Profiling of Heavy Metals in Mackerel Tuna (Euthynnus affinis) and Seawater and Bottom Sediments in Sarangani Coastline, Southern Philippines

Abstract

Heavy metals have the ability to accumulate in the human body and disrupt functions of some body organs. These metals can find their way into humans by consumption of metal-contaminated fish. In this study, the presence of heavy metals was assessed in muscle tissues of mackerel tuna (Euthynnus affinis), locally known as “kawakawa,” collected from General Santos City and Kiamba fish landing sites. Heavy metal presence was also evaluated in seawater and bottom sediments samples collected along the Sarangani coastline. Cadmium (Cd) and lead (Pb) were analyzed using atomic absorption spectrophotometry; while mercury (Hg), through cold vapor atomic absorption spectrophotometry. Results revealed that the three samples from GSCFP had Hg concentrations ranging from 0.045 to 0.108 mg·kg−1, below the limit set by the United States Food and Drug Administration (US FDA). In the case of Cd, 0.095 mg·kg−1 Cd was detected from only one out of six samples taken from Kiamba, which exceeded the limit of 0.05 mg·kg−1 prescribed by the US FDA, US Environmental Protection Agency (US EPA), and the European Commission (EC). The data generally indicates that the tuna samples do not pose a serious threat to the health of the consumers. Sediments obtained from Sarangani coastline showed presence of Pb at 62.27 mg·kg−1, which is also below the 128 mg·kg−1 limit. Assessment of pollution status of the study area revealed that the bottom sediments can be classified as unpolluted to moderately polluted based on the levels of Cd, Pb, and Hg, implying minimal heavy metal exposure of this tuna species from the two sampling areas. To ensure no incremental contamination of seawater and bottom sediments occurs, developmental and anthropogenic activities, such as the indiscriminate disposal of industrial and domestic wastes that may be possible sources of heavy metals, should be regulated and more stringent effluent standards adopted.