Heavy metal accumulation in and food safety of shark meat from Jeju Island, Republic of Korea

Overview

Kim and colleagues measured heavy metals in muscle from six shark species sold at Jeju Island fish markets in the Republic of Korea. The paper reports wet-weight concentrations for total chromium, iron, copper, zinc, total arsenic, selenium, cadmium, tin, antimony, lead, total mercury, and methylmercury, then compares the shark-meat findings with source-cited regulatory limits and biological variables such as species, habitat, body length, body weight, and age.

Key numbers

All concentration values below are source-reported as mg/kg wet weight; multiply by 1000 to express the same values as ppb. The source uses total arsenic (tAs) and total mercury (tHg) for the ICP-MS/DMA measurements, with separate methylmercury (MeHg) analysis.

Publication and sampling frame: PLOS ONE 14(3): e0212410, published 2019-03-13; DOI 10.1371/journal.pone.0212410. Sharks were sampled from Jeju Island fish markets from 2017-10 to 2017-12: 19 sharks from Moseulpo fish market and 6 from Hallim fish market, 25 sharks total.

Table 1 - sampled shark characteristics: the six species were Carcharhinus brachyurus (n=15, total body length 124.02 +/- 32.70 cm, range 68-190, body weight 15.33 +/- 12.06 kg, range 4.5-45, age 2.64 +/- 1.86 yr, range 0-7, Moseulpo); Carcharhinus obscurus (n=2, 116.00 +/- 2.83 cm, range 114-118, 8.45 +/- 0.78 kg, range 7.9-9, age 0.0 +/- 0.0 yr, Moseulpo); Isurus oxyrinchus (n=2, 123.50 +/- 19.09 cm, range 110-137, 12.60 +/- 7.21 kg, range 7.5-17.7, age 1.0 +/- 0.0 yr, Moseulpo); Triakis scyllium (n=3, 70.00 +/- 3.77 cm, range 66.5-74, 1.70 +/- 0.00 kg, range 1.7-1.7, age 2.0 +/- 0.0 yr, Hallim); Mustelus manazo (n=2, 68.00 +/- 22.63 cm, source-listed range 84-52, 0.50 +/- 0.00 kg, range 0.5-0.5, age 2.0 +/- 0.0 yr, Hallim); and Cephaloscyllium umbratile (n=1, total body length 63.0 cm, body weight and age not available, Hallim). Missing-value proportions were 4% for total body length, 32% for body weight, and 24% for age.

Table 2 - average metal concentrations by species: source-reported mean +/- SD values in mg/kg wet weight were:

Table 2 notes: values under the detection limit were substituted with half the detection-limit value for statistical analysis. The article states that average concentrations decreased in the order Fe > tAs > Zn > Cu > Se > tHg > MeHg > Cr > Pb > Sn > Sb > Cd. The average moisture composition ratio was 74.6%.

Table 3 - MANOVA p-values: for all sharks, multivariate significance was 0.024 for species, 0.909 for sex, and 0.240 for habitat. Species-level univariate p-values were Fe 0.346, Cu 0.261, Zn 0.045, tAs 0.001, Se 0.740, tHg 0.471, and MeHg 0.452. Habitat-level p-values were Fe 0.459, Cu 0.208, Zn 0.234, tAs 0.016, Se 0.474, tHg 0.313, and MeHg 0.451. For C. brachyurus, the sex MANOVA multivariate significance was 0.289, with Fe 0.264, Cu 0.395, Zn 0.452, tAs 0.069, Se 0.489, tHg 0.334, and MeHg 0.337.

Habitat and family comparisons: the source reports benthic sharks had average tHg 0.14 mg/kg, 44% lower than pelagic sharks at 0.25 mg/kg; benthic MeHg averaged 0.08 mg/kg, 53% lower than pelagic sharks at 0.17 mg/kg. tAs concentrations were significantly higher in benthic sharks (p < 0.05) and differed among Carcharhinidae, Isuridae, and Triakidae (p < 0.05).

Table 4 - multivariate regression p-values: for all sharks, body weight p-values for tHg and MeHg were 0.001 and 0.002; girth p-values for Fe, Zn, Se, tHg, and MeHg were 0.032, 0.031, 0.029, 0.008, and 0.017; total-body-length p-values for Fe, Se, tHg, and MeHg were 0.033, 0.043, 0.001, and 0.001. For C. brachyurus, body weight p-values for tHg and MeHg were 0.002 and 0.005, and total-body-length p-values for tHg and MeHg were 0.009 and 0.011.

Figure 3 and text - copper shark mercury relationship: for C. brachyurus, tHg and MeHg were strongly correlated (Pearson's r = 0.990, p < 0.05). The source’s polynomial regression comparison reported equations and R-squared values for tHg versus body weight (y = 7.1073E-4x^2 - 0.0116x + 0.1598, R^2 = 0.987) and total body length (y = 1.2324E-4x^2 - 0.0259x + 1.4367, R^2 = 0.841). Prediction intervals for the source-cited 0.4 mg/kg tHg regulatory maximum were body weight 25.3-31.4 kg and total body length 130.8-174.0 cm. The article summarizes this as C. brachyurus over 25 kg body weight or 130 cm total body length being likely to exceed that tHg reference value.

MeHg/tHg ratio: among C. brachyurus, the average MeHg/tHg ratio was 61.5% +/- 8.3%, with range 46.3-83.3%. I. oxyrinchus had the highest species-average MeHg/tHg ratio (66.6%), and T. scyllium had the lowest (55.8%).

Individual high-Cu observation: SNU-MO-0012, a C. brachyurus by-caught just after birth, had Cu 8.91 mg/kg; the other 14 C. brachyurus sharks averaged Cu 0.92 mg/kg. The source reports this value was at cumulative percentage 99.9%.

Pb and inter-metal correlations: in C. brachyurus, Pb was positively related to body weight (Pearson's r = 0.729, p < 0.05); across all 25 sharks the corresponding value was Pearson's r = 0.578, p < 0.05. In C. brachyurus, reported inter-metal correlations were Fe-Cr Pearson's r = 0.538, p < 0.01; Sn-Pb Pearson's r = 0.437, p < 0.05; and tHg-Pb Pearson's r = 0.752, p < 0.001. Se and tHg were not significantly correlated in C. brachyurus (Pearson's r = 0.04) or all 25 sharks (Pearson's r = 0.02).

Table 5 - source regulatory comparison: Table 5 compares source-reported shark values with source-cited regulatory limits. The listed regulatory maximum limits are Cr 0.25 mg/day, Cu 5 mg/day, Zn 25 mg/day, tAs 3 mg/kg, Se 0.3 mg/day, Cd 0.05-1 mg/kg, Sn 50 mg/kg, Sb 0.15 mg/kg, Pb 0.2-2 mg/kg, tHg 0.4-1 mg/kg, and MeHg 0.3-1 mg/kg. Source-comparison rows were C. brachyurus: Cr 0.01, Cu 0.12, Zn 0.51, tAs 6.98, Se 0.04, Cd 0.00, Sn 0.03, Sb 0.01, Pb 0.04, tHg 0.25, MeHg 0.16; C. obscurus: 0.03, 0.22, 0.65, 7.85, 0.03, 0.00, 0.09, 0.00, 0.08, 0.26, 0.17; I. oxyrinchus: 0.00, 0.35, 0.26, 2.06, 0.03, 0.00, 0.07, 0.00, 0.06, 0.27, 0.19; T. scyllium: 0.02, 0.01, 0.27, 8.32, 0.05, 0.00, 0.00, 0.00, 0.02, 0.13, 0.07; M. manazo: 0.01, 0.03, 0.17, 17.59, 0.03, 0.00, 0.00, 0.00, 0.01, 0.12, 0.08; and C. umbratile: 0.01, 0.05, 1.08, 8.09, 0.02, 0.00, 0.00, 0.08, 0.07, 0.18, 0.11. In the source table, all species except I. oxyrinchus exceeded the 3 mg/kg tAs comparison value; Hg and MeHg averages were below the source-cited reference values except for individual outliers described in the text.

Text-reported outliers: two C. brachyurus sharks, SNU-MO-0006 and SNU-MO-0001, had tHg concentrations at 268% and 102% of the 0.4 mg/kg source-cited maximum, respectively. Only SNU-MO-0006, the shark with the longest total body length and largest body weight, exceeded the MeHg comparison value, at 297%.

Supporting information files: the PDF lists S1-S5 tables and S1 Fig as supporting files. The in-PDF captions state that S5 Table contains the sampled sharks’ heavy-metal concentrations and biological data, with concentrations under detection limit marked <DL, all concentrations wet weight, and sex labels F and M. Those DOCX/TIF support files are not embedded in this PDF artifact.

Methods (brief)

The authors sampled epaxial shark muscle from fish sold at two Jeju Island markets. ICP-MS measured total Cr, Fe, Cu, Zn, As, Se, Cd, Sn, Sb, and Pb after wet digestion of approximately 0.1 g homogenized wet muscle with 10 mL HNO3 at 200 deg C for 2 h; the method reported calibration with certified reference materials from 0.1-100 ppb and detection limit 0.0001 mg/kg. Total Hg was measured on approximately 0.01 g freeze-dried muscle using a Milestone DMA-80 Direct Mercury Analyzer; DOLT-5 recovery averaged 103.7% +/- 9.8% (n=13), and the DMA detection limit was 0.06 ng/g. MeHg was measured after KOH/methanol extraction, ethylation, Tenax trapping, GC separation, and cold-vapor atomic fluorescence spectroscopy; DOLT-5 recovery averaged 101.6% +/- 8.1% (n=9).

Dry-weight tHg and MeHg concentrations were converted to wet-weight values using the moisture composition ratio. For statistical analysis, non-detects were replaced with one-half the detection limit when non-detects comprised less than 15% of data; the authors applied this detailed statistical workflow to Fe, Cu, Zn, tAs, Se, tHg, and MeHg. Statistical analysis used R, Box-Cox transformation, MANOVA, multivariate regression, Pearson correlations, and OriginPro regression plotting.

Speciation discipline: arsenic is total arsenic by ICP-MS, not inorganic arsenic. Mercury is reported both as total mercury by DMA and methylmercury by GC-CVAFS; these are kept separate.

Implications

Certification: This is direct occurrence evidence for shark meat / predatory marine fish, with wet-weight values for tHg, MeHg, tAs, Pb, Cd, Sn, Sb, Cr, Cu, Zn, Fe, and Se. It should be routed as literature evidence, not converted into an HMTc threshold or product percentile on this source page.

Courses: Useful for teaching apex-predator bioaccumulation, the tHg/MeHg distinction, species and habitat stratification, and why total arsenic values in seafood need speciation caution.

App: Supports shark as a high-attention seafood ingredient/product context, especially for total arsenic and mercury species. The sample is Jeju-market shark meat from 2017, not a global shark-meat distribution.

Microbiome: No microbiome findings.

Wiki pages updated on ingest

• Fish — marine, predatory (tuna, swordfish, shark, king mackerel)
• Shark
• Fish
• Seafood
• Mercury, Total
• Methylmercury
• Arsenic, Total
• Cadmium
• Lead
• Chromium
• Tin
• Antimony
• Copper
• Zinc
• Iron

Verification notes

Identity checks. On 2026-07-27, DOI grep for 10.1371/journal.pone.0212410, DOI-slug grep for 10-1371-journal-pone-0212410, raw-handle grep for RPHG_10-1371-journal-pone-0212410, checksum grep for 1b0fd005196f21eab524337d0192e8cf1b21b4ea38c3af2ec951804ec32f524d, author/title grep for Sang Wha Kim / shark meat, and cite-key collision checks found no existing wiki/sources/ page. This is a fresh source page.

Raw artifact. The PDF has 18 pages, file size 1339157 bytes, title metadata Heavy metal accumulation in and food safety of shark meat from Jeju island, Republic of Korea, and SHA-256 1b0fd005196f21eab524337d0192e8cf1b21b4ea38c3af2ec951804ec32f524d. pdfimages -list reports article figures on pages 4, 9, and 11 plus recurring PLOS header images.

Evidence tier. A. This is a peer-reviewed PLOS ONE primary occurrence study with explicit sample frame, analytical methods, wet-weight concentration tables, detection-limit handling, and source-cited regulatory comparison.

Firewall check. The page reports source values and source-cited comparison values only. It does not calculate HMTc thresholds, pooled percentiles, clean/dirty rows, or brand-level findings. No brand data are present in the source.

Number verification. Numbers in the Key numbers section were checked once against full-PDF extracted text and a second time against rendered pages or surrounding article text before commit. Table 1 was checked against rendered page 6; Table 2 against rendered page 8; Table 3 against rendered page 9; Table 4 against rendered page 10; Figure 3 and the regression text against rendered page 11; Table 5 against rendered page 12; and supporting-information captions against page 14 text.

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