Raju et al. 2021 — Cadmium and lead in freshwater clam and marine mussel, Cagayan Valley, Philippines

This paper measured Pb and Cd in soft tissues of two bivalve species collected from Cagayan Valley, Philippines: freshwater clam (Corbicula fluminea) and marine mussel (Mytilus edulis). The tissue was digested in nitric acid and analyzed by graphite furnace atomic absorption spectrophotometry (GFAAS). Reported concentrations were low relative to the Malaysian comparator values used by the authors, but the study is a thin regional data point: the number of individual specimens is not reported, the results are single species-level values without variability statistics, and no Philippine regulatory framework is cited.

Key numbers

• Corbicula fluminea (freshwater clam): Pb 0.006 µg/g dry weight; Cd 0.016 µg/g dry weight.
• Mytilus edulis (marine mussel): Pb 0.011 µg/g dry weight; Cd 0.015 µg/g dry weight.
• Equivalent dry-weight concentrations: Pb 6 µg/kg (clam) and 11 µg/kg (mussel); Cd 16 µg/kg (clam) and 15 µg/kg (mussel). No wet-weight conversion is possible because moisture content is not reported.
• Malaysian comparator values are internally inconsistent in the source: the prose states Pb 1.00 µg/g and Cd 2.00 µg/g, while Figure 1’s Malaysian Food Regulation columns show Cd 1.00 µg/g and Pb 2.00 µg/g. These are comparator values from another jurisdiction, not Philippine limits.
• LOD/LOQ, recovery, CRM validation, and analytical replicate variability are not reported.
• No Hg, As, Ni, Al, Cr, Sn, or metal speciation measurements are reported.

Unit clarification: The PDF text extraction drops the Greek micro symbol in several places, displaying g/g; the publisher’s abstract page preserves the values as µg/g, and the table context is dry-weight tissue. Treat the values as µg/g dry weight, not g/g and not wet weight. Do not compare these values directly to wet-weight EU/Codex shellfish limits without a moisture correction.

Methods (brief)

Freshwater clam and marine mussel were collected from Cagayan Valley sites with a BFAR Region 02 permit. Shells and byssus were removed; soft tissues were washed, drained, weighed, homogenized, dried, and digested. Approximately 1 g of dried sample was treated with 10 mL of 65% nitric acid, predigested, heated in a digestion block at about 130 °C until clear, filtered, diluted to 25 mL with deionized water, and stored at 4 °C. Cd and Pb were analyzed by GFAAS at the DOST Region 02 laboratory. Sample count per species is not explicitly stated; results are single-point values, not means ± SD.

Evidence tier B: published in Scholars Academic Journal of Biosciences (SAJB), an open-access journal with variable peer-review rigor. Limited methodological detail (no CRM validation, no LOD/LOQ, no explicit n per species). Data useful as a regional data point but not for quantitative synthesis without additional validation.

Implications for wiki use

This source can route to bivalve-mollusc and shellfish pages as a low-weight regional occurrence point for Pb and Cd in Philippine bivalves. Because the paper reports dry-weight values without moisture content, individual-specimen counts, analytical recovery, or variability statistics, it should not be pooled into wet-weight product distributions or used to infer compliance with wet-weight standards.

The study is useful for source inventory and methods-context purposes, especially as a reminder that bivalves can be used as aquatic bioindicators, but it is not strong enough for quantitative shellfish standards math without additional corroborating sources.

Wiki pages this source may touch

• cadmium
• lead
• bivalve-molluscs
• shellfish
• molluscs
• seafood
• shellfish
• seafood

Verification notes

• The source does not report the number of individual bivalves analyzed; sample_n is therefore left null rather than treating the two species as two analytical samples.
• The paper reports Cd and Pb only; no mercury, arsenic, chromium, aluminum, nickel, tin, or speciation data are present.

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.