Affiliations: Department of Biology, South China Normal University,
Guangzhou 510631, China. E-mail: fangzq@163.net | Department of Biology and Chemistry, City University
of Hong Kong, 83 Tat Chee Avenue,Kowloon, Hong Kong | Institute for Natural Resources and Waste Management,
and Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong
Kong
Abstract: Molluscs are able to accumulate heavy metals and impose health
hazard to consumers. The main objective of the present study is to investigate
the heavy metal concentrations in edible bivalves and gastropods available in
major markets of the Pearl River Delta. Fourteen species of edible molluscs
were purchased from six markets in Hong Kong and Guangdong Province. The fresh
of these biota were tested for their cadmium (Cd), copper (Cu), zinc (Zn), lead
(Pb), nickel (Ni), chromium (Cr), antimony (Sb) and tin (Sn)concentrations
(based on wet weight). The results indicated that amongst the 14 edible
molluscs, only Cd, Pb, Ni, Cr, Sb and Sn concentrations in three
species(Ruditapes philippinarum, Perna viridis and Hemifusus tuba) were within
the local regulatory limits. Over 60% of bivalve species exceeded maximum
permitted levels of Cd (2 µg/g) and Cr (1 µg/g), while over 40% of
gastropod species exceeded the maximum levels of Sb (1 µg/g) and Cr(1
µg/g). Most of the samples collected from Hong Kong had significantly
higher contents of Pb and Sb, but similar levels of Cd, Cu and Zn when compared
with samples collected across the border (p<0.5; p<0.01; p<0.001
respectively). In general, the molluscs purchased in Guangdong markets had
higher metal contents than those purchased from the Hong Kong markets. When
compared with the Provisional Tolerable Weekly Intake or Maximum Acceptable
Daily Load recommended by FAO/WHO Expert Committee on Food Additives, Cd levels
of five species (Anadara ferruginea, Pinna pectinata, Chlamys nobilis,
Babylonia lutosa and Hemifusus terntanus) and Cr levels of seven species
(Anadara ferruginea, Paphia undulata, Pinna pectinata, Babylonia lutosa,
Hemifusus terntanus, Cymbium melo and Cipangopaludina chinensis) were higher
than both the human daily acceptable limits (for Cd and Cr respectively) and
the local regulatory levels (for Cd and Cr respectively).
Keywords: Heavy metals, edible molluscs, human health, Pearl River Delta
