RESEARCH TEAM MEMBERS

1. IRG 33: Evaluation of nutrient quality and safety of seafood products in Lagos and Delta States, Nigeria. • RESEARCH TEAM MEMBERS Prof. T.A. Arowolo (Professor, Analytical Chemistry & Environmental Management) Dr. F.O.A. George (AQ & FM; Fish Utilization & Safety) Dr. D.O. Odulate (AQ & FM; Fisheries Management) Dr. W.O. Alegbeleye (AQ & FM; Fish Utilization) Dr. A.O. Agbon (Fish Toxicology) Dr. A.O. Obadina (FST; Food Microbiology)

2. STUDY OBJECTIVES • To assess the level of heavy metals (particularly mercury and arsenic) arising from industrial and petroleum wastes’ pollution of water in major fish resources of Lagos and Delta states respectively. • To quantitatively assess the level of pathogenic and toxin forming microorganisms in fish and fish products in these states. • To quantitatively assess the level of major nutrients (protein and lipid) in selected fish species in the states.

3. THE STUDY AREA

4. Introduction • Nigeria is a coastal state and fisheries contributes significantly: • Economically: Nigeria exports valuable fish species • Socially: Fisheries is a source of livelihoods to millions of people and contributes significantly to rural development and employment. • Nutritionally: Fish is an excellent source of easily –digested protein (15-28%) which is rich in essential amino acids, vitamins (A & D and minerals (Iodine, selenium) • Health: Fish consumption enhances health, although some risks are associated with consumption of fish from polluted or contaminated sources.

5. Environmental contaminants in seafood • Persistent organic pollutants (POPs) e.g. dioxins, polychlorinated biphenols (PCBs), brominated flame retardants and various chlorinated pesticides (these arise mainly from industrial processes, forest fires and volcanic eruptions). POPs are generally persistent, oil soluble and semi-volatile • Heavy metals e.g. lead, arsenic, mercury, copper, chromium, cadmium zinc etc.

6. JUSTIFICATION FOR STUDY • Nigeria is a coastal state and produces fish both for internal consumption and export • Lagos State is Nigeria’s industrial and commercial centre with a population of over 20million people • Delta state is an oil producing coastal state • There are concerns about the safety of fish from highly industrial and oil producing areas like Lagos and Delta states • Sole (Solea solea) and croaker (Pseudotolithus spp) selected for the study are important economic species from both Lagos and Delta states

7. Materials and methods • Pseudotholithus spp (croaker) and Solea solea (sole) which are lenthic and benthic fishes respectively were used for the study. • Sampling was done four times in June, August, October and December for both states. • Fish samples were bought fresh from fishermen at Koko (Delta state) and Makoko (Lagos state) respectively and kept under frozen storage (below -200C) in the laboratory until required for analysis. • Proximate analysis was carried out according to standard AOAC methods. • The frozen fish samples were allowed to defrost, cut open with knife and allowed to thaw for about two (2) hours before being oven dried at 1050C for about 12hours until constant weight was obtained. The dried fish samples were homogenized using a ceramic mortar and pestle. Dried samples were kept in desiccators and oven-drying was continued the next day.

8. Materials & methods continued • Glass wares used were washed and rinsed severally with distilled water and then washed in 10% HCl. • Wet digestion of samples was done using the method of Asegbeloyin et al. (2010). About 10.00g of dried sample was digested in 60.00 mls of freshly prepared 1:1 HNO3/ H2O2 solution at 1600C on a hot plate for about one hour until the contents came to about 5.00 mls. This was then filtered and the filtrate transferred to a standard flask and made up to 25.00 mls with distilled de-ionized water. Digested sample was stored in plastic bottles and the concentrations of Pb, Cr, Cu, Cd and Zn were evaluated using the air-acetylene flame AAS (AAnalyst 200, Perkin Elmer). • Data obtained were subjected to a one-way Analysis of Variance (ANOVA) according to Steel and Torrie (1980). Differences in means were separated using Duncan’s multiple range tests (Duncan, 1955). Values obtained were presented as Least Significance Differences (LSD) of means at (p<0.05).

9. Results: Levels of heavy metals in fish compared to standards

10. Discussion • Generally metal concentrations in sole (a benthic fish) fish were higher than in croaker, a pelargic fish; except for Cu, where the concentrations in croaker were higher than in sole and Cd where concentrations found in Croaker for Lagos State were higher than in Sole. • As indicated in the results, lead concentrations for sole from Lagos (LS) with 0.330µg/g was higher than the standard of 0.2µg/g (EC, 2005). • In general, lead values obtained in this study correspond with previous studies by Eletta et al. (2002). Lead is known to exert its most significant effects on the nervous system, the blood and the kidney. It has effects on the nervous system including motor disturbances. • The concentration of Cadmium in all the experimental fish were higher than the EC, 2005 limit of 0.05µg/g, except in croaker (from Delta state) with a concentration of 0.029µg/g. Cadmium concentrations in this study were higher than those reported earlier by Edem et al. (2009). Adverse effects of excessive chronic cadmium exposure may include chronic renal failure, kidney stones, liver damage (rare), lung cancer, osteomalacia, possibly hypertension, prostate cancer and proteinuria. Chronic cadmium exposure has been reported to cause mild anemia, skeletal lesions, Itai-itai disease, anemia, and yellowing of teeth. Cadmium is a cumulative toxin. Its levels in the body increase over time because of its slow elimination. It accumulates chiefly in the liver and kidneys. However, it also accumulates in muscles and bone.

11. Discussion continued • Chromium concentrations in this study are lower than previously reported (Burgera and Gochfeld, 2005) but ARE HIGHER than the standard for chromium 0.730µg/g (IAEA-407).Haemolysis, renal and liver failure, damage to circulatory and nerve tissue and cancer are some of the health effects of ingesting chromium at a concentrations higher than the standard in the human body. • Zinc concentrations were lower than the standard (3.280ppm; IAEA-407). Zinc deficiency has been associated with dermatitis, anorexia, growth retardation; poor wound healing, hypogonadism with impaired reproductive capacity, • This study also indicated higher metal pollution of fish samples from Lagos lagoon than in Koko; except for Zn, where the concentrations in Delta were higher than those of Lagos state. The concentrations of Zinc were much lower than the tolerable values stated in the standard

12. Conclusion • Demersal (bottom dwelling) fish species e.g. Sole have higher metal concentrations than pelargic fishes. • Fish samples from Lagos have higher concentrations of metals than those from Koko, Delta state, suggesting that Lagos waters are more polluted. • It is important that these findings are published to educate consumers, particularly those in coastal areas on the health and safety hazards associated with fish consumption and also for the Ministry of environment to take steps to regulate waste disposal into Nigeria’s coastal waters .

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