Khandaker 2021 - Malaysian seaweed metal(loids)

Khandaker and colleagues measured 17 elements in cultivated Malaysian Eucheuma cottoni seaweed from Langkawi, Semporna, and Kota Belud. The study reports dry-weight concentrations in microgram per gram and estimates dietary intake, noncarcinogenic hazard, and carcinogenic risk for an assumed East Asian adult seaweed consumer. The paper labels chromium as Cr-VI and arsenic as As (III), but the analytical method was ICP-OES rather than a chromatographic speciation method.

Key numbers

Fresh seaweed samples were collected from Kota Belud and Semporna in March 2018 and from Pulau Dangli, Langkawi in September 2018. The authors collected 4 kg of fresh whole seaweed from each location, with samples obtained from at least four sublocations at each farming site. Table 3 reports location group sizes of LKW n = 3, SPN n = 3, and KBL n = 2.

Table 3 reports metal concentrations in microgram per gram as mean ± relative standard deviation (RSD), with range in parentheses:

Table 2 reports LoD values in µg/kg: Pb 11.31, Cd 2.15, Al 3.08, Mn 1.20, Cu 1.89, Zn 0.89, Fe 1.01, As 14.51, Ni 1.97, Cr 4.66, Ag 0.35, and Si 37.94.

Table 1 reports CRM 7405-a recovery checks for HMT-relevant analytes: Pb certified 0.43 ± 0.03 mg/kg, recovered 0.45 ± 0.04, recovery 104.7%; Cd certified 0.79 ± 0.02, recovered 0.75 ± 0.03, recovery 94.9%; Al certified 147 ± 7, recovered 141 ± 6, recovery 95.9%; As certified 35.8 ± 0.9, recovered 35.26 ± 0.88, recovery 98.5%; Ni certified 2.2 ± 0.1, recovered 2.3 ± 0.08, recovery 104.6%; Cr certified 3.4 ± 0.1, recovered 3.29 ± 0.09, recovery 96.8%.

Table 4 estimates daily intake in Microgram Per Kilogram/kg/Day for an assumed East Asian adult consuming Malaysian seaweed at 10 g/adult/day and body weight 65 kg. Mean daily intakes were Pb 1.2, Cd 0.3, As 0.7, Ni 1.5, Cr-VI 4.0, Al 6.3, and Ag 0.03.

Table 5 reports noncarcinogenic and carcinogenic risk estimates for the same assumed intake scenario: Pb HQ 0.203 and LTCR 6.08 × 10−4; Cd HQ 0.171 and LTCR 4.89 × 10−3; As HQ 1.547 and LTCR 5.22 × 10−2; Ni HQ 0.053 and LTCR 1.34 × 10−1; Cr-VI HQ 0.912 and LTCR 1.03 × 10−1. The summed hazard index is 4.38, and the summed lifetime carcinogenic risk is 2.94 × 10−1.

Methods (brief)

Fresh Eucheuma cottoni seaweed was collected from three Malaysian farming locations, washed, cut, dried at 70 °C to constant dry weight, blended, and sieved through a 25 µm mesh. For each analysis, 0.5 g dw was digested with 10 mL HNO3 and 3 mL HCl on a hot plate at 100 °C for 2 h, filtered through Whatman No. 41 paper, diluted with 10 mL deionized water, and analyzed by ICP-OES (Optima 5300DV, PerkinElmer). Calibration used Agilent multi-element standard solution 2A in 5% HNO3; validation used NIST SRM 1400 and NMIJ CRM 7405-a. The authors state each sample was analyzed in duplicate.

Implications

This source provides dry-weight occurrence data for cultivated Malaysian seaweed in the seaweed-kelp-foods product row. It is directly relevant for Pb, Cd, Al, Ni, and the source-reported As (III) and Cr-VI values, while downstream extraction should keep the ICP-OES speciation limitation visible. The paper’s risk calculations are source-reported scenario estimates, not HMTc threshold calculations.

Verification notes

• PDF text extracted with pdftotext -layout; title page, sample preparation, Tables 1-5, arsenic-speciation discussion, and conclusions were readable.
• DOI 10.3390/foods10020381, raw handle MFK_khandaker2021, and cite-key checks found no existing source page before creation.
• Table 3 concentration values, Table 2 LoDs, Table 1 recovery checks, Table 4 intake estimates, and Table 5 risk estimates were checked against extracted text. Units are preserved as microgram per gram, µg/kg, mg/kg, and Microgram Per Kilogram/kg/Day; no conversion was performed.
• Speciation: the source labels the arsenic row As (III) and chromium row Cr-VI. However, the method was ICP-OES, and the text acknowledges that ICP-OES usually provides elemental arsenic rather than a particular species. This page preserves the source labels in Key numbers and frontmatter while flagging that limitation.
• Brand firewall: no sampled product brands are attached to contamination values. Instrument and standard vendors appear only in Methods.
• Frontmatter slugs were checked against docs/gpt-collaboration/taxonomy-snapshot.md; no new slug was invented.

Page history

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