# Smoked fish from Gabon: nutritional benefits vs. contaminant risks

Alice Guillot, Rose Ngo Tona, Solène Connan, Marie-Laure Rouget, Justine Receveur, Gaël Le Croizier, François Le Loc'h, Manon Buscaglia, Jean-Marie Munaron, Nestor Ngoua Aba'A, et al.

► To cite this version:

Alice Guillot, Rose Ngo Tona, Solène Connan, Marie-Laure Rouget, Justine Receveur, et al. "Smoked fish from Gabon: nutritional benefits vs. contaminant risks." Food Control, 2026, 180, pp.111643. 10.1016/j.foodcont.2025.111643. hal-05269197v2

HAL Id: hal-05269197

https://hal.univ-brest.fr/hal-05269197v2

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# Smoked fish from Gabon: nutritional benefits vs. contaminant risks

Alice Guillot<sup>a</sup>, Rose Ngo Tona<sup>b</sup>, Solène Connan<sup>a, ID</sup>, Marie-Laure Rouget<sup>c</sup>, Justine Receveur<sup>d</sup>, Gaël Le Croizier<sup>a</sup>, François Le Loc'h<sup>a, ID</sup>, Manon Buscaglia<sup>a, ID</sup>, Jean-Marie Munaron<sup>a</sup>, Nestor Ngoua Aba'a<sup>e, ID</sup>, Sylvain Petek<sup>a, ID</sup>, Anne Lorrain<sup>a</sup>, Gauthier Schaal<sup>a</sup>, Fany Sardenne<sup>a, *, ID</sup>

## ARTICLE INFO

### Keywords:

Ethmalosa fimbriata

Artisanal smoking process

Fatty acids

Trace elements

PAHs

Nutritional composition

Risk assessment

## ABSTRACT

Smoked fish is the most common form of fish consumption in many African countries. Smoking is likely to cause changes in nutritional value and in the concentration of certain toxic elements. We assessed these changes in the Bonga shad (*Ethmalosa fimbriata*, Bowdich 1825). Fatty acids (26), vitamin A, trace elements (14) and polycyclic aromatic hydrocarbons (PAHs, 24) were examined in *E. fimbriata* at different smoking durations (fresh, 24 h, 48 h and 72 h). Composition of smoked fish revealed high inter-individual variability. Smoking did not affect total fatty acid concentrations, but it led to a 4.5-fold decrease in vitamin A and a decrease in the concentrations of Ca, Mg, Mn, Pb and Sr. Meanwhile, it increased the concentrations of PAHs (by a factor of 42), Cd, Mo and Na. Despite these changes, toxic metals (As, Cd and Pb) and PAHs levels remained within safety limits, except for the B(a)P Toxic Equivalent (TEQ) in 72 h-smoked fish. High inter-individual variability in toxic metals, PAHs and nutrients concentrations is suspected to originate from the heterogeneity of the smoking process, and to natural variation in fish. Overall, our results highlight the safety of artisanal smoked fish for human consumption when processed under certain conditions. To further enhance consumer safety, dietary recommendations would advise ensuring fish skin integrity in order to reduce flesh contamination.

## 1. Introduction

Fish is a vital food source in Western and Central Africa, as more than 30 % of the African population relies on it as their primary source of animal protein (FAO, 2022). Fish also serve as a crucial source of essential micronutrients, such as iron (Fe), calcium (Ca), zinc (Zn) and vitamin A (Kawarazuka & Béné, 2011). This is particularly the case for sub-Saharan countries, which face chronic nutritional insecurity, with the highest reported rates of inadequate intake of vitamin A and of anemia (Beal et al., 2017; WHO, 2011) alongside an increased risk of Ca and Zn deficiencies, affecting 80 % and 20 % of the population, respectively (Kumssa et al., 2015).

Among fish, small pelagic fish (Clupeiformes order) are especially important from a nutritional perspective and constitute the main catch in the fisheries of Western and Central Africa coastal countries (Dème et al., 2024; Failler, 2014). For instance, the Bonga shad *Ethmalosa*

*fimbriata* represents 30–40 % of total catch in Gabon (Doumambila-Bantsantsa et al., 2000). Small pelagic fish are also high-quality sources of proteins and contain high concentrations of vitamin A, Ca, Fe, Zn and long-chain omega-3 fatty acids, i.e. eicosa-pentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), which are essential for human health (Aakre et al., 2020), underlying the potential of those species to tackle micronutrient deficiencies at the global scale (Hasselberg et al., 2022; Hicks et al., 2019). As a result, collective awareness about nutritional benefits and economic potential of increasing aquatic food consumption is rising in many African nations (Okon et al., 2024).

Smoking is the most common preservation method in Africa, where 70–80 % of the domestic marine and freshwater catch is consumed as smoked fish (Adeyeye & Oyewole, 2016). Artisanal smoking allows fish preservation thanks to water loss, which limits microbial, bacterial and oxidant development (Adeyeye, 2019). This process also minimizes fish

<footnote><sup>a</sup>IRD, CNRS, Univ. Brest, Ifremer, LEMAR, IUEM, F-29280, Plouzane, France</footnote>

<footnote><sup>b</sup> WCS, Libreville, Gabon</footnote>

<footnote><sup>c</sup> Univ. Brest, CNRS, Ifremer, UAR 3113, IUEM, F-29280, Plouzané, France</footnote>

<footnote><sup>d</sup> CEDRE, 715, Rue Alain Colas/CS 41836, Cedex 2, 29218, Brest, France</footnote>

<footnote><sup>e</sup>CENAREST/IRAF, B.P. 2246, Libreville, Gabon</footnote>

<footnote>* Corresponding author.</footnote>

<footnote>E-mail address: fany.sardenne@ird.fr (F. Sardenne).</footnote>
spoilage and increases shelf life of fish products, allowing to transport fish in inland areas (Adeyeye & Oyewole, 2016). However, burning wood generates smoke that can be a vector of pyrolytic chemical compounds such as polycyclic aromatic hydrocarbons (PAHs) (Tongo et al., 2017) and ash that carry non-essential trace metals such as lead (Pb) or arsenic (As) (Etchie et al., 2020), which could have adverse effects on human health. Dietary exposure is the major source of PAHs for humans (Mahugija & Njale, 2018), especially benzo-a-pyrene (B(a)P), the most carcinogenic and mutagenic PAH (Stolyhwo & Sikorski, 2005). Artisanal smoked fish, such as sole, catfish and other freshwater fish, often exhibited elevated levels of PAHs (Kafeelah et al., 2015; Sroy et al., 2023), sometimes higher than those produced by industrial smoking methods (Adeyeye et al., 2016), raising concerns about the toxic exposure to consumers of artisanal smoked fish.

Smoking can also reduce the levels of certain nutrients in fish, particularly heat-sensitive nutrients (apart from the concentration process associated with water loss). For instance, fatty acids and vitamin A are sensitive molecules that degrade when exposed to heat or UV radiation (Chittchang et al., 1999; Idah & Nwankwo, 2013; Smith & Hole, 1991). However, reported effects of smoking on fatty acid concentrations diverged: the smoking process can reduce the concentration of fatty acids through fat dripping (Friedman, 1996) or increase it through water loss (Bouriga et al., 2020; Manzkoule et al., 2024). Similarly, the effect of smoking on fish concentrations of nutrients such as magnesium (Mg) and Zn varies greatly between studies, either increasing (Olopade et al., 2023) or decreasing (Kiczorowska et al., 2019). Overall, smoking effects on fish composition seem to be highly dependent on the specific artisanal smoking conditions (Adeyeye, 2019). For example, conventional ovens and kilns lack regulation of temperature and smoke density,

leading to inconsistent fish quality (Clucas, 1981; Stolyhwo & Sikorski, 2005). This raises questions about the nutritional benefits of consuming artisanal smoked small pelagic fish.

Those contrasted results regarding the effects of smoking on both the nutritional value and contaminant concentrations in fish make it difficult to predict the cost-benefits associated to smoked fish consumption, especially in areas where data are lacking. In this context, the aim of this study is to investigate the nutritional benefits and the toxicological risks associated with the consumption of small pelagic fish smoked using artisanal methods, with a particular focus on characterizing the variability of the smoking process. To this end, we studied the artisanal smoking process of *E. fimbriata* in Gabon, focusing on nutrient concentrations (vitamins A₁ and A₂, fatty acids including omega-3 and trace elements including Fe, Ca, Zn and Se) and contaminants (As, Cd, Pb and PAHs).

## 2. Material and methods

### 2.1. *Sampling*

Bonga shad *E. fimbriata* were caught in a haul by local fishermen on the 29th of April 2024 in Corisco bay, Gabon. Twenty-one individuals of similar size (21.7 ± 1.2 cm in fork length) were selected and marked by cutting out the gill operculum, then smoked on the same day with the artisanal method by the women fish processors (Fig. 1). This method consists in three smoking cycles, typically carried out over a period of three days.

<figure><img src="image_3.png" /><figcaption>**Fig. 1.** Smoking process of Bonga shad *E. fimbriata*. (A) Fresh Bonga shad before smoking process. (B) Smoked Bonga shad after one smoking cycle (24 h). (C) Smoked Bonga shad after two smoking cycles (48 h).</figcaption></figure>
- Cycle 1: the fish is placed vertically on the grill (upside down), and a fire is lit underneath using sawmill waste (planks and hardwood); this stage consists of draining the fish of all its water and cooking it.

- Cycle 2: the fish is turned over, still on the same grill, and a fire is lit underneath with the sawdust residue, which only releases smoke, giving the fish its golden color.

- Cycle 3: the sawdust residue is put back in to dry the fish thoroughly.

Five to six individuals were randomly sampled at the four steps of the process: fresh (n = 6), after one cycle (24 h, n = 5), after two cycles (48 h, n = 5) and at the end of the smoking process (72 h, n = 5).

After smoking, whole fish were kept in aluminum foil (previously preheated at 450 °C for 6 h to remove any trace of organic contaminants) then stored at -20 °C for a week and then at -80 °C for a month before being analyzed. For analyses, pieces of dorsal white muscle were sampled: 1 g for fatty acid and trace element quantification, another for vitamin A, and 5 g in aluminum foil for PAHs analysis.

## 2.2. Moisture

The aliquots for fatty acid and trace element analysis were weighed to the nearest 0.1 mg, freeze-dried for 48 h and weighed again to obtain moisture content (in %).

## 2.3. Trace elements

About 175 mg of freeze-dried fish muscle samples were digested in HNO₃ 70 % and H₂O₂ 30 % (both ultrapure quality) in Teflon vessels. Mineralization was performed on a hotplate for 4 h at 100 °C. An aliquot was diluted in ultrapure water and stored at 5 °C before analysis. Trace elements (As, Ca, Cd, Co, Cu, Fe, Mg, Mn, Mo, Na, Pb, Se, Sr, and Zn) were analyzed with an Element XR ICP-MS (Thermo Scientific). Accuracy was checked using three certified reference materials (lobster hepatopancreas TORT-3, fish protein DORM-4 and dogfish liver DOLT-5, NRCC). Recovery, limits of detection (LOD) and limits of quantification (LOQ) are detailed in Table S1. Multi-element standard ranges were used to calculate trace element concentrations, which were normalized to a 40 µg.L⁻¹ internal standard of rhodium and expressed in mg.g⁻¹ dry weight (dw).

## 2.4. Fatty acids analysis

Fatty acids were extracted from 50 mg of freeze-dried muscle using a mixture of chloroform and methanol (2:1, v/v) (Folch et al., 1957). Extracts were vortexed, flushed with nitrogen and stored at -20 °C for at least 12 h. An internal standard (23:0) was added to the lipid extract, evaporated until dryness then saponified with KOH 0.5 M and heated for 30 min at 80 °C. They were then transmethylated with H₂SO₄ in MeOH (3.4 %, v/v) and heated at 100 °C for 10 min. Fatty Acid Methyl Esters (FAME) were washed 3 times with hexane-saturated distilled water, together with hexane. FAME were analyzed with a TRACE 1300 gas chromatograph equipped with a splitless injector and a flame-ionization detector (GC-FID, Thermo Scientific), with hydrogen as vector gas, and a DB-HeavyWAX column (30 m × 0.25 mm ID x 0.2 µm). FAME were identified by comparing samples retention time to a mix of commercial standards (Supelco 37 component FAME, PUFA1 and PUFA3, Sigma Aldrich) using Chromeleon 7.2 software. Twenty-six FAME with contributions >0.5 % of total fatty acids were kept for data analysis. All fatty acid concentrations were computed based on the internal standard recovery and were expressed in µg.mg⁻¹ dry weight (dw).

## 2.5. Vitamin A

Vitamin A is a generic term for compounds that possess the biological activity of retinol and include two isomers, vitamin A₁ (retinol) and A₂ (3,4-didehydroretinol, with 120 % of the biological activity of vitamin

A₁) (Blomhoff & Blomhoff, 2006). Vitamins A₁ and A₂ contents were determined using a modified method from Moxness Reksten et al. (2020). They were extracted three times from approximately 1.25 mg of fresh-frozen muscle with 4 mL of ethanol with 0.1 % pyrogallol and 0.1 % BHT. After evaporation to approximately 4 mL, extracts were saponified with 0.5 mL of KOH 20 % and 0.5 mL of saturated EDTA heated in a water bath for 40 min at 80 °C. Free vitamins A₁ and A₂ were then extracted in hexane: samples were rinsed 3 times with 2.4 mL of hexane and 3 mL of distilled water saturated with hexane, recovered into new glass vials then evaporated until dryness. Samples were recovered in methanol and transferred in amber glass vials after filtration on a 0.22 µm PVDF membrane. Samples (100 µL) were analyzed with HPLC with a Dionex Ultimate 3000 UHPLC system (Thermo Scientific, Germany) equipped with a C18 column (RP-18e Lichrospher, 250 × 4.2 mm, 5 µm) with an isocratic mobile phase of 95 % methanol and 5 % milliQ water (flow rate: 0.8 mL min⁻¹). The column temperature was set at 25 ± 1 °C and the injector temperature at 5 ± 1 °C. Chromatograms were recorded with a UV-vis photodiode array detector at 325 nm (A₁) and 350 nm (A₂). External calibration was achieved with 8 solutions of all-trans-retinol 95 % in methanol in the range of 0.5–25 mg.L⁻¹. LOD was computed as 9 times the relative standard deviation of the less concentrated quantifiable standard. Vitamins concentrations were determined with integration of chromatograms with Chromeleon 7.10 software and expressed in µg.100 g⁻¹ dw after conversion from wet weight using moisture.

## 2.6. Polycyclic aromatic hydrocarbons

PAHs were determined using the method described by Lacroix et al. (2014). The concentrations of twenty-four PAHs (list with abbreviations in Table S1) were determined using stir-bar sorptive extraction–thermal desorption–gas chromatography–tandem mass spectrometry at the CEDRE laboratory, Brest, France. Extraction was performed from 2 g of fresh muscle with 10 mL of an ethanolic solution with KOH. Samples were digested for 3 h at 80 °C before addition of 100 mL of reverse osmosis water (ROW) (Merck Millipore, Darmstadt, Germany). Bars coated with liquid polydimethylsiloxane sorbent phase were placed in the solution and stirred at 700 rpm for 2 h, then rinsed with ROW and dried. PAHs were thermodesorbed at 280 °C for 5 min and cryofocused at 10 °C. Quantification of PAHs was performed in duplicate, using a gas chromatograph system Agilent 7890A coupled to an Agilent 7000 triple quadrupole mass spectrometer (Agilent Technologies, Little Falls, USA). Analytes were analyzed using MassHunter software. LOQ were calculated as 10*S/b, where S is the standard deviation of the response and b is the slope of the calibration curve (Shrivastava & Gupta, 2011) and LOD were estimated by dividing LOQ by 3 (Table S1).

## 2.7. Data analysis

### 2.7.1. Changes in nutrient and contaminant concentrations during the smoking process

For statistical analysis purposes, non-detected (<LOD) and non-quantifiable (<LOQ) compounds were replaced with half of their respective values. All compound concentrations were expressed on a dry weight basis in order to avoid the confounding effect of water loss induced by smoking on underlying processes (i.e. to detect concentration changes due to degradation or contamination). However, health benefits and risks were calculated on a wet weight basis (raw weight after smoking) in order to assess the consumption of smoked fish as experienced by consumers. Differences in mean concentrations among fresh fish and smoked fish with one, two or three smoking cycles were tested by one-way ANOVA followed by Tukey's HSD test whenever applicable (normal and homogeneous residual distributions, tested with Shapiro and Bartlett tests), or with Kruskall-Wallis non-parametric test, followed by Dunn test with a Bonferroni adjustment (non-normal and/or non-homogeneous residuals). Correlations among compounds were
computed using Spearman correlation rank test. All calculation was realized using Rstudio software (version 4.4.3). Statistical significance was set at p < 0.05.

### 2.7.2. Assessment of health benefits

Trace elements were classified as nutrients (Ca, Co, Cu, Fe, Mg, Mn, Na, Se, Zn), others (Mo, Sr) or contaminants (Cd, As, Pb). To assess the contribution of fish consumption to nutritional requirements, covered percentage of Recommended Daily Allowances (% covered RDA) were computed for nutrients at each smoking cycle. The portion size, estimated as the Daily Fish consumption (DFC), was calculated as 0.0852 kg/d based on annual per capita fish consumption of 31.1 kg in Gabon in 2021 (FAO, 2021). RDA values were taken from the National Institutes of Health of the U.S.A. (National Institutes of Health, Office of Dietary Supplements, 2025) (Table S4).

### 2.7.3. Assessment of health risk

Four indicators were calculated to estimate the health risks associated with the consumption of *E. fimbriata* during the smoking process.

* The benzo-a-pyrene (B(a)P) is a PAH used as a marker of occurrence and effects of carcinogenic PAHs in food (Rey-Salgueiro et al., 2009). To evaluate its toxicity, Nisbet and LaGoy (1992) have developed a toxic equivalent factor (TEF) relative to B(a)P for each of the 16 U.S. EPA PAHs. The B(a)P Toxic Equivalent (TEQ, mg.kg⁻¹) was calculated as follow:

$$TEQ = \sum_{16PAH}^{i} C_i \times TEF_i$$

where $\sum_{16PAH}^{i}$ is the sum of the concentrations of the 16 PAHs ($C_i$ in mg. kg⁻¹) and $TEF_i$ is the Toxic Equivalent Factor of the compound i relative to B(a)P.

* The Excess Cancer Risk (ECR, dimensionless) was calculated using the following equation:

$$ECR = \frac{\sum_{16PAH}^{i} Q \times (C_i \times TEF_i) \times DFC \times ED}{body weight \times ED \times EFr}$$

where Q is the carcinogenic potency of B(a)P, calculated using the U.S. EPA's integrating risk information system at 7.3 mg kg⁻¹.d⁻¹ (Han et al., 2010; Yoon et al., 2007). The exposure duration (ED) is fixed at 65.1 years, with regards to the average lifetime of 65.1 years in Gabon (WHO, 2021). DFC was set as 0.0852 kg/d (FAO, 2021). The body weight of an adult man is considered 70 kg, as used by the WHO (2010). The exposure frequency (EFr) refers to the number of days in a year (365.25 days for a daily consumption). According to the U.S. EPA, a lifetime ECR of one in a million (10⁻⁶) over a 65.1-year lifespan is considered acceptable. In contrast, an ECR of one in ten thousand (10⁻⁴) or higher is considered as serious.

* The PAH4 is the sum of four single PAH according to the following equation:

$$PAH4 = B(a)P + B(a)A + CH + B(b)F$$

where B(a)P is the benzo-a-pyrene, B(a)A the benzo-a-anthracene, CH the chrysene and the B(b)F the benzo-b-fluoranthene.

* The Target Hazard Quotient (THQ, dimensionless) was calculated for each trace metal j as follow:

$$THQ_j = \frac{EFr \times ED \times DFC \times C_j}{RFD_j \times body weight \times ED \times EFr}$$

where $C_j$ is the trace element j concentration (µg.g⁻¹) and $RFD_j$ is the oral reference dose of trace element j (mg.kg⁻¹.d⁻¹) taken from the U.S. EPA (US EPA, 2013) (Table S4). THQ index for arsenic was calculated assuming 3 % of total arsenic is the toxic fraction of arsenic in fish, i.e. inorganic arsenic iAs (Copat et al., 2013).

* The Total Target Hazard Quotient (TTHQ, dimensionless) is the cumulative risk of trace metals contamination in fish and was calculated as follow (Chien et al., 2002; Fan et al., 2025):

$$TTHQ = THQ_{Cd} + THQ_{Co} + THQ_{Cu} + THQ_{Fe} + THQ_{Mn} + THQ_{iAs} + THQ_{Zn} + THQ_{Pb}$$

## 3. Results

### 3.1. Moisture

As smoking induced gradual water loss via evaporation, moisture decreased from 72 % to 42 % throughout smoking cycles (Table S3).

### 3.2. Trace element composition

Smoking did not affect As concentrations (2.8 ± 0.7 µg.g⁻¹ dw) but induced Cd contamination, with values below the detection limits in fresh fish that progressively increased to a maximum of 0.003 ± 0.001 µg.g⁻¹ dw after three smoking cycles (Dunn, p < 0.05) (Fig. 2). Pb concentration decreased by a factor of six between fresh fish (0.011 ± 0.005 µg.g⁻¹ dw) and after three smoking cycles (0.002 ± 0.002 µg.g⁻¹ dw) (Tukey HSD, p < 0.05). Ca, Mn, and Mg concentrations decreased throughout the smoking process (respectively for Ca from 6443 ± 2297 to 1475 ± 1141 µg.g⁻¹ dw, for Mn from 4.8 ± 1.4 to 1.3 ± 1.0 µg.g⁻¹ dw and for Mg from 2222 ± 225 to 1532 ± 154 µg.g⁻¹ dw) (Fig. 2). The strongest decrease happened between fresh and three smoking cycles (respectively by a factor of 4.5, 3.5, and 1.5). Zn (21.1 ± 3.0 µg.g⁻¹ dw) and Se (2.6 ± 0.5 µg.g⁻¹ dw) concentrations were not affected by smoking, and Fe concentrations varied throughout the smoking process (Tukey HSD, p < 0.05), with no clear trend (coefficient of variation = 300 %) (Fig. 2). Co tended to increase during the first smoking cycle (Dunn p < 0.05) but not thereafter. Sr concentrations decreased by four after three smoking cycles (from 14.3 ± 5.0 to 3.7 ± 3.0 µg.g⁻¹ dw, Tuckey HSD, p < 0.05), and Mo showed the strongest increase among smoking cycles, with concentrations 40 times higher and exceeding 0.4 mg kg⁻¹ after three smoking cycles (Dunn, p < 0.001) (Fig. 2). Finally, deterioration of major trace elements during smoking followed this order: Ca > Sr > Mn > Mg (−77 %, −74 %, −73 % and −31 % respectively). Table S3 contains all concentrations and statistical results of comparisons.

### 3.3. Fatty acids

The total fatty acids content in the muscle of *E. fimbriata* ranged from 18 to 257 µg.mg⁻¹. Polyunsaturated Fatty Acids (PUFA) were the most concentrated (9–88 µg.mg⁻¹) followed by Monounsaturated Fatty Acids (2–56 µg.mg⁻¹) and Saturated Fatty Acids (2–39 µg.mg⁻¹), regardless of the number of smoking cycles. The smoking process did not affect total fatty acids concentrations in *E. fimbriata* (Tuckey HSD, p = 0.06), which was highly variable among fish regardless of the processing step (coefficient of variation = 125 %, Fig. 3).

EPA+DHA, omega-3 and PUFA concentrations did not differ among smoking conditions. However, their relative proportions (% of total fatty acids) decreased by an average of 8 % between fresh and smoked fish (p < 0.05, p < 0.05 and p < 0.01, respectively), but remained similar among the three smoking cycles.

For a fish portion of 85.2 g, smoked fish covered a higher proportion of the RDA for EPA+DHA than fresh fish (5–88 % and 7–22 % respectively, Table S2) as the smoking process induce water loss, which
Concentration (µg.g⁻¹ dw)

<figure><img src="image_4.png" /><figcaption>**Fig. 2.** Trace element concentrations (in µg.g⁻¹ dw) throughout smoking process in muscle of *E. fimbriata*. Different letters indicate differences in post-hoc comparisons. Trace element without letters indicate no differences in trace elements concentrations.</figcaption></figure>
concentrated the fatty acids.

## 3.4. Vitamin A

Vitamin A in fresh and smoked *E. fimbriata* ranged from 45 to 641 µg.100g⁻¹. Total vitamin A content decreased gradually throughout smoking cycles: it was on average 4.5 times lower at the end of the smoking process than in fresh fish (Tuckey HSD, *p* < 0.01, Table S3). The concentration of the vitamin A₂ decreased by a factor of 10 during smoking (i.e. between fresh fish and after 3 smoking cycles), while concentration of the vitamin A₁ decreased by a factor of 2.5. As a result, the vitamin A₁ accounted for 43 % of total vitamin A in fresh fish but for 80 % in smoked fish (Fig. 3).

However, the water loss induced by smoking didn't concentrated vitamin A enough to compensate this nutrient degradation by heat (smoked fish: 5-6%, fresh fish: 12-15 %, Table S2).

## 3.5. Polycyclic aromatic hydrocarbons

The total PAHs concentration in *E. fimbriata* ranged from 11.7 ± 6.9 ng.g⁻¹ dw to 498.8 ± 373.3 ng.g⁻¹ dw and increased by a factor of 42 between fresh and three smoking cycles fish (Dunn, *p* < 0.005) (Fig. 4).

PAHs with two rings were those whose concentrations increased the most during the smoking process (Fig. 4). Total PAHs concentration was not correlated with total fatty acid concentration (Spearman, *ρ* = 0.1, *ρ* = 0.3). Total PAHs concentration was the most variable among individuals after the first smoking cycle (coefficient of variation = 101 %), and still important after three smoking cycle (coefficient of variation = 59 %).

No fish exceeded PAHs or metals health risks indices except three smoking cycles fish, which display a mean TEQ > 2 µg.kg⁻¹ (2.5 ± 2.3 µg.kg⁻¹) (Table 1). One fish largely exceeded the PAH4 limit after three smoking cycles (33 µg.kg⁻¹), but the mean PAH4 index for fish after three smoking cycles is below the EFSA limit of 12 µg.kg⁻¹ (EFSA, 2023).

However, no samples exceeded EFSA limit of 2 µg.kg⁻¹ (EFSA, 2008) for B(a)P, nor the ECR (range: 3.3E-09 ± 1.4E-10 to 6.2E-08 ± 5.6E-08 < 1E-06) or the TTHQ (range: 0.13 ± 0.16 to 0.23 ± 0.19 < 1) (Table 1).

## 4. Discussion

Nutritional and toxicological assessment of *E. fimbriata* muscle composition throughout an artisanal smoking process revealed high inter-individual variability. Nutrients such as total fatty acids, Cu, Se

<figure><img src="image_5.png" /><figcaption>**Fig. 3.** Nutrient contents throughout smoking process in muscle of *E. fimbriata*. (A) Fatty acid concentrations (µg.g⁻¹ dw), (B) Fatty acid proportions (% of total fatty acids), (C) Vitamin A concentrations (A₁ and A₂ isomers; µg.100g⁻¹ dw). *n* = number of fish analyzed.</figcaption></figure>
<figure><img src="image_6.png" /><figcaption>Fig. 4. Concentration of polycyclic aromatic hydrocarbons (PAHs) during the smoking process in the muscle of *E. fimbriata* (geometric means). LMW = Low Molecular Weight, HMW = High Molecular Weight. Letters above the bar plots indicate significant differences in total PAHs concentrations.</figcaption></figure>

<caption>**Table 1**</caption>

Health risk indices in *E. fimbriata* muscle for fresh and smoked individuals, expressed as mean ± standard deviation wet weight. (n) is the number of samples exceeding the safety limits.

<table><thead><tr><th rowspan="2">Indices</th><th colspan="4">PAHs indices</th><th rowspan="2">Metals index</th></tr><tr><th>B(a)P</th><th>TEQ</th><th>ECR</th><th>PAH4</th><th>TTQH</th></tr></thead><tbody><tr><td>Unit</td><td>µg.kg<sup>-1</sup></td><td>µg.kg<sup>-1</sup></td><td>-</td><td>µg.kg<sup>-1</sup></td><td>-</td></tr><tr><td>Safety limits</td><td>2</td><td>2</td><td>1E-06</td><td>12</td><td>1</td></tr><tr><td rowspan="2">Fresh</td><td>0.04 ±</td><td>0.12 ±</td><td>3.3E-09 ±</td><td>0.0 ± 0.0</td><td>0.13 ±</td></tr><tr><td>0.00</td><td>0.01</td><td>1.4E-10</td><td></td><td>0.16</td></tr><tr><td rowspan="2">1 smoking cycle</td><td>0.44 ±</td><td>0.57 ±</td><td>1.4E-08 ±</td><td>3.3 ± 4.7</td><td>0.17 ±</td></tr><tr><td>0.65</td><td>0.53</td><td>1.3E-08</td><td></td><td>0.14</td></tr><tr><td rowspan="2">2 smoking cycles</td><td>0.20 ±</td><td>0.58 ±</td><td>1.4E-08 ±</td><td>0.8 ± 1.1</td><td>0.23 ±</td></tr><tr><td>0.22</td><td>0.30</td><td>7.4E-09</td><td></td><td>0.18</td></tr><tr><td rowspan="2">3 smoking cycles</td><td>0.59 ±</td><td>2.5<sup>(3)</sup> ±</td><td>6.2E-08 ±</td><td>7.7<sup>(1)</sup> ±</td><td>0.23 ±</td></tr><tr><td>0.76</td><td>2.3</td><td>5.6E-08</td><td>14.2</td><td>0.19</td></tr></tbody></table>

and Zn were not affected by smoking, whereas vitamin A, Ca, Mn and Mg were deteriorated. Mean PAHs and Cd contents increased during the smoking process without exceeding safety limits.

## 4.1. Inter-individual and fish smoking variability

One common feature between all analyzed compounds is the strong inter-individual variability between fish samples. This variability certainly result from the combined effects of biological variability and the variability of the smoking process itself on fish composition. The similar sizes of analyzed individuals (21.7 ± 1.2 cm in fork length) reflects the high degree of uniformity in body size in fish schools (Pavlov &

Kasumyan, 2000) and suggests that individual size does not contribute to observed variability. However *E. fimbriata* can breed all year in a wide variety of habitats (open sea, estuaries and rivers) (FAO, 1985). As muscle fat appear to be the primary energy reserve controlling maturity, especially for pelagic fish like clupeids (Cowey & Sargent, 1972), different maturity stages and sex distribution could have led to different fat content within a fish school. Several studies also highlighted pre-contamination of muscle tissue by PAHs through polluted waters (Pirsaheb et al., 2020).

The heterogeneity in nutrient and potential hazardous compounds concentrations in smoked fish can also be related to fish handling, or fish position on grills (discussed in “4.3. Contaminant and health risks” section). Although this strong intra-specific variability can mask specific processes associated with the smoking cycles, it reflects the variability of food composition, as consumed locally.

## 4.2. Nutrients and health benefits

### 4.2.1. Fatty acids, trace elements and vitamin A in *E. fimbriata*

Some nutrients and major trace elements are affected by the smoking process. As vitamin A₂ decrease by a factor of 10 with smoking, total vitamin A decrease by 84 % during smoking, which is comparable to the total vitamin A decrease of 94 % observed in smoked Siamese mud carp (Sroy et al., 2023).

Conversely, several essential elements such as total fatty acids, including EPA+DHA, vitamin A₁, Cu, Zn and Se concentrations are not affected by the smoking process. Fatty acid preservation had already been reported for species with different heat-based treatments, such as boiled and fried herring, sole and cod (Gladyshev et al., 2007). This tolerance suggests that smoking can be a valuable low-cost option to
preserve the nutritional qualities of seafood. Besides conservation, some of those compounds exhibit particularly high concentrations. Mean EPA+DHA concentrations in *E. fimbriata* (17 µg.mg⁻¹ dw) make it one of the richest species in omega-3 according to Gladyshev et al. (2018). Vitamin A₁ concentration in smoked *E. fimbriata* (100 µg.100g⁻¹ dw) is 10 times higher than in other processed marine species, such as round sardinella *Sardinella aurita* (11 µg.100g⁻¹ dw) and freshwater species such as tilapia *Tilapia* spp. (6 µg.100g⁻¹ dw), but lower than coastal brackish species such as African moonfish *Selene dorsalis* (324 µg.100g⁻¹ dw) (Hasselberg et al., 2020).

Interestingly, EPA+DHA, PUFA and omega-3 concentrations are not affected by smoking, while their relative proportions decreased (by 9 %, 7 % and 8 %, respectively). A decrease in PUFA proportion with smoking had also been observed in smoked zander fish (Bouriga et al., 2020). We suggest that the fatty acids analyzed in smoked fish muscle partly reflect subcutaneous fatty acid composition. Water loss during heat cooking treatment promotes the migration of subcutaneous and perivisceral lipids to the muscle, thereby increasing fat content in the fillets (Gall et al., 1983; Sardenne et al., 2021). This could indicate that subcutaneous and/or perivisceral fat exhibit a different fatty acid composition than muscle, with smaller concentrations of EPA+DHA, omega-3 and PUFA, as already suggested (Nichols et al., 1994; Weil et al., 2013), or that smoking induces selective migration of saturated and monounsaturated fatty acids from subcutaneous fat to the muscle (Puke & Galoburda, 2020).

### 4.2.2. Nutritional benefits of smoked *E. fimbriata* to Gabonese people

A smoked fish portion covers a significant proportion of EPA+DHA (5–88 %) and Se (263 %) recommended daily allowances (Table S2). *E. fimbriata*'s vitamin A content (439 µg.100g⁻¹ dw) is close to the high range of vitamin A concentration (500–1500 µg.100g⁻¹ dw) according to Roos et al. (2007). Vitamin A degradation during smoking reduced its mean contribution to RDA, with fresh fish consumption covering 12–15 % of RDA, and three smoking cycles fish covering 5–6 % of RDA. Despite degradation, both fresh and smoked fish remain good dietary sources of vitamin A, suggesting that their consumption can contribute to reduce vitamin A deficiency in Gabon. Women are especially vulnerable to vitamin A deficiency, as more than 20 % of pregnant women in Gabon are considered to be at severe risk, with serum retinol <0.7 µmol.L⁻¹ (World Health Organization, 2009). Na was the only essential element for which smoking quadrupled its contribution to RDA (3 % in fresh fish to 14 % in three smoking cycles fish). However, decreased concentrations of major macronutrients with smoking, such as Mn, Mg or Ca, highlight the variability of the smoking process on the different nutrients. This issue is more worrying for Ca, as sub-Saharan countries, including Gabon, still have a prevalence of inadequate Ca intake over 80 % (Beal et al., 2017).

## 4.3. Contaminants and health risks

### 4.3.1. PAHs and toxic metals in *E. fimbriata*

Smoking is a vector of PAHs and Cd in fish, but has no effect on As concentration and induces a decrease in Pb concentration. High individual variability in total PAHs content is suspected to originate from fish disposition on grills, as well as fish surface deterioration. Fats dripping onto hot coals produce PAHs that are transferred to the fish skin (Lijinsky & Shubik, 1964), which acts as a physical barrier against PAHs penetration into the fish muscle (Duedahl-Olesen et al., 2010). Thereby, damaged skin can offer an easy pathway for PAHs to enter fish muscle. Three cycles smoked fish are the most PAHs contaminated fish (16 U.S. EPA PAHs of 349 ng.g⁻¹ dw) but still present on average half as much PAHs as smoked *Sardinella aurita* from Ghana (891 ng.g⁻¹ dw) (Essumang et al., 2013) or from Nigeria (740 ng.g⁻¹ dw) (Iwegbue et al., 2020). However, *E. fimbriata* processed in local drum kilns in Nigeria is 4.2 times less contaminated (82 ng.g⁻¹ dw) (Adeyeye et al., 2016). Cd concentrations in fresh individuals all fall below the detection limit, as

for other small pelagic fish in the Gulf of Guinea (Botwe, 2021), but are twenty times lower than fresh *E. fimbriata* from Nigeria (Ibanga et al., 2020). Arsenic (As) concentrations in *E. fimbriata* (2.8 µg.g⁻¹ dw) is 55 times higher than in the same species smoked in Cameroon (0.05 µg.g⁻¹ dw) (Manzkoule et al., 2024). Finally, *E. fimbriata* is also less contaminated with toxic metals than freshwater species from Gabon (Mikala Okouyi et al., 2024)

### 4.3.2. Health risks for consumers of smoked *E. fimbriata*

PAHs concentrations in fish are below safety limits for B(a)P, PAH4 and ECR, but exceed the safety limits of 2 µg.kg⁻¹ for TEQ after three smoking cycles, i.e. 72 h (2.5 ± 2.3 µg.kg⁻¹). The high variation after three smoking cycles fish indicates substantial inter-individual variability and reflects that the heterogeneity of the smoking process may result in acute toxicity in fish muscle. However, chronic risk assessment (ECR for PAHs and TTHQ for metals) indicates no significant lifetime health risk from smoked fish consumption.

Neither of the toxic metals (As, Cd and Pb) exceed their respective maximum tolerable levels nor the upper limit for TTHQ. Consumption of 85.2 g of fish (daily fish consumption in Gabon) corresponds to the ingestion of 7.1 µg of the toxic form of arsenic inorganic arsenic (iAs), which is below the safety limits for a 70 kg man, i.e. 0.06µg.kg⁻¹ of body weight per day (EFSA, 2024). Cd concentration in three smoking cycles fish (0.0016 µg.g⁻¹ ww, after conversion from dw) does not exceed the EFSA maximum limit of 0.050 µg.g⁻¹ ww for fish (Novakov et al., 2017). European regulations do not set strict safety limits for the Pb concentration in smoked fish (CE N°1881/2006) but decreasing concentrations of Pb with smoking suppose a nonhazardous consumption of smoked fish regarding Pb. However, to our knowledge, no assessment has been conducted on the potential cumulative or cocktail effects of trace metals and PAHs mixtures in smoked fish or other foods, although such evaluations would be crucial for a more relevant assessment of toxicological risks.

The assessment of contaminants indicated a safe consumption of *E. fimbriata* as smoked in the way studied here in Gabon, which seems virtuous compared to other observations (Aborisade et al., 2023; Diop et al., 2023). This is probably because artisanal smoking is not a standardized process (Iko Afé et al., 2021). For example, differences in smoked fish composition are induced by smoking parameters such as wood type (Essumang et al., 2013), smoking temperature and duration (Savin et al., 2024; Sérot et al., 2009), or smoking practices: in some regions, fish is smoked over open flames that char it (see Fig. S5). Our study, however, suggests that artisanal smoking of fish is not necessarily a major source of contamination, provided it is carried out under the right conditions, particularly avoiding direct contact with flames and ensuring that the fish skin remains intact (Duedahl-Olesen et al., 2010). The long-term storage of smoked fish on nutrients concentrations prior to consumption still need to be assessed.

## 5. Conclusion

We analyzed the nutritional and toxicological composition of a small pelagic fish during an artisanal smoking process to evaluate changes in fatty acids, trace elements, vitamin A and PAHs concentrations. High variability among individuals reflects the reality of available seafood. *E. fimbriata* is an important source of vitamin A, and vitamin A₁ is more stable than vitamin A₂ during smoking. Smoking also induce the formation of PAHs, and increase Cd concentration. However, the concentrations of hazardous compounds remained within safety limits (PAH4 < 12 and TTHQ <1), suggesting that artisanal smoking is not a major source of contamination when done under the right conditions. However the variability of the smoking process, especially skin deterioration, can lead in acute toxicity in some individuals (TEQ). To further enhance consumer safety, dietary recommendations would advise ensuring fish skin integrity in order to reduce flesh contamination. Comparisons of nutritional and toxicological profiles of commonly consumed seafood
such as bivalves, or other processing methods such as boiling or frying would help assessing relevant benefits-risks balances associated to their consumption.

## CRediT authorship contribution statement

**Alice Guillot:** Writing – original draft, Visualization, Investigation, Formal analysis, Data curation, Conceptualization. **Rose Ngo Tona:** Investigation. **Solène Connan:** Validation, Methodology. **Marie-Laure Rouget:** Validation, Methodology. **Justine Receveur:** Validation, Methodology, Formal analysis. **Gaël Le Croizier:** Resources, Investigation. **François Le Loc'h:** Resources, Funding acquisition. **Manon Buscaglia:** Validation, Formal analysis. **Jean-Marie Munaron:** Methodology, Formal analysis, Data curation. **Nestor Ngoua Aba'a:** Investigation. **Sylvain Petek:** Methodology, Investigation. **Anne Lorrain:** Investigation. **Gauthier Schaal:** Writing – review & editing, Validation, Supervision, Funding acquisition, Conceptualization. **Fany Sardenne:** Writing – review & editing, Validation, Supervision, Project administration, Methodology, Funding acquisition, Conceptualization.

## Funding

This work is part of AG's doctoral thesis, supported by a grant from the *Ecole Doctorale des Sciences de la Mer*, University of Brest, France. We acknowledge the French *Institut de Recherche pour le Développement* and the scientific advisory board of Institut Universitaire Européen de la Mer (IUEM) for their funding support.

## 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.

## Acknowledgement

We would like to thank all the fishermen and women processors from Bac Aviation in Libreville, Gabon for their welcome, their help and explanations about the smoking process. We are grateful for Laboratoire d'Hydrobiologie et d'Ichyologie (LHI) from CENAREST/IRAF, Libreville, Gabon, for their workplace. We also thank the Lipidocean and the Pôle Spectrométrie Ocean (PSO) core facilities and the ECOM technical platform, IUEM, University of Brest, France, that enabled us to carry out this work.

## Appendix A. Supplementary data

Supplementary data to this article can be found online at https://doi.org/10.1016/j.foodcont.2025.111643.

## Data availability

All data are provided in the supplementary material

## References

Aakre, I., Bøkevoll, A., Chaira, J., Bouthir, F. Z., Frantzen, S., Kausland, A., & Kjellevold, M. (2020). Variation in nutrient composition of seafood from North West Africa: Implications for food and nutrition security. *Foods*, 9(10), 1516. https://doi.org/10.3390/foods9101516

Aborisade, A. B., Adetutu, A., & Adegbola, P. I. (2023). Polycyclic aromatic hydrocarbons distribution in fish tissues and human health risk assessment on consumption of four fish species collected from Lagos Lagoon, Nigeria. *Environmental Science and Pollution Research*, 30(58), 122740-122754. https://doi.org/10.1007/s11356-023-30954-2

Adeyeye, S. A. O. (2019). Smoking of fish: A critical review. *Journal of Culinary Science & Technology*, 17(6), 559-575. https://doi.org/10.1080/15428052.2018.1495590

Adeyeye, S. A. O., & Oyewole, O. B. (2016). An overview of traditional fish smoking in Africa. *Journal of Culinary Science & Technology*, 14(3), 198-215. https://doi.org/10.1080/15428052.2015.1102785

Adeyeye, S. A. O., Oyewole, O. B., Obadina, O., Adeniran, O. E., Oyedele, H. A., Olugbile, A., & Omemu, A. M. (2016). Effect of smoking methods on microbial safety, polycyclic aromatic hydrocarbon, and heavy metal concentrations of traditional smoked fish from Lagos State, Nigeria. *Journal of Culinary Science & Technology*, 14(2), 91-106. https://doi.org/10.1080/15428052.2015.1080644

Beal, T., Massiot, E., Arsenault, J. E., Smith, M. R., & Hijmans, R. J. (2017). Global trends in dietary micronutrient supplies and estimated prevalence of inadequate intakes. *PLoS One*, 12(4), Article e0175554. https://doi.org/10.1371/journal.pone.0175554

Blomhoff, R., & Blomhoff, H. K. (2006). Overview of retinoid metabolism and function. *Journal of Neurobiology*, 66(7), 606-630. https://doi.org/10.1002/neu.20242

Botwe, B. O. (2021). Heavy metal concentrations in five fish species from the Gulf of Guinea and their human health implications. *Regional Studies in Marine Science*, 44, Article 101763. https://doi.org/10.1016/j.rsma.2021.101763

Bouriga, N., Bejaoui, S., Jemmali, B., Quignard, J. P., & Trabelsi, M. (2020). Effects of smoking processes on the nutritional value and fatty acid composition of Zander fish (*Sander luciopera*). *Grasas Y Aceites*, 71(1), Article 1. https://doi.org/10.3989/gya.1061182

Chien, L.-C., Hung, T.-C., Choang, K.-Y., Yeh, C.-Y., Meng, P.-J., Shieh, M.-J., & Han, B.-C. (2002). Daily intake of TBT, Cu, Zn, Cd and as for fishermen in Taiwan. *Science of The Total Environment*, 285(1-3), 177-185. https://doi.org/10.1016/S0048-9697(01)00916-0

Chittchang, U., Jittinandana, S., Sungpuag, P., Chavasit, V., & Wasantwisut, E. (1999). Recommending vitamin A-rich foods in southern Thailand. *Food and Nutrition Bulletin*, 20(2), 238-242. https://doi.org/10.1177/156482659902000210

Clucas. (1981). *Fish handling, preservation and processing in the tropics: Part 1*. https://agri.s.fao.org/search/en/providers/123819/records/64735fa008fd68d546038c40.

Copat, C., Arena, G., Fiore, M., Ledda, C., Fallico, R., Sciacca, S., & Ferrante, M. (2013). Heavy metals concentrations in fish and shellfish from eastern Mediterranean Sea: Consumption advisories. *Food and Chemical Toxicology*, 53, 33-37. https://doi.org/10.1016/j.fct.2012.11.038

Cowey, C. B., & Sargent, J. R. (1972). Fish nutrition. In *Advances in marine biology* (Vol. 10, pp. 383-394). Elsevier. https://doi.org/10.1016/S0065-2881(08)064019-8

Dème, B., hadj, E., & Failler, P. (2024). Small Pelagics in West Africa face the multiple challenges of food security, wealth creation and regional governance. *Marine Policy*, 170, Article 106374. https://doi.org/10.1016/j.marpol.2024.106374

Diop, E. H. M., Ndiaye, B., Sow, A., Sambe, F. M., Sall, M., & Thiam, M. S. (2023). Polycyclic Aromatic Hydrocarbon (PAH) contents of four species of smoked fish from different sites in Senegal. *International Journal of Analytical Chemistry*, 2023(1), Article 2931615. https://doi.org/10.1155/2023/2931615

Doumambila-Bantsantsa, J., Mbokou, R., Maloueki, L., Sousa, A., & Fréon, P. (2000). *Ethmalosa fimbriata*. In *Report of the workshop on the small pelagic resources of Angola, Congo and Gabon* (Vol 618, pp. 146-147). FAO Fisheries Reports.

Duedahl-Olesen, L., Christensen, J. H., Højgård, A., Granby, K., & Timm-Heinrich, M. (2010). Influence of smoking parameters on the concentration of polycyclic aromatic hydrocarbons (PAHs) in Danish smoked fish. *Food Additives & Contaminants: Part A*, 27(9), 1294-1305. https://doi.org/10.1080/19440049.2010.487074

Essumang, D. K., Dodoo, D. K., & Adjei, J. K. (2013). Effect of smoke generation sources and smoke curing duration on the levels of polycyclic aromatic hydrocarbon (PAH) in different suites of fish. *Food and Chemical Toxicology*, 58, 86-94. https://doi.org/10.1016/j.fct.2013.04.014

Etchie, A. T., Etchie, T. O., Elemile, O. O., Boladale, O., Oni, T., Akanno, I., Bankole, D. T., Ibitoye, O. O., Pillarisetti, A., Sivanesan, S., AfoLABI, T. Y., Krishnamurthi, K., & Swaminathan, N. (2020). Burn to kill: Wood ash a silent killer in Africa. *Science of The Total Environment*, 748, Article 141316. https://doi.org/10.1016/j.scitotenv.2020.141316

European Food Safety Authority. (2008). Polycyclic aromatic hydrocarbons in food—scientific opinion of the panel on contaminants in the food chain. *EFSA Journal*, 6(8), 724. https://doi.org/10.2903/j.efsa.2008.724

Failler, P. (2014). Climate variability and food security in Africa: The case of small pelagic fish in West Africa. *Journal of Fisheries & Livestock Production*, 2(2). https://doi.org/10.4172/2332-2608.1000122

Fan, W., Li, W., Hu, H., Yan, Y., Ding, X., Luo, Y., & Tang, L. (2025). Trace elements contamination in fish and human health risks from the upper reaches of the Pearl River Basin. *Marine Pollution Bulletin*, 213, Article 117659. https://doi.org/10.1016/j.marpolbul.2025.117659

FAO. (1985). FAO species catalogue (Vol. 7). *Clupeoid fishes of the world (Suborder Clupeoidei)*. An annotated and illustrated catalogue of the herrings, sardines, pilchards, sprats, shads, anchovies and wolf-herrings. Part 1. *Chirocentridae, Clupeidae & Pristigasteridae* https://openknowledge.fao.org/items/0d0c79b9-7fa7-4d84-932d-1d1686178d10.

FAO. FAO Yearbook. *Fishery and Aquaculture Statistics 2019/FAO annuário. Estadísticos de pesca e de l'aquacultura 2019*. Rome/Roma. https://doi.org/10.4060/cb7874t.

Folch, J., Lees, M., & Stanley, G. H. S. (1957). A simple method for the isolation and purification of total lipides from animal tissues. *Journal of Biological Chemistry*, 226(1), 497-509. https://doi.org/10.1016/S0021-9258(18)64849-5

Friedman, M. (1996). Food browning and its prevention: An overview. *Journal of Agricultural and Food Chemistry*, 44(3), 631-653. https://doi.org/10.1021/jf950394r

Gall, K. L., Otwell, W. S., Koburgier, J. A., & Appledorf, H. (1983). Effects of four cooking methods on the proximate, mineral and fatty acid composition of fish fillets. *Journal of Food Science*, 48(4), 1068-1074. https://doi.org/10.1111/j.1365-2621.1983.tb09163.x

Gladyshev, M. I., Sushchik, N. N., Gubanenko, G. A., Demirchieva, S. M., & Kalachova, G. S. (2007). Effect of boiling and frying on the content of essential polyunsaturated fatty acids in muscle tissue of four fish species. *Food Chemistry*, 101(4), 1694-1700. https://doi.org/10.1016/j.foodchem.2006.04.029
Gladyshev, M. I., Sushchik, N. N., Tolomeev, A. P., & Dgebuadze, Y. Y. (2018). Meta-analysis of factors associated with omega-3 fatty acid contents of wild fish. *Reviews in Fish Biology and Fisheries*, 28(2), 277–299. https://doi.org/10.1007/s11160-017-9511-0

Han, Y., Xia, Y., Zhu, P., Qiao, S., Zhao, R., Jin, N., Wang, S., Song, L., Fu, G., & Wang, X. (2010). Reproductive hormones in relation to polycyclic aromatic hydrocarbon (PAH) metabolites among non-occupational exposure of males. *Science of The Total Environment*, 408(4), 768–773. https://doi.org/10.1016/j.scitotenv.2009.11.021

Hasselberg, A. E., Nostbakken, O. J., Akre, I., Madsen, L., Atter, A., Steiner-Asiedu, M., & Kjellevold, M. (2022). Nutrient and contaminant exposure from smoked European anchovy (*Engraulis encrasicolus*): Implications for children's health in Ghana. *Food Control*, 134, Article 108650. https://doi.org/10.1016/j.foodcont.2021.108650

Hasselberg, A. E., Wessels, L., Aakre, I., Reich, F., Atter, A., Steiner-Asiedu, M., Amponsah, S., Pucher, J., & Kjellevold, M. (2020). Composition of nutrients, heavy metals, polycyclic aromatic hydrocarbons and microbiological quality in processed small indigenous fish species from Ghana: Implications for food security. *PLoS One*, 15(11), Article e0242086. https://doi.org/10.1371/journal.pone.0242086

Hicks, C. C., Cohen, P. J., Graham, N. A. J., Nash, K. L., Allison, E. H., D'Lima, C., Mills, D. J., Roscher, M., Thilsted, S. H., Thorne-Lyman, A. L., & MacNeil, M. A. (2019). Harnessing global fisheries to tackle micronutrient deficiencies. *Nature*, 574 (7776), 95–98. https://doi.org/10.1038/s41586-019-1592-6

Ibanga, I. J., Moses, E. A., Edet, E. J., & Moses, A. E. (2020). Microbial and some heavy metals analysis of smoked fishes sold in urban and rural markets in Akwa Ibom State, Nigeria. *Calabar Journal of Health Sciences*, 3, 73–79. https://doi.org/10.25259/CJHS_15_2019

Idah, & Nwankwo. (2013). Effects of smoke-drying temperatures and time on physical and nutritional quality parameters of Tilapia. *African Journal of Agricultural Economics and Rural Development*.

Iko Afé, O. H., Kpoclou, Y. E., Douny, C., Anihouvi, V. B., Igout, A., Mahillon, J., Hounhouigan, D. J., & Scippo, M. (2021). Chemical hazards in smoked meat and fish. *Food Science and Nutrition*, 9(12), 6903–6922. https://doi.org/10.1002/fns3.2633

Iwegbue, C. M. A., Odogbor, D., Egobueze, F. E., Emoyan, O. O., Tesi, G. O., Odali, E. W., Nwajei, G. E., & Martinchig, B. S. (2020). Polycyclic aromatic hydrocarbons in smoked *Ethmalosa fimbriata* and *Gymnarchus niloticus* from selected fish markets in the Niger Delta, Nigeria. *Polycyclic Aromatic Compounds*, 40(5), 1367–1380. https://doi.org/10.1080/10406638.2018.1550794

Kafeelah, A. Y., Lucy, N. E., Kafayat, A. F., Shehu, L. A., Julius, I. A., & Titus, O. O. (2015). Influence of fish smoking methods on polycyclic aromatic hydrocarbons content and possible risks to human health. *African Journal of Food Science*, 9(3), 126–135. https://doi.org/10.5897/AJFS2014.1227

Kawarazuka, N., & Béné, C. (2011). The potential role of small fish species in improving micronutrient deficiencies in developing countries: Building evidence. *Public Health Nutrition*, 14(11), 1927–1938. https://doi.org/10.1017/S1368980011000814

Kiczorowska, B., Samolińska, W., Grela, E. R., & Bik-Małodzińska, M. (2019). Nutrient and mineral profile of chosen fresh and smoked fish. *Nutrients*, 11(7). https://doi.org/10.3390/nut11071448. Article 7.

Kumssa, D. B., Joy, E. J. M., Ander, E. L., Watts, M. J., Young, S. D., Walker, S., & Broadley, M. R. (2015). Dietary calcium and zinc deficiency risks are decreasing but remain prevalent. *Scientific Reports*, 5(1), Article 10974. https://doi.org/10.1038/srep10974

Lacroix, C., Le Cuff, N., Receveur, J., Moraga, D., Auffret, M., & Guyomarch, J. (2014). Development of an innovative and “green” stir bar sorptive extraction–thermal desorption–gas chromatography–tandem mass spectrometry method for quantification of polycyclic aromatic hydrocarbons in marine biota. *Journal of Chromatography A*, 1349, 1–10. https://doi.org/10.1016/j.jchroma.2014.04.094

Lijinsky, W., & Shubik, P. (1964). Benzo(a)pyrene and other polynuclear hydrocarbons in charcoal-broiled meat. *Science*, 145(3627), 53–55. https://doi.org/10.1126/science.145.3627.53

Mahugija, J. A. M., & Njale, E. (2018). Levels of polycyclic aromatic hydrocarbons (PAHs) in smoked and sun-dried fish samples from areas in Lake Victoria in Mwanza, Tanzania. *Journal of Food Composition and Analysis*, 73, 39–46. https://doi.org/10.1016/j.jfca.2018.07.010

Manzkoule, J. C., Mathieu, N., Marlène, Y. T., Valery Jean François, N., Merlin, N. N., & Inocent, G. (2024). Assessment of cooking methods and freezing on the nutritional value and health risks of heavy metals in four fish species consumed in Doula, Cameroon. *Helyon*, 10(7), Article e28316. https://doi.org/10.1016/j.heliyon.2024.e28316

Mikala Okouyi, C., Kamdem, M. M., Voua Otomo, P., & Maganga, G. D. (2024). Metal accumulation in fish species of a vast hydrographic network in the Moyen-Ogooué and Haut-Ogooué Provinces of Gabon: Implications for human health. *Toxicology Reports*, 13, 101842. https://doi.org/10.1016/j.toxrep.2024.101842

Moxness Reksten, A., Joao Correia Victor, A. M., Baptista Nascimento Neves, E., Myhre Christiansen, S., Ahern, M., Uzomah, A., Lundebye, A.-K., Kolding, J., & Kjellevold, M. (2020). Nutrient and chemical contaminant levels in five marine fish species from Angola—The EAF-Nansen Programme. *Foods*, 9(5), 629. https://doi.org/10.3390/foods9050629

National Institutes of Health, Office of Dietary Supplements. (2025). Office of dietary supplements—nutrient recommendations and databases. https://ods.nih.gov/HealthInformation/nutrientrecommendations.aspx

Nichols, D. S., Williams, D., Dunstan, G. A., Nichols, P. D., & Volkman, J. K. (1994). Fatty acid composition of Antarctic and temperate fish of commercial interest. *Comparative Biochemistry and Physiology Part B: Comparative Biochemistry*, 107(2), 357–363. https://doi.org/10.1016/0305-0491(94)90059-0

Nisbet, I. C. T., & LaGoy, P. K. (1992). Toxic equivalency factors (TEFs) for polycyclic aromatic hydrocarbons (PAHs). *Regulatory Toxicology and Pharmacology*, 16(3), 290–300. https://doi.org/10.1016/0273-2300(92)90009-X

Novakov, N. J., Mihaljev, Ž. A., Kartalović, B. D., Blagojević, B. J., Petrović, J. M., Cirković, M. A., & Rogan, D. R. (2017). Heavy metals and PAHs in canned fish supplies on the Serbian market. *Food Additives and Contaminants: Part B*, 10(3), 208–215. https://doi.org/10.1080/19393210.2017.1322150

Okon, E. M., Okocha, R. C., Folowosele, D. O., Oluwafemi, P. T., & Falana, B. M. (2024). Aquatic food resources in tropical Africa: A comprehensive analysis. *Frontiers in Sustainable Food Systems, 8*, Article 1252119. https://doi.org/10.3389/fsufs.2024.1252119

Olopade, A. O., Dienye, H. E., Denson, G. C., & Onyekwe, V. C. (2023). EFFECTS OF SMOKING PROCESSES ON THE NUTRITIONAL VALUE OF CULTURED CATFISH (*Clarias Gariepinus*). *Food and Environment Safety Journal*, 22(1), Article 1. http://fens.usv.ro/index.php/FENS/article/view/956.

Pavlov, D. S., & Kasumyan, A. O. (2000). *Patterns and mechanisms of schooling behavior in fish: A review* (Vol. 40).

Pirsaheb, M., Irandost, M., Asadi, F., Fakhri, Y., & Asadi, A. (2020). Evaluation of polycyclic aromatic hydrocarbons (PAHs) in fish: A review and meta-analysis. *Toxin Reviews*, 39(3), 205–213. https://doi.org/10.1080/15569543.2018.1522643

Puke, S., & Galoburda, R. (2020). *Factors affecting smoked fish quality: A review* (Vols. 132–139). https://doi.org/10.22616/rrd.26.2020.020

Rey-Salgueiro, L., Martínez-Carballo, E., García-Falcón, M. S., González-Barreiro, C., & Simal-Gándara, J. (2009). Occurrence of polycyclic aromatic hydrocarbons and their hydroxylated metabolites in infant foods. *Food Chemistry*, 115(3), 814–819. https://doi.org/10.1016/j.foodchem.2008.12.095

Roos, N., Chamnan, C., Loeung, D., Jakobsen, J., & Thilsted, S. H. (2007). Freshwater fish as a dietary source of vitamin A in Cambodia. *Food Chemistry*, 103(4), 1104–1111. https://doi.org/10.1016/j.foodchem.2006.10.007

Sardenne, F., Puccinelli, E., Vagner, M., Pecquerie, L., Bideau, A., Le Grand, F., & Soudant, P. (2021). Post-mortem storage conditions and cooking methods affect long-chain omega-3 fatty acid content in Atlantic mackerel (*Scomber scombrus*). *Food Chemistry*, 359, Article 129828. https://doi.org/10.1016/j.foodchem.2021.129828

Savin, R.-L., Ladoşi, D., Ladoşi, I., Păpuc, T., Becze, A., Cadar, O., Torök, I., Simedru, D., Mariş, Ş. C., & Coroian, A. (2024). Influence of fish species and wood type on polycyclic aromatic hydrocarbons contamination in smoked fish meat. *Foods*, 13 (12). https://doi.org/10.3390/foods13121790. Article 12.

Sérot, T., Baron, R., Cardinal, M., Cataneo, C., Knockaert, C., Bizec, B. L., Prost, C., Monteau, F., & Varlet, V. (2009). *Evaluation des effets du processus de génération de la fumée et des paramètres de fumage sur la perception organoleptique, les niveaux des composés plus odorants et la teneur en HAP des fillets de saumon fumé*.

Shrivastava, A., & Gupta, V. (2013). Methods for the determination of limit of detection and limit of quantitation of the analytical methods. *Chronicles of Young Scientists*, 2 (1), 21. https://doi.org/10.4103/2229-5186.79345

Smith, G., & Hole, M. (1991). Browning of salted sun-dried fish. *Journal of the Science of Food and Agriculture*, 55(2), 291–301. https://doi.org/10.1002/jsfa.2740550214

Sroy, S., Avallone, S., Servent, A., In, S., & Arnaud, E. (2023). Does drying preserve the nutritional quality of small freshwater fish without excessive concentrations of heavy metals? *Current Research in Food Science*, 6, Article 100489. https://doi.org/10.1016/j.crfs.2023.100489

Stolyhwo, A., & Sikorski, Z. E. (2005). Polycyclic aromatic hydrocarbons in smoked fish – A critical review. *Food Chemistry*, 91(2), 303–311. https://doi.org/10.1016/j. foodchem.2004.06.012

Tongo, I., Ogbeide, O., & Ezemonye, L. (2017). Human health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in smoked fish species from markets in Southern Nigeria. *Toxicology Reports*, 4, 55–61. https://doi.org/10.1016/j. toxrep.2016.12.006

U.S. EPA. (2013). *Integrated Risk Information System [Reports and Assessments]*. https://www.epa.gov/iris

Weil, C., Lefèvre, F., & Bugeon, J. (2013). Characteristics and metabolism of different adipose tissues in fish. *Reviews in Fish Biology and Fisheries*, 23(2), 157–173. https://doi.org/10.1007/s11160-012-9288-0

WHO. (2010). https://www.who.int/europe/news-room/fact-sheets/item/a-healthy-life-style—who-recommendations.

World Health Organization. (2009). *Global prevalence of vitamin A deficiency in populations at risk 1995–2005: WHO global database on vitamin A deficiency* (Vol. 55).

Yoon, E., Park, K., Lee, H., Yang, J.-H., & Lee, C. (2007). Estimation of excess cancer risk on time-weighted lifetime average daily intake of PAHs from food ingestion. *Human and Ecological Risk Assessment: An International Journal*, 13(3), 669–680. https://doi.org/10.1080/10807030701226871

FAO. 2022. *The State of World Fisheries and Aquaculture 2022. Towards Blue Transformation*. Rome, FAO. https://doi.org/10.4060/cc0461en. (Accessed August 18, 2025).

World Health Organisation (WHO). The global prevalence of anaemia in 2011; 2015; 1–48 [accessed August 18, 2025; https://apps.who.int/iris/bitstream/handle/10665/177094/9789241564960_eng.pdf?sequence=1.

2025 CE. 2025. CE n°1881/2006. RÈGLEMENT (CE) N o 1881/2006 DE LA COMMISSION du 19 décembre 2006 portant fixation de teneurs maximales pour certains contaminants dans les denrées alimentaires (Texte présentant de l'intérêt pour l'EEE). (Accessed on August 18, 2025). https://eur-lex.europa.eu/legal-content/FR/TXT/PDF/?uri=CELEX:32006R1881.
2021 WHO. 2021. *Health data overview for the Gabonese Republic*. (Accessed on August 18, 2025), https://data.who.int/countries/266.

EFSA. 2023. CE N°2023/915. COMMISSION REGULATION (EU) 2023/915 of 25 April 2023 on maximum levels for certain contaminants in food and repealing Regulation

(EC) No 1881/2006. (Accessed on August 18, 2025), https://eur-lex.europa.eu/lega
l-content/EN/TXT/PDF/?uri=CELEX:32023R0915.

EFSA. 2024. *Update of the risk assessment of inorganic arsenic in food*. DOI: 10.2903/j.efsa.2024.8488.