Axelle Leufroy

L'arsenic est un élément présent dans tous les compartiments de l'environnement, et les produits de la pêche représentent une source majeure d'exposition à l'arsenic par le biais de l'alimentation. Même s'il n'existe pas à ce jour de législation sur les teneurs en arsenic dans les aliments en France, les agences gouvernementales évaluent généralement les risques liés à la présence d'arsenic dans les produits de la pêche en se basant essentiellement sur la concentration totale de l'élément, sans tenir compte des différentes espèces présentes ni de leur bioaccessibilité. Par conséquent, le développement de méthodes d'analyse de spéciation revêt un intérêt particulier dans le cadre de l'évaluation des risques. La première partie de ce mémoire présente des informations générales sur les propriétés de l'arsenic, son occurrence dans les différents compartiments de l'environnement et sa toxicité, ainsi qu'une étude bibliographique des méthodes analytiques existantes pour étudier la spéciation de l'arsenic dans les matrices alimentaires, en particulier les produits de la pêche (extraction et séparation/détection). Les différentes approches pour l'évaluation de sa bioaccessibilité et de celle d'autres éléments traces métalliques d'intérêt sont également présentées. La deuxième partie de ces travaux porte sur la validation d'une méthode d'analyse de spéciation des principales espèces d'arsenic dans les produits la pêche (As(III), MA,DMA, As(V), AsB, TMAO, AsC) par couplage entre la chromatographie d'échange d'ions (IEC) et la spectrométrie de masse à plasma induit (ICP-MS) après extraction assistée par micro-ondes (MAE). L'évaluation des performances analytiques de la méthode, les contrôles qualités internes et externes mis en place et les différentes applications, en particulier les données d'occurrence des différentes espèces d'arsenic dans les produits de la pêche les plus consommés par la population française sont présentés et discutés. Dans la troisième partie, la bioaccessibilité maximale de l'arsenic et d'autres éléments d'intérêt est estimée à l'aide d'une méthode de lixiviation en ligne (impliquant la mesure en temps réel par ICP-MS de la fraction libérée par les différents fluides digestifs artificiels). La combinaison de ce procédé avec la méthode d'analyse de spéciation validée permet ainsi d'estimer la bioaccessibilité des différentes espèces d'arsenic.

Edible insects are becoming increasingly popular as protein alternatives to traditional animal-based products. As such, information on their elemental composition is important to ensure they are safe for human consumption. This article describes the development and validation of a rapid, reliable method for the simultaneous determination of 19 elements (Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Pb, Se, Sr, and Zn) in edible insects by inductively coupled plasma mass spectrometry (ICP-MS) following closed vessel microwave digestion. The method was validated using three insect certified reference materials, namely black soldier fly larvae meal (BFLY-1), cricket flour (KRIK-1), and mealworm powder (VORM-1). The method was applied to analyze twelve different (whole) insect species. The maximum amount of each sample was calculated for As, Cd, and Pb with respect to their provisional tolerable daily intake values established by the Food and Agricultural Organization/World Health Organization. Most of the samples, except for scorpions and tarantulas, were safe to consume at large doses (1000–10,000 insects per day). Furthermore, most of the samples contained high levels of Fe, K, Na, and Zn, providing a preliminary overview of the nutritional profile of these novel protein alternatives.

This study addresses the development and validation of an analytical method for speciation analysis of mercury (inorganic/Hg²⁺ and methylmercury/CH₃Hg⁺) in fishery products. The Hg species are separated by reversed-phase (RP) high-performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICP-MS). The effective separation of Hg²⁺ and CH₃Hg⁺ was achieved in 3Hg⁺ and 1.2 µg/kg (ww) for Hg²⁺. The intermediate reproducibility in terms of coefficient of variation (CV_R) was 3Hg⁺ and Hg²⁺ in fishery products. The method is intended to be applied for the analysis of the panel of fishery products and fish-based foods in the framework of the (ongoing) third French Total Diet Study.

This study addresses the effect of various cooking approaches on total Hg (Hg_T) and total Se (Se_T) contents in three predatory fish species. For this purpose, samples of swordfish, dogfish, and tuna from regular French (fish) markets were cooked by boiling, steaming, grilling, and frying, respectively. The levels of Hg_T and Se_T in raw and cooked samples were determined by inductively coupled plasma-mass spectrometry. The data showed a significant increase in Hg_T and Se_T levels between raw and cooked samples (33% of the samples for Se_T and 67% for Hg_T) due to the water loss during the cooking. High intra-species variation related to Hg_T and Se_T levels was found. Considering the level of exposure to Hg_T through fish consumption and taking also into account the possible protective effect of Se (expressed here via the Se/Hg molar ratio), the safest cooking approach corresponds to grilled swordfish, fried tuna, and steamed dogfish, which show Se/Hg molar ratios of (1.0 ± 0.5), (4.3 ± 4.2), and (1.0 ± 0.6), respectively.

Levels of 14 trace elements (Al, Ti, V, Cr, Mn, Co, Ni, Zn, As, Se, Cd, Sn, Hg, and Pb) and 5 arsenic species (arsenite/As(III), arsenate/As(V), monomethylarsonic acid/MA, dimethylarsinic acid/DMA, and arsenobetaine/AsB) were assessed in the gonads of sea urchin samples (Paracentrotus lividus) from North-West Mediterranean Sea (French coast). The samples were collected from 13 sites characterized by different types and levels of chemical contamination. Trace elements levels were measured by inductively coupled plasma-mass spectrometry (ICP-MS) following microwave (acid) digestion in a closed system, whereas As speciation analysis was carried out by ion-exchange liquid chromatography coupled with ICP-MS after microwave-assisted extraction. High levels of trace elements were found in sea urchins sampled from Corsica whereas the samples from Théoule were found to be the least contaminated. From all the analyzed urchin samples, none showed Cd, Hg, or Pb concentrations above the regulatory levels set by the European Community (EC) No. 1881/2006 for seafood or bivalve mollusks. Regarding arsenic speciation, AsB was confirmed to be the predominant species. Inorganic As (As(III) + As(V)) was mainly constituted by As(III), which was quantified in all samples. Methylated As forms (MA and DMA) represent 9 to 23% of the total As.

This study reports the development and validation of a new analytical method for simultaneous speciation analysis of Se and Hg in fish muscle. For this purpose, four Se species (selenite/Se(IV), selenate/Se(VI), selenomethionine/SeMet, and selenocysteine/SeCys) and two Hg species (inorganic mercury/iHg and methylmercury/MeHg) were extracted simultaneously by microwave-assisted enzymatic hydrolysis and then separated by HPLC in less than 15 min by using a column with both anion and cation exchange mechanisms and a mobile phase consisting of a mixture of methanol 5% (v/v), 45 mM HNO₃, 0.015% 2-mercaptoethanol, and 1.5 mM sodium 3-mercapto-1-propanesulfonate. The separated species of Hg and Se were detected online by inductively coupled plasma-mass spectrometry (ICP-MS). The speciation analysis method was validated by means of the accuracy profile approach by carrying out three series of measurements in duplicate on three different days over a time-span of 3 weeks. The limits of quantification (LOQ) are in the range of 0.010–0.013 mg/kg wet weight (ww) for all selenium species, except for Se(IV) (0.15 mg/kg ww), while the coefficient of variation in terms of intermediate reproducibility (CV_R) was < 7%. The LOQ for MeHg was 0.006 mg/kg ww, while the CV_R was 3%. The method was successfully applied to the analysis of muscle samples from four different fish species: rainbow trout, tuna, swordfish, and dogfish. Graphical Abstract

Levels of 14 trace elements (Al, Ti, V, Cr, Mn, Co, Ni, Zn, As, Se, Cd, Sn, Hg and Pb) and 5 arsenic species (arsenite/As(III), arsenate/As(V), monomethylarsonic acid/MA, dimethylarsinic acid/DMA and arsenobetaine/AsB) were assessed in the gonads of sea urchin samples (Paracentrotus lividus) from North-West Mediterranean Sea (French coast). The samples were collected from 13 sites characterized by different types and levels of chemical contamination. Trace elements levels were measured by inductively coupled plasma-mass spectrometry (ICP-MS) following microwave (acid) digestion in a closed system, whereas As speciation analysis was carried out by ion-exchange liquid chromatography coupled with ICP-MS after microwave assisted extraction. High levels of trace elements were found in sea urchins sampled from Corsica whereas the samples from Théoule were found to be the least contaminated. From all the analyzed urchin samples, none showed Cd, Hg or Pb concentrations above the regulatory levels set by the European Community (EC) No. 1881/2006 for seafood or bivalve mollusks. Regardin arsenic specation, AsB was confirmed to be the predominant species. Inorganic As (As(III) + As(V)) was mainly constituted by As(III), which was quantified in all samples. Methylated As forms (MA and DMA) represent 9 to 23% of the total As.

Between 1966 and 1974, France conducted 41 atmospheric nuclear weapon tests in Mururoa and Fangataufa in the southeastern part of the Tuamotu-Gambier archipelago of French Polynesia (FP).¹ To evaluate the potential association of fallout from atmospheric nuclear tests with the incidence of differentiated thyroid carcinoma (DTC) observed in FP, we performed a case-control study between 2003 and 2006 including 229 DTC cases diagnosed before 2003 individually matched on sex and birth date to 373 controls from the general population. This study permitted us to better understand risk factors associated with DTC in this population,^2-5 in particular the association of a large number of pregnancies² and body mass index with a large increase in risk.³ We also showed that a diet closer to the traditional Polynesian diet could be associated with protection from DTC^6,7 and identified FP as an area of moderate iodine deficiency, where an increased diary iodine intake may be associated with a lower risk of thyroid cancer.⁷