Risk assessment of polychlorinated biphenyls (PCBs) and trace metals in River Nile up- and downstream of a densely populated area

Abstract

Cairo city is the largest populated area along the whole course of River Nile with a wide range of anthropogenic activities. Efforts to restore fish habitat and recreational use of the river have raised concerns about its water, sediment and biota quality. This study provides a baseline data on the levels of PCBs and trace metals in River Nile along Cairo sector and implements the formulation of monitoring activities of the river's pollution status. Water, sediment and Nile tilapia (Oreochromis niloticus) samples were collected during summer season, 2013 from two sites, up- and downstream, for detection and determination of 11 PCB congeners (PCBs 28, 44, 52, 70, 101, 105, 118, 138, 152, 180 and 192) as well as six trace metals (Cu, Zn, Mn, Cd, Pb and Fe). Evidences of long- or short-term exposures to these contaminants as well as its accumulation tendency were assessed by integrating the obtained analytical results of biotic and abiotic components of this aquatic ecosystem. All calculated lifetime cancer risk values for PCBs showed unacceptable risk of cancer for human consumers at both normal and subsistence fish consumption rates. The calculated hazard index for total PCBs indicates that fish are not safe for human consumption except in site 1 at normal consumption rate. Meanwhile, trace metals do not pose unacceptable risks at both consumption rates except for Pb in site 1 at subsistence consumption rate.

Organochlorine pesticides, polybrominated diphenyl ethers and polychlorinated biphenyls in surficial sediments of the Awash River Basin, Ethiopia

“…This might show a relatively low consumption of these products. Similar concentrations of PCB were reported from Danube Delta and Nile River sediments [ 38 , 39 ].…”

“…The sediments from Awash River Basin were found to be less contaminated with PBDEs compared with reports from Zhujiang River of China [ 48 ], Cinca River of Spain [ 49 ] and Niagara River, North America [ 50 ]. The PCBs concentration of the study area was higher than reports from River Nile in Egypt [ 39 ]. Lower concentration of PCBs was detected in the Awash River Basin compared with the Huveaune River of France [ 51 ] and the Umgeni River of South Africa [ 52 ].…”

Human Health Risks Due to Fish Consumption from Nile River at Beni-Suef-Governorate- Egypt

“…The whole course of the Nile receives agricultural, domestic and industrial waste water from both pointed and non-pointed polluted sources. Such pollutants may explain the Nile water quality deterioration in Egypt [4][5][6][7][8]. Metals monitoring for both essential and non-essential elements in aquatic ecosystems become crucial because of their toxicity, non-degradable nature, tendency to accumulate in different biota, and their transmission throughout the food chain and biomagnification in high trophic level organisms [3,9,10,11].…”

“…Continuous exposure of living organisms and human beings to metals and other toxic substances may cause the decline of humans' health and aquatic ecosystem status [14,15]. Risk assessment aims to quantify the potential environmental hazards to human health into a numerical value [8,14]. The selection of a fish as a model for toxic risk assessment is because fish provide a model of exposure that is relevant to natural settings; also the safety of the aquatic products has a great concern recently [16][17][18].…”

“…The selection of a fish as a model for toxic risk assessment is because fish provide a model of exposure that is relevant to natural settings; also the safety of the aquatic products has a great concern recently [16][17][18]. Tilapia was identified as a potential fish model for the present study to determine the probability of inducing adverse human health effects because of its high production in the Middle East and North Africa [19], its large tissue mass, its low price in relative to other fish models, in addition to the wide acceptance of the Egyptian consumers to tilapia [7].…”