Environmental Toxicology and Chemistry, Feb 1, 2002
ABSTRACT Pesticides are known to transform in the environment, but so far the study of their effe... more ABSTRACT Pesticides are known to transform in the environment, but so far the study of their effects in the environment has concentrated on the parent compounds, thereby neglecting the effects of the degradation products. The embryotoxic, developmental, and teratogenic effects of chloroacetanilide herbicides and their environmentally stable aniline degradation products were investigated in this study in view of the massive application of alachlor and metolachlor. Embryos at midblastula to early gastrula stages of a locally abundant African clawed frog Xenopus laevis were used as test organisms. The embryos were exposed to the test chemicals for 96 h in each experiment. Alachlor is more embryotoxic (the concentration causing 50% embryo lethality, 96-h LC50 = 23 microM [6.1 mg/L]) and teratogenic (teratogenic index [TI] = 1.7) than metolachlor (96-h LC50 = 48 microM [13.6 mg/L], TI = 0.2). The degradation products of alachlor and metolachlor, respectively, 2,6-diethylaniline (96-h LC50 = 13 microM [19.4 mg/L], TI = 2.1) and 2-ethyl-6-methyaniline (96-h LC50 = 509 microM [68.8 mg/L], TI = 2.7), are less embryotoxic but more teratogenic than their parent compounds. The most common teratogenic effects observed were edema for alachlor as opposed to axial flexures and eye abnormalities for 2,6-diethylaniline and 2-ethyl-6-methylaniline. Metolachlor is found to be an example of a nonteratogenic herbicide that upon degradation loses toxicity but gains teratogenicity, and both the herbicides, metolachlor and alachlor, are potential sources of teratogenic transformation products.
Alachlor, metolachlor and their respective environmentally stable aniline degradation products, 2... more Alachlor, metolachlor and their respective environmentally stable aniline degradation products, 2,6-diethylaniline and 2-ethyl-6-methylaniline were analyzed in water and sediment samples from 9 sites along River Nzoia, Kenya using gas chromatography. The degradation products were detected in > 90% of the sediment and water samples, while the parent compounds occurred in < 14% of the water samples. Much higher concentrations of the pesticides and their degradation products occurred in the sediment than in the water (1.4 up to 10 800-fold), indicating an accumulation of the compounds in the sediment. The constant occurrence of the degradation products in the sediment during the study period infers a persistence of these compounds. It is hypothesized that the prevailing tropical climatic conditions favor a quick breakdown of the pesticides to their environmentally stable degradation products, thereby making the latter more important pollutants than their parent products in the study area.
The optimisation of a TEVA column separation provides a simple, robust, and cost-effective method... more The optimisation of a TEVA column separation provides a simple, robust, and cost-effective method with low achievable detection limits, applicable to the detection of ultra-trace fallout Pu in African soils.
The impact of population expansion through economic growth and development has been identified as... more The impact of population expansion through economic growth and development has been identified as one of the key drivers of both water and sediment contamination from potentially harmful elements (PHEs). This presents a major hazard not only to aquatic ecosystems but local riparian communities and beyond who rely heavily on this natural resource for drinking water and fish—a valuable source of dietary micronutrients and protein. The present study measured biogeochemical concentration of PHEs in water, sediment and fish from locations pooled into four zones within Winam Gulf and Lake Victoria area of Kenya. Captured fish were used as a sentinel receptor of lake health to evaluate potential risks to fisheries and aquaculture food security. In water, concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu) and lead (Pb) were observed above the United States Environmental Protection Agency (US EPA) maximum contamination level drinking water guidelines (MCL), with alumini...
Studies on parasite biogeography and host spectrum provide insights into the processes driving pa... more Studies on parasite biogeography and host spectrum provide insights into the processes driving parasite diversification. Global geographical distribution and a multi-host spectrum make the tapewormLigula intestinalisa promising model for studying both the vicariant and ecological modes of speciation in parasites. To understand the relative importance of host association and biogeography in the evolutionary history of this tapeworm, we analysed mtDNA and reduced-represented genomic SNP data for a total of 139 specimens collected from 18 fish-host genera across a distribution range representing 21 countries. Our results strongly supported the existence of at least 10 evolutionary lineages and estimated the deepest divergence at approximately 4.99-5.05 Mya, which is much younger than the diversification of the fish host genera and orders. Historical biogeography analyses revealed that the ancestor of the parasite diversified following multiple vicariance events and was widespread throu...
Wastewater from pulp and paper processing industries pose varieties of problems to the receiving ... more Wastewater from pulp and paper processing industries pose varieties of problems to the receiving environment if not treated to the required discharge guidelines (Chandra et al., 2018; Kamali et al., 2019; Zainith et al., 2019). Processing of wood into pulp and its conversion into paper consumes huge amounts of fresh water, subsequently releasing enormous amounts of wastewater into the environment. The wastewater contains toxic and very complex recalcitrant organic and inorganic pollutants (Singh and Chandra, 2019). The industry has long been recognized as a significant point source of toxic contaminants of aquatic ecosystems (Hossain and Ismail, 2015). Compounds of varying toxicological significance have been identified in the pulp and paper effluents (Mehta, 2014). The wastewater contains toxins such as furans, terpenes, resin acid, chlorinated lignosulphonic acids, chlorinated resin acids, chlorinated phenols and chlorinated hydrocarbon (Barapatre and Jha, 2016). The treatment of ...
Oesophageal squamous cell carcinoma (ESCC) is one of the most common cancers in most Eastern and ... more Oesophageal squamous cell carcinoma (ESCC) is one of the most common cancers in most Eastern and Southern African countries, but its aetiology has been understudied to date. To inform its research agenda, we undertook a review to identify, of the ESCC risk factors that have been established or strongly suggested worldwide, those with a high prevalence or high exposure levels in any ESCC-affected African setting and the sources thereof. We found that for almost all ESCC risk factors known to date, including tobacco, alcohol, hot beverage consumption, nitrosamines and both inhaled and ingested PAHs, there is evidence of population groups with raised exposures, the sources of which vary greatly between cultures across the ESCC corridor. Research encompassing these risk factors is warranted and is likely to identify primary prevention strategies.
American Journal of Environmental Engineering, 2016
Pesticides have many different properties that affect their behaviour in the environment. Pestici... more Pesticides have many different properties that affect their behaviour in the environment. Pesticide’s solubility in water has a great impact on leaching potential and environmental fate. The objective of this study was to determine the relationship between organic carbon based partition coefficient (koc) and pesticides solubility (S) of pesticides used along the shore of Lake Naivasha using regression analysis. The properties (S, and soil/water equilibrium partition coefficient (kd)) of pesticides selected from an inventory of pesticides used in farms around Lake Naivasha, were determined from the manufacturers’ materials safety data sheets. The organic carbon (foc) of the soil from the study area was then determined using the loss-on-ignition (LOI) method and used to calculate koc. The results showed that the soils around Lake Naivasha had a mean organic carbon (foc) content of 1.770% and a regression equation for koc and S for the area to be log koc = -0.368logS + 3.256. It was co...
About nine million Artisanal and Small-scale Gold Mining (ASGM) workers in Africa and people livi... more About nine million Artisanal and Small-scale Gold Mining (ASGM) workers in Africa and people living near ASGM activities are highly exposed to geogenic and anthropogenic potentially toxic elements (PTEs). Despite the hazards and risks posed by ASGM being well characterized, coordinated multidisciplinary environmental characterization with combined public health studies are limited, with often piecemeal and snapshot studies reported, as highlighted by this review. Furthermore, studies are often not connected with efforts to minimize hazards holistically. Given this, we systematically reviewed the scientific literature on human health hazards associated with ASGM in Africa through Google Scholar, Science Direct, and Pubmed databases. One hundred and seventy-three peer-reviewed papers published between 1996 and June 2023 from 30 African countries were identified. Toxicological environmental hazards were reported in 102 peer-reviewed papers, notably As, Cd, CN, Cr, Hg, Pb, respirable Si...
Lakes and Reservoirs: Research and Management, Feb 24, 2010
Use of some fish parasites as bioindicators of heavy metal pollution has been demonstrated as a p... more Use of some fish parasites as bioindicators of heavy metal pollution has been demonstrated as a promising approach because of their capacity to bioconcentrate such elements. This study evaluated the effects of a cestode parasite, Ligula intestinalis, on the accumulation ...
Artisanal and small-scale gold mining (ASGM) represents 20% of gold supply and 90% of gold mining... more Artisanal and small-scale gold mining (ASGM) represents 20% of gold supply and 90% of gold mining workforce globally, which operates in highly informal setups. Pollutants from mined ores and chemicals introduced during gold processing pose occupational and inadvertent health risks to the extent that has not been well elucidated in Africa. Trace and major elements were analysed using inductively coupled plasma mass spectrometry in soil, sediment and water samples from 19 ASGM villages in Kakamega and Vihiga counties. Associated health risks for residents and ASGM workers were assessed. This paper focuses on As, Cd, Cr, Hg, Ni and Pb for which 96% of soil samples from mining and ore processing sites had As concentrations up to 7937 times higher than the US EPA 12 mg kg−1 standard for residential soils. Soil Cr, Hg and Ni concentrations in 98%, 49% and 68% of the samples exceeded respective USEPA and CCME standards, with 1–72% bioaccessibility. Twenty-five percentage of community drink...
Pesticide application in agricultural and residential areas is a worldwide practice. However, hum... more Pesticide application in agricultural and residential areas is a worldwide practice. However, human pesticide poisoning and environmental pollution through pesticide residues remain a challenge in the developing world. The present study investigated the intensity of pesticide application in large-scale farms in Trans-Nzoia County to screen and prioritize the pesticides for potential human health and environmental risks. A cross-sectional survey involving 348 farmers was conducted in the study area, and data was analyzed using SPSS. Environmental Exposure Potential (EEP) and Toxicity Potentials (TP) were analyzed from the Pesticide Properties Database (PPDB). Majority (99.4%) of the farms surveyed apply various pesticide classes that include: organophosphates (34.78%), neonicotinoids (15.22%), carbamates (10.87%), pyrethroids (10.87%), organochlorines (8.7%), triazoles (6.5%), copper-based (4.34%), avermectines (2.17%), triazines (2.17%), and amidines (2.17%), with the use of organic...
Groundwater contamination by pesticides is an environmental health concern throughout the world. ... more Groundwater contamination by pesticides is an environmental health concern throughout the world. Many pesticides do not leach because they are adsorbed on the soil particles or organic matter even though they may have a relatively high solubility. The objective of this study was to determine the relationship between soil permeability and organic carbon in the transport of pesticides into groundwater along the shore of Lake Naivasha, using regression analysis of soil permeability and organic carbon data collected along the shore. The results showed that the soil organic carbon (foc) positively affected the soil permeability (k) and were related by the equation k= 80.724(1.726) foc . It was concluded that organic carbon increased soil permeability by 30%, thereby recharging the aquifer while at the same time reducing pesticide transport into groundwater. Based on these findings the study recommended that the use of compost (organic amendments) should be increased in place of inorganic...
Environmental Toxicology and Chemistry, Feb 1, 2002
ABSTRACT Pesticides are known to transform in the environment, but so far the study of their effe... more ABSTRACT Pesticides are known to transform in the environment, but so far the study of their effects in the environment has concentrated on the parent compounds, thereby neglecting the effects of the degradation products. The embryotoxic, developmental, and teratogenic effects of chloroacetanilide herbicides and their environmentally stable aniline degradation products were investigated in this study in view of the massive application of alachlor and metolachlor. Embryos at midblastula to early gastrula stages of a locally abundant African clawed frog Xenopus laevis were used as test organisms. The embryos were exposed to the test chemicals for 96 h in each experiment. Alachlor is more embryotoxic (the concentration causing 50% embryo lethality, 96-h LC50 = 23 microM [6.1 mg/L]) and teratogenic (teratogenic index [TI] = 1.7) than metolachlor (96-h LC50 = 48 microM [13.6 mg/L], TI = 0.2). The degradation products of alachlor and metolachlor, respectively, 2,6-diethylaniline (96-h LC50 = 13 microM [19.4 mg/L], TI = 2.1) and 2-ethyl-6-methyaniline (96-h LC50 = 509 microM [68.8 mg/L], TI = 2.7), are less embryotoxic but more teratogenic than their parent compounds. The most common teratogenic effects observed were edema for alachlor as opposed to axial flexures and eye abnormalities for 2,6-diethylaniline and 2-ethyl-6-methylaniline. Metolachlor is found to be an example of a nonteratogenic herbicide that upon degradation loses toxicity but gains teratogenicity, and both the herbicides, metolachlor and alachlor, are potential sources of teratogenic transformation products.
Alachlor, metolachlor and their respective environmentally stable aniline degradation products, 2... more Alachlor, metolachlor and their respective environmentally stable aniline degradation products, 2,6-diethylaniline and 2-ethyl-6-methylaniline were analyzed in water and sediment samples from 9 sites along River Nzoia, Kenya using gas chromatography. The degradation products were detected in > 90% of the sediment and water samples, while the parent compounds occurred in < 14% of the water samples. Much higher concentrations of the pesticides and their degradation products occurred in the sediment than in the water (1.4 up to 10 800-fold), indicating an accumulation of the compounds in the sediment. The constant occurrence of the degradation products in the sediment during the study period infers a persistence of these compounds. It is hypothesized that the prevailing tropical climatic conditions favor a quick breakdown of the pesticides to their environmentally stable degradation products, thereby making the latter more important pollutants than their parent products in the study area.
The optimisation of a TEVA column separation provides a simple, robust, and cost-effective method... more The optimisation of a TEVA column separation provides a simple, robust, and cost-effective method with low achievable detection limits, applicable to the detection of ultra-trace fallout Pu in African soils.
The impact of population expansion through economic growth and development has been identified as... more The impact of population expansion through economic growth and development has been identified as one of the key drivers of both water and sediment contamination from potentially harmful elements (PHEs). This presents a major hazard not only to aquatic ecosystems but local riparian communities and beyond who rely heavily on this natural resource for drinking water and fish—a valuable source of dietary micronutrients and protein. The present study measured biogeochemical concentration of PHEs in water, sediment and fish from locations pooled into four zones within Winam Gulf and Lake Victoria area of Kenya. Captured fish were used as a sentinel receptor of lake health to evaluate potential risks to fisheries and aquaculture food security. In water, concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu) and lead (Pb) were observed above the United States Environmental Protection Agency (US EPA) maximum contamination level drinking water guidelines (MCL), with alumini...
Studies on parasite biogeography and host spectrum provide insights into the processes driving pa... more Studies on parasite biogeography and host spectrum provide insights into the processes driving parasite diversification. Global geographical distribution and a multi-host spectrum make the tapewormLigula intestinalisa promising model for studying both the vicariant and ecological modes of speciation in parasites. To understand the relative importance of host association and biogeography in the evolutionary history of this tapeworm, we analysed mtDNA and reduced-represented genomic SNP data for a total of 139 specimens collected from 18 fish-host genera across a distribution range representing 21 countries. Our results strongly supported the existence of at least 10 evolutionary lineages and estimated the deepest divergence at approximately 4.99-5.05 Mya, which is much younger than the diversification of the fish host genera and orders. Historical biogeography analyses revealed that the ancestor of the parasite diversified following multiple vicariance events and was widespread throu...
Wastewater from pulp and paper processing industries pose varieties of problems to the receiving ... more Wastewater from pulp and paper processing industries pose varieties of problems to the receiving environment if not treated to the required discharge guidelines (Chandra et al., 2018; Kamali et al., 2019; Zainith et al., 2019). Processing of wood into pulp and its conversion into paper consumes huge amounts of fresh water, subsequently releasing enormous amounts of wastewater into the environment. The wastewater contains toxic and very complex recalcitrant organic and inorganic pollutants (Singh and Chandra, 2019). The industry has long been recognized as a significant point source of toxic contaminants of aquatic ecosystems (Hossain and Ismail, 2015). Compounds of varying toxicological significance have been identified in the pulp and paper effluents (Mehta, 2014). The wastewater contains toxins such as furans, terpenes, resin acid, chlorinated lignosulphonic acids, chlorinated resin acids, chlorinated phenols and chlorinated hydrocarbon (Barapatre and Jha, 2016). The treatment of ...
Oesophageal squamous cell carcinoma (ESCC) is one of the most common cancers in most Eastern and ... more Oesophageal squamous cell carcinoma (ESCC) is one of the most common cancers in most Eastern and Southern African countries, but its aetiology has been understudied to date. To inform its research agenda, we undertook a review to identify, of the ESCC risk factors that have been established or strongly suggested worldwide, those with a high prevalence or high exposure levels in any ESCC-affected African setting and the sources thereof. We found that for almost all ESCC risk factors known to date, including tobacco, alcohol, hot beverage consumption, nitrosamines and both inhaled and ingested PAHs, there is evidence of population groups with raised exposures, the sources of which vary greatly between cultures across the ESCC corridor. Research encompassing these risk factors is warranted and is likely to identify primary prevention strategies.
American Journal of Environmental Engineering, 2016
Pesticides have many different properties that affect their behaviour in the environment. Pestici... more Pesticides have many different properties that affect their behaviour in the environment. Pesticide’s solubility in water has a great impact on leaching potential and environmental fate. The objective of this study was to determine the relationship between organic carbon based partition coefficient (koc) and pesticides solubility (S) of pesticides used along the shore of Lake Naivasha using regression analysis. The properties (S, and soil/water equilibrium partition coefficient (kd)) of pesticides selected from an inventory of pesticides used in farms around Lake Naivasha, were determined from the manufacturers’ materials safety data sheets. The organic carbon (foc) of the soil from the study area was then determined using the loss-on-ignition (LOI) method and used to calculate koc. The results showed that the soils around Lake Naivasha had a mean organic carbon (foc) content of 1.770% and a regression equation for koc and S for the area to be log koc = -0.368logS + 3.256. It was co...
About nine million Artisanal and Small-scale Gold Mining (ASGM) workers in Africa and people livi... more About nine million Artisanal and Small-scale Gold Mining (ASGM) workers in Africa and people living near ASGM activities are highly exposed to geogenic and anthropogenic potentially toxic elements (PTEs). Despite the hazards and risks posed by ASGM being well characterized, coordinated multidisciplinary environmental characterization with combined public health studies are limited, with often piecemeal and snapshot studies reported, as highlighted by this review. Furthermore, studies are often not connected with efforts to minimize hazards holistically. Given this, we systematically reviewed the scientific literature on human health hazards associated with ASGM in Africa through Google Scholar, Science Direct, and Pubmed databases. One hundred and seventy-three peer-reviewed papers published between 1996 and June 2023 from 30 African countries were identified. Toxicological environmental hazards were reported in 102 peer-reviewed papers, notably As, Cd, CN, Cr, Hg, Pb, respirable Si...
Lakes and Reservoirs: Research and Management, Feb 24, 2010
Use of some fish parasites as bioindicators of heavy metal pollution has been demonstrated as a p... more Use of some fish parasites as bioindicators of heavy metal pollution has been demonstrated as a promising approach because of their capacity to bioconcentrate such elements. This study evaluated the effects of a cestode parasite, Ligula intestinalis, on the accumulation ...
Artisanal and small-scale gold mining (ASGM) represents 20% of gold supply and 90% of gold mining... more Artisanal and small-scale gold mining (ASGM) represents 20% of gold supply and 90% of gold mining workforce globally, which operates in highly informal setups. Pollutants from mined ores and chemicals introduced during gold processing pose occupational and inadvertent health risks to the extent that has not been well elucidated in Africa. Trace and major elements were analysed using inductively coupled plasma mass spectrometry in soil, sediment and water samples from 19 ASGM villages in Kakamega and Vihiga counties. Associated health risks for residents and ASGM workers were assessed. This paper focuses on As, Cd, Cr, Hg, Ni and Pb for which 96% of soil samples from mining and ore processing sites had As concentrations up to 7937 times higher than the US EPA 12 mg kg−1 standard for residential soils. Soil Cr, Hg and Ni concentrations in 98%, 49% and 68% of the samples exceeded respective USEPA and CCME standards, with 1–72% bioaccessibility. Twenty-five percentage of community drink...
Pesticide application in agricultural and residential areas is a worldwide practice. However, hum... more Pesticide application in agricultural and residential areas is a worldwide practice. However, human pesticide poisoning and environmental pollution through pesticide residues remain a challenge in the developing world. The present study investigated the intensity of pesticide application in large-scale farms in Trans-Nzoia County to screen and prioritize the pesticides for potential human health and environmental risks. A cross-sectional survey involving 348 farmers was conducted in the study area, and data was analyzed using SPSS. Environmental Exposure Potential (EEP) and Toxicity Potentials (TP) were analyzed from the Pesticide Properties Database (PPDB). Majority (99.4%) of the farms surveyed apply various pesticide classes that include: organophosphates (34.78%), neonicotinoids (15.22%), carbamates (10.87%), pyrethroids (10.87%), organochlorines (8.7%), triazoles (6.5%), copper-based (4.34%), avermectines (2.17%), triazines (2.17%), and amidines (2.17%), with the use of organic...
Groundwater contamination by pesticides is an environmental health concern throughout the world. ... more Groundwater contamination by pesticides is an environmental health concern throughout the world. Many pesticides do not leach because they are adsorbed on the soil particles or organic matter even though they may have a relatively high solubility. The objective of this study was to determine the relationship between soil permeability and organic carbon in the transport of pesticides into groundwater along the shore of Lake Naivasha, using regression analysis of soil permeability and organic carbon data collected along the shore. The results showed that the soil organic carbon (foc) positively affected the soil permeability (k) and were related by the equation k= 80.724(1.726) foc . It was concluded that organic carbon increased soil permeability by 30%, thereby recharging the aquifer while at the same time reducing pesticide transport into groundwater. Based on these findings the study recommended that the use of compost (organic amendments) should be increased in place of inorganic...
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