Original Articles
DO Jegede, OS Shokunbi, AA Ogu
Abstract
A possible route of heavy metal ingestion by human is via heavy metal contaminated food items. Three different commonly eaten species of fresh fish sourced from Igbona market, Osogbo, Nigeria were spectrophtometrically assessed for possible heavy metal contamination. Fifteen (15) fish samples, five each, of Sardine (Scardinella maderensis), Croaker (Johnius bellangeri) and atlantic mackerel (Scomber scrombus) were ashed while digestion of 2.0 g of the ashed sample was done using 5 mL of concentrated nitric acid, filtered and made up to 50 mL with deionized water. Zinc (Zn), iron (Fe), chromium (Cr), copper (Cu), and lead (Pb) contents of the digest were determined using Buck Scientific 210 Variant Giant Pulses (VGP) Atomic Absorption Spectrophotometer (AAS). The three fish samples were very rich in iron with ranges of 24.04 ± 0.42 - 31.01± 0.53, 11.87 ± 0.75 - 22.25 ± 0.57 and 11.98 ± 0.13 -16.03 ± 0.22 µg/g for Scardinella maderensis, Scomber scrombus and Johnius beangerri fishes respectively. Lead, the most toxic of all the studied analytes, was almost not detected in two fish species (Scardinella maderensis and Scomber scrombus), while it was completely not detected in Johnius beangerri. The order of decrease of metals studied in Scardinella maderensis is iron (114.68) > zinc (22.45) > copper (13.43) > chromium (2.34) > lead (0.03) µg/g while that of Scomber scrombus and Johnius beangerri are iron (67.28) > zinc (44.78) > copper (15.36) > chromium (14.05) > lead (0.02) µg/g and iron (55.19) > zinc (22.16) > copper (12.54) > chromium (7.81) > lead (ND) µg/g respectively. The order showed similarity, thus the likelihood of same sources for the heavy metal uptake. It can be concluded that fish samples are rich in essential metals (iron, zinc, copper) and low in xenobiotic metals (lead and chromium). Hence, the fishes found in the study area pose little or no threat to consumption by human.