Distribution of inorganic arsenic and methylated arsenic in marine organisms

Overview

Kaise, Hanaoka, Tagawa, Hirayama, and Fukui measured total arsenic and hydride-generation species in 60 marine-organism specimens including edible seaweeds, bivalves, gastropods, crustaceans, and fish. The paper separates water-soluble and lipid-soluble fractions and reports inorganic arsenic, methylated arsenic, dimethylated arsenic, trimethylated arsenic, and total arsenic as arsenic. It is useful for speciation context because total arsenic was often high while inorganic arsenic was not detected in most rows.

Key numbers

Table 1 reports arsenic as As in ug g-1; the extracted PDF text renders the micro sign inconsistently as p. Parenthetical percentages in the source are species shares of total arsenic and are not repeated here.

The Results text states that 14 of the 60 specimens contained total arsenic above 30 ug g-1: seven seaweeds, four carnivorous gastropods, and three crustaceans. Of six Phaeophyceae seaweeds, five contained total arsenic over 30 ug g-1.

High total-arsenic animal rows in Table 1 were dominated by trimethylated arsenic rather than inorganic arsenic:

The discussion states that the arsenic content of fish was generally low, under 10 ug g-1. Table 1 fish rows with higher totals included Oplegnathus fasciatus muscle at 9.38, Stephanolepis cirrhifer viscera at 9.28, and Pleuronichthys cornutus viscera at 8.08.

The source states that water-soluble inorganic arsenic was almost at the undetectable level in most marine organisms except Hizikia fusiforme. The two Hizikia fusiforme rows listed inorganic arsenic (iAs) 1.47 and 8.69 ug g-1; those are not interchangeable with total arsenic or methylated arsenic species.

Methods (brief)

Samples were collected from the Miura Peninsula in Kanagawa Prefecture and the coast of Shimonoseki in Yamaguchi Prefecture from March to October 1987, with some specimens obtained from a market. Each fish and shellfish was dissected into muscle and viscera. Total arsenic was measured after nitric/sulfuric/perchloric acid digestion by continuous arsine generation atomic absorption spectrophotometry. Speciation used chloroform/methanol extraction, water/lipid fractionation, alkaline digestion, hydride generation with sodium borohydride, and cold-trap GC-MS selected-ion monitoring for arsine, methylarsine, dimethylarsine, and trimethylarsine.

Implications

This paper provides historical primary speciation evidence showing why seafood and seaweed total arsenic must not be treated as inorganic arsenic. Seaweeds and some carnivorous gastropods or crustaceans had high total arsenic, but most rows reported inorganic arsenic as ND; Hizikia fusiforme was the main inorganic-arsenic exception. Routing should keep total arsenic and inorganic arsenic separate and treat the methylated arsenic species as source-reported speciation context, not as elemental arsenic thresholds.

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.