Findings and scope
The study collected the agarophyte red seaweed Gracilaria chilensis from Los Albatros Beach, in the Quintero-Puchuncaví industrial zone of central Chile, and tested whether a 1 h tap-water submersion followed by 21 days of culture in filtered seawater would lower its metal content (PDF p.8). Eleven elements were measured by ICP-MS at four time points. Total arsenic fell from a highest value of 2.1 mg/kg to between 0.8 and 0.90 mg/kg after submersion and stayed there; cadmium was 0.02 to 0.03 mg/kg at 14 and 21 days (PDF p.3, p.5). Lead and total chromium did not change significantly. The material analysed was whole seaweed biomass intended for nutraceutical use; agar was not extracted or measured.
Key numbers
Concentrations after 21 days of culture, as printed (Table 2, PDF p.5), in mg/kg labelled as fresh biomass; mean ± SD, n = 3.
| Metal | 21-day concentration |
|---|---|
| Total arsenic | 0.90 ± 0.07 |
| Lead | 0.23 ± 0.04 |
| Total chromium | 0.12 ± 0.01 |
| Nickel | 0.12 ± 0.01 |
| Cadmium | mean not printed (”± 0.01”) |
The text gives total arsenic as 2.1 mg/kg at its highest and 0.8 mg/kg at its lowest, without naming the time points; Figure 1 shows the highest bar for the field-collected biomass and the lowest after the first tap-water submersion (PDF p.3 and p.4). Percentage depuration relative to the field-collected biomass (Table 1, PDF p.5) at 21 days ranged from 53 to 57% for total arsenic, 37 to 51% for cadmium, −6 to 40% for nickel, −106 to 73% for total chromium and −158 to 33% for lead; negative values denote accumulation.
Methods and Evidence Fitness
About 350 g of fresh biomass was sampled in triplicate at each time point, stored at −80 °C, and analysed by ICP-MS following USEPA method 6020B after microwave digestion of “1 g of dry grounded sample” in nitric acid, hydrochloric acid and hydrogen peroxide (PDF p.8). Detection limits are printed (total arsenic 0.025, cadmium 0.005, chromium and nickel 0.013, lead 0.002 mg/kg) and reagent blanks were run (PDF p.9). No certified reference material or recovery is reported. Arsenic was not speciated.
Evidence Fitness is Modeled or limited evidence. The data support a within-study contrast for one batch of seaweed from one polluted site. The basis is uncertain: Figure 1 and Table 2 label the values as fresh tissue, while the methods describe digestion of dried, ground material with no moisture correction (PDF p.4, p.5, p.8). If the values are in fact per dry weight, they are not comparable with the fresh-weight seafood limits the authors cite. Baseline values for lead, cadmium, chromium and nickel appear only as bars in Figure 1 and were not captured.
Assessment limits
The time point T1 is defined inconsistently. Table 1 and Figure 1 describe it as the biomass after the first tap-water submersion, while the Supplementary Materials list states that T1, T2 and T3 are 7, 14 and 21 days of culture (PDF p.5, p.10). The abstract and discussion state that depuration of 32 to 92% was achieved for 10 metals including lead, but the results report no significant change in lead, and Table 1 shows lead ranges with negative depuration at every time point (PDF p.1, p.3, p.5, p.6). The cadmium cell of Table 2 omits the mean. The authors compared total arsenic with Codex and Chilean limits written for other foods; no seaweed limit was applied (PDF p.5). The min to max ranges in Table 1 are not explained. Zinc increased during culture, which the authors attribute to zinc in the Quintay seawater.
Provenance notes
The PDF (12 pages) was delivered in batch 03 of order HMI-GAP-INGEST-1 on 22 October 2026, filed under the agar ingredient folder. The SHA-256 matches the batch manifest. The PDF prints DOI 10.3390/molecules27206832 on the first page and in the running footer, and the printed title matches the manifest. Supplementary Tables S1 and S2 and Figure S1 (seawater metals) are not part of the PDF and were not consulted.
Related evidence
Update history
22 October 2026: Ingested from the batch-03 PDF. 39 records were added to the evidence register (38 reviewed, 1 rejected).
Update history
No substantive edit history is available in this build. The full commit record is available in git.