Prioritizing hazardous pollutants in two Nigerian water supply schemes: a risk-based approach

Objective To rank pollutants in two Nigerian water supply schemes according to their effect on human health using a risk-based approach. Methods Hazardous pollutants in drinking-water in the study area were identified from a literature search and selected pollutants were monitored from April 2010 to December 2011 in catchments, treatment works and consumer taps. The disease burden due to each pollutant was estimated in disability-adjusted life years (DALYs) using data on the pollutant's concentration, exposure to the pollutant, the severity of its health effects and the consumer population. Findings The pollutants identified were microbial organisms, cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead and zinc. All were detected in the catchments but only cadmium, cobalt, chromium, manganese and lead exceeded World Health Organization (WHO) guideline values after water treatment. Post-treatment contamination was observed. The estimated disease burden was greatest for chromium in both schemes, followed in decreasing order by cadmium, lead, manganese and cobalt. The total disease burden of all pollutants in the two schemes was 46 000 and 9500 DALYs per year or 0.14 and 0.088 DALYs per person per year, respectively, much higher than the WHO reference level of 1 × 10−6 DALYs per person per year. For each metal, the disease burden exceeded the reference level and was comparable with that due to microbial contamination reported elsewhere in Africa. Conclusion The estimated disease burden of metal contamination of two Nigerian water supply systems was high. It could best be reduced by protection of water catchment and pretreatment by electrocoagulation

Source Apportionment of Heavy Metals in Utility Water Sources

Heavy metals cause cancer and non-cancer health effects in humans when consumed via drinking water. Therefore, the importance of assessing the levels and sources of heavy metals in utility water sources, with a view to proffering mitigation measures, cannot be overemphasized as not all toxic metals can be removed by conventional water treatment processes. A total of 40 composite water samples were randomly collected from utility dams and their feeding rivers from January, 2010 to December, 2011. The concentrations of metals were determined by atomic absorption spectrometry and were found to vary with season. The concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn (mg L-1) in the water sources ranged from 0.02 to 0.49, 0.01 to 0.17, 0.03 to 0.38, 0.09 to 0.48, 0.17 to 3.25, 0.05 to 0.34, 0.02 to 0.33, 0.13 to 0.61 and 0.09 to 1.07, respectively, in the dry seasons, and from 0.08 to 0.68, 0.02 to 0.58, 0.13 to 0.87, 0.02 to 0.69, 0.28 to 5.62, 0.31 to 1.28, 0.09 to 1.08, 0.23 to 1.98 and 0.26 to 1.59, respectively, in the wet season, indicating that the concentrations of Cd, Cr, Fe, Ni, and Pb exceed regulatory limits in both seasons. Furthermore, the result of principal component analysis on absolute principal component scores (PCA/APCS) used to apportion sources to the metals in the dams and rivers revealed two major anthropogenic sources accounting for over 90% of the metals. Source 1 represents anthropogenic release from small-scale entrepreneurial enterprises, such as automobile-mechanic, panel beaters, vehicle sprayers and battery recharger workshops generating and spilling wastes such as lubricating oil, grease, petrol, diesel, battery electrolytes, contributing 96.2, 99.2, 95.9, 100, 99.4, 99.9, 100 and 95.2%, of Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn, respectively, while source 2 represents the release from agricultural activities, such as from fertilizers and fungicides and contributes 63.2, 100 and 51.6% of Cd, Co and Cr, respectively

Chronic exposure to heavy metals in public water supply and human health risk assessment.

Historic disasters resulting from heavy metals contamination of drinking water emphasis the need to assess the quality of public water supply. Currently, millions of people in and around Bangladesh are facing chronic health risk of arsenic poisoning via drinking water. Therefore, to prevent the re-occurrence of these tragic episodes, heavy metals levels in public water supply at Agodi-residential area of Ibadan were determined and health risk assessment was done for metals whose levels were detected higher than the US EPA maximum contaminant levels for drinking water. These metals are Cd, Co, Cr+6 and Mn. Sampling was spread from January to July, 2010 to account for variations in rainy and dry seasons. 10 public taps were sampled at 5 different times making a total of 50 water samples collected. Metals determination was done using atomic absorption spectrophotometry. The mean concentrations (mg/L) of Cd, Co, Cr+6 and Mn were 0.053 ± 0.019 , 0.142±0.020, 0.211±0.070 and 0.171±0.017 respectively. These values are significantly higher than the metals’ maximum contaminant levels in drinking water. Health risk assessment conducted for adult and child residents, via oral and dermal routes of exposure, using the US EPA default parameters in the absence of site specific values, gave overall hazard index values of 19.1 and 44.8 respectively, while the estimated cancer risk values were 1.5E-03 and 9E-04 respectively. These values significantly exceed the target non-cancer hazard index of 1 and target cancer risk of 1.0E-06. Hence, it was concluded that the concentration of the investigative metals in the public water supply was high enough to cause carcinogenic and non-carcinogenic health effects for adults and children residing in the study area

Source Apportionment of Heavy Metals in Utility Water Sources

Heavy metals cause cancer and non-cancer health effects in humans when consumed via drinking water. Therefore, the importance of assessing the levels and sources of heavy metals in utility water sources, with a view to proffering mitigation measures, cannot be overemphasized as not all toxic metals can be removed by conventional water treatment processes. A total of 40 composite water samples were randomly collected from utility dams and their feeding rivers from January, 2010 to December, 2011. The concentrations of metals were determined by atomic absorption spectrometry and were found to vary with season. The concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn (mg L-1) in the water sources ranged from 0.02 to 0.49, 0.01 to 0.17, 0.03 to 0.38, 0.09 to 0.48, 0.17 to 3.25, 0.05 to 0.34, 0.02 to 0.33, 0.13 to 0.61 and 0.09 to 1.07, respectively, in the dry seasons, and from 0.08 to 0.68, 0.02 to 0.58, 0.13 to 0.87, 0.02 to 0.69, 0.28 to 5.62, 0.31 to 1.28, 0.09 to 1.08, 0.23 to 1.98 and 0.26 to 1.59, respectively, in the wet season, indicating that the concentrations of Cd, Cr, Fe, Ni, and Pb exceed regulatory limits in both seasons. Furthermore, the result of principal component analysis on absolute principal component scores (PCA/APCS) used to apportion sources to the metals in the dams and rivers revealed two major anthropogenic sources accounting for over 90% of the metals. Source 1 represents anthropogenic release from small-scale entrepreneurial enterprises, such as automobile-mechanic, panel beaters, vehicle sprayers and battery recharger workshops generating and spilling wastes such as lubricating oil, grease, petrol, diesel, battery electrolytes, contributing 96.2, 99.2, 95.9, 100, 99.4, 99.9, 100 and 95.2%, of Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn, respectively, while source 2 represents the release from agricultural activities, such as from fertilizers and fungicides and contributes 63.2, 100 and 51.6% of Cd, Co and Cr, respectively

Source identification of chemical contaminants in a rural settlement

Principal Component Analysis (PCA) was used to identify the source of contaminants in Ubeji settlement. The contaminants assessed are oil and grease, TPH and related heavy metals (Cd, Cr, Cu, Ni, Pb and Zn). A total of 48 groundwater, 100 surface water, 160 soil and 100 sediment samples were collected from the study site from March to August, 2011. Measurements of oil and grease and TPH in samples were done gravimetrically, while atomic absorption spectrophotometry was used for determination of heavy metals. The results show significant contamination, as TPH levels in groundwater and surface water range from 22 to 96 mg L-1, while soil and sediment levels range from 600 to 2300 mg kg-1. Also, Cd, Cr and Pb levels in the groundwater and surface water range from 0.02 to 0.47, 0.51 to 1.3 and 1.7 to 4.1 mg L-1, respectively while soil and sediment levels range from 0.04 to 0.48, 28 to 66, 45 to 69 mg kg-1, respectively. However, Cu, Ni and Zn are within safe limits. PCA revealed that the source of the contaminants is a refinery and petrochemical company located close to the settlement

Evaluation of total petroleum hydrocarbons (TPH) and some related heavy metals in soil and groundwater of Ubeji settlement, Warri Metropolis, Nigeria.

Soil and groundwater samples in areas of oil spill in Ubeji settlement, Warri metropolis, Nigeria, were collected in order to determine the oil and grease, total petroleum hydrocarbons (TPH) and some related heavy metals in the samples. Control samples were taken from a low density residential area in Delta State (Ekrejeta in Abraka) which is relatively free from petroleum activities. The parameters were evaluated in order to determine the quality of the soil and groundwater of Ubeji settlement, as a follow up on an earlier research conducted on the surface water and sediment of the settlement’s river. This research is so important because the local population uses the soil and water resources for agricultural and domestic purposes. Measurements of oil and grease and TPH in samples were done gravimetrically, while atomic absorption spectrophotometry was used for determination of heavy metals. For oil and grease and TPH, the soil had mean concentrations of 1064.90 ± 7.70 and 579.10 ± 9.30 mg kg-1, respectively, while groundwater had 315.15 ± 11.60 and 28.70 ± 1.30 mg L-1, respectively. Mean heavy metal concentration of the soil and groundwater varied between 0.30 ± 0.01 to 215.49 ± 25.33 mg kg-1 and 0.03 ± 0.01 to 3.05 ± 0.07 mg L-1, respectively. These values reveal that the investigated samples had higher levels of oil and grease, TPH and heavy metals than the control samples and regulatory standard limits. This however, is an indication of pollution of soil and groundwater of the settlement by petroleum hydrocarbons

Evaluation of total petroleum hydrocarbons (TPH) and some related heavy metals in soil and groundwater of Ubeji settlement, Warri Metropolis, Nigeria.

Soil and groundwater samples in areas of oil spill in Ubeji settlement, Warri metropolis, Nigeria, were collected in order to determine the oil and grease, total petroleum hydrocarbons (TPH) and some related heavy metals in the samples. Control samples were taken from a low density residential area in Delta State (Ekrejeta in Abraka) which is relatively free from petroleum activities. The parameters were evaluated in order to determine the quality of the soil and groundwater of Ubeji settlement, as a follow up on an earlier research conducted on the surface water and sediment of the settlement’s river. This research is so important because the local population uses the soil and water resources for agricultural and domestic purposes. Measurements of oil and grease and TPH in samples were done gravimetrically, while atomic absorption spectrophotometry was used for determination of heavy metals. For oil and grease and TPH, the soil had mean concentrations of 1064.90 ± 7.70 and 579.10 ± 9.30 mg kg-1, respectively, while groundwater had 315.15 ± 11.60 and 28.70 ± 1.30 mg L-1, respectively. Mean heavy metal concentration of the soil and groundwater varied between 0.30 ± 0.01 to 215.49 ± 25.33 mg kg-1 and 0.03 ± 0.01 to 3.05 ± 0.07 mg L-1, respectively. These values reveal that the investigated samples had higher levels of oil and grease, TPH and heavy metals than the control samples and regulatory standard limits. This however, is an indication of pollution of soil and groundwater of the settlement by petroleum hydrocarbons

The burden of disease attributable to ambient PM2.5-bound PAHs exposure in Nagpur, India

Exposure to PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) can elicit several types of cancer and non-cancer effects. Previous studies reported substantial burdens of PAH-induced lung cancer, but the burdens of other cancer types and non-cancer effects remain unknown. Thus, we estimate the cancer and non-cancer burden of disease, in disability-adjusted life years (DALYs), attributable to ambient PM2.5-bound PAHs exposure in Nagpur district, India, using risk-based approach. We measured thirteen PAHs in airborne PM2.5 sampled from nine sites covering urban, peri-urban and rural areas, from February 2013 to June 2014. We converted PAHs concentrations to benzo[a]pyrene equivalence (B[a]Peq) for cancer and non-cancer effects using relative potency factors, and relative toxicity factors derived from quantitative structure-activity relationships, respectively. We calculated time-weighted exposure to B[a]Peq, averaged over 30 years, and adjusted for early-life susceptibility to cancer. We estimated the DALYs/year using B[a]Peq exposure levels, published toxicity data, and severity of the diseases from Global Burden of Disease 2016 database. The annual average concentration of total PM2.5-bound PAHs was 458±246 ng/m3 and resulted in 49,500 DALYs/year (0.011 DALYs/person/year). The PAH-related DALYs followed this order: developmental (mostly cardiovascular) impairments (55.1%) > cancer (26.5%) or lung cancer (23.1%) > immunological impairments (18.0%) > reproductive abnormalities (0.4%)

Prioritizing hazardous pollutants in two Nigerian water supply schemes: a risk-based approach

Objective To rank pollutants in two Nigerian water supply schemes according to their effect on human health using a risk-based approach. Methods Hazardous pollutants in drinking-water in the study area were identified from a literature search and selected pollutants were monitored from April 2010 to December 2011 in catchments, treatment works and consumer taps. The disease burden due to each pollutant was estimated in disability-adjusted life years (DALYs) using data on the pollutant’s concentration, exposure to the pollutant, the severity of its health effects and the consumer population. Findings The pollutants identified were microbial organisms, cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead and zinc. All were detected in the catchments but only cadmium, cobalt, chromium, manganese and lead exceeded World Health Organization (WHO) guideline values after water treatment. Post-treatment contamination was observed. The estimated disease burden was greatest for chromium in both schemes, followed in decreasing order by cadmium, lead, manganese and cobalt. The total disease burden of all pollutants in the two schemes was 46 000 and 9500 DALYs per year or 0.14 and 0.088 DALYs per person per year, respectively, much higher than the WHO reference level of 1 × 10−6 DALYs per person per year. For each metal, the disease burden exceeded the reference level and was comparable with that due to microbial contamination reported elsewhere in Africa. Conclusion The estimated disease burden of metal contamination of two Nigerian water supply systems was high. It could best be reduced by protection of water catchment and pretreatment by electrocoagulation