Background.Industrialization and urbanization, while associated with increased productivity, are also potential causes of increased air pollution. Urban air quality has the potential to affect the health and wellbeing of residents of urban areas.Objectives.The present study investigated the levels of air pollutants around residential areas and transport sector locations (TSLs) in Lagos, Nigeria. Residential areas were defined as areas around inner streets and living quarters, while TSLs included busy roads, dual carriage roads, bus stops and major car parks in the Yaba Local Council Development Area of Lagos Mainland, Lagos, Nigeria.Methods.Air quality parameters were assessed in situ using calibrated hand-held devices at selected residential and TSLs. Each sampling location was geo-referenced and concentrations of the various parameters were used to plot distribution maps.Results.The findings from the monitoring exercise showed that levels of the measured air pollutants: carbon monoxide (CO), particulate matter (PM10 and PM2.5), sulphur dioxide (SO2), noise, temperature and humidity were within the ranges of 1.00 – 6.0 5.97 ppm, 43.345.2 – 127.2159.7 μg/m3, 20.3 23.25 – 69.058.16 μg/m3, 0.0 0 – 0.20.17 ppm, 47.7 50 - 65 70.1 dB, 26.2227.2 – 35.536.7°C and 57.0157.6 – 91.8492.3%, respectively, around residential areas. Values of the measured air pollutants at the TSLs ranged as follows: 2.011.0 – 5.397.7 ppm, 103.3360.7 – 179.77404.0 μg/m3, 50.2832.3 – 91.01184.0 μg/m3, 0.00 – 0.40 ppm, 64.2153.1 – 71.1376.3 dB, 27.1826.2 –27.9332.6°C and 60.3660.0 – 75.0178.0%, respectively. Hydrogen sulphide (H2S), ammonia (NH3), nitrogen oxide (NO2) were below detection limits in both sampling locations while volatile organic carbons (VOCs) ranged from 0.00 – 0.10 ppm in the TSLs.Discussion.Most assessed air quality parameters were significantly higher around bus stops (P < 0.05), except for CO and humidity. In addition, PM10 and PM2.5 were much higher than the World Health Organization (WHO) guidelines. The results indicated that the quality of air (particulate matter) in the study area was poor, especially in the TSLs.Conclusions.The Federal Ministry of Environment, through its relevant agencies, must create policies to address urban air pollution, taking into consideration long term exposures and people that are most vulnerable within the population.Competing Interests.The authors declare no competing financial interests.

Freshwater fishes are faced with increasing threats due to intensification of agriculture. This study evaluated the haematological and genotoxic effects of exposure of the African Catfish, Clarias gariepinus to sublethal concentrations of commonly used pesticides in agricultural settings. The evaluated pesticides were abamectin, carbofuran, chlorpyrifos, cypermethrin, deltamethrin, dichlorvos, dimethoate, fipronil, lambda-cyhalothrin and paraquat. The fishes were initially exposed singly to the pesticides for 96 h periods to determine their LC 50 , followed by exposure to sublethal concentrations (1/100 th 96 h LC 50 ) over a 21 d period. In all cases, a control experiment with catfishes kept in dechlorinated municipal water was monitored simultaneously. The 96 h LC 50 values was found to vary widely from 2.043 μgL -1 (Lambda-cyhalothrin) to 10284.288 μgL -1 (Paraquat). Significant differences (P < 0.05) were observed between mean haematological parameters-WBC, RBC, HGB, HCT, MCH and MCHC in the exposed and control catfishes. More so, micronucleus and nuclear abnormalities occurred at significantly higher proportions in pesticide exposed catfishes. Holistic cradle to grave approach as well as fate analysis is required to mitigate the potential harmful effects of pesticides to fresh water fishes.

Economic advancements in developing countries have seen an increase in urbanisation and industrialisation with a rise in the levels of discharge of effluents and municipal waste into aquatic ecosystems. Unfortunately, aquatic environmental regulations in these countries are often rudimentary and the development of environmental monitoring programmes will help identify ecological risks. As an example, the current study assesses the pollution status of 11 sampling sites in Lagos lagoon, Nigeria. The organic solvent sediment extracts were assessed for cytotoxicity and genotoxicity in rainbow trout gill-W1 cells. The induction of oestrogenic activities using the yeast oestrogen screen was also determined. The sediments were analysed for polycyclic aromatic hydrocarbons (PAHs) and other contaminants (polychlorinated biphenyls, organochlorine and organophosphate pesticides). Only sediments from three sites were cytotoxic at both 25 and 12.5mg eQsed/ml using the Alamar Blue cell viability assay. The alkaline Comet assay showed that all sites caused significant DNA damage at 7 mg eQsed/ml; the extent of the damage was site specific. The measure of oxidative damage to DNA via the formamidopyrimidine DNA-glycosylase-modified Comet assay revealed similar results. Toxicity to yeast cells was observed in extracts from six sites; of the remaining sites, only two exhibited oestrogenic activity. There was no strong consistent relationship between sediment PAH concentrations and the cell toxicity endpoints. The dynamic nature of Lagos lagoon with its tides and freshwater inputs are suggested as factors that make it difficult to link the sources of pollution observed at each site with PAH levels and toxic endpoints. The study has demonstrated that the Comet assay is a sensitive endpoint to identify sediments that possess genotoxic contaminants, and this in vitro bioassay has the potential to be incorporated into an environmental monitoring framework for Lagos lagoon.

Aquatic organisms are often exposed briefly to high pesticide concentration. Survival time model was used to study risk of death in C. gariepinus and O. niloticus fingerlings exposed to 24 mg/L atrazine, 42 mg/l mancozeb, 1 mg/L chlorpyrifos and 0.75 µg/L lambda cyhalothrin for 15, 30, 45 and 60 minutes and continuously for 96 hours. Mortality, time-to-death, weight, length, and condition factor of the fingerlings were recorded. Results obtained showed tilapia was more susceptible than catfish to continuous exposure but not pulse exposure. The survival probability of both species was similar when exposed for 15, 30 and 45 minutes (p > 0.05) but differed after 60 minutes (p < 0.05). Risk of death of catfish exposed briefly to atrazine, mancozeb and chlorpyrifos for 60 minutes was similar to 96 hours continuous exposure, same for tilapia exposed to 1 mg/L chlorpyrifos (p > 0.05). Survival probability of tilapia exposed to chlorpyrifos for 15, 30, 45 and 60 minutes was similar (p > 0.05) and was not influenced by pulse length. Pesticide hazard and risk of death decreased as fish size (weight, length, and condition factor) increased. Pulse toxicity assessment using survival models could make pesticides exposure assessment more realistic by studying factors that can influence the toxicity of pesticides.

Background.Antifouling paints are enriched with biocides and employed in the maritime industry to protect moving and fixed surfaces from fouling activities of sea dwelling invertebrates. There is limited information on their effect on the non-target African catfish, Clarias gariepinus, a commonly consumed fish in Lagos.Objectives.This study investigated the effects of two commonly used antifouling paints (Berger TBT-free (A/F783 (H)), reddish brown color and Silka Marine lead based paint, pale orange color) on a non-target catfish species, Clarias gariepinus.Methods.The study involved an initial 96-hour acute toxicity assay followed by chronic toxicity evaluation (using 1/10th and 1/100th 96-hour median lethal concentration (LC50) values) for 28 days to determine the ability of the paints to induce micronucleus and red blood cell abnormalities, and histopathological as well as oxidative stress effects in the catfish.Examined anti-oxidative stress enzyme activities include superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH) and glutathione-s-transferase (GST).Results.Acute toxicity evaluation results indicated that the Berger paint was 16.1-times more toxic than Silka paint with 96-hour LC50 values of 0.71 mg/L and 11.49 mg/L, respectively. Results from the biochemical assay indicated significantly higher (P<0.05) levels of a lipid peroxidation product, malondialdehyde, in Silka-exposed catfish compared to the control. All enzymes showed significantly higher activities in Berger paint-exposed catfish compared to the control. There was evidence of micronucleated and binucleated cells in the red blood cells of fish exposed to both paints. Histopathological assessment indicated that the exposed fish gills showed evidence of abnormalities such as curved lamellae epithelial necrosis, epithelial lifting and hyperplasia. The liver samples of the catfish showed evidence of portal inflammation as well as mild to severe steatosis, while the gonads showed varying percentages of follicle degeneration.Conclusions.The present study combined an array of biomarkers to determine the negative health impacts of two commonly used antifouling paints on non-target catfish inhabiting Lagos Lagoon. Further in situ studies are recommended to determine the current status of the lagoon fish.Ethics Approval.Ethical approval was obtained from the Department of Zoology, University of Lagos, Post-Graduate Committee. Note that this work commenced before the establishment of the University of Lagos Ethical Committee for the use of animals and humans in scientific studies. The committee does not give retroactive approval but stands by existing approvals before its establishment. However, this study followed the World Medical Association principles on the treatment of animals used in research (https://www.wma.net/policies-post/wma-statement-on-animal-use-in-biomedical-research/), and also American Fisheries Society Guidelines for the Use of Fishes in Research (https://fisheries.org/policy-media/science-guidelines/guidelines-for-th...