Total arsenic, mercury, lead, and cadmium contents in edible dried seaweed in Korea

Overview

Hwang and colleagues measured total arsenic, total mercury, lead, and cadmium in 426 dried edible seaweed samples sold in Korea during 2007-2008. The study covers laver, brown seaweed, kelp, and sea lettuce, with results reported on a dry-weight basis. Arsenic was measured as total arsenic, not inorganic arsenic.

Key numbers

The study analyzed 426 dried seaweed samples: laver n = 125, brown seaweed n = 153, kelp n = 102, and sea lettuce n = 46. Production-coast counts were east n = 137, west n = 71, and south n = 218.

The abstract reports average concentrations in mg kg−1 dry weight: total arsenic 17.4 (<LOD to 88.8), mercury (Hg) 0.01 (0.001 to 0.050), lead 0.7 (<LOD to 2.7), and cadmium 0.50 (<LOD to 2.9).

Table 3 reports final-total average concentrations as mg kg−1 dry weight: mercury 0.011 (0.001-0.050), lead 0.703 (<LOD to 2.719), cadmium 0.504 (<LOD to 2.931), and total arsenic 17.382 (<LOD to 88.790).

Table 3 product subtotals report:

The Results text states that mercury in brown seaweed and kelp was statistically higher than in laver and sea lettuce (p < 0.01), and that arsenic in kelp (23.26 mg kg−1) was significantly higher than in the other seaweed types (p < 0.01). It also states that brown seaweed, laver, kelp, and sea lettuce had lead levels of 0.770, 0.710, 0.669, and 0.539 mg kg−1, respectively, without statistically significant product-kind differences for lead.

Table 4 reports intake estimates using 8.5 g day−1 seaweed consumption and Korean standard adult weight. Daily intakes were total mercury 0.014 µg day−1 per capita, lead 5.976 µg day−1 per capita, cadmium 4.284 µg day−1 per capita, and total arsenic 147.747 µg day−1 per capita. Total weekly intakes were total mercury 0.010 µg kg−1 body weight week−1, lead 0.658 µg kg−1 body weight week−1, cadmium 0.472 µg kg−1 body weight week−1, and total arsenic 2.325 µg kg−1 body weight day−1 as a total daily intake comparison.

Table 4 risk indices were total mercury 0.2%, lead 2.63%, cadmium 6.74%, and total arsenic 4.65% of the source-selected tolerable-intake comparator.

Method quality-control values reported trueness from CRMs ranging from 85% to 104%. Average spiking trueness percentages for total arsenic, lead, cadmium, and total mercury were 101% ± 10%, 97% ± 5%, 99% ± 8%, and 105% ± 12%, respectively. The mercury LOD was 0.0047 ng; ICP/OES LODs for lead, cadmium, and arsenic were 0.002, 0.001, and 0.021 µg ml−1, respectively.

Methods (brief)

Samples were purchased as dried material and as coastal-production products from Korean markets, washed with deionized water, dried, and ground to powder. Mercury was measured with a DMA80 Direct Mercury Analyzer following USEPA Method 7473. Total arsenic, lead, and cadmium were measured after microwave digestion using modified USEPA Method 3052 and ICP/OES following USEPA Method 6010B. Quality control used NRC MESS-3 marine sediment, ERM-CE 278 mussel tissue, NIST-SRM 1566b oyster tissue, and IAEA-407 fish homogenate. The study measured total arsenic only; it did not measure inorganic arsenic speciation.

Implications

This source contributes Korean-market dried-seaweed occurrence data for total arsenic, total mercury, lead, and cadmium. It is directly relevant to seaweed-kelp-food routing, but downstream arsenic use must keep the measured tAs values separate from any inorganic-arsenic estimate. The paper’s own discussion notes that total arsenic is not a useful toxicological substitute for inorganic arsenic.

Update history

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