Two hundred forty-nine groundwater samples collected from 55 irrigation water supply wells in Al-Mahala Al-Kubra, Samannoud, and Al-Santa districts of the Gharbiya Governorate (Egypt) during a monitoring survey carried out in January, June, and in November in 3 years (2013–2015). The prime objective was to document, for the first time, the status and sustained trends in the concentrations of pesticides in the shallow Nile Delta aquifer. The non-parametric Mann–Kendall and Thiel–Sen trend statistical tests were applied for detection and estimation of trends and their magnitude. Violation of standards clarified emergence of methyl parathion (98.1%), endrin (97.9%), endosulfan sulfate (96.5%), dieldrin (55.3%), atrazine (42.3%), and simazine (40.4%), in decreasing order of abundances. Malathion obeyed the permissible limits (900 μg L⁻¹) in all samples. Methyl parathion showed an average rate of deterioration (μg L⁻¹ year⁻¹) of 0.82 that was largest in Al-Santa (1.0) followed by Al-Mahala Al-Kubra (0.63). Malathion proved the second largest rate emerging in Al-Mahala Al-Kubra (0.67) followed by Al-Santa (0.65). Endosulfan sulfate came third in deterioration rate (av. 0.37) followed by endrin (av. 0.32), atrazine (av. 0.32), dieldrin (av. 0.25), and simazine (av. 0.23). Groundwater improvements of pesticide contents propagated faster eastward and northward associated with larger surface water recharge rates from dense complex irrigation canals through thicker topmost silty clay layer and thicker peat layers inter-bedded in the sediments. For sustainable agriculture to alleviate negative impacts on groundwater resources and the environment, the use of ecofriendly bio-degradable or quickly deactivated pesticides along with awareness of farmers with the health hazards and the protective measures while handling pesticides are strongly recommended.

The impact of some organic pollutants on some residents of Tanta and Ismailia cities of Egypt through their consumption of vegetables, fruits and fish (Nile tilapia and catfish) was examined. Residues of organochlorine (OCS) and organophosphorus (OPS) as some polychlorinated biphenyls (PCBS) were compared with pesticides as well maximum residue limits (MRLS). Probable health risk to consumers was also assessed. P, P′-DDT, P, P′-DDE, P, P′-DDD, endrin, α-BHC, (lindane), and hexachlorbenzene (HCB) were the most detected organochlorine compounds, but did not exceed MRLs.However, OPS residues were the most frequently detected contaminants. PCBs congeners 28, 70, 52, and 180 were detected in tilapia fish from Tanta, but congeners 28 and 180 were the only detected congeners in samples collected from Ismailia region. ∑PCBS values in all matrices did not exceed MRLS. Hazard index (HI) exhibited unity for all compounds at 50 the decreasing order: catfish > vegetables > fruits > Nile tilapia in Tanta, while in Ismailia the order was Nile tilapia > fruit > vegetables. Results also revealed that risk values for adults were greater than those of children categories.

Production and use of most organochlorine pesticides (OCPs) was banned through the Stockholm Convention on persistent organic pollutants. However, appreciable amounts are still detected in the environment due to their persistence, illegal use, and releases from contaminated soils and obsolete stocks. The present study investigated the levels of OCP residues in Nairobi River. Sediment and water samples were collected from three sites along the river and screened for 17 OCPs using gas chromatography electron capture detector (GC-ECD). Mean pesticide residues ranged from 0.01 to 41.9 μg kg⁻¹ in sediment and below detection limit to 39.7 ng L⁻¹ in water. In sediment α-HCH, β-HCH, γ-HCH, heptachlor epoxide, and p,p′-DDD were detected in all samples, while α-HCH, γ-HCH, δ-HCH, heptachlor epoxide, endosulfan I, and endrin were detected in all water samples. Levels of OCPs in water were below the WHO maximum allowable limits for surface water. However, values higher than the sediment quality guidelines for sediment samples in Racecourse Road Bridge and Outering Road Bridge were reported, thus confirming the toxicity to aquatic organisms. Consequently, as these compounds are known to bio-accumulate in fatty tissues, continued use of the river water poses a health risk to animals and humans.