Overview
Sirisangarunroj et al. measured total arsenic, cadmium, mercury, and lead in 15 commonly consumed fish species (7 freshwater, 8 marine) purchased from three local fish markets in or near Bangkok, Thailand. All analyses used ICP-MS-MS (Agilent 8800 triple-quadrupole) following microwave acid digestion and AOAC Official Method 2015.01; concentrations are reported as mg/kg fresh weight (FW) with n=3 markets per species. No HPLC-ICP-MS speciation was performed; all arsenic values are total arsenic (tAs), not inorganic arsenic. The study found grouper to be the highest-risk species, exceeding both Thailand’s national As standard (2 mg/kg) at 8.51 mg/kg and the Codex Hg standard (0.5 mg/kg) at 0.55 mg/kg FW (mercury in cooked form). Lead was below LOQ in all 15 species. Risk assessment using national food consumption survey data found a high arsenic margin of exposure concern for young children (0–5.9 years) consuming high-arsenic marine fish and striped snake-head fish; a high mercury HQ risk was identified for marine fish under high-consumption or high-mercury scenarios.
Key numbers
All concentrations in mg/kg fresh weight (FW), mean ± SD, n=3 markets.
| Species | Type | tAs | Cd | tHg | Pb |
|---|---|---|---|---|---|
| Nile tilapia | FW | 0.10 ± 0.07 | ND | <LOQ | <LOQ |
| Pangasius dory | FW | <LOQ | ND | <LOQ | <LOQ |
| Red tilapia | FW | 0.15 ± 0.10 | ND | <LOQ | <LOQ |
| Common silver barb | FW | 0.02 ± 0.02 | ND | <LOQ | <LOQ |
| Snakeskin gourami | FW | 0.02 ± 0.01 | ND | <LOQ | <LOQ |
| Striped snake-head fish | FW | 0.48 ± 0.14 | <LOQ | 0.02 ± 0.01 | <LOQ |
| Walking catfish | FW | 0.01 ± 0.00 | ND | <LOQ | <LOQ |
| Atlantic mackerel | Marine | 1.11 ± 0.24 | 0.02 ± 0.01 | 0.06 ± 0.04 | <LOQ |
| Grouper | Marine | 8.51 ± 1.60 | 0.01 ± 0.00 | 0.38 ± 0.17 | <LOQ |
| Indo-Pacific mackerel | Marine | 0.97 ± 0.16 | 0.04 ± 0.02 | 0.02 ± 0.01 | <LOQ |
| King mackerel | Marine | 1.36 ± 0.26 | <LOQ | 0.09 ± 0.06 | <LOQ |
| Longtail tuna | Marine | 1.92 ± 0.27 | 0.02 ± 0.02 | 0.07 ± 0.02 | <LOQ |
| Mullet | Marine | 0.46 ± 0.13 | <LOQ | <LOQ | <LOQ |
| Seabass | Marine | 1.32 ± 0.28 | ND | 0.02 ± 0.01 | <LOQ |
| Silver pomfret | Marine | 0.61 ± 0.09 | 0.01 ± 0.00 | 0.06 ± 0.02 | <LOQ |
ND = not detected (<LOD 0.0009 mg/kg for Cd; 0.0007 mg/kg for As); <LOQ: As and Cd = 0.006 mg/kg FW; Hg and Pb = 0.012 mg/kg FW.
Standard exceedances: Grouper tAs 8.51 mg/kg exceeds Thailand’s national As limit of 2 mg/kg; grouper tHg 0.55 mg/kg FW (post-yield-factor cooked estimate) exceeds Codex Hg limit of 0.5 mg/kg but is below Thailand’s notification level of 0.5 mg/kg for the raw sample (0.38 mg/kg raw < 0.5 mg/kg). Longtail tuna tAs 1.92 mg/kg FW is near but just below the 2 mg/kg national standard.
Methods (brief)
ICP-MS-MS (Agilent 8800 triple-quadrupole) after microwave acid digestion with HNO3/H2O2; AOAC 2015.01. Internal standard: Au + Lu. CRMs: NIST SRM 1566b (oyster tissue) and NMIJ 7402-a (codfish tissue). Recoveries: As 90 ± 5%, Cd 100 ± 5%, Hg 111 ± 4%, Pb 110 ± 4%. LOD: As 0.0007, Cd 0.0009, Hg 0.0011, Pb 0.0011 mg/kg FW. LOQ: As 0.0063, Cd 0.0062, Hg 0.0124, Pb 0.0123 mg/kg FW. All arsenic is total arsenic; no HPLC speciation was performed. For risk assessment, the authors applied published %iAs fractions by fish food group (ranging from 2.5% for Indo-Pacific mackerel to 23.6% for striped snake-head fish) as a secondary calculation; direct iAs measurements were not made.
Implications
Certification: Grouper from Thai markets showed tAs 8.51 mg/kg FW and tHg 0.38 mg/kg FW raw, the highest values in this dataset. All other freshwater species were substantially cleaner; lead was below LOQ in all 15 species.
Courses: Illustrates the species-level variation in marine vs freshwater fish metal burdens in Southeast Asia; grouper and large predatory marine species carry disproportionate arsenic and mercury loads.
App: Total arsenic in marine fish (Bangkok markets) ranges from <LOQ to 8.51 mg/kg FW; tHg ranges from <LOQ to 0.38 mg/kg FW raw. Cd is low to trace in all species (<0.04 mg/kg). Pb universally <LOQ.
Related evidence
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