Bioaccumulation of Mercury, Cadmium, Lead, and Arsenic

Overview

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Key numbers

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is vital to Türkiye’s fisheries sector, significantly contributing to species are presented in Table 1.
Research indicates that marine organisms, especially bottom- in Table 1.
Based on previous research (Capodiferro et al. 2022; Ulusoy were 104.9%, 96.1%, and 98.7%, respectively. Calibration stan-
et al. 2025), we hypothesize that whiting may exhibit higher Hg dards were prepared from a 10,000 μg/kg stock solution of the
analyzed elements, with concentrations set at 0.2, 0.5, 1, 5, 10, 0.002 μg/kg for Cd, 0.001 μg/kg for Pb, and 0.005 μg/kg for Hg.
20, 50, 100, and 200 μg/kg for Hg, Cd, Pb, and As. The limits Trace element analyses were conducted on a wet weight (ww)
of detection (LODs) for these elements were 0.004 μg/kg for As, basis, and the results were presented as mg/kg.
is 71 years for males and 76 years for females. According to • Mercury (Hg): 0.0001 mg/kg/day,
• Cadmium (Cd): 0.0001 mg/kg/day,
groups. In order to lower the risk of developing acute coronary • Inorganic Arsenic (iAs): 0.0003 mg/kg/day (US
and 8–12 oz (~340 g) per week for pregnant or breastfeeding • Lead (Pb): 8.5 × 10 −3 (mg/kg-day) −1,
• Inorganic Arsenic (iAs): 1.5 (mg/kg-day)−1 (US EPA 2023b).
arsenic (iAs) accounted for 10% of the total As content, repre- Additionally, TR was calculated for Pb and iAs.
• IFR: Food ingestion rate (g/day), missing data (particularly for Pb, with 68.1% missing), no im-
independently based on available data. Only 19.1% of the sam-
Additionally, a normalized composite contamination index were higher in whiting (mean: 0.43 μg/g) compared to tub gur-
was constructed to integrate all four elements and assess the nard (mean: 0.29 μg/g; p = 0.0007). In contrast, no significant
first two principal components explained over 80% of the total this finding is limited by the high proportion of missing Pb data
nificantly higher in whiting (mean: 1.69 μg/g) than in tub gur- and PC2) explained a cumulative 80.0% of total variance (51.7%
nard (mean: 0.60 μg/g; p = 0.0009). Similarly, Hg concentrations and 28.3%, respectively) (Figure 3A,B). As shown in the loading
able limits (limits of detection Cd: 0.002; Pb: 0.001 μg/kg); ±, standard deviation; −, the species was not captured at the location.
In the PCA biplot (Figure 3C), whiting samples clustered dis- (0.964–1.411 mg/kg). On the other hand, Hg levels of tub gur-
contamination levels, whereas tub gurnard samples showed permissible limit (0.020–0.104 mg/kg) (Reis et al. 2020).
For whiting, the maximum level for Hg is set at 0.30 mg/kg tured. There is no maximum limit for arsenic, except for var-
and 0.640 mg/kg in whiting, which were higher than the thresh- 4.556 mg/kg in whiting and 0.135–1.347 mg/kg in tub gurnard.
0.15 mg/kg and fortunately remained under the limit. These Hg 0.00225 mg/kg, respectively, in comparison to our study.
the Sea of Marmara. On the other hand, the allowed concentra- 0.015 mg/kg, equal to our L2 sampling area (Şirin et al. 2024).
tion for fish species that are not directly addressed is 0.50 mg/kg. In another investigation from the Black and Aegean Seas, the
els in tub gurnard exceeded 0.30 mg/kg at locations L1, L3, and which were 0.55 mg/kg for Cd and 0.93 mg/kg for Pb (Uluozlu
L5. Ulusoy et al. (2025) reported that the mean Hg concentra- et al. 2007). Differing from our study, Türkmen et al. (2008)
tion was 0.299 mg/kg in tub gurnard from the Sea of Marmara, observed higher Cd (0.02 mg/kg) and Pb (0.33 mg/kg) levels
which was below the limit. Similar Hg levels (0.328 mg/kg) in in gurnard samples (Trigla gurnardus) from the Yalova region
when compared to locations L1 and L3, while lower values were centrations (0.40 and 6.80 mg/kg) were detected in whiting
concentrations at particular regions demonstrate that there Çiçek 2011). Unlikely, Mol et al. (2017) detected higher mean
concentrations of Cd (0.02 mg/kg) and Pb (0.360 mg/kg), but and 340 g (8–12 oz) (FDA 2024). Therefore, the average weekly
lower As value (4.09 mg/kg) in whiting captured from the consumption amount was considered to be 300 g in this study.
value of Cd (0.031 mg/kg) and As (6.34 mg/kg) were observed Health risk calculations are crucial to identify potential hazards,
Saros Bay, Aegean Sea, were 0.043 and 0.574 mg/kg, respec- to a toxic substance during a lifetime. The THQ values above 1
kg and Pb levels of 0.12–0.42 mg/kg were detected from On the other hand, TR is the estimated cancer risk index result-
and As levels in tub gurnard were 0.01, 0.14, and 1.38 mg/ This approach to risk management acknowledges that a range
concentrations were determined, namely 0.46 and 1.26 mg/ “acceptable” for carcinogenic risk. Values greater than 10 −4 in-
Sea of Marmara (0.01 mg/kg for Cd; 0.27 mg/kg for Pb) (Ateş

Methods (brief)

None of the samples reached the limit values set for Cd and Pb. Although no official limit has been established for As in fish, its
samples from the western region of the sea, exceeding 1 for all individuals, further underscoring the potential risk associated
iments, and hypoxic conditions promote deposition. These nard collected from different locations in the Sea of Marmara.
(Cucu et al. 2019). Whiting (Merlangius merlangus euxinus Nordmann, 1840) and
ical indicators of aquatic pollution (Pragnya et al. 2021). This sea trawling depths, and the number of samples collected from each
faces increasing challenges from pollution, overfishing, and cli- rity of the samples. The frozen samples were transported to the
ite sample representative of that location. All fish length mea-
for monitoring aquatic pollution, with trace elements from ben- The homogenized samples, weighing between 0.1 and 0.2 g,
ing human health (Zhao et al. 2012; Cabrini et al. 2018). Toxic (for digestion) using a microwave digestion system (MWS-4,
ingestion of Pb, which can lead to developmental and neurolog- ide and nitric acid in a 1:2 ratio. The digestion method followed
dustrial pollution, which can cause kidney damage and weaken and was performed in duplicate. After digestion, the extracts
bones over time. Similarly, Hg, particularly in its organic form were transferred to 50 mL sample tubes to prepare them for
methylmercury, poses neurotoxic risks when bioaccumulated in analysis using inductively coupled plasma mass spectrometry
fish (Ahmed et al. 2019). Thus, accurately evaluating the health (ICP-MS; ELAN-DRC-e, Perkin Elmer, USA). Each set of sam-
risks associated with consuming seafood contaminated with ples included a blank sample and certified reference material
FIGURE 1 | Map of the study area where whiting and tub gurnard were collected in the Sea of Marmara.
Note: n: number of the individuals captured from each location. Weight and length of the samples were given as Mean ± Standard Deviation.
of detection (LODs) for these elements were 0.004 μg/kg for As, basis, and the results were presented as mg/kg.

Implications

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Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised