Emerging PFAS</td><td rowspan="4">Fluorotelomer sulfonic acid</td><td>4:2 FTS</td><td>4:2 fluorotelomer sulfonic acid</td><td>0.00 %</td><td>0.100</td><td>–</td><td>–</td><td>–</td></tr><tr><td>6:2 FTS</td><td>6:2 fluorotelomer sulfonic acid</td><td>53.30 %</td><td>0.100</td><td>2.22 ± 4.21</td><td>0.45</td><td>0.15–16.0</td></tr><tr><td>8:2 FTS</td><td>8:2 fluorotelomer sulfonic acid</td><td>86.70 %</td><td>0.100</td><td>0.57 ± 0.33</td><td>0.53</td><td>LOD – 1.42</td></tr><tr><td>10:2 FTS</td><td>10:2 fluorotelomer sulfonic acid</td><td>86.70 %</td><td>0.100</td><td>0.67 ± 0.64</td><td>0.46</td><td>LOD – 2.36</td></tr><tr><td rowspan="2">Fluorotelomer carboxylic acid</td><td>5:3 FTCA</td><td>5:3 fluorotelomer carboxylic acid</td><td>0.00 %</td><td>0.025</td><td>–</td><td>–</td><td>–</td></tr><tr><td>7:3 FTCA</td><td>7:3 fluorotelomer carboxylic acid</td><td>86.70 %</td><td>0.016</td><td>0.09 ± 0.09</td><td>0.05</td><td>LOD – 0.47</td></tr><tr><td rowspan="8">Fluoroalkylether compounds</td><td>GenX or 33-PFECA (HPFO-DA)</td><td>hexafluoropropylene oxide dimer acid</td><td>0.00 %</td><td>0.025</td><td>–</td><td>–</td><td>–</td></tr><tr><td>333-PFECA (HPFO-TA)</td><td>hexafluoropropylene oxide trimer acid</td><td>0.00 %</td><td>0.025</td><td>–</td><td>–</td><td>–</td></tr><tr><td>3333-PFECA (HPFO-TeA)</td><td>hexafluoropropylene oxide tetramer acid</td><td>23.30 %</td><td>0.005</td><td>0.01 ± 0.00</td><td>0.01</td><td>0.01–0.01</td></tr><tr><td>33333-PFECA (5 × 3-PFECA)</td><td>hexafluoropropylene oxide pentamer acid</td><td>0.00 %</td><td>0.050</td><td>–</td><td>–</td><td>–</td></tr><tr><td>333333-PFECA (6 × 3-PFECA)</td><td>hexafluoropropylene oxide hexamer acid</td><td>0.00 %</td><td>0.025</td><td>–</td><td>–</td><td>–</td></tr><tr><td>ADONA (3H-133-PFECA)</td><td>dodecafluoro-3H-4,8-dioxanonoate</td><td>0.00 %</td><td>0.003</td><td>–</td><td>–</td><td>–</td></tr><tr><td>F-53B (w-Cl-62-PFES)</td><td>chlorinated polyfluoroalkyl ether sulfonic acid</td><td>0.00 %</td><td>0.003</td><td>–</td><td>–</td><td>–</td></tr><tr><td>PFECHS</td><td>perfluoroethylcyclohexane sulfonate</td><td>100.00 %</td><td>0.010</td><td>0.06 ± 0.15</td><td>0.03</td><td>0.01–0.85</td></tr></tbody></table>
<figure><img src="image_3.png" /><figcaption>**Fig. 1.** Mean ± Standard error of the concentrations of emerging and legacy PFAS (expressed as ng g⁻¹ of yolk ww) in egg yolks of yellow-legged gulls from the Frioul Islands, Marseille, France. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)</figcaption></figure>

the dominating compound is a common pattern in seabird eggs (Kesic et al., 2023; Sun et al., 2023), this may reflect high ongoing (releases from consumer product) and former (manufacture) emissions, resulting in elevated concentrations in the diet, intensified by the longer half-life of PFOS in organisms compared to other long-chain PFAS (Tarazona et al., 2015; Yoo et al., 2009). Branched isomer (brPFOS) percentages relative to $\sum_{PFOS}$ (brPFOS and linPFOS) was found to be on average 20 %. In contrast, branched PFOS isomers appear to be much less prevalent in eggs of black-legged Kittiwakes from Svalbard (8%; Jouanneau et al., 2022). BrPFOS was produced along with linPFOS until the early 2000s when PFOS was manufactured using the electrochemical fluorination (ECF) process (Schulz et al., 2020). Differences in the geographical distribution of the linear PFOS isomer has been hypothesized, as a region that produced PFAS via ECF for many years would have a higher ratio of branched isomers than one that produces PFAS using telomerization (Schulz et al., 2020). Furthermore, brPFOS was also suggested to differ from linPFOS with regard to environmental transport potential and trophic magnification factor (Benskin et al., 2010; Simmonet-Laprade et al., 2019). It is thus possible that differences in foraging ecology and migratory behavior influence the pattern of PFOS isomers found in eggs of yellow-legged gulls and black-legged Kittiwakes. Yellow-legged gulls from the Marseille population forage over costal and urban areas with a few individuals undergoing winter migratory movements to western and northern Europe where they use coastal and terrestrial habitats (Souc et al., 2023). Black-legged Kittiwakes from Svalbard forage over pelagic waters during breeding (Goutte et al., 2014) and mostly spend the winter in pelagic waters off Canada where most of PFAS exposure occurs (Leandri-Breton et al., 2024).

Among PFCAs, longer-chain compounds were found in higher concentrations in eggs than short-chain homologues (Table 1 & Fig. 1). This could result from the positive correlation between PFCAs carbon chain length and bioaccumulation potential or maternal transfer efficiency (Conder et al., 2008; Jouanneau et al., 2022). A similar pattern has been observed for PFCAs in American herring gulls (*Larus smithsonianus*) eggs from the Great Lakes region in the US (Gebbink and Letcher, 2012). It worth noticing that many species of seabirds usually exhibit higher concentrations of odd-numbered PFAS than even-numbered ones (Herzke et al., 2022; Jang et al., 2022; Lucia et al., 2015; Norden et al., 2013; Su et al., 2017), but this pattern is not as clear in the yellow-legged gull (Table 2). The underlying reasons for this pattern are unknown, but Herzke et al. (2022) suggested that it may be related to species-specific PFAS toxicokinetic, habitat, or diet.

In the literature, PFAS in wild bird eggs was mostly measured in homogenized eggs content and not in the yolk, which makes comparison to other studies difficult (Jang et al., 2022; Kesic et al., 2024; Lopez-Antia et al., 2017; Wang et al., 2021b). Eggs yolk contains most of the

PFAS burden of the whole egg, due to their high lipid and protein content (Gebbink and Letcher, 2012), therefore using homogenized eggs to measure PFAS provides diluted and hence lower concentrations. However, PFAS were measured in the yolk of yellow-legged gull eggs from the Mediterranean Sea. In Northern Italy, PFOS burden was found to be similar and PFCAs in slightly higher concentrations than those described in the present study (Table 2 and Fig. 2). In particular, PFOA was 4 times higher in the Italian colony (Parolini et al., 2020). This high concentration of PFOA is believed to be caused by a local contamination hot-spot due to a fluoropolymer plant discharging its wastes to the Po River (Parolini et al., 2020). PFOS and PFCAs measured in homogenized yellow-legged gull eggs have also been investigated along Spanish and Portuguese coasts and were found in either similar or much higher concentrations than those of the present study depending on the colony (Table 2 and Fig. 2; Morales et al., 2012; Vicente et al., 2012; Bertolero et al., 2015; Colomer-Vidal et al., 2022). This suggests lower levels of PFAS in the diet of adults from the colony from Marseille compared to other Mediterranean yellow-legged gull colonies, which may be potentially related to lower emissions of PFAS at a local scale, faster dilution due to regional currents or different ecology among the Mediterranean populations. Indeed, PFAS concentrations in yellow-legged gull eggs from the southern France colony were much lower than PFAS levels in eggs of the Spanish Mediterranean coast (Colomer-Vidal et al., 2022), suggesting that the contamination is linked to the nesting location rather than the wintering grounds, suggesting the usefulness of eggs as bioindicators of local environmental contamination of PFAS. Nonetheless, a few factors may limit the accuracy of the inter-colony comparison in PFAS concentrations: the investigated matrices (either egg yolk or homogenized eggs), the different sampling years and the rank of the egg in the laying order (the first-laid egg or the last-laid egg, respectively the most and the least contaminated egg of the clutch; Vicente et al., 2015; Parolini et al., 2020; Jouanneau et al., 2022).

Measurements made in the local abiotic environment suggested that elevated PFAS concentrations would be accumulated in seabird eggs since PFOS concentration in seawater of the Bay of Marseille was found to exceed the European environmental quality standard and high concentrations of PFCAs were highlighted (Schmidt et al., 2019). Indeed, the coast nearby the city of Marseille is largely industrialized, which may contribute to establish high PFAS concentrations in seawater locally. Additionally, large inputs from the Rhône River, known to transport elevated concentrations of PFCAs, as well as surface currents, may contribute to the local environmental PFAS burden (Brumovsky et al., 2016; Munoz et al., 2015). Most PFCAs are believed to reflect recent uptakes, when the longest chain PFCAs ($C_{10}$, $C_{11}$) and PFSAs (perfluoroalkyl sulfonic acids), especially PFOS, may represent a larger accumulation period owing to their much longer half-life in tissues due
<table><caption>Table 2<br>Summary of the values (means; ng g<sup>-1</sup> ww) found in eggs of different yellow-legged gull colonies for the legacy PFAS investigated in eggs from Southern France. Concentrations obtained from whole eggs were translated into yolk-equivalent units using a conversion factor of 2.94 which represents the yolk to albumen mass ratio of yellow-legged gull eggs extracted from Rubolini et al., 2005, 2006 and assuming a similar volumetric mass density between yolk and albumen.</caption><thead><tr><th>Tissue</th><th>Sampling year</th><th>Location</th><th>Sample size</th><th>PFHXS</th><th>PFOS</th><th>PFOA</th><th>PFNA</th><th>PFDCa</th><th>PFUnA</th><th>PFDOA</th><th>PFTiA</th><th>PFTEA</th><th>PFHDA</th><th>ΣPFAS</th><th>Reference</th></tr></thead><tbody><tr><td rowspan="3">Yolk</td><td>2021</td><td>France (Frioul Islands)</td><td>30</td><td>1.76</td><td>55.4</td><td>0.93</td><td>0.98</td><td>1.46</td><td>1.66</td><td>2.00</td><td>2.78</td><td>2.62</td><td>0.68</td><td>70.2</td><td>Present study</td></tr><tr><td>2016</td><td>Italy (Comacchio Lagoon)</td><td>15</td><td>0.80</td><td>35.0</td><td>3.80</td><td>1.7</td><td>2.40</td><td>2.10</td><td>2.30</td><td>-</td><td>-</td><td>-</td><td>-</td><td>48.8</td><td>Parolini et al., 2020</td></tr><tr><td></td><td>Spain (Atlantic Islands)</td><td>36</td><td>-</td><td>33.5</td><td>-</td><td>1.68</td><td>1.47</td><td>7.73</td><td>2.79</td><td>6.47</td><td>-</td><td>-</td><td>-</td><td>53.5</td><td></td></tr><tr><td rowspan="3">Whole eggs<sup>a</sup></td><td rowspan="3">2018<sup>b</sup></td><td>Spain (Medes Island)</td><td>36</td><td>-</td><td>201</td><td>1.12</td><td>7.82</td><td>3.79</td><td>13.97</td><td>15.6</td><td>35.0</td><td>-</td><td>-</td><td>-</td><td>278</td><td>Colomer-Vidal et al., 2022</td></tr><tr><td>Spain (Ebro Delta)</td><td>36</td><td>-</td><td>182</td><td>-</td><td>5.62</td><td>12.6</td><td>24.4</td><td>9.20</td><td>18.0</td><td>-</td><td>-</td><td>-</td><td>252</td><td></td></tr><tr><td>Spain (Chafarinas Islands)</td><td>36</td><td>-</td><td>32.6</td><td>-</td><td>1.32</td><td>1.50</td><td>2.23</td><td>1.03</td><td>1.59</td><td>-</td><td>-</td><td>-</td><td>40.3</td><td></td></tr></tbody></table>

<sup>a</sup> PFAS values converted in yolk-equivalents units.

<sup>b</sup> On the 2009–2018 time period used in the Colomer-Vidal et al., 2022 study, only the measurements of the most recent year are provided in this table.

to a lower excretion rate (Tarazona et al., 2015; Yoo et al., 2009; Zhang et al., 2013). Eggs C10 and C11 PFCAs as well as PFSAs may therefore be partially accumulated during the winter and if this would still be representative of the contamination of the Bay of Marseille is open to debate, especially since overwintering sites of this species are not well known. The yellow-legged gull is a generalist and may exploit different habitats, including marine, coastal and terrestrial environments while breeding and foraging up to 40 km away from the colony (Mendes et al., 2018). Elevated PFAS concentrations in eggs may also originate from anthropogenic sources (e.g., landfill and wastes) easily exploitable in an urban environment. Coupling contaminants with GPS tracking of the female birds as well as the determination of egg yolk stable isotopes data would be useful to better understand the main environmental sources of PFAS for this species.

Compared to other studies on Laridae that reported PFOS concentrations in egg yolk, yellow-legged gull eggs from Marseille exhibited much higher PFOS concentrations than those of black-legged kittiwakes in the Norwegian arctic (Jouanneau et al., 2022), but respectively 3 and 8 times lower levels than those of Audouin's gulls (Larus audouinii) from Spain and herring gulls (Larus argentatus) from Sweden (Norden et al., 2013; Vicente et al., 2015). Conversely, egg yolks from Norwegian arctic black-legged kittiwakes contained higher PFCAs concentrations than those of yellow-legged gull eggs from the present study (for the same compounds, ΣPFAS: YLG = 13.1 ± 4.66; BLK = 42.5 ± 19.9; Jouanneau et al., 2022). Though, in Swedish herring gulls, PFCAs exhibited much higher concentrations, especially for C10 to C13 compounds (Norden et al., 2013). Although legacy PFAS inputs in seabirds are known to be increase or decrease along the latitude depending on the compound (Leandri-Breton et al., 2024), local hotspots may also play a part in the observed differences.

### 3.3. Alternative, emerging PFAS in egg yolks

Regarding emerging PFAS, PFECHS, an alternative to PFOS used in airplanes, was found in 100 % of the egg samples of the present study, with an average concentration of 0.06 ng g⁻¹ ww. This compound was recently detected in abiotic matrices (marine, freshwater and terrestrial environment) and within human, fish, mammals and bird species in the northern hemisphere and is considered to have a global distribution (Haque et al., 2023; Mahoney et al., 2022; Wang et al., 2021a). PFECHS was recently identified as top priority in the need on toxicity assessment (Mahoney et al., 2022). Other emerging alternatives to legacy PFAS, including the fluoroalkylether substances (ether-PFAS: GenX, ADONA and F-53B), were not detected in any of our samples (Table 1). ADONA was, to the best of our knowledge, found only once in biota, in a single egg yolk of black-legged kittiwakes (Jouanneau et al., 2022). GenX and F-53B were previously detected in several black-tailed gull eggs sampled at different locations on the coast of South Korea (Wang et al., 2021b). Indeed high bioaccumulation potential has been suggested and this compound have been found in biota in previous studies (Munoz et al., 2019). The concentrations of fluoroalkylether substances in yellow-legged gull eggs indicate that the Bay of Marseille is presently not a hotspot for these emerging PFAS. It is worth noticing however that HPFO-TeA, a compound that may degrade to GenX (Bentel et al., 2020), was detected in a few samples (Table 1).

Among other emerging PFAS, the fluorotelomer sulfonic acids (FTSs) including 6:2; 8:2 and 10:2 FTS are scarcely found in biota, but they were only targeted relatively recently (Ankley et al., 2021). Although detected in some fish, birds and mammals species (Androulakakis et al., 2022), 6:2 FTS was suggested to have little bioaccumulation potential (Yeung and Mabury, 2013). It was nonetheless measured above LOD in several egg yolks of the present study, together with its 8:2 and 10:2 homologues (Table 1). 6:2 FTS was present in much higher concentrations in eggs of the Bay of Marseille than in egg yolks from Antarctic petrels (Thalassioica Antarctica; Alfaro Garcia et al., 2022), but in lower concentration than in bald eagle (Haliaeetus leucocephalus) eggs from the
<figure><img src="image_4.png" /><figcaption>**Fig. 2.** ΣPFOS (brPFOS and linPFOS) and ΣPFCAs (PFNA, PFDcA, PFUnA and PFDoA) values measured in yellow-legged gull eggs of different colonies of the Mediterranean Sea and the Atlantic Ocean. All values were obtained from Parolini et al., 2020, Colomer-Vidal et al., 2022 (black circles) and the present study (blue triangle), only compounds measured in all these studies were included in the ΣPFCAs here. For the Ebro Delta colony, only the most recent values were used. See Table 2 for additional details. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)</figcaption></figure>

Great Lakes region (Wu et al., 2020). 6:2 FTS was also recently found in significant concentrations in PFAS screening studies on marine mammals from various places of the Northern hemisphere (Spaan et al., 2020; Wang et al., 2021a). FTSs are a major component of aqueous film-forming foams among others (Shaw et al., 2019; Yeung and Mabury, 2013). Aqueous film-forming foams are massively used in airports for firefighting trainings and FTSs may be emitted in the environment during these events. It is however unknown if local airports are significant sources for these contaminants in the Bay of Marseille. Another fluorotelomer, 7:3 FTCA, is a fluorotelomer carboxylic acid seldom investigated but increasingly found, especially in Arctic biota (Barrett et al., 2021; Guruge et al., 2011; Muir et al., 2019; Schultes et al., 2020; Spaan et al., 2020). Regarding birds, 7:3 FTCA has recently been found in eggs of both terrestrial and marine birds (Eriksson et al., 2016; Jouanneau et al., 2022). Its toxicity, as those of other fluorotelomers, is largely unknown for vertebrates (Pelch et al., 2022), although FTCAs toxicity potential was suggested to be much higher than those of long-chain PFCAs in experimental studies on crustaceans, insects and plants (Mitchell et al., 2011; Phillips et al., 2007).

## 3.4. Toxicity potential for developing embryos

Hazards inherent to PFAS exposure in adult seabirds include oxidative stress, genotoxicity, and disrupted metabolism, endocrine system, carotenoid-base ornamentation, telomere length, spermatic quality, eggshell thickness and hatching success (Ask et al., 2021; Blévin et al., 2017a; Blévin et al., 2020; Blévin et al., 2017b; Choy et al., 2022; Costantini et al., 2022; Costantini et al., 2019; Humann-Guilleminot et al., 2024; Jouanneau et al., 2023; Sebastiano et al., 2020a; Sebastiano et al., 2020b; Sebastiano et al., 2023; Tartu et al., 2014; Wells et al., 2023). However, few toxicity thresholds have been proposed for avian species in the literature and even less have been established using eggs. Since PFAS are maternally deposited in eggs, eggs were suggested to be a useful medium to estimate toxicity risks for the mother. For example, a toxicity reference value (TRV) of 1700 ng mL⁻¹ and a predicted no effect concentration (PNEC) of 1000 ng mL⁻¹ have been estimated for PFAS in egg yolk of high trophic level avian predators (Newsted et al., 2005). More recently, a chronic toxicity value (CTV) of 92.4 ng g⁻¹ of homogenized egg corresponding to the lowest observable adverse effect (LOAE) in adults have been proposed after chronic exposure to PFOS in

northern bobwhite quails (Colinus virginianus; Dennis et al., 2022). These values being much higher than the observed concentration in egg yolks of the present study, we may consider female yellow-legged gulls from Marseille not likely leading to adverse outcomes.

Although several studies investigated the concentrations of legacy PFAS in seabird eggs, including the yellow-legged gulls, very few examined the toxicity of these compounds during the development and it is challenging to conclude on the threats that the observed levels of PFAS may cause to embryogenesis in this population of gulls. In the black-legged kittiwake, some long-chain PFCAs (PFNA, PFDcA, PFUnA) were found to be associated with disrupted maternal testosterone deposition in the eggs which may have substantial adverse consequences for the embryo (Jouanneau et al., 2023), although this was found for higher PFCAs values than those of the present study, suggesting a lower risk for maternal hormone distribution. Most other studies focused on PFOS and PFOA in the domestic chicken (Gallus gallus domesticus) and found several impacts on immunological, morphological, and neurological endpoints as well as embryonic survival, however at much higher dose than those measured in the present study (Jiang et al., 2013; Mattsson et al., 2015; Nordén et al., 2016; Peden-Adams et al., 2009). Some studies nonetheless investigated the effect of concentrations of PFOS similar to those of the present study (2 to 10 times the maximum value found in eggs of Marseille), and related reduced hatchability, lower hearth rate or impaired lipid metabolism (Briels et al., 2018; Geng et al., 2019; Molina et al., 2006). However, in yellow-legged gull embryos specifically, there were no significant effects of PFOS on morphological endpoints or oxidative and genetic damages, at concentrations equivalent to the highest found in our study (Parolini et al., 2016). Concerning other PFAS, the toxicity of PFHxS and PFHxA was also examined in chicken and numerous adverse effects of PFHxS, but not of PFHxA, were found, nonetheless at much higher concentrations than in yellow-legged gull eggs of the present study (Cassone et al., 2012a; Cassone et al., 2012b). A mixture of all long-chain PFSAs and PFCAs, in similar or lower concentrations than those we measured in eggs' yolk, were however found to affect immune and endocrine systems as well as gene expression of chicken embryos (Mattsson et al., 2019).

Overall, although most studies suggest low to no effects of PFAS at the concentrations measured in eggs from Marseille, the high variance in the results listed above illustrates how difficult it is to conclude on toxicity and risk of PFAS for wild bird embryos. In addition, the toxicity
mechanisms of PFAS are complex and still largely unknown, especially regarding cumulative effects (Custer, 2021). Moreover, most studies are restricted to legacy PFAS while emerging compounds received very little attention, although the predominant PFAS are not always the more toxic during embryogenesis (Strömqvist et al., 2012).

## 4. Conclusion

This study provides the first baseline data for legacy and alternative emerging PFAS present in eggs of a seabird from France and for Mediterranean seabirds regarding emerging PFAS specifically. We found relatively high levels of linPFOS, increasing concentrations of PFCAs with the carbon chain length, and the occurrence of a few emerging PFAS including PFECHS and some fluorotelomeres (8:2 FTS, 10:2 FTS and 7:3 FTCA). In general, legacy PFAS concentrations in eggs from Marseille were lower than levels experimentally found to affect health parameters in chicken, although some concentrations were relatively close (two times lower). There is a need in investigating the effects of PFAS during embryogenesis in seabirds, especially for emerging compounds still largely overlooked in toxicity studies. It is noteworthy that focusing on a few targeted PFAS gives a glimpse of the total contamination to fluorinated compounds, in future studies, using recently developed methods for an extensive characterization of PFAS burden such as non-target screening or total oxidizable precursors assay would also help in obtaining a global picture of yellow-legged gull exposure to PFAS.

### CRediT authorship contribution statement

**William Jouanneau:** Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Writing – original draft. **Thierry Boulinier:** Resources, Writing – review & editing. **Dorte Herzke:** Resources, Validation, Writing – review & editing. **Vladimir A. Nikiforov:** Resources, Validation, Writing – review & editing. **Geir W. Gabrielsen:** Supervision, Writing – review & editing. **Olivier Chastel:** Conceptualization, Funding acquisition, Investigation, Methodology, Project administration, Resources, Supervision, Validation, Writing – review & editing.

### Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

### Acknowledgements

This project was supported by ANR ToxSeaBird (ANR-21-CE34-0019). W. Jouanneau was funded by a PhD grant from La Rochelle University, France and by ANR ToxSeaBird. Authors would like to express their gratitude to J. Lamb from CEFE for the collection of the eggs, R. Estali from "Ville de Marseille", G. Palos, O. Feirrera, L. Anselme and A. Mante from the "Parc National des Calanques" and M. Coudrillier from the DDTM13 for their help and logistic support for the field season.

### Data availability

Data will be made available on request.

### References

* Alfaro Garcia, L.A., Descamps, S., Herzke, D., Chastel, O., Carravieri, A., Cherel, Y., Labadie, P., Budzinski, H., Munoz, G., Bustamante, P., Polder, A., Gabrielsen, G.W., Bustnes, J.O., Borgå, K., 2022. Bioaccumulation of per and polyfluoroalkyl substances in antarctic breeding south polar skuas (Catharacta maccormicki) and their prey. Front. Mar. Sci. 9, 819525.

* Androulakakis, A., Alygizakis, N., Gkotsis, G., Nika, M.C., Nikolopoulou, V., Bizani, E., Chadwick, E., Cincinelli, A., Classen, D., Danielsson, S., Dekker, R., Duke, G., Glowacka, N., Jansman, H.A.H., Krone, O., Martellini, T., Movalli, P., Persson, S., Roos, A., O'Rourke, E., Siebert, U., Treu, G., van den Brink, N.W., Walker, L.A., Deaville, R., Slobodnik, J., Thomaidis, N.S., 2022. Determinants of per- and polyfluoroalkyl substances in top predators and their prey from Northern Europe by LC-MS/MS. Chemosphere 287, 131775.

* Ankley, G.T., Cureton, P., Hoke, R.A., Houde, M., Kumar, A., Kurias, J., Lanno, R., McCarthy, C., Newsted, J., Salice, C.J., Sample, B.E., Sepulveda, M.S., Steevens, J., Valsecchi, S., 2021. Assessing the ecological risks of per- and Polyfluoroalkyl substances: current state-of-the science and a proposed path forward. Environ. Toxicol. Chem. 40, 564–605.

* Ask, A.V., Jenssen, B.M., Tartu, S., Angelier, F., Chastel, O., Gabrielsen, G.W., 2021. Per- and Polyfluoroalkyl substances are positively associated with thyroid hormones in an Arctic seabird. Environ. Toxicol. Chem. 40, 820–831.

* Barrett, H., Du, X., Houde, M., Lair, S., Verreault, J., Peng, H., 2021. Suspect and nontarget screening revealed class-specific temporal trends (2000-2017) of poly- and Perfluoroalkyl substances in St. Lawrence Beluga whales. Environ. Sci. Technol. 55, 1659–1671.

* Benskin, J.P., De Silva, A.O., Martin, J.W., 2010. Isomer profiling of Perfluorinated substances as a tool for source tracking: a review of early findings and future applications. In: De Voogt, P. (Ed.), Reviews of Environmental Contamination and Toxicology, Perfluorinated Alkylated Substances, Volume 208. Springer, New York, New York, NY, pp. 111–160.

* Bentel, M.J., Yu, Y., Xu, L., Kwon, H., Li, Z., Wong, B.M., Men, Y., Liu, J., 2020. Degradation of Perfluoroalkyl ether carboxylic acids with hydrated electrons: structure-reactivity relationships and environmental implications. Environ. Sci. Technol. 54, 2489–2499.

* Bertolero, A., Vicente, J., Meyer, J., Lacorte, S., 2015. Accumulation and maternal transfer of perfluorooctane sulphonic acid in yellow-legged (Larus michahellis) and Audouin's gull (Larus audouinii) from the Ebro Delta Natural Park. Environ. Res. 137, 208–214.

* Blévin, P., Angelier, F., Tartu, S., Bustamante, P., Herzke, D., Moe, B., Bech, C., Gabrielsen, G.W., Bustnes, J.O., Chastel, O., 2017a. Perfluorinated substances and telomeres in an Arctic seabird: cross-sectional and longitudinal approaches. Environ. Pollut. 230, 360–367.

* Blévin, P., Tartu, S., Ellis, H.I., Chastel, O., Bustamante, P., Parenteau, C., Herzke, D., Angelier, F., Gabrielsen, G.W., 2017b. Contaminants and energy expenditure in an Arctic seabird: organochlorine pesticides and perfluoroalkyl substances are associated with metabolic rate in a contrasted manner. Environ. Res. 157, 118–126.

* Blévin, P., Shaffer, S.A., Bustamante, P., Angelier, F., Picard, B., Herzke, D., Moe, B., Gabrielsen, G.W., Bustnes, J.O., Chastel, O., 2020. Contaminants, prolactin and parental care in an Arctic seabird: contrasted associations of perfluoroalkyl substances and organochlorine compounds with egg-turning behavior. Gen. Comp. Endocrinol. 291, 113420.

* Briels, N., Ciesielski, T.M., Herzke, D., Jaspers, V.L.B., 2018. Developmental toxicity of Perfluorooctanesulfonate (PFOS) and its chlorinated Polyfluoroalkyl ether sulfonate alternative F-53B in the domestic chicken. Environ. Sci. Technol. 52, 12859–12867.

* Brumovsky, M., Karaskova, P., Borghini, M., Nizzetto, L., 2016. Per- and polyfluoroalkyl substances in the Western Mediterranean Sea waters. Chemosphere 159, 308–316.

* Cassone, C.G., Taylor, J.J., O'Brien, J.M., Williams, A., Yauk, C.L., Crump, D., Kennedy, S.W., 2012a. Transcriptional profiles in the cerebral hemisphere of chicken embryos following in ovo perfluorohexane sulfonate exposure. Toxicol. Sci. 129, 380–391.

* Cassone, C.G., Vongphachan, V., Chiu, S., Williams, K.L., Letcher, R.J., Pelletier, E., Crump, D., Kennedy, S.W., 2012b. In ovo effects of perfluorohexane sulfonate and perfluorohexanoate on pipping success, development, mRNA expression, and thyroid hormone levels in chicken embryos. Toxicol. Sci. 127, 216–224.

* Chen, Y., Fu, J., Ye, T., Li, X., Gao, K., Xue, Q., Lv, J., Zhang, A., Fu, J., 2021. Occurrence, profiles, and ecotoxicity of poly- and perfluoroalkyl substances and their alternatives in global apex predators: a critical review. J. Environ. Sci. 109, 219–236.

* Choy, E.S., Elliott, K.H., Esparza, I., Patterson, A., Letcher, R.J., Fernie, K.J., 2022. Potential disruption of thyroid hormones by perfluoroalkyl acids in an Arctic seabird during reproduction. Environ. Pollut. 305, 119181.

* Colomer-Vidal, P., Bertolero, A., Alcaraz, C., Garreta-Lara, E., Santos, F.J., Lacorte, S., 2022. Distribution and ten-year temporal trends (2009-2018) of perfluoroalkyl substances in gull eggs from Spanish breeding colonies. Environ. Pollut. 293, 118555.

* Conder, J.M., Hoke, R.A., De Wolf, W., Russell, M.H., Buck, R.C., 2008. Are PFCAs bioaccumulative? A critical review and comparison with regulatory criteria and persistent lipophilic compounds. Environ. Sci. Technol. 42, 995–1003.

* Costantini, D., Blévin, P., Herzke, D., Moe, B., Gabrielsen, G.W., Bustnes, J.O., Chastel, O., 2019. Higher plasma oxidative damage and lower plasma antioxidant defences in an Arctic seabird exposed to longer perfluoroalkyl acids. Environ. Res. 168, 278–285.

* Costantini, D., Blévin, P., Bustnes, J.O., Esteve, V., Gabrielsen, G.W., Herzke, D., Humann-Guilleminot, S., Moe, B., Parenteau, C., Récapet, C., Bustamante, P., Chastel, O., 2022. Integument carotenoid-based colouration reflects contamination to perfluoroalkyl substances, but not mercury, in arctic black-legged kittiwakes. Front. Ecol. Evol. 10.

* Custer, C.M., 2021. Linking field and laboratory studies: reproductive effects of perfluorinated substances on avian populations. Integr. Environ. Assess. Manag. 17, 690–696.

* Danovaro, R., 2003. Pollution threats in the Mediterranean Sea: an overview. Chem. Ecol. 19, 15–32.
Dennis, N.M., Hossain, F., Subbiah, S., Karnjanapiboonwong, A., Dennis, M.L., McCarthy, C., Jackson, W.A., Crago, J.P., Salice, C.J., Anderson, T.A., 2022. Species- and tissue-specific chronic toxicity values for northern brownwhite quail (Colinus virginianus) exposed to Perfluorohexane sulfonic acid and a binary mixture of Perfluorooctane sulfonic acid and Perfluorohexane sulfonic acid. Environ. Toxicol. Chem. 41, 219–229.

Elliott, J.E., Elliott, K.H., 2013. Tracking marine pollution. Science 340, 556–558.

Eriksson, U., Roos, A., Lind, Y., Hope, K., Ekblad, A., Karrman, A., 2016. Comparison of PFASs contamination in the freshwater and terrestrial environments by analysis of eggs from osprey (Pandion haliaetus), tawny owl (Strix aluco), and common kestrel (Falco tinnunculus). Environ. Res. 149, 40–47.

Evich, M.G., Davis, M.J.B., McCord, J.P., Acrey, B., Awkerman, J.A., Knappe, D.R.U., Lindstrom, A.B., Speth, T.F., Tebes-Stevens, C., Strynar, M.J., Wang, Z., Weber, E.J., Henderson, W.M., Washington, J.W., 2022. Per- and polyfluoroalkyl substances in the environment. Science 375, eabg9065.

Fenton, S.E., Ducatman, A., Boobis, A., DeWitt, J.C., Lau, C., Ng, C., Smith, J.S., Roberts, S.M., 2021. Per- and polyfluoroalkyl substance toxicity and human health review: current state of knowledge and strategies for informing future research. Environ. Toxicol. Chem. 40, 606–630.

Gebbink, W.A., Letcher, R.J., 2012. Comparative tissue and body compartment accumulation and maternal transfer to eggs of perfluoroalkyl sulfonates and carboxylates in Great Lakes herring gulls. Environ. Pollut. 162, 40–47.

Gebbink, W.A., Bignert, A., Berger, U., 2016. Perfluoroalkyl acids (PFAs) and selected precursors in the Baltic Sea environment: do precursors play a role in food web accumulation of PFAs? Environ. Sci. Technol. 50, 6354–6362.

Geng, D., Musse, A.A., Wigh, V., Carlsson, C., Engwall, M., Oresic, M., Scherbak, N., Hytylanden, T., 2019. Effect of perfluorooctanesulfonic acid (PFOS) on the liver lipid metabolism of the developing embryo. Ecotoxicol. Environ. Saf. 170, 691–698.

Giesy, J.P., Kannan, K., 2001. Global distribution of perfluorooctane sulfonate in wildlife. Environ. Sci. Technol. 35, 1339–1342.

Glüge, J., Scheringer, M., Cousins, I.T., DeWitt, J.C., Goldenman, G., Herzke, D., Lohmann, R., Ng, C.A., Trier, X., Wang, Z., 2020. An overview of the uses of per- and polyfluoroalkyl substances (PFAS). Environ. Sci.: Process. Impacts 22, 2345–2373.

Goutte, A., Angelier, F., Bech, C., Clement-Chastel, C., Dell'Omo, G., Gabrielsen, G.W., Lendvai, A.Z., Moe, B., Noreen, E., Pinaud, D., Tartu, S., Chastel, O., 2014. Annual variation in the timing of breeding, pre-breeding foraging areas and corticosterone levels in an Arctic population of black-legged tikiwakes. In: Marine Ecology Progress Series, 496, pp. 233–247.

Guruge, K.S., Yeung, L.W., Li, P., Taniyasu, S., Yamashita, N., Nakamura, M., 2011. Fluorinated alkyl compounds including long chain carboxylic acids in wild bird livers from Japan. Chemosphere 83, 379–384.

Hamid, N., Junaid, M., Sultan, M., Yoganandham, S.T., Chuan, O.M., 2024. The untold story of PFAS alternatives: insights into the occurrence, ecotoxicological impacts, and removal strategies in the aquatic environment. Water Res. 250, 121044.

Hansen, K.J., Clemen, L.A., Ellefson, M.E., Johnson, H.O., 2001. Compound-specific, quantitative characterization of organic fluorochemicals in biological matrices. Environ. Sci. Technol. 35, 766–770.

Haque, F., Soerensen, A.L., Sköld, M., Awad, R., Spaan, K.M., Lauria, M.Z., Plassmann, M., Benskin, J.P., 2023. Per- and polyfluoroalkyl substances (PFAS) in white-tailed sea eagle eggs from Sweden: Temporal trends (1969-2021), spatial variations, fluorine mass balance, and suspect screening. In: Environmental Science: Processes & Impacts.

Helsel, D.R., 2011. Statistics for Censored Environmental DataUsing Minitab® and R.

Herzke, D., Nikiforov, V.A., Yeung, L.W.Y., Moe, B., Routti, H., Nygård, T., Gabrielsen, G. W., Hanssen, L., 2022. Targeted Pfas analyses and extractable organofluorine – enhancing our understanding of the presence of unknown Pfas in Norwegian Wildlife. SSRN Electron. J. 171, 107640.

Hummann-Guilllemot, S., Blevin, P., Gabrielsen, G.W., Herzke, D., Nikiforov, V.A., Jouanneau, W., Moe, B., Parenteau, C., Helfenstein, F., Chastel, O., 2024. PFAS exposure is associated with a lower spermatogenic quality in an Arctic seabird. Environ. Sci. Technol. 58, 19617–19626.

Jang, M., Shim, W.J., Han, G.M., Ha, S.Y., Cho, Y., Kim, M., Hong, S.H., 2022. Spatial distribution and temporal trends of classical and emerging persistent organic pollutants (POPs) in black-tailed gull (Larus crassirostris) eggs from Korea. Sci. Total Environ. 845, 157244.

Jiang, Q., Lust, R.M., DeWitt, J.C., 2013. Perfluorooctanoic acid induced-developmental cardiotoxicity: are peroxisome proliferator activated receptor α (PPARα) and bone morphogenic protein 2 (BMP2) pathways involved? J. Toxicol. Environ. Health A 76, 635–650.

Jouanneau, W., Leandri-Breton, D.J., Corbeau, A., Herzke, D., Moe, B., Nikiforov, V.A., Gabrielsen, G.W., Chastel, O., 2022. A bad start in life? Maternal transfer of legacy and emerging poly- and Perfluoroalkyl substances to eggs in an Arctic seabird. Environ. Sci. Technol. 56, 6091–6102.

Jouanneau, W., Leandri-Breton, D.J., Herzke, D., Moe, B., Nikiforov, V.A., Pallud, M., Parenteau, C., Gabrielsen, G.W., Chastel, O., 2023. Does contaminant exposure disrupt maternal hormones deposition? A study on per- and polyfluoroalkyl substances in an Arctic seabird. Sci. Total Environ. 161413.

Julian, P., Helsel, D.R., 2024. Package 'NADA2', 1.1.8.

Kesic, R., Elliott, J.E., Elliott, K.H., Lee, S.L., Maisonneuve, F., 2023. Perfluoroalkyl substances in seabird eggs from Canada's Pacific coast: temporal trends (1973-2019) and interspecific patterns. Environ. Sci. Technol. 57, 10792–10803.

Kesic, R., Elliott, J.E., Lee, S.L., Elliott, K.H., 2024. Legacy and emergent contaminants in glaucous-winged gull eggs from Canada's Pacific coast: spatial distribution, temporal trends, and risks for human consumers. Environ. Pollut. 363.

Leandri-Breton, D.J., Jouanneau, W., Legagneux, P., Tarroux, A., Moe, B.R., Angelier, F., Blevin, P., Brathen, V.S., Fauchald, P., Gabrielsen, G.W., Herzke, D., Nikiforov, V.A., Elliott, K.H., Chastel, O., 2024. Winter tracking data suggest that migratory seabirds transport per- and polyfluoroalkyl substances to their Arctic nesting site. Environ. Sci. Technol. 58, 12909–12920.

Letcher, R.J., Su, G., Moore, J.N., Williams, L.L., Martin, P.A., de Solla, S.R., Bowerman, W.W., 2015. Perfluorinated sulfonate and carboxylate compounds and precursors in herring gull eggs from across the Laurentian Great Lakes of North America: temporal and recent spatial comparisons and exposure implications. Sci. Total Environ. 538, 468–477.

Lopez-Antia, A., Dauwe, T., Meyer, J., Maes, K., Bervoets, L., Eens, M., 2017. High levels of PFOS in eggs of three bird species in the neighbourhood of a fluoro-chemical plant. Ecotoxicol. Environ. Saf. 139, 165–171.

Lucia, M., Verboven, N., Strom, H., Miljeteig, C., Gavrilo, M.V., Braune, B.M., Boertmann, D., Gabrielsen, G.W., 2015. Circumpolar contamination in eggs of the high-Arctic ivory gull Pagophila eburnea. Environ. Toxicol. Chem. 34, 1552–1561.

Mahoney, H., Xie, Y., Brinkmann, M., Giesy, J.P., 2022. Next generation per- and poly- fluoroalkyl substances: status and trends, aquatic toxicity, and risk assessment. Eco- Environment & Health 1, 117–131.

Mattsson, A., Karrman, A., Pinto, R., Brunstrom, B., 2015. Metabolic profiling of chicken embryos exposed to Perfluorooctanoic acid (PFOA) and agonists to peroxisome proliferator-activated receptors. PloS One 10, e0143780.

Mattsson, A., Sjoberg, S., Karrman, A., Brunstrom, B., 2019. Developmental exposure to a mixture of perfluoroalkyl acids (PFAs) affects the thyroid hormone system and the bursa of Fabricius in the chicken. Sci. Rep. 9, 19808.

Mendes, R.F., Ramos, J.A., Paiva, V.H., Calado, J.G., Matos, D.M., Ceia, F.R., 2018. Foraging strategies of a generalist seabird species, the yellow-legged gull, from GPS tracking and stable isotope analyses. Mar. Biol. 165.

Mitchell, R.J., Myers, A.L., Mabury, S.A., Solomon, K.R., Sibley, P.K., 2011. Toxicity of fluorotelomer carboxylic acids to the algae Pseudokirchneriella subcapitata and Chlorella vulgaris, and the amphipod Hyalella azteca. Ecotoxicol. Environ. Saf. 74, 2260–2267.

Molina, E.D., Balander, R., Fitzgerald, S.D., Giesy, J.P., Kannan, K., Mitchell, R., Bursian, S.J., 2006. Effects of air cell injection of perfluorooctane sulfonate before incubation on development of the white leghorn chicken (Gallus domesticus) embryo. Environ. Toxicol. Chem. 25, 227–232.

Moralés, L., Martrat, M.G., Olmos, J., Parera, J., Vicente, J., Bertolero, A., Abalos, M., Lacorte, S., Santos, F.J., Abad, E., 2012. Persistent organic pollutants in gull eggs of two species (Larus michahellis and Larus audouinii) from the Ebro delta Natural Park. Chemosphere 88, 1306–1316.

Muir, D., Bossi, R., Carlsson, P., Evans, M., De Silva, A., Halsall, C., Rauert, C., Herzke, D., Hung, H., Letcher, R., Rigét, F., Roos, A., 2019. Levels and trends of poly- and perfluoroalkyl substances in the Arctic environment – an update. Emerging Contaminants 5, 240–271.

Munoz, G., Giraudel, J.L., Botta, F., Lestremau, F., Devier, M.H., Budzinski, H., Labadie, P., 2015. Spatial distribution and partitioning behavior of selected poly- and perfluoroalkyl substances in freshwater ecosystems: a French nationwide survey. Sci. Total Environ. 517, 48–56.

Munoz, G., Liu, J., Vo Duy, S., Sauvé, S., 2019. Analysis of F-53B, gen-X, ADONA, and emerging fluoroalkylether substances in environmental and biomonitoring samples: a review. Trends in Environmental Analytical Chemistry 23, e00066.

Newsted, J.L., Jones, P.D., Coady, K., Giesy, J.P., 2005. Avian toxicity reference values for perfluorooctane sulfonate. Environ. Sci. Technol. 39, 9357–9362.

Norden, M., Berger, U., Engwall, M., 2013. High levels of perfluoroalkyl acids in eggs and embryo livers of great cormorant (Phalacrocorax carbo sinensis) and herring gull (Larus argentatus) from Lake Vanern, Sweden. Environ. Sci. Pollut. Res. Int. 20, 8021–8030.

Nordén, M., Berger, U., Engwall, M., 2016. Developmental toxicity of PFOS and PFOA in great cormorant (Phalacrocorax carbo sinensis), herring gull (Larus argentatus) and chicken (Gallus gallus domesticus). Environ. Sci. Pollut. Res. Int. 23, 10855–10862.

Parolini, M., Colombo, G., Valsecchi, S., Mazzoni, M., Possenti, C.D., Caprioli, M., Dalle-Donne, I., Milzani, A., Saino, N., Rubolini, D., 2016. Potential toxicity of environmentally relevant perfluorooctane sulfonate (PFOS) concentrations to yellow-legged gull Larus michahellis embryos. Environ. Sci. Pollut. Res. Int. 23, 426–437.

Parolini, M., Cappelli, F., De Felice, B., Possenti, C.D., Rubolini, D., Valsecchi, S., Polesello, S., 2020. Within- and among-clutch variation of yolk Perfluoroalkyl acids in a seabird from the northern Adriatic Sea. Environ. Toxicol. Chem. 40, 744–753.

Peden-Adams, M.M., Stuckey, J.E., Gaworecki, K.M., Berger-Ritchie, J., Bryant, K., Jodice, P.G., Scott, T.R., Ferrario, J.B., Guan, B., Vigo, C., Boone, J.S., McGuinn, W. D., DeWitt, J.C., Keil, D.E., 2009. Developmental toxicity in white leghorn chickens following in ovo exposure to perfluorooctane sulfonate (PFOS). Reprod. Toxicol. 27, 307–318.

Pelch, K.E., Reade, A., Kwiatkowski, C.F., Merced-Nieves, F.M., Cavalier, H., Schultz, K., Wolfe, T., Varshavsky, J., 2022. The PFAS-Tox database: a systematic evidence map of health studies on 29 per- and polyfluoroalkyl substances. Environ. Int. 167, 107408.

Phillips, M.M., Dinglasan-Panlilio, M.J., Mabury, S.A., Solomon, K.R., Sibley, P.K., 2007. Fluorotelomer acids are more toxic than perfluorinated acids. Environ. Sci. Technol. 41, 7159–7163.

Powley, C.R., George, S.W., Ryan, T.W., Buck, R.C., 2005. Matrix effect-free analytical methods for determination of perfluorinated carboxylic acids in environmental matrices. Anal. Chem. 77, 6353–6358.

R.C.T., 2024. R: A Language and Environment for Statistical Computing, 4.4.1 ed. R Foundation for Statistical Computing, Vienna, Austria.
Rubolini, D., Romano, M., Boncoraglio, G., Ferrari, R.P., Martinelli, R., Galeotti, P., Fasola, M., Saino, N., 2005. Effects of elevated egg corticosterone levels on behavior, growth, and immunity of yellow-legged gull (Larus michahellis) chicks. Horm. Behav. 47, 592–605.

Rubolini, D., Romano, M., Martinelli, R., Saino, N., 2006. Effects of elevated yolk testosterone levels on survival, growth and immunity of male and female yellow-legged gull chicks. Behav. Ecol. Sociobiol. 59, 344–352.

Schmidt, N., Fauvelle, V., Castro-Jimenez, J., Lajaunie-Salla, K., Pinazo, C., Yohia, C., Sempere, R., 2019. Occurrence of perfluoroalkyl substances in the Bay of Marseille (NW Mediterranean Sea) and the Rhone River. Mar. Pollut. Bull. 149, 110491.

Schultes, L., van Noordenburg, C., Spaan, K.M., Plassmann, M.M., Simon, M., Roos, A., Benskin, J.P., 2020. High concentrations of unidentified extractable Organofluorine observed in blubber from a Greenland killer whale (Orcinus orca). Environ. Sci. Technol. Lett. 7, 909–915.

Schulz, K., Silva, M.R., Klaper, R., 2020. Distribution and effects of branched versus linear isomers of PFOA, PFOS, and PFHxS: a review of recent literature. Sci. Total Environ. 733, 139186.

Sebastiano, M., Angelier, F., Blevin, P., Ribout, C., Sagerup, K., Descamps, S., Herzke, D., Moe, B., Barbraud, C., Bustnes, J.O., Gabrielsen, G.W., Chastel, O., 2020a. Exposure to PFAS is associated with telomere length dynamics and demographic responses of an Arctic top predator. Environ. Sci. Technol. 54, 10217–10226.

Sebastiano, M., Jouanneau, W., Blevin, P., Angelier, F., Parenteau, C., Gernigon, J., Lemesle, J.C., Robin, F., Pardon, P., Budzinski, H., Labadie, P., Chastel, O., 2020b. High levels of fluoroalkyl substances and potential disruption of thyroid hormones in three gull species from South Western France. Sci. Total Environ. 765, 144611.

Sebastiano, M., Jouanneau, W., Blevin, P., Angelier, F., Parenteau, C., Pallud, M., Ribout, C., Gernigon, J., Lemesle, J.C., Robin, F., Pardon, P., Budzinski, H., Labadie, P., Chastel, O., 2023. Physiological effects of PFAS exposure in seabird chicks: a multi-species study of thyroid hormone triiodothyronine, body condition and telomere length in South Western France. Sci. Total Environ. 165920.

Shaw, D.M.J., Munoz, G., Bottos, E.M., Duy, S.V., Sauve, S., Liu, J., Van Hamme, J.D., 2019. Degradation and defluorination of 6:2 fluorotelomer sulfonamidoalkyl betaine and 6:2 fluorotelomer sulfonate by Gordonia sp. strain NB4-1Y under sulfur-limiting conditions. Sci. Total Environ. 647, 690–698.

Simmonet-Laprade, C., Budzinski, H., Babut, M., Le Menach, K., Munoz, G., Lauzent, M., Ferrari, B.J.D., Labadie, P., 2019. Investigation of the spatial variability of poly- and perfluoroalkyl substance trophic magnification in selected riverine ecosystems. Sci. Total Environ. 686, 393–401.

Souc, C., Sadoul, N., Blanchon, T., Vittecoq, M., Pin, C., Vidal, E., Mante, A., Choquet, R., McCoy, K.D., 2023. Natal colony influences age-specific movement patterns of the yellow-legged gull (Larus michahellis). Mov. Ecol. 11, 11.

Spaan, K.M., van Noordenburg, C., Plassmann, M.M., Schultes, L., Shaw, S., Berger, M., Heide-Jorgensen, M.P., Rosing-Asvid, A., Granquist, S.M., Dietz, R., Sonne, C., Riget, F., Roos, A., Benskin, J.P., 2020. Fluorine mass balance and suspect screening in marine mammals from the northern hemisphere. Environ. Sci. Technol. 54, 4046–4058.

Strömqvist, M., Olsson, J.A., Karrman, A., Brunstrom, B., 2012. Transcription of genes involved in fat metabolism in chicken embryos exposed to the peroxisome proliferator-activated receptor alpha (PPARalpha) agonist GW7647 or to perfluorooctane sulfonate (PFOS) or perfluorooctanoic acid (PFOA). Comp. Biochem. Physiol., Part C: Toxicol. Pharmacol. 156, 29–36.

Su, G., Letcher, R.J., Moore, J.N., Williams, L.L., Grasman, K.A., 2017. Contaminants of emerging concern in Caspian tern compared to herring gull eggs from Michigan colonies in the Great Lakes of North America. Environ. Pollut. 222, 154–164.

Sun, J., Xing, L., Chu, J., 2023. Global Ocean contamination of per- and polyfluoroalkyl substances: a review of seabird exposure. Chemosphere 330, 138721.

Tarazona, J.V., Rodriguez, C., Alonso, E., Saez, M., Gonzalez, F., San Andres, M.D., Jimenez, B., San Andres, M.I., 2015. Toxicokinetics of perfluorooctane sulfonate in birds under environmentally realistic exposure conditions and development of a kinetic predictive model. Toxicol. Lett. 232, 363–368.

Tartu, S., Gabrielsen, G.W., Blevin, P., Ellis, H., Bustnes, J.O., Herzke, D., Chastel, O., 2014. Endocrine and fitness correlates of long-chain perfluorinated carboxylates exposure in Arctic breeding black-legged kittiwakes. Environ. Sci. Technol. 48, 13504–13510.

Van Paassen, A.G., Veldman, D.H., Beinterna, A.J., 1984. A simple device for determination of incubation stages in eggs. Wildfowl 35, 173–178.

Verreault, J., Houde, M., Gabrielsen, G.W., Berger, U., Haukas, M., Letcher, R.J., Muir, D. C., 2005. Perfluorinated alkyl substances in plasma, liver, brain, and eggs of glaucous gulls (Larus hyperboreus) from the Norwegian arctic. Environ. Sci. Technol. 39, 7439–7445.

Vicente, J., Bertolero, A., Meyer, J., Viana, P., Lacorte, S., 2012. Distribution of perfluorinated compounds in yellow-legged gull eggs (Larus michahellis) from the Iberian Peninsula. Sci. Total Environ. 416, 468–475.

Vicente, J., Sanpera, C., Garcia-Tarrason, M., Perez, A., Lacorte, S., 2015. Perfluoroalkyl and polyfluoroalkyl substances in entire clutches of Audouin's gulls from the Ebro Delta. Chemosphere 119 (Suppl), S62-S68.

Wang, Y., Chang, W., Wang, L., Zhang, Y., Zhang, Y., Wang, M., Wang, Y., Li, P., 2019. A review of sources, multimedia distribution and health risks of novel fluorinated alternatives. Ecotoxicol. Environ. Saf. 182, 109402.

Wang, Q., Ruan, Y., Jin, L., Zhang, X., Li, J., He, Y., Wei, S., Lam, J.C.W., Lam, P.K.S., 2021a. Target, nontarget, and suspect screening and temporal trends of per- and Polyfluoroalkyl substances in marine mammals from the South China Sea. Environ. Sci. Technol. 55, 1045–1056.

Wang, W., Lee, J., Oh, J.K., Lee, S.J., Choi, S.D., Oh, J.E., 2021b. Per- and polyfluoroalkyl substances and their alternatives in black-tailed gull (Larus crassirostris) eggs from South Korea islands during 2012-2018. J. Hazard. Mater. 411, 125036.

Wells, M.R., Coggan, T.L., Stevenson, G., Singh, N., Askeland, M., Lea, M.A., Philips, A., Carver, S., 2023. Per- and polyfluoroalkyl substances (PFAS) in little penguins and associations with urbanisation and health parameters. Sci. Total Environ. 912, 169084.

Wu, Y., Simon, K.L., Best, D.A., Bowerman, W., Venier, M., 2020. Novel and legacy per- and polyfluoroalkyl substances in bald eagle eggs from the Great Lakes region. Environ. Pollut. 260, 113811.

Xiao, F., 2017. Emerging poly- and perfluoroalkyl substances in the aquatic environment: a review of current literature. Water Res. 124, 482–495.

Yeung, L.W., Mabury, S.A., 2013. Bioconcentration of aqueous film-forming foam (AFFF) in juvenile rainbow trout (Oncorhyncus mykiss). Environ. Sci. Technol. 47, 12505–12513.

Yoo, H., Guruge, K.S., Yamanaka, N., Sato, C., Mikami, O., Miyazaki, S., Yamashita, N., Giesy, J.P., 2009. Depuration kinetics and tissue disposition of PFOA and PFOS in white leghorn chickens (Gallus gallus) administered by subcutaneous implantation. Ecotoxicol. Environ. Saf. 72, 26–36.

Zhang, Y., Beesoon, S., Zhu, L., Martin, J.W., 2013. Biomonitoring of perfluoroalkyl acids in human urine and estimates of biological half-life. Environ. Sci. Technol. 47, 10619–10627.