BACKGROUND: Levels of toxic metal exposure in indigenous inhabitants are key bioindicators of the severity of environmental contamination. This study measured the seasonal variation of heavy metals and metallothionein (MT) contents in Asian swamp eels (Monopterus albus) from a paddy field situated in Tumpat, Kelantan, Malaysia, to identify prevalence, patterns and associations and togain insight on the suitability of MT as a biomarker for metal exposure.
METHODS: Gill, muscle and liver tissues of M. albus (n = 50) sampled during the ploughing, seedling, growing and harvesting phases of rice growing were collected. The concentrations of copper (Cu), zinc (Zn), lead (Pb), nickel (Ni), and cadmium (Cd) in these tissues were determined by flame atomic absorption spectrometry. MT from each sample was isolated and purified, and subsequently quantitated using UV spectrophotometry. Associations between metal and MT concentrations, season and tissue type were evaluated using Pearson correlation and ANOVA with post-hoc Tukey HSD analysis.
RESULTS: Zn was present in higher quantities in gill and liver tissues, while Cu levels were elevated solely in liver. Patterns of non-essential metal accumulation were varied: Cd was detected in low concentrations in all tissues, while Pb and Ni were abundant in gill tissues across all seasons. MT concentration in liver tissue was consistently higher than that found in muscle or gill tissue, except during the growing phase. Moreover, significant correlations (P
* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.