# Unveiling rare earth elements in beers:evidence for gadolinium contamination

Aéla Bordeneuve-Pérès, Jean-Alix Barrat, Germain Bayon, Marie-Laure

Rouget, Raphaël Tripier, Douraied Ben Salem

► To cite this version:

Aéla Bordeneuve-Pérès, Jean-Alix Barrat, Germain Bayon, Marie-Laure Rouget, Raphaël Tripier, et al. Unveiling rare earth elements in beers:evidence for gadolinium contamination. Food Chemistry, 2025, 493, pp.145953. 10.1016/j.foodchem.2025.145953. hal-05288092

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# Unveiling rare earth elements in beers:evidence for gadolinium contamination

Aéla Bordeneuve-Pérès<sup>a,b,f,*</sup>, Jean-Alix Barrat<sup>b,c</sup>, Germain Bayon<sup>d</sup>, Marie-Laure Rouget<sup>e</sup>, Raphaël Tripier<sup>a</sup>, Douraied Ben Salem<sup>f</sup>

## ARTICLE INFO

Key words::

ICP-MS
beverages
micropollutants
Gadolinium
REE anomalies

## Abstract.

Despite evidence that rare earth elements have become emerging environmental micropollutants, their distribution in food and beverages remains poorly documented. Rare earth element (REE) concentrations in freshwater or organic matter are usually very low, thereby requiring specific analytical protocols to allow for precise and accurate elemental abundance analyses. Here, we report on a routine procedure for the determination of REE concentrations in beers and in sugar-rich drinks. Our exploratory investigation indicates relatively low, but varying, REE abundances in beers (n = 30), and in an energy drink. The resulting shale-normalized REE patterns display both positive or negative Ce anomalies, and positive Y anomalies. Importantly, many studied samples exhibit positive anomalies in gadolinium, hence pointing towards the presence of anthropogenic sources. Additionally, a few samples show significant Pr excess, which we interpret as being linked to industrial pollution. These results demonstrate that REE contamination, albeit in relatively small amounts, is now common in industrially-produced beverages including beers and sugar-rich drinks.

## 1. Introduction

Rare Earth Elements (REE) are a group of 16 chemically similar

metallic elements including the lanthanides (Z = 57 to 71) and Y (Z = 39). These elements have a wide range of industrial applications, including catalysts (La, Ce, Nd, Sm, Lu), magnets (Pr, Nd, Sm, Gd, Tb, Dy, Ho, Tm), polishing activities (Ce), in batteries (La), metallurgy (Pr, Nd, Ho, Er, Yb, Lu) and lasers (Dy, Ho, Er, Tm, Yb) (Goodenough et al., 2018). Some of them are also used for medical purposes. This is the case of La, which is prescribed daily to patients with kidney issues to prevent hyperphosphatemia (Aktar & Toyoda, 2024). Gadolinium, on the other hand, is essential for magnetic resonance imaging (MRI). As REEs are used in such a wide variety of fields, with high and rapidly increasing consumption (ca. 147.5 kt of rare earth oxides were used in 2020, Roskill., 2021), it is not surprising that these elements are becoming emerging pollutants.

One of the best-documented REE pollutions is that of Gd generated by medical imaging. During an examination, patients may receive an injection of Gadolinium-Based Contrast Agents (GBCAs). These compounds are eliminated through the kidneys (73%-99%, within 24 h depending on the GBCA and the patient's renal function (Levine et al., 2018)) and end up in urine flowing into waste waters. Since it is not removed during conventional water treatment processes, anthropogenic gadolinium is released into rivers and ultimately reaches coastal waters (Bau & Dulski, 1996). Today, in densely populated countries with

<footnote><sup>a</sup> Univ Brest, UMR CNRS 6521, CEMCA, 6 Avenue Victor Le Gorgeu, 29200 Brest, France.</footnote>

<footnote><sup>b</sup> Univ Brest, UMR 6539 CNRS, Ifremer, IRD, LEMAR, Institut Universitaire Européen de la Mer (IUEM), rue Dumont d'Urville, 29280 Plouzané, France.</footnote>

<footnote><sup>c</sup> Institut Universitaire de, France, Paris.</footnote>

<footnote><sup>d</sup> Univ Brest, UMR 6538, CNRS, Ifremer, Geo-Ocean, F-29280 Plouzané, France.</footnote>

<footnote><sup>e</sup> Univ Brest, CNRS UMS 3113, Institut Universitaire Européen de la Mer (IUEM), 29280 Plouzané, France.</footnote>

<footnote><sup>f</sup> Univ Brest, INSERM UMR 1101, LaTIM, 22, Avenue C. Desmoulins, 29238 Brest Cedex 3, France.</footnote>

<footnote>* Corresponding author at: Univ Brest, UMR CNRS 6521, CEMCA, 6 Avenue Victor Le Gorgeu, 29200 Brest, France.
E-mail address: bordeneuve@univ-brest.fr (A. Bordeneuve-Pérès).</footnote>
significant medical activity, traces of Gd are commonly detected in rivers and aquifers (Elbaz-Poulichet et al., 2002; Knappe et al., 2005; Möller et al., 2002), as well as in coastal waters, where gadolinium concentrations are increasing over time (Hatje et al., 2016). Gadolinium excesses are also detected in tap water, and therefore in beverages derived from it, as exemplified by sodas served in German fast food restaurants (Schmidt et al., 2019). This contamination is also detected in marine molluscs (e.g., Barrat et al., 2022; Le Goff et al., 2019; Merschel & Bau, 2015), and it can be considered that the marine food webs can potentially record it. Readers should bear in mind that the excesses of Gd detected are fingerprints of the drug pollution carried via patients' urine, and that their presence can be considered as a sentinel parameter of potential pollution by other molecules with the same origin. Nevertheless, we must emphasise that the levels of Gd measured in the environment to date are not high enough to have significant environmental or human health issues. However, it is relevant to monitor the level of this contamination (as well as possibly that generated by other uses of REY) in the environment, but also in human food, for which there is little data available now. This is explained firstly by a still limited perception of this question, but also by the difficulty of measuring REY in low concentrations in food and drinks. In this context, our objective was first to develop an analytical protocol to routinely determine the REY concentrations in various beverages. We then applied this protocol to industrially produced beverages to get a snapshot of the situation. Here we present the analyses obtained on a series of beers.

## 2. Samples and analytical methods

### 2.1. Samples

A series of 30 beers of different brands, brewed in Europe, Asia and South, were purchased between November 2024 and April 2025 in local stores. Some beers less drank in France were bought in specialized shops (such as the ones brewed in Asia), or sent by collaborators. The studied beers were chosen regardless of the nature of their containers (Table S1). Twenty-five beers are from Europe: seven from Belgium (Affligem, Bud, Grimbergen, Hoegaarden, La Chouffe, Leffe blonde, Rince Cochon), two from Czech Republic (Budweiser budwar, Pilsner Urqell), Six from France (1664, Bourbon, Desperados, Heineken, Kronenbourg, Pelforth), three from Germany (Eku 28, Löwenbrau Munchen, Paulaner Münchner Hell), one from Poland (Namysłów Pils), one from Turkey (EFES), one from England (Bombardier), one from Ireland (Guinness), and two directly taken back from Portugal (Sagres, Super Bok), and one from Spain (Estrella). Four beers are from Asia: one from China (Tsingtao), one directly taken back from Japan (Asahi Super Dry), one from South Korea (Cass) and one from Thailand (Chang). One beer is from Peru (Pilsen Callao). Two sodas were purchased in the same period in the same local stores: a Red Bull original (made in Austria) and a Fuze Tea peach (made in France).

### 2.2. Analytical methods

#### 2.2.1. Procedure for the analysis of beers and non-alcoholic beverages

We adapted for organic matter-rich beverage, a procedure routinely used in our laboratory for the analysis of natural waters (Bayon et al., 2011). Upon opening, all the samples (beers and non-alcoholic beverages) were first degassed for about a week. This step consists in pouring the samples in clean vials, which are not hermetically closed and placed in a fridge to prevent evaporation. When degassed, about 25 g of sample were precisely weighted in a Teflon beaker and spiked with a known amount of a solution of Tm (typically about 7 ng of Tm were added). The addition of this small amount of Tm is used to precisely calculate the elemental concentrations of the samples by creating a positive anomaly (see Barrat et al. (1996) for more details on the principles and calculations). The spiked solutions were dried, and the residues were taken up with 2 mL of 14 N HNO₃. The beakers were then placed on a hot plate at

65 °C during at least 24 h, in order to digest the organic compounds, and then evaporated to dryness again. Dried samples were then taken up with 20 mL of ultra-pure Milli-Q, to which were added 300 µL of a solution of Fe PlasmaCAL at 1000 ppm, plus about 1 mL of ammonia and left 4 h on a hotplate at 140 °C. This step leads to the co-precipitation of Fe-hydroxide phases, which results in efficient scavenging of reactive elements such as REE (Bayon et al., 2011). After centrifugation (5 min/5600 rpm), the resulting supernatants were discarded. The residues containing the Fe oxyhydroxide precipitates were first rinsed with ultra-pure Milli-Q water and centrifuged. This step was repeated until the supernatant was clear. Finally, the precipitates were dissolved with 3 mL of 0.4 N HNO₃ and analysed. The REY abundances were determined by sector-field ICP-MS at the Pôle Spectrométrie Océan (PSO), Plouzané, using a Thermo Scientific sector-field ELEMENT XR™ mass spectrometer operated with a low-resolution mode. Each solution was analysed in triplicate. Isobaric interferences were corrected (Barrat et al., 1996). The reader is referred to Bayon et al. (2011) or Charles et al. (2020) for more details on the setting of the instrument and the data acquisition procedure.

#### 2.2.2. Procedure for the analysis of bentonite

A sample of bentonite used to clarify beers (Benton) was also analysed following the usual protocol for silicates in our laboratory (e.g., Barrat et al., 2012).

#### 2.2.3. Normalisation to PAAS

The concentrations were normalized to the Post Archean Australian Shale (PAAS) obtained by Pourmand et al. (2012) adjusted to our own standard values (Barrat et al., 2020). The Gd, Ce and Pr anomalies were calculated using XSN/XSN* ratios, where XSN is the concentration of X normalized to PAAS and XSN* represents the theoretical concentration assuming a 'smooth' REE pattern.

GdSN/GdSN* can be estimated through extrapolation from Dy and Tb abundances (Eq. (1)):

$$ \frac{\mathrm{Gd}_{\mathrm{SN}}}{\mathrm{Gd}_{\mathrm{SN}^{*}}} = \frac{\mathrm{Gd}_{\mathrm{SN}} \times \mathrm{Dy}_{\mathrm{SN}}}{\mathrm{Tb}_{\mathrm{SN}^{2}}} \quad (1) $$

CeSN/CeSN* can be estimated through interpolation of SmSN and NdSN (Eq. (2)):

$$ \mathrm{Ce}_{\mathrm{SN}} / \mathrm{Ce}_{\mathrm{SN}^{*}} = \mathrm{Ce}_{\mathrm{SN}} \times \mathrm{Sm}_{\mathrm{SN}} / \mathrm{Nd}_{\mathrm{SN}^{2}} \quad (2) $$

PrSN/PrSN* can be estimated through extrapolation of SmSN and NdSN (Eq. (3)):

$$ \frac{\mathrm{Pr}_{\mathrm{SN}}}{\mathrm{Pr}_{\mathrm{SN}^{*}}} = \frac{\mathrm{Pr}_{\mathrm{SN}} \times \mathrm{Sm}_{\mathrm{SN}}^{1/2}}{\mathrm{Nd}_{\mathrm{SN}}^{3/2}} \quad (3) $$

Due to the presence of Gd anomalies, the Eu anomalies are estimated using the (Eu/Sm)SN ratio. Y anomalies can be calculated using the Y/Ho ratio with non-normalized concentrations.

#### 2.2.4. Reproducibility

We analysed five samples of Guinness taken from the same bottle and processed as independent samples to assess the reproducibility of our procedure (Table S1). We chose this beer because its REY concentrations are among the lowest measured here (of the order of 10⁻⁷ × PAAS). The results are consistent and the relative standard deviations are better than 10 %. We have also duplicated a few REE-enriched beer samples in the same way, with a reproducibility around 5 % for concentrations above 10⁻⁶ × PAAS.

## 3. Results

### 3.1. REY patterns

To present and discuss the results, the abundances normalized to PAAS and REY patterns will be used. The principles of this type of data
processing is well known in geochemistry and cosmochemistry since the 1960s (Coryell et al., 1963; Masuda, 1962). Since REE distributions in the environment and in organic matter are not immune to the Oddo-Harkins effect, these diagrams are well suited for studies on food and drinks. Readers who are not familiar with this type of diagrams are referred to review papers summarizing their properties and their utility in environmental studies (e.g., Barrat & Bayon, 2024).

The REY concentrations in the beers and sodas investigated in this study are given in the supplementary material (Table S1), showing significant variability over 4 orders of magnitude (from $3.10^{-8}$ to $3.10^{-5} \times \text{PAAS}$). The shape of the calculated REY patterns is quite variable. Studied beers never display any La anomaly, but can show anomalies in Ce, Eu and Y, which are well known in natural systems at the Earth's surface. Positive anomalies in Gd, and in some cases in Pr, are also encountered in several beers. These last two anomalies are obviously anthropogenic, and will be discussed separately below. Based on the above-mentioned results, and in particular on the Ce/Ce* ratio, we can identify 4 different types of samples in this study (Figs. 1–4).

## 3.2. Beers with positive Ce anomalies

Beers with positive Ce anomalies (Ce/Ce* = 1.23–2.34, Fig. 1) have relatively unfractionated patterns (($La/Yb)_{SN} = 0.49–0.91$), with variable anomalies in Eu (($Eu/Sm)_{SN} = 1.25–1.89$) and Y (Y/Ho = 32.00–45.11). Their REY abundances are low, between $10^{-7}$ and $3.10^{-6} \times \text{PAAS}$. Guinness and Tsing Tao beers belong to this group.

## 3.3. Beers without marked Ce anomalies

Beers without marked Ce anomalies (Ce/Ce* = 0.21–1.34, Fig. 2). Two groups are apparent. The beers richest in REY, with concentrations $>10^{-6} \times \text{PAAS}$ (Fig. 2a), show remarkably similar patterns, characterised by ($La/Sm)_{SN}$ ratios close to 1 (($La/Sm)_{SN} = 0.70–1.13$), positive Eu anomalies (($Eu/Sm)_{SN} = 1.51–1.79$), weak or absent Y anomalies (Y/Ho = 30.5–34.2), and a small depletion of heavy REE (($Tb/Yb)_{SN} = 1.12–2.16$). Sagres, Kronenbourg and Bud beers belong to this group. Beers with lower REY concentrations ($<10^{-6} \times \text{PAAS}$, Fig. 2b) show different patterns to the previous ones, with heavy REE enrichments (($Tb/Yb)_{SN} = 0.52–0.83$), and sometimes positive Y anomalies (Y/Ho = 29.40–43.51). Desperados and Hoegaarden beers belong to this group.

## 3.4. Beers with negative Ce anomalies

The third type of sample we will present are beers with negative Ce

<figure><img src="image_3.png" /><figcaption>**Fig. 1.** Post-Archean Australian shale (PAAS)-normalized REY patterns for beers from Europe and Asia displaying positive Ce anomalies.</figcaption></figure>

<figure><img src="image_4.png" /><figcaption>**Fig. 2.** PAAS-normalized REY patterns of beers with no large Ce anomalies.</figcaption></figure>

anomalies (Ce/Ce* = 0.39–0.85, Fig. 3). Once again, two groups can be identified. The vast majority of beers have regular patterns with, in general, slightly increasing standardised concentrations from Pr to Yb (Fig. 3a). The patterns do not show any strong anomalies in Eu, but often show marked anomalies in Y (Y/Ho = 27.48–41.94). Asahi and EFES beers belong to this group. Two samples show distinctive patterns (Fig. 3b): Chang and Paulaner Münchner Hell. Apart from the negative anomaly in Ce, these two samples show overall flat patterns from La to Er but quite unusual depletion in Yb and Lu (($Er/Yb)_{SN} = 3.33–7.36$). These patterns are so surprising that another aliquot from the same bottles were independently analysed, and in both cases the shape of the patterns and the abundances have been confirmed.

Independently of their shapes, the PAAS-normalized REY patterns can show positive anomalies in Gd of varying degrees of severity (Gd/Gd* = 0.98–21.86, the highest Gd anomaly being the one of the Sagres-1), indicating the presence of anthropogenic Gd in a large number of the samples analysed. Several samples (one of the two La Chouffe samples and the two Pelforth samples) also show positive Pr anomalies. As this element is not decoupled from the other REEs by natural processes, these anomalies can only be of anthropogenic origin.

## 3.5. Non-alcoholic drinks

The patterns of the two non-alcoholic industrial drinks on which we have tested our procedure, are different from those of the beers (Fig. 4). Fuze Tea displays the highest REY content that we have analysed here, with heavy REE concentrations exceeding $10^{-5} \times \text{PAAS}$. Its pattern is depleted in light REE compared to PAAS (($La/Sm)_{SN} = 0.48$), has a weak positive anomaly in Eu (($Eu/Sm)_{SN} = 1.79$) and in Y (Y/Ho =
<figure><img src="image_5.png" /><figcaption>**Fig. 3.** PAAS-normalized REE patterns of beers from Europe, Asia and America showing negative Ce anomalies.</figcaption></figure>

<figure><img src="image_6.png" /><figcaption>**Fig. 4.** PAAS-normalized REY patterns in two sugar-rich drinks: Fuze Tea and Red Bull.</figcaption></figure>

34.39–40.06). The REY concentrations in Red Bull are much lower, ranging from $7.10^{-8}$ × PAAS for light REEs to $10^{-6}$ × PAAS for Yb and Lu. The resulting heavy-REE enriched pattern ((La/Lu)SN = 0.09–0.27) displays positive anomaly in Ce (Ce/Ce* = 1.17–3.86), but above all very significant positive Gd anomalies (Gd/Gd* = 4.12–9.02), showing that Gd contamination is also present in other industrial drinks.

# 4. Discussion

## 4.1. Preliminary remarks

Beers are complex beverages resulting from different recipes, involving water as the main ingredient, but also plants, yeasts and clarifiers. To explain and, above all, model the REY concentrations would require measuring the REY concentrations of the ingredients used to produce specifically the analysed beer sample, but also to evaluate the incoming and outgoing REY flux during brewing. As plants are not rich in REY (Fu et al., 2001), and their REY are not necessarily dissolved during the brewing, their contribution to the REY content of beer is a completely open question. On the other hand, the use of clarifiers can have a considerable effect, even in small quantities. Although the broad outlines of the entire brewing process are known, the breweries do not disclose the details of their beer production nor the precise origin of the ingredients they use. Moreover, animal products (gelatine, isinglass) may be used in the brewing process, and this information may have significant commercial consequences for certain customer segments (especially vegan customers).

Even if industrial beers have constant taste characteristics, the trace element contents of the water and other ingredients can vary significantly over time. Therefore, the analysis of the contents of a bottle or a metal can cannot be representative of the entire production of a brewery. The detection of a pollutant in a sample is obviously not sufficient to confirm that the entire production run is contaminated.

## 4.2. Anomalies and REY patterns

### 4.2.1. Impossibility to identify the origin of beers

Firstly, the REY patterns do not allow us to identify the origin of the beers. Beers of the same brand can have very different patterns. This is illustrated by the two Heineken samples, one with a negative Ce anomaly and the other with a positive one (Figs. 1 and 3). And on the other hand, beers from different breweries can have similar REY abundances. This is the case, for example, with one of our Heineken beers, which has similar REY abundances to Tsingtao beer (Fig. 1).

### 4.2.2. REY patterns

The REY patterns are not linked to the type of beer either. For example, lagers have patterns belonging to each of the groups we have defined (for example, Tsingtao beer has a positive anomaly in Ce, Bud does not, and Asahi SD beer has one). Beers of different types can also have similar patterns. This is the case, for example, with Guinness stout, whose pattern is parallel to that of Cass lager (Fig. 1).

The similarities of the REY patterns of beers without significant anomalies in Ce (Fig. 2a) are astonishing. The patterns do not have the expected shape of those of water. Their similarities suggest the use of a component rich in REY, which would have buffered the characteristics of all the ingredients. These patterns could result from the use of a bentonite-type clarifier, commonly used to treat wine (Blade & Boulton, 1988) and beer (Siebert & Lynn, 1997). Compared to water, these clays have REE concentrations in the order of those of PAAS, i.e. in the order of $10^5–10^6$ times richer than water (Mihucz et al., 2006; Tatár et al., 2007). The similarities with the patterns of these beers and bentonite (Fig. 2a, sample Benton) is in agreement with this interpretation.

### 4.2.3. Ce anomalies

The origin of positive or negative Ce anomalies in beers is a
completely open question. Cerium is an element that has two valence states on the Earth's surface, which can easily be decoupled from neighbouring REE by redox processes. It is conceivable that beers with a negative Ce anomaly (those in Fig. 3a) have inherited it from the water from which they were brewed. Moreover, the shape of their patterns is quite comparable to that of fresh water (Goldstein & Jacobsen, 1988). Alternatively, the causes of the positive Ce anomalies encountered in some beers could result from certain brewing conditions (note that during brewing, the pH of liquids changes from neutral to acidic), or be inherited from ingredients or products used.

### 4.2.4. Unusual REY patterns

The origin of the extremely high Er/Yb ratios displayed by the Chang and Paulaner München Hell beers is, at first glance, enigmatic (Fig. 3b). REY patterns such as those of these samples do not correspond to those of continental water, rock or soil. These unusual patterns must result from the use of a particular component during the brewing of these beers (both lagers, though the other lagers we analysed did not have these unusual patterns). However, patterns of this type have been described for phosphatic fossils very rich in REE (10 × PAAS, see Figs. 2, 3, and 5 in Picard et al., 2002). We speculate that a mineral clarifier containing this type of phosphates as an impurity would have been used. As beer is slightly acidic, these phosphates would have been preferentially dissolved, thus imposing their signatures on the beers due to their high REE content.

All these aspects are new and would merit further work, which is well beyond the scope of this exploratory study. On the other hand, the data we obtained allows us to give a fresh look at the contamination in REE of industrially produced drinks, which was one of our initial objectives.

## 4.3. Gd anomalies

### 4.3.1. Origin of Gd anomalies

The beers we analysed show positive anomalies in Ce, Pr, Eu, Gd and Y. Of these anomalies, only those in Gd and Pr cannot be caused by natural processes. The enrichments shown by the PAAS-normalized REY patterns can only be the result of contamination by these two elements.

Since the discovery of positive Gd anomalies in the waters of German rivers, and their links with magnetic resonance imaging (MRI) by Bau and Dulski (1996), much work has been devoted to this topic. It has been found in all densely populated regions where medical activity is

<figure><img src="image_7.png" /><figcaption>**Fig. 5.** Gd/Gd\* vs. Tb plot. The Gd/Gd\* ratio depends on the excess of Gd and the abundance of REE in the drink. The richer the latter in REE, the less noticeable the effect of Gd pollution will be. The dotted curves show the Gd/Gd\* ratios of beers initially devoid of anthropic Gd (Gd/Gd\* = 1) after the addition of 1 pg/g and 5 pg/g of Gd. The observed dispersions show that the majority of the beers we analysed contain less than 5 pg/g of anthropic Gd.</figcaption></figure>

significant. In these regions, surface water is often affected by this problem to varying degrees, and consequently tap water (Bau & Dulski, 1996; Kulaksız & Bau, 2011; Kulaksız & Bau, 2013). It was therefore not surprising to discover that the sodas prepared with this water in German fast-food restaurants were also contaminated. The data obtained here are the first concerning industrial beverages, and it is not surprising to find the imprint of this contamination there as well. The GBCAs used in MRI are prepared from extremely pure Gd oxides (Ben Salem & Barrat, 2021; Veiga et al., 2020), and their introduction into the environment does not produce any other elemental anomaly. A marked positive Gd anomaly will be easily produced by a tiny amount of GBCA in water low in REE. A much weaker anomaly will be obtained with the same quantity of GBCA if the water is richer in REEs.

### 4.3.2. Gd anomalies in beverages

Beers and the Red Bull show an anomaly in Gd. This anomaly is generally much less marked for beers richer in REEs. Our calculations show that Gd contamination does not exceed 5 pg/g in most cases (Fig. 5). However, one beer (Sagres, brewed near Lisbon, southwest Portugal) shows much higher contamination. It displays a very significant Gd anomaly (Gd/Gd\* = 21.9) produced by an excess of Gd of the order of 30 pg/g. This beer is probably brewed using water produced from the Tagus, whose Gd-contamination has been previously established (Brito et al., 2022). We analysed another beer produced by the same brewery, but from a more recent batch, and did not find any anomalies of the same magnitude (Gd/Gd\* = 1.7), showing that the water used does not have constant characteristics. Other beers show marked positive anomalies in Gd, such as Asahi SD beer (Tokyo), La Chouffe (Belgium) and Pelforth (Northern France), but the excesses of Gd producing them are much lower (of the order of 1 pg/g). The latter two, also show positive anomalies in Pr. We are confident that these excesses are anthropogenic in origin. Excesses of Pr have already been reported in effluents discharged into the Rhine (Kulaksız & Bau, 2013), as well as in mollusc shells collected from the banks of this river (see Fig. 5B in Merschel & Bau, 2015). The presence of this anomaly, albeit relatively minor, indicates that this element is an emerging contaminant in northern France and Belgium. The study of the water used by breweries in the regions concerned would be necessary to find the origin of this contamination, and assess its extent.

Finally, it has been shown that other REEs such as La and Sm can be emerging pollutants in surface water (Kulaksız & Bau, 2013; Aktar & Toyoda, 2024). In this study, positive La and Sm anomalies were not observed in our series of samples, suggesting that contamination for these elements might still be limited.

## 5. Conclusion

The technique we developed for measuring REY in organic-rich beverages has enabled us to determine the abundance of these elements in a bit more than thirty beers, as well as in two other alcohol-free commercial drinks.

REY concentrations and patterns in beers are variable. The origin of these variations must first be sought in the diversity of the ingredients used during brewing, but also probably in the diversity of the clarifiers used. Explaining the REY abundances of a beer is a complicated task, but one that can be carried out during chemical monitoring of the different stages of brewing, and also approached experimentally.

On the other hand, we confirm that beer or other industrial drinks show varying degrees of Gd contamination, thus extending the work carried out by Schmidt et al. (2019) on soft drinks sold in German fast food restaurants. This contamination, albeit relatively minor, should not be neglected. Our work should be considered as a snapshot of this contamination in industrially-produced drinks, and other studies will be required in the coming years to assess how this pollution may evolve through time.

Finally, some beers from northern France and Belgium are not only
contaminated with Gd, but also with Pr. The source of this contamination is unknown, and work now needs to be carried out to assess its origin and extent.

### CRediT authorship contribution statement

**Aélà Bordeneuve-Pérès:** Writing – review & editing, Writing – original draft, Validation, Methodology, Investigation, Data curation.
**Jean-Alix Barrat:** Writing – review & editing, Validation, Supervision, Project administration, Methodology, Funding acquisition, Formal analysis, Data curation, Conceptualization.
**Germain Bayon:** Writing – review & editing, Validation, Methodology.
**Marie-Laure Rouget:** Writing – review & editing, Validation, Methodology.
**Raphaël Tripier:** Writing – review & editing, Validation, Supervision, Investigation, Conceptualization.
**Douraied Ben Salem:** Writing – review & editing, Validation, Supervision, Investigation, Conceptualization.

### 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

We thank Dr. Isabel Castanheira for the editorial handling, and the three anonymous reviewers for their constructive reviews. We are grateful to Estelle Barrat for providing samples from Spain and Portugal, and Dr. Christophe Rivière-Paya for providing the beer taken back from Tokyo. This work was supported by the Chaire Industrielle MeGadoRe of the Fondation UBO (Univ Brest), and by an IUF grant to J.A. Barrat.

### Appendix A. Supplementary data

Supplementary data to this article can be found online at https://doi.org/10.1016/j.foodchem.2025.145953.

### Data availability

The data are in the supplementary table

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