Hoy et al. 2023 - Arsenic speciation in freshwater fish

This peer-reviewed review summarizes arsenic speciation in freshwater fish and the analytical challenges created by lower arsenic concentrations, complex fish matrices, and a large unidentified arsenic fraction. The review distinguishes total arsenic (tAs) from inorganic arsenic (iAs), contrasts freshwater-fish values with marine-fish values, and describes the extraction, chromatographic, and mass-spectrometric methods used to separate and identify arsenic species.

Key numbers

Global aquatic-food context: apparent aquatic-food consumption reached 20.5 kg/capita in 2019. In 2020, global aquatic-animal production was estimated at 178 million tons, including 66 million tons from inland waters and 112 million tons from marine waters.

Marine comparison context: arsenic concentrations in marine organisms are generally 5-100 mg/kg dry mass, and a large proportion of arsenic in marine crustaceans and fish is present as arsenobetaine.

Freshwater-versus-marine comparisons cited by the review:

• Germany total diet study: freshwater fish had mean tAs 0.03 mg/kg, lower than migratory fish at 0.73 mg/kg and marine fish at 2.82 mg/kg.
• Zhangzhou sea area, China: 14 saltwater fish species had tAs 0.42-6.22 mg/kg dry weight, while two freshwater species from the same area had 0.02-0.07 mg/kg dry weight; saltwater fish were 6-311 times higher.
• Shandong Province markets, China: freshwater fish averaged 0.075 mg/kg wet weight (range 0.007-0.500 mg/kg), while marine fish averaged 1.4 mg/kg wet weight (range 0.2-5.0 mg/kg).

Table 2 - selected freshwater-fish tAs and iAs values:

• Canada, Yellowknife Bay, dry weight: lake whitefish tAs 1.82 +/- 2.00 mg/kg and iAs 0.098 +/- 0.035 mg/kg (n=8); northern pike tAs 1.59 +/- 0.61 mg/kg and iAs 0.078 +/- 0.015 mg/kg (n=9); burbot liver tAs 4.56 +/- 2.94 mg/kg and iAs 0.094 +/- 0.043 mg/kg (n=5).
• Canada, Lower Martin Lake, dry weight: lake whitefish tAs 5.97 +/- 1.46 mg/kg and iAs 0.050 +/- 0.025 mg/kg (n=10); northern pike tAs 3.67 +/- 0.72 mg/kg and iAs 0.038 +/- 0.016 mg/kg (n=10).
• China, Changsha fishery, dry weight: crucian carp muscle tAs 0.16 +/- 0.02 mg/kg (n=14); crucian carp intestine 0.033 +/- 0.03 mg/kg (n=14); crucian carp liver 0.02 +/- 0.00 mg/kg (n=14); iAs not reported for these rows.
• China, Pearl River Delta fish ponds, wet weight: mandarin fish tAs 0.13 +/- 0.04 mg/kg (n=27); northern snakehead 0.37 +/- 0.12 mg/kg (n=25); grass carp 0.12 +/- 0.08 mg/kg (n=42).
• France, multiple hydrographic basins, wet weight: European eel tAs 0.026-0.647 mg/kg (n=53); bream 0.029-0.331 mg/kg (n=19); roach 0.027-0.255 mg/kg (n=57); common carp 0.060-0.209 mg/kg (n=4).
• Thailand, Chao Phraya or Tha Chin River, dry weight: tilapia tAs 0.623-1.22 mg/kg and iAs 0.088-0.130 mg/kg (n=14); silver barb tAs 0.622-1.38 mg/kg and iAs 0.078-0.154 mg/kg (n=14); striped catfish tAs 0.573-0.965 mg/kg and iAs 0.072-0.126 mg/kg (n=15); striped snakehead tAs 0.924-1.89 mg/kg and iAs 0.188-0.414 mg/kg (n=14).

Unknown arsenic fraction: studies from Canada, Hungary, Japan, and Norway reported that 31%-74% of total arsenic in fish was not accounted for by the sum of identified arsenic species. The review notes that the remaining fraction may include arsenic not fully extracted from tissue and unidentified arsenic species.

Methods (brief)

This is a review article; it reports no new primary measurements. It summarizes published freshwater-fish arsenic-speciation studies and analytical methods. Fish samples are typically homogenized, and arsenic species are extracted using water/methanol with sonication and enzyme treatment. Species are commonly separated by high-performance liquid chromatography (HPLC) and detected by inductively coupled plasma mass spectrometry (ICPMS). Electrospray ionization tandem mass spectrometry (ESI-MS/MS), used with HPLC and ICPMS, supplies complementary molecular and fragment-ion information for identifying unknown arsenic species. The review emphasizes that extraction efficiency, chromatographic resolution, detection sensitivity, and characterization capability remain limiting issues for freshwater-fish matrices.

Implications for wiki use

This source is a methods-and-context anchor for freshwater-fish arsenic. It supports treating iAs and tAs as non-substitutable fields: total arsenic can describe occurrence, but speciation is needed for risk interpretation because arsenic toxicity varies by chemical form and because large portions of freshwater-fish tAs may remain unidentified.

For product routing, the source is strongest for fresh freshwater fish and broader seafood context. It is not a finished-product canned-fish study and does not supply brand, retail-category, or infant-food measurements.

For methods documentation, the source is useful for explaining why arsenic speciation generally requires chromatographic separation plus element-specific detection, and why ICPMS alone cannot identify co-eluting or unknown arsenic compounds without complementary molecular techniques.

Wiki pages this source may touch

• arsenic
• arsenic-inorganic
• arsenic-total
• fish
• freshwater-fish
• seafood
• fresh-fish
• fish-freshwater
• seafood

Verification notes

• Manual-fetch merge-enhance (Codex, 2026-05-18): corrected raw metadata for P0174, replaced over-specific matrix terms with broad fish, corrected the Changsha crucian-carp rows to dry weight, removed old HMTc/course/app language, and retained only taxonomy-backed source links.

Page history

The five most recent substantive edits to this page. 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.