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Background Cowpea is a leguminous crop commonly grown and eaten in Nigeria. Organophosphate insecticides are frequently used to control insect populations in cowpea crops. Objectives The present study was conducted to investigate the concentrations of organophosphate insecticide residues in cowpea varieties in Gwagwalada, Nigeria, and assess health risks to consumers. Methods Samples of brown and white cowpea varieties were collected from Gwagwalada market, Abuja, Nigeria. Concentrations of organophosphate insecticide residues in the cowpea samples were analyzed by gas chromatography-mass spectrometry with selective ion monitoring. Risk evaluation was carried out by the determination of estimated daily intake, hazard quotient and chronic hazard index. Results The organophosphates detected in the cowpea varieties were malathion, parathion, ethion and carbophenothion. The concentrations of insecticides in the cowpea types were higher than the maximum residue limits recommended by the European Union (EU) and the Agency for Toxic Substances and Disease Registry (ATSDR). The hazard quotient values were less than 100% for malathion, parathion and ethion in the cowpea varieties for adults and children. The hazard quotient of carbophenothion for adults was below 100% for the cowpea types, while the hazard quotient surpassed 100% for children. The chronic hazard indexes for children were 364% and 276% for the brown and white cowpea types, respectively. Conclusions The results obtained in the present study indicate that consumers, particularly children, may be exposed to health risks through the consumption of cowpea types. Consequently, monitoring and regulation of organophosphate insecticide usage in Nigeria should be intensified.

Summary The aim of this study was to evaluate the effect of different fractions of the aqueous crude extract of Detarium senegalense stem bark on castor oil-induced diarrhea. Castor oilinduced diarrhea, gastrointestinal motility and castor oil-induced enteropooling methods were used to evaluate the antidiarrheal effects of the fractions. Castor oil was used to induce diarrhea and the effect of all the fractions (chloroform, ethyl acetate, n-butanol, methanol and residual aqueous) were evaluated at the doses of 200 and 400 mg/kg body weight. The results show that all fractions significantly (p<0.05) decreased the frequency of defecation in rats following the induction of diarrhea with castor oil. Ethyl acetate which produced the highest antidiarrheal activity was further subjected to gastrointestinal motility and castor oil-induced enteropooling tests. In the gastrointestinal motility, two test doses of the extract (200 and 400 mg/kg) were administered orally to two groups of rats (n=5), while the third group of rats (control), were treated with normal saline, and the fourth group were treated with diphenoxylate, a conventional anti-diarrheal drug. In the castor oil-induced enteropooling experiment, normal saline was used for the control animals, while 200 and 400 mg/kg of the extract was administered to groups two and three, respectively and atropine, a standard drug, was administered to rats in group four. The ethyl acetate fraction significantly (p<0.05) decreased the gastro-intestinal motility, as shown by the extent of movement of the charcoal meal in the treated rats. It also significantly inhibited the fluid accumulation within the intestine. These findings suggest that the ethyl acetate fraction possess antidiarrheal effect, which may be due to the presence of some phytochemical constituents (alkaloids, flavonoids and tannins) in the plant, which may either be working alone or in combination with each other. This study has demonstrated that D. senegalense fractions, especially the ethyl acetate fraction, possess antidiarrheal activity thus supporting the use of the plant in the treatment of diarrheal diseases.

Detarium senegalense JF Gmelin stem bark aqueous extract was investigated for its phytochemical contents as well as its anti-diarrhoea effects. The aqueous extract which is normally used in folkloric medicine was subjected to phytochemical screening. Graded doses of the extract (100, 200 and 400 mg per kg) were administered orally to three groups of rats (n = 5) before induction of diarrhoea with castor oil. Another two groups of animals were treated with normal saline (control) and diphenoxylate, a conventional anti-diarrhoea drug respectively. In two separate experiments, gastrointestinal transits of charcoal meal and gastro-intestinal enteropooling with the same graded doses of the aqueous extracts were used for comparison. The extract produced a significant inhibition of the castor oil induced diarrhoea in the animals. The gastrointestinal transit of charcoal meal was also reduced by the various doses used in this study. However, the intestinal fluid accumulation was only slightly reduced especially by 400 mg/kg dose of the extract. The aqueous extract alone dose dependently reduced the contractile amplitude of the jejunal tissue. The aqueous extract also decreased the contractile amplitude of isolated jejunal segment exposed to 0.2 ml of 10 µg/ml of acetylcholine. Phytochemical analysis of the stem bark extract revealed the presence of secondary metabolites such as alkaloids, tannins, flavonoids, terpenes and steroids, saponins and glycosides. The findings suggest that, the aqueous stem bark extract of D. senegalense possesses antidiarrhoeal effect, which could be related to inhibition of gastro-intestinal motility and secretion.

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Concerns about inappropriate disposal of waste into unsanitary municipal solid waste landfills around the world has been on the increase; and this pose a public health challenge due to leachate production. The neurotoxic effect of Gwagwalada landfill leachate (GLL) was investigated in male adult Wistar rats. Rats were exposed to 10% concentration of GLL for 21days. Control group received tap water for same period of experiment. Our results showed that neurobehavior, absolute body and brain weights and brain histomorphology as well as parvalbumin interneurons were severely altered, with consequent astrogliosis and microgliosis after 21 days of administrating GLL. Specifically, there was severe loss and shrinkage of purkinje cells, with their nucleus, and severe diffused vacuolations of the white matter tract of GLL exposed rat brains. There was severe cell loss in the granular layer of the cerebellum resulting to reduced thickness of the layer. Also. there was severe loss of dendritic arborization of the purkinje cells in GLL exposed rat brains, and damage as well of reduced populations of parvalbumin-containing fast-spiking GABAminergic interneurons in various regions of the brain. In conclusion, data from the present study demonstrated the detrimental effects of Gwagwalada landfill leachate on the brain which may be implicated in neuropsychological conditions.