Monitoring of pesticide residues in fresh fruits and vegetables available in Nigerian markets and assessment of their associated health risks.

The presence of pesticide residues in agricultural products is posing serious health concerns for consumers. This study monitored the concentrations of pesticide residues in some selected fruit and vegetables, and their potential health risks were also assessed. Organochlorine (OCPs) and organophosphate (OPPs) residues were extracted and quantified with a gas chromatography-pulsed flame photometric detector. A total of 38 pesticide residues were identified and the results showed mean concentration (mg/kg fresh weight) of (OCPs) residues ranging from 0.02 to 0.37 and (OPPs) residues ranging from 0.01 to 0.33. The concentrations (mg/kg) of isodrin, heptachlor, dicofol, prothiophos, profenofos and dichlorvos were above the maximum residue limit. The non-carcinogenic health risk estimates revealed a possible potential health risk from consumption of the fruits and vegetables in adults and children for most of the pesticide residues. The cancer risk assessment estimates gave values below 10-6 which suggests no probable cancer risk. As a result of the increasing trend in pesticide use in Nigeria, routine monitoring of pesticide residues in agricultural produce is a necessity to ensure the safety of consumers.

Risk assessment of heavy metal contamination of paddy soil and rice (Oryza sativa) from Abakaliki, Nigeria.

The study assessed the concentration and bioavailability of Pb, Cd, Zn, Cr and Fe metals in soil from rice fields in Abakaliki, Nigeria. The concentrations of these heavy metals in rice grains were also determined, with a view to assessing their human health risk on consumers. Heavy metal concentrations in soil and rice were determined using FAAS after digestion with 5:1 HNO3:HClO4 while Tessier's sequential extraction method was used to obtain the fractionated soil digests. The mean concentrations (µg/g) of the total heavy metal ranged from 1.036 ± 1.86 (Cd) to 6900.537 ± 734.82 (Fe) in soil while that of rice grains ranged from 0.024 ± 0.07 (Cd) to 101.446 ± 75.26 (Fe).The concentrations of Fe and Cd in most of the soil samples and Pb in rice grains exceeded some Nigerian and International standards. The heavy metal sequential extractions of soil samples showed that lead and zinc were less mobile in the soil and are bioavailable for plant uptake. The estimated daily intake of the metals was below the tolerable daily intake. The hazard quotient and the total hazard index were less than one showing that at present, there is no possible adverse health effect on rice consumers.

Hydrochemistry and Water Quality Index of groundwater resources in Enugu north district, Enugu, Nigeria.

The physicochemical parameters of groundwater in 12 cluster boreholes in Enugu North district/region, southeast Nigeria, were studied. Twelve physicochemical parameters were determined in triplicates at monthly intervals for 3 months in dry season and then repeated in rainy season in 120 boreholes grouped into 12 clusters for 2 years. The range of values obtained during dry season include phosphate (0.12-0.87 mg/L), nitrate (1.24-8.72 mg/L), sulfate (20.10-24.34 mg/L), pH (4.9-7.5), E.C. (10.0-410.0 µS/cm), total acidity (0.06-1.24 mg/L), total alkalinity (28.0-22.10 mg/L), total hardness (100.0-140.1 mg/L), TSS (70.0-270.0 mg/L), TDS (0.00-210.0 mg/L), TS (70.0-390.0 mg/L), and turbidity (3.4-50.0 mg/L) while rainy season values were phosphate (0.30-10.60 mg/L), nitrate (1.20-120.0 mg/L), sulfate (0.0-100.0 mg/L), pH (4.9-7.5), E.C. (10.0-360.0 µS/cm), total acidity (0.10-10.5 mg/L), total alkalinity (10.0-52.1 mg/L), total hardness (100-130 mg/L), TSS (100.0-280.0 mg/L), TDS (0.0-260.0 mg/L), TS (110.0-560.0 mg/L), and turbidity (3.80-56.0 mg/L). When compared with standard guideline values recommended by regulatory bodies, rainy season nitrate values in some samples and phosphate mean values were higher than recommended values. Seasonal variations of the parameters in the samples were observed. Statistical analysis showed statistically significant variations between the 12 borehole water physicochemical parameters in dry and rainy seasons. Water quality index (WQI) analysis categorized all the water samples within the range of good to excellent.