School of Pure and Applied Sciences

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    Glutathione S-Transferases: α-Naphthyl Acetate Activity and Possible Role in Insecticide Resistance
    (1995) Lalah, Joseph O; Chien, Cheng-I; Motoyama, Naoki; Dauterman, Walter C
    Rat liver and house fly, Musca domestica L., glutathione S-transferases were purified by affinity chromatography and chromatofocusing. The specific activity with α-naphthyl acetate (a substrate, for general esterase activity) was determined. Some of the esterase activity that is normally assayed for resistance is apparently caused by the activity of the glutathione S-transferase.
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    The Persistence and Fate of Malathion Residues in Stored Beans (Phaseolus vulgaris) and Maize (Zea mays)
    (1996) Lalah, Joseph O; Wandiga, Shem O
    Two experimental models simulating the traditional storage conditions prevalent in Kenya, i.e. the open basket model and the modern wooden box model, were used to study the rate of dissipation and fate of malathion residues in maize grains and beans stored for periods of up to one year at ambient temperatures averaging 23°C. The grain samples were initially treated with 10·36 mg kg−1 of radiolabelled malathion dust prior to storage and portions analysed at regular intervals for malathion, malaoxon and the transformation products isomalathion, malathion α-monocarboxylic acid and malathion β-monocarboxylic acid using a combination of chromatographic, radioisotopic and mass-spectrometric techniques. The findings showed a gradual penetration of malathion into the grains in amounts which were slightly higher in maize than in beans irrespective of the method of storage. After 51 weeks of storage, 34–60% of the initial residues persisted in all the grains. The total residual levels were slightly higher in beans than in maize irrespective of the storage methods though the persistence was a little higher in the wooden box than in the open basket. The rates of dissipation of the pesticide from the grains decreased with storage time and followed a biphasic pattern. Applying first-order reaction kinetics, the following half-lives were obtained: maize grains stored in open basket: 194 days; maize grains stored in closed wooden box: 261 days; beans stored in open basket: 259 days; beans stored in closed wooden box: 405 days. Beans stored in the wooden box had higher levels of bound residues than those sampled from the open basket. This trend was similar in maize grains although the concentrations were lower. The analysis of malathion metabolites confirmed the degradation trend of the residues.
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    The metabolism and distribution of [14C‐phenyl]‐ethyl parathion in a tropical soil under field conditions
    (1999) Lalah, Joseph O; Wandiga, Shem O
    The persistence, distribution and metabolism of [l4C‐phenyl]‐ethyl parathion applied to soil columns in an agricultural farm were investigated under tropical field conditions. Volatilization, soil microbial activity, moisture levels and pH were found to influence the persistence, distribution and metabolism of this pesticide in the soil. There was rapid distribution of the pesticide in the soil matrix with time resulting in high levels of bound residues which reduced the overall rate of disappearance of parathion residues from the soil. The soil was slightly acidic but the metabolites, paraoxon, p‐nitrophenol and p‐aminophenol were detected in the soil extracts 7 days after pesticide application. After 72 days, 43.7% of the applied pesticide remained in soil composed of 18.9% extractable and 24.8% bound residues. A mechanism for the metabolism of ethyl parathion in this soil is given.
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    Regioselective Synthesis of a Branched Isomer of Nonylphenol, 4-(3′,6′-Dimethyl-3′-heptyl)phenol, and Determination of its Important Environmental Properties
    (2001) Lalah, Joseph O; Schramm, Karl-Werner; Lenoir, Dieter; Henkelmann, Bernhard; Hertkorn, Norbert; Kettrup, Antonius; Günther, Klaus
    A method for the synthesis of a pure nonylphenol isomer, 4-(3′,6′-dimethyl-3′-heptyl)phenol, by Friedel–Crafts reaction between anisole and 3-bromo-3,6-dimethylheptane that gives a 47.3 % overall yield is reported. The reactions were followed by GC-MS, and the chemical structures are in agreement with the NMR and IR spectra. The log Kow value for this compound, its water solubility, vapor pressure, and Henry's Law constant were also determined. These physicochemical properties were required for prediction of the compound's behavior in aquatic ecosystems.
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    The effect of boiling on the removal of persistent malathion residues from stored grains
    (Elsevier, 2002) Lalah, Joseph O; Wandiga, Shem O
    This study aimed at finding the fate of malathion in maize grains and beans stored in a tropical laboratory for 12 months at temperatures of 20–24°C, relative humidity of 42–80% and grain moisture contents of 11.7–12.5% in maize grains and 14.1–15.3% in beans. Malathion and its degradation products malaoxon, malathion α-monocarboxylic acid and β-monocarboxylic acid were found in stored maize grains and beans treated with a mixture of pure radiolabelled malathion and 2% malathion dust after 12 months of storage. A significant percentage of these residues were removed from the grains by cooking in boiling water. Though malathion and its polar metabolites, malathion α- and malathion β-monocarboxylic acids were completely eliminated by boiling, malaoxon was still detected in quite high quantities in the solvent extracts of cooked beans and maize. Addition of NaCl to the grains increased the rate of removal of the residues from both maize grains and beans by boiling water. The data obtained clearly showed a distinction in persistence, distribution and metabolism of malathion between the two types of crop, indicating also that more adverse windy, humid and hot tropical conditions contributed to higher rates of metabolism and loss of the pesticide from the grains. The accuracy and ease of using radiolabelled malathion in investigating its fate and behaviour in the two matrices is shown in this study.
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    The bioaccumulation and fate of a branched 14C-p-nonylphenol isomer in Lymnaea stagnalis L.
    (2003) Lalah, Joseph O.; Behechti, Akbar; Severin, Gabriele F; Lenoir, Dieter; Günther, Klaus; Kettrup, Antonius; Schramm, Karl-Werner
    A single branched isomer of p-nonylphenol, 4(3′,6′-dimethyl-3′-heptyl)-phenol, previously identified by gas chromatography-mass spectrometry as one of the major constituent isomers in p-nonylphenol (constituting approximately 10% of all its isomers), was synthesized and used in studies of its bioaccumulation and excretion in the hermophroditic pond snail Lymnaea stagnalis L. Branched isomers of nonylphenol are perceived to have more estrogenlike toxicity than the straight-chain isomers in addition to being more resistant to biodegradation in the environment. With an average static exposure concentration of 104 μg/L (range: 92–116 μg/L) in water at 19°C for 8 d, the uptake of the compound was found to be fairly rapid, reaching a peak concentration of 23,548 μg/kg of whole tissue wet weight after 5 d and a peak bioaccumulation factor (BAFw) of 242 (5,562, based on lipid weight) after 3 d. The uptake data fitted into a logarithmic expression C(t) = 5,231 ln(t) + 11,956, where C(t) is the amount of residues accumulated in whole tissue in micrograms per kilogram tissue wet weight after a period of time, t, and t is the period of exposure in days. By determination of the excretion of 14C-residues released in water and in feces, an average loss of 96% of the accumulated residues was achieved after 22 d of continuous exposure to clean water. By first-order kinetics analysis of the excretion data, an average half-life of excretion of 4.9 d was obtained. By high-performance liquid chromatography and gas-liquid chromatography-mass spectrometry, a catechol metabolite, 4(3′,6′-dimethyl-3′-heptyl)-catechol, was detected in tissue extracts (after hydrolysis with β-glucuronidase) and in feces, in addition to the parent isomer, suggesting that the isomer may have been metabolized by glucuronic acid conjugation and hydroxylation at the ortho position of its phenolic ring.
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    Polynuclear aromatic compounds in kerosene, diesel and unmodified sunflower oil and in respective engine exhaust particulate emissions
    (2005) Lalah, Joseph O; Kaigwara, Peter N
    Polynuclear aromatic compounds (PAC) were characterized in diesel fuel, kerosene fuel and unmodified sunflower oil as well as in their respective engine exhaust particulates. Diesel fuel was found to contain high amounts of different PAC, up to a total concentration of 14,740 ppm, including carbazole and dibenzothiophene, which are known carcinogens. Kerosene fuel was also found to contain high amounts of different PAC, up to a total concentration of 10,930 ppm, consisting mainly of lower molecular weight (MW) naphthalene and its alkyl derivatives, but no PAC component peaks were detected in the unmodified sunflower oil. Engine exhaust particulates sampled from a modified one-cylinder diesel engine running on diesel, kerosene and unmodified sunflower oil, respectively, were found to contain significantly high concentrations of different PAC, including many of the carcinogenic ones, in the soluble organic fraction (SOF). PAC concentrations detected at the exhaust outlet indicated that most of the PAC that were present in diesel and kerosene fuels before the test runs got completely burnt out during combustion in the engine whereas some new ones were also formed. The difference between the character and composition of PAC present in the fuels and those emitted in the exhaust particulates indicated that exhaust PAC were predominantly combustion generated. High amounts of PAC, up to totals of 52,900 and 4830 µg m−3 of burnt fuel, in diesel and kerosene exhaust particulates, respectively, were detected in the dilution tunnel when the exhaust emissions were mixed with atmospheric air. Significant amounts of PAC were also emitted when the engine was run on unmodified sunflower oil with a total concentration of 17,070 µg m−3 of burnt fuel detected in the dilution tunnel. High proportions of the combustion-generated PAC determined when the engine was run on diesel, kerosene and unmodified sunflower, respectively, consisted of nitrogen-containing PAC (PANH) and sulphur-containing PAC (PASH).
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    Astronomy in the cultural heritage of African societies
    (2006) Baki, Paul
    The African perspectives of astronomy are explored from the point of view of using indigenous knowledge of the night sky for purposes of addressing local challenges such as food insecurity and periodic natural weather phenomena such as droughts and floods. The local ethnic groups use stellar positions, and plant and animal behaviour changes for purposes of forecasting the weather and climate for the coming seasons. These traditional indicators give rise to an interdisciplinary discourse that could benefit the community in environmental protection measures and boost the tourism industry in some countries in Africa
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    Seasonal variability of persistent organochlorine pesticide residues in marine fish along the Indian Ocean coast of Kenya
    (Taylor & Francis, 2008-05-01) Lalah, Joseph O.; Barasa, M. W.; Wandiga, S. O.
    The adsorption behaviour of DDT in a tropical silt-clay soil from Kenya showed that addition of increasing metal ion concentrations from 10 to 100 lg/g of soil, reduced the % DDT adsorption in the soil by factors ranging from 6.1% to 15.4% depending on the type of metal ion. The inhibition of adsorption by metal ions was most observed in the lower ranges of metal ion concentrations in soil, i.e. up to 100 lg/g, beyond which additional increase in metal ion concentration did not result in any further increase in % adsorption. In the standard adsorption test procedure with different soil samples saturated with 100 lg/g of metal ions, the rate of adsorption of the pesticide varied with the type of metal ion and the equilibrium maximum adsorption of DDT was lowered with addition of metal ions, with the % adsorption of 78.4% (control) being reduced to lower values in the range of 67%–77.4%, depending on the type of metal ion. The data for control and samples fitted well into the Freundlich adsorption model and showed that addition of metal ions lowered the Kf values compared with control. The results suggested that in the natural soil–water environments where there was no disturbance, aggregation of humic substances-pesticide molecule complexes altered the observed lowering of adsorption caused by inhibition by metal ions, and enhanced binding to solid soil phase occurred instead. In the leaching experiments, DDT was found to leach more extensively in soils with lower %OC
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    Anthropogenic Sources of Heavy Metals in the Indian Ocean Coast of Kenya
    (Springer Science+Business Media, LLC, 2008-11-28) Lalah, Joseph O.
    Water and surface sediment samples from Rivers Sabaki, Ramisi and Vevesi that flow into the Indian Ocean coast of Kenya were analysed for heavy metals. The sediment concentrations of exchangeable cations (in μg/g) for Co, Cu, Mn, Ni, Pb, Sn and Zn ranged from 0.10 to 506.75 (for Mn at Sabaki), constituting between 2% and 20% of the total metal concentrations obtained by digestion with strong acid. Cu, Mn, Ni, Pb and Zn were more leachable with 0.1 N HCl. The total dissolved metal in water and the total sediment concentrations for Ag, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sn and Zn are given in the text. For dissolved metals, the metal/Mn ratios indicated higher concentrations of Ag in Sabaki River, Cd in Ramisi, Ni in Sabaki and Pb in Ramisi, respectively. In sediments, the metal/Mn ratios showed higher enrichment of Ag in Ramisi, Cd in Sabaki and Vevesi, and Zn in Sabaki, respectively. Enrichment factors showed elevated levels of Cd, Pb and Zn in sediment in River Sabaki and River Vevesi that were due to anthropogenic inputs through Athi River. The total dissolved metal concentration ranges for the three rivers were comparable with those ranges reported in rivers in South Africa but the sediment concentrations were below those of rivers in Europe and Asia where anthropogenic addition of some of the toxic elements such as Cu, Pb and Cd is evidently higher.
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    Spartial and Seasonal Variations in Concentrations of Polycyclic Aromatic Hydrocarbons in Water and Sediment of Kisumu City Bay of Winam Gulf, Lake Victoria-Kenya
    (2009) Kwach, Bowa O; Lalah, Joseph O; Wandiga, O. Shem
    Seasonal and offshore concentration variations for selected sixteen priority pollutant polycyclic aromatic hydrocarbons (PAHs) in surface sediments and water of Car Wash and Kisat areas of Winam Gulf, Lake Victoria, have been investigated. PAHs concentrations in sediments and water range from 0.4 to 31.95 μg/g dry weight and 3.32 to 55.8 μg/L, respectively. Statistical analysis of the PAHs concentrations showed that the most contaminated samples are found during rainy season (April, 2006), 5 m offshore for sediments and 10 m offshore for water. Dry season (October, 2005) generally recorded lower concentrations. The variations showed significant difference (p ≤ 0.05) with season and distance of sampling from the shore.
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    The dissipation of hexazinone in tropical soils under semi-controlled field conditions in Kenya
    (2009) Lalah, Joseph O; Muendo, Bonface M.; Getenga, Zachary M
    The dissipation of hexazinone (Velpar) in two tropical soil types in Kenya was studied under field and semi-controlled conditions for a period of 84 days. The dissipation was found to be very rapid and this could be attributed to adverse weather conditions including high initial rainfall as well as to low soil-organic-matter content, volatilization, surface run-off and biodegradation. The DT50 values of dissipation obtained by first order kinetics were 20 days and 21.3 days in clay and loam soil types, respectively. The influence of bargasse compost (1000 μg/g dry soil) was also studied and was found to enhance dissipation to some extent, giving DT50 values of 18 days and 18.3 days in clay and loam soil types, respectively.
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    Trace metals in Lates niloticus and Rastrineobola argentea samples for human consumption at Winam Gulf of Lake Victoria
    (2009) Ongeri, DMK; Lalah, JO; Wandiga, SO; Schrammc, K.-W; Michalke, B
    Trace metals were determined in the two most abundant fish species in the Winam Gulf of Lake Victoria (Lates niloticus and Rastrineobola argentea). The results show that the concentratios of the metals have no significant difference (p < 0.05) among the different sampling sites for each species. This situation was attributed to the mobility trends of fish. The abundance trend of the metals in L. niloticus was Fe>Cu>Pb>Cd, while that of Rastrineobola argentea was Zn>Fe>Cu>Pb>Cd. The difference in the trends was attributed to the fact that Rastrineobola argentea is consumed wholly, while the internal organs of L. niloticus are gotten rid of before consumption. This same reason explains why the concentrations of the metals were significantly higher in Rastrineobola argentea compared to those in L. niloticus. Rastrineobola argentea was found to be a major source of trace metals intake by humans.
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    The Effects of Mn2+, Ni2+, Cu2+, Co2+ and Zn2+ Ions on Pesticide Adsorption and Mobility in a Tropical Soil
    (Springer, 2009-05) Lalah, Joseph. O.; Njogu, S. N.; Wandiga, S. O.
    The adsorption behaviour of DDT in a tropical silt-clay soil from Kenya showed that addition of increasing metal ion concentrations from 10 to 100 lg/g of soil, reduced the % DDT adsorption in the soil by factors ranging from 6.1% to 15.4% depending on the type of metal ion. The inhibition of adsorption by metal ions was most observed in the lower ranges of metal ion concentrations in soil, i.e. up to 100 lg/g, beyond which additional increase in metal ion concentration did not result in any further increase in % adsorption. In the standard adsorption test procedure with different soil samples saturated with 100 lg/g of metal ions, the rate of adsorption of the pesticide varied with the type of metal ion and the equilibrium maximum adsorption of DDT was lowered with addition of metal ions, with the % adsorption of 78.4% (control) being reduced to lower values in the range of 67%–77.4%, depending on the type of metal ion. The data for control and samples fitted well into the Freundlich adsorption model and showed that addition of metal ions lowered the Kf values compared with control. The results suggested that in the natural soil–water environments where there was no disturbance, aggregation of humic substances-pesticide molecule complexes altered the observed lowering of adsorption caused by inhibition by metal ions, and enhanced binding to solid soil phase occurred instead. In the leaching experiments, DDT was found to leach more extensively in soils with lower
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    High Concentrations of Polycyclic Aromatic Hydrocarbons Found in Water and Sediments of Car Wash and Kisat Areas of Winam Gulf, Lake Victoria-Kenya
    (Springer Science+Business Media, 2009-08-28) Lalah, Joseph O.
    Mean concentrations of selected USEPA priority polycyclic aromatic hydrocarbons (PAHs) in surface sediments and water samples from Car Wash and Kisat areas of Winam Gulf, Lake Victoria in Kenya have been determined using GC-FID and GC-MS. Sampling was done during the rainy season in April 2006. The PAH concentrations in sediment and water ranged from 0.04 to 31.95 lg/ g dry weight and 3.32 to 55.8 lg/L, respectively, depending upon the sampling location. The total concentration levels of PAHs in both the sediment and water phase in this study were found to be much higher compared with those reported from other regions worldwide, revealing significant PAH pollution of Car Wash and Kisat areas of Kisumu city bay as a consequent of anthropogenic activities as described in the text. The GC-detected PAHs were confirmed by GC-MS.
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    Soil and water contamination with carbofuran residues in agricultural farmlands in Kenya following the application of the technical formulation Furadan
    (2010) Otieno, Peter O; Lalah, Joseph O; Virani, Munir; Jondiko, Isaac O; Schramm, Karl-Werner
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    Carbofuran and its Toxic Metabolites Provide Forensic Evidence for Furadan Exposure in Vultures (Gyps africanus ) in Kenya
    (2010) Otieno, Peter O; Lalah, Joseph O; Virani, Munir; Jondiko, Isaac O; Schramm, Karl-Werner
    Forensic analysis of carbofuran residues in weathered tissue samples for evidence of Furadan exposure in vultures (Gps africanus) by HPLC gave concentration (mg/Kg dry tissue weight) ranges of bdl – 0.07 (carbofuran), bdl – 0.499 (3-ketocarbofuran) and 0.013–0.147 (3-hydroxycarbofuran) in beaks, bdl–0.65 (carbofuran), 0.024–0.190 (3-ketocarbofuran) and 0.017–0.098 (3-hydroxycarbofuran) in feet, 0.179–0.219 (3-ketocarbofuran) and 0.081–0.093 (3-hydroxycarbofuran) in crop content, 0.078–0.082 (3-ketocarbofuran) and 0.091–0.101 (3-hydroxycarbofuran) in muscle of a laced carcass and 0.006–0.014 (carbofuran), 0.590–1.010 (3-ketocarbofuran) and 0.095–0.135 (3-hydroxycarbofuran) in soil sampled from a poisoning site. These compounds were confirmed by GC-MS. The results showed that HPLC combined with GC-MS is suitable for forensic analysis of carbofuran residues in bird tissue samples and that forensic investigation should include its two toxic metabolites, 3-hydroxycarbofuran and 3-ketocarbofuran.
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    Soil and water contamination with carbofuran residues in agricultural farmlands in Kenya following the application of the technical formulation Furadan
    (2010) Otieno, Peter O; Lalah, Joseph O; Viranib, Munir; Schramm, Karl-Werner; Jondiko, Isaac O
    This study was undertaken to determine the concentrations of carbofuran residues in water, soil and plant samples from selected sites in the farmlands in Kenya and to demonstrate the impact of Furadan use on the local environment. Soil, water and plant samples obtained from agricultural farmlands where the technical formulation Furadan has been used extensively showed high environmental contamination with concentrations of carbofuran and its two toxic metabolites 3-hydroxycarbofuran and 3-ketocarbofuran, separately, ranging from 0.010–1.009 mg/kg of dry surface soil, 0.005–0.495 mg/L in water samples from two rivers flowing through the farms and bdl-2.301 mg/L in water samples from ponds and dams located close to the farms. Maize plant samples contained these residues in concentrations ranging from 0.04–1.328 mg/kg of dry plant tissue. The significantly high concentration levels of carbofuran and its metabolites, 3-ketocarbofuran and 3-hydroxycarbofuran, found in various matrices demonstrate that Furadan was used extensively in the two areas and that there was environmental distribution and exposure of residues in water which posed risks when used for domestic purposes or as drinking water for animals in two wildlife conservancies where the dams and ponds are located. Surface soil contamination was also high and posed risks through run-off into the dams and rivers as well as through secondary exposure to small birds and mammals.
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    Analysis of Moss and Topsoil to Monitor Metal Emissions from a Pulp and Paper Mill in Western Kenya
    (Springer, 2010-07-05) Lalah, Joseph O.
    The mean concentrations of Zn, Cu, Cd, Cr and Fe in mosses around Webuye Pan Paper factory were found to be significantly higher than in controls taken from Kakamega, indicating atmospheric contribution from the anthropogenic activities within the factory, shown within a radius of 1 km around the factory. The mean concentrations (lg/g dry weight) in the mosses ranged from 60.9–124.5, 22.6–34.2, 13.3–14.7, 20.1–33.3 and 1,822.4– 2,079.2, respectively. The mean concentrations of Pb in mosses sampled from the eastern and western side of the factory were also significantly higher than in controls. The mean concentrations of Zn, Cu, Cd, Cr, Pb and Fe in topsoil samples ranged from 7 (Pb)–2,310 (Fe) mg/kg dry wt, depending on sample means based on site direction, distance from the factory and season. There was no clear variation in metal concentrations in mosses and topsoils with direction from the factory which was consistent with the observed fluctuations in wind direction which changed from south-west in the mornings to north and south-west in the afternoons during sampling.