Sawmill Activities Near the Lagos Lagoon, Nigeria: Polycyclic Aromatic Hydrocarbons and Embryotoxic Evaluations of Sediment Extracts Using Clarias gariepinus

Short-term in situ Exposure of Guinean Tilapia and Blue Crab Near a Sawmill Wastes-impacted Coastal Ecosystem Reveal Significant Oxidative Stress Effects

Coastal ecosystems are characterized by various human activities with potential adverse impacts. This study aimed to evaluate the potential oxidative stress effects in representative aquatic biota deployed in situ at a sawmill wastes dump (test site) and reference site in a coastal ecosystem for a short term (28 days) period. PAHs and OCPs were analysed using GC-FID and GC-MS respectively in surface water and sediments. Oxidative stress indices (malondialdehyde, glutathione-s-transferase, reduced glutathione, catalase and superoxide dismutase) were evaluated following standard methods in Coptodon guineensis (Guinean Tilapia) and Callinectes amnicola (Blue crab) over a period of 28 days. Sum PAHs in the test site sediments, oxidative stress indices in C. guineensis liver and C. amnicola haemolymph after 28 days exposure were significantly higher (p < 0.0.5) compared to the reference site. The results showed the adverse impacts to biota of sawmill wastes which are continuously burnt at the test site with potential for long-term effects. Sustainable sawmill wastes management at the test site are recommended to sustain life below water (UNSDG 14).

Polycyclic aromatic hydrocarbons in fish (fresh and dried) and public health in Nigeria: a systematic review

In Nigeria, environmental pollution linked with PAHs has been increasing, and PAHs in fish pose a threat to all, especially those that rely upon fish. This systematic review aimed at evaluating human health effect of PAHs concentration in dried and fresh fish in Nigeria. A systematic literature search was carried out on PubMed, MedLine, Web of Science and Science Direct, etc. From the total of 31 articles reviewed, 19 studies reported on fresh fish and 9 on dried fish. 54.8% of the selected research reported on high-level PAH accumulation in fresh fish. PAH contamination was mainly from petrogenic and pyrogenic sources. The major health outcomes from this study were cancer and non-carcinogenic risks, skin irritations, gastrointestinal, child deformities, respiratory disorders, emotional distresses, neurological and haematological effects. It is recommended that regulations be made to abate and monitor the environmental exposure of humans to PAHs to ameliorate the public health effects.

Public health implications of endocrine disrupting chemicals in drinking water and aquatic food resources in Nigeria: A state-of-the-science review

This state-of-the-science review is aimed at identifying the sources, occurrence, and concentrations of EDCs, including potential public health risks associated with drinking water and aquatic food resources from Nigerian inland waters. A total of 6024 articles from scientific databases (PubMed, Scopus, Web of science, ScienceDirect, Google Scholar, and African Journals Online) were identified, out of which, 103 eligible articles were selected for this study. Eleven (11) classes of EDCs (OCPs, PCBs, PBDEs, PAHs, BPA, OTs, PEs, PCs, PPCPs, sterols and n-alkanes) were identified from drinking waters, river sediments and aquatic food species from Nigerian rivers, showing that OCPs were the most studied and reported EDCs. Analytical methods used were HPLC, LC-MS/MS, GC-FID, GC-ECD and GC-MS with all EDCs identified to originate from anthropogenic sources. Carcinogenic, mutagenic, and teratogenic effects were the highest (54.4 %) toxicological effects identified, while reproductive/endocrine disruptive effects (15.2 %) and obesogenic effects (4.3 %) were the least identified toxicological effects. The targeted hazard quotient (THQ) and cancer risk (CR) were generally highest in children, compared to the adult populations, indicating age-specific toxicity. PEs produced the highest THQ (330.3) and CR (1.2) for all the EDCs in drinking water for the children population, suggesting enhanced vulnerability of this population group, compared to the adult population. Due to associated public health, wildlife and environmental risk of EDCs and their increasing concentrations in drinking water and food fish species from Nigerian inland waters, there is an urgent need for focused and strategic interventions, sensitization and policy formulation/implementation towards public health and aquatic food safety in Nigeria.

How sawmill wastes impact surface water, sediment, macrobenthic invertebrates, and fish: a case study of the Lagos lagoon, Okobaba Area, South-western Nigeria

The Okobaba area of the Lagos Lagoon, Nigeria, is characterised by sawmilling activities which are potential threats to resident aquatic organisms. This study was aimed at evaluating the effect of sawmilling activities on the environmental quality of the Lagos lagoon at Okobaba area, Lagos, Nigeria. Surface water, sediment, macrobenthic invertebrates, and fish species were sampled monthly from six stations for 3 months (July-September 2018). Relevant stakeholders were administered a cross-sectional questionnaire to determine their knowledge of the environmental effects of their activities. Environmental samples were analysed following standard methods. Descriptive and inferential statistics were performed using SPSS 20.0 and PAST 1.97. Results showed that surface water dissolved oxygen and chemical oxygen demand were significantly lower, while sediment total organic matter and nitrates were significantly higher at the test site compared to the reference site. A total of 389 macrobenthic invertebrates comprising eight species and two macrobenthic invertebrates comprising one species as well as 121 fishes comprising nine species and 70 fishes comprising nine (9) species were recorded at the reference and test sites respectively. About 46.3% of respondents alluded to improper waste disposal as the major cause of pollution at the test site among others, 66.7% responded that wastes were disposed of by burning among other disposal methods, and 66.6% agreed that the sawmilling activities contributed to reduction of aquatic animal population. We recommend urgent regulatory intervention to address the indiscriminate discharge of wastes and facilitate adequate environmental risk advocacy to sustain life below water (United Nations Sustainable Development Goal 14).