Lead, Mercury and Cadmium in Fish and Shellfish from the Indian Ocean and Red Sea (African Countries): Public Health Challenges

Overview

Tamele and Loureiro reviewed lead, mercury, and cadmium occurrence in seafood from African countries on the Indian Ocean and Red Sea coasts. The paper is a narrative review and monitoring-context source, not a primary market-sampling study. Its seafood occurrence table compiles concentrations from cited studies in Egypt, Djibouti, Kenya, Tanzania, Mozambique, and South Africa and reports the occurrence unit as mgKg−1.

Key numbers

The review states that heavy-metal concentrations in seafood from the African Indian Ocean and Red Sea literature ranged from 0.004 to 49.65 and 0.01 to 18.5 mgKg−1, respectively, while noting that most data were concentrated in the Red Sea.

Table 4 reports Egyptian Red Sea and Gulf of Suez seafood values as mgKg−1. Selected high or routeable rows include unknown fish species from Hourghada, Suez, and Ismaila in 1986-1989 with cadmium (Cd) 1.24 and lead (Pb) 0.82; Tridacna maxima shell from Gulf of Suez, Hurghada harbor, and El-Esh in 2004 with Cd 35.83, 44.65, and 39.45, and Pb 1.79, 1.76, and 1.65; Erugosquilla massavensis muscle from Suez and Ismailia in 2014 with mercury (Hg) 4.91 and 4.00, Pb 11.49 and 9.70, and Cd 0.57 and 0.44; Lake Timsah mollusks in 2006-2007 with Ruditapes decussatus Cd 5.00 and Pb 16.50, and Venerupis pullastra Cd 9.30 and Pb 19.00; Gulf of Suez mollusks in 2003 with Barbatus barbatus Pb 126.74 and Cd 3.02, and Patella caerulea Pb 147.55 and Cd 3.74.

For Egyptian fish muscle from the Gulf of Suez in 2010-2011, Table 4 reports Pb/Cd pairs as mgKg−1: Epinephelus sp. 0.45/0.20, Synodus sp. 0.28/0.04, Nemipterus japonicus 0.28/0.04, Sardinella sp. 0.50/0.38, Trachurus mediterraneus 0.40/0.20, and Lethrinus sp. 0.25/0.23. Shalateen fish rows include Epinephelus sp. Pb 0.88 and Cd 0.12, Carangoides bajad Pb 0.52 and Cd 0.08, Lutjanus bohar Pb 0.51 and Cd 0.08, and Thunnus albacares Pb 0.32 and Cd 0.06.

For Djibouti shark muscle from the Gulf of Tadjoura in 2016-2018, Table 4 reports Sphyrna lewini Cd 0.48, Hg 12.51, and Pb 0.08; Rhizoprionodon acutus Cd 14.50, Hg 0.68, and Pb 0.16. The text identifies Rhizoprionodon acutus as the species with the highest Hg content, although Table 4 lists the larger Hg value for Sphyrna lewini.

For Kenya, Table 4 reports Mombasa 1997-1998 fish muscle values as mgKg−1, including Cd 18.5 and Pb 0.76 in Leiognathus equula, Cd 9.8 and Pb 0.09 in Sphraena jello, Cd 6.0 and Pb 0.4 in Upeneus spp., Cd 6.0 and Pb 0.2 in Siganus sutor, Cd 5.8 and Pb 0.2 in Leptoscarus vaigiensis, and Cd 5.0 and Pb 0.1 in Mugil mugil.

For Tanzania, Table 4 reports Dar es Salaam 2015 fish muscle values of Cd 0.04 and Pb 0.045 in Siganus sutor, Cd 0.14 and Pb 0.144 in Lethrinus harak, and Cd 0.13 and Pb 0.067 in Rastrelliger kanagurta. It also reports Pb 7.22 in Octopus cyanea muscle from Dar es Salaam and Pb 3.24 from Tanga in 2013, and oyster soft tissue from Dar es Salaam in 2007-2008 with Cd 1.00, Pb 2.00, and Hg 0.081.

For Mozambique Channel fish muscle, Table 4 reports 2004 East of Madagascar values for Xiphias gladius Cd 0.60, Pb 0.01, and Hg 3.97; Thunnus albacares Cd 0.26, Pb 0.02, and Hg 1.15; Katsuwonus pelamis Cd 0.61, Pb 0.07, and Hg 0.67; and Coryphaena hippurus Cd 0.13, Pb 0.06, and Hg 0.21. In the northern part, Table 4 reports Xiphias gladius Cd 1.04, Pb 0.12, and Hg 1.61; Thunnus albacares Cd 0.25, Pb 0.09, and Hg 0.56; and Coryphaena hippurus Cd 0.12, Pb 0.14, and Hg 0.98.

For South Africa, Table 4 reports Cape Town 2011 Mytilus galloprovincialis bivalve mollusk values of Cd 1.99, Pb 7.30, and Hg 4.93 mgKg−1.

Methods (brief)

This is a narrative review of Pb, Hg, and Cd in seafood from African countries bordering the Indian Ocean and Red Sea. The review defines “HM” as Pb, Hg, and Cd, and “seafood” as fish and shellfish. It compiles concentration rows from cited primary studies and lists analytical methods reported by those studies, including AAS, FAAS, ICP-MS, ICP-AES, ICP-OES, semi-automatic mercury analyzer, and Advanced Mercury Analyzer. Table 2 discusses mercury speciation and methods, but Table 4 occurrence rows report Hg without methylmercury speciation; this page records those occurrence rows as total/unspecified mercury (tHg).

Implications

This source contributes secondary literature context for seafood, marine fish, and shellfish occurrence of Pb, Cd, and total/unspecified Hg in African Indian Ocean and Red Sea coastal settings. It is useful as a route-discovery and regional context source, but downstream occurrence extraction should preferentially chase the cited primary studies when product row fit, basis, sample size, and statistic type are needed. It should not be used as a primary pooled benchmark source without auditing the primary rows behind Table 4.

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.