Research Repository :: Browsing by Author "Mahugija, John A.M."

Browsing by Author "Mahugija, John A.M."

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Assessment of Pesticide Residues in Tomatoes and Watermelons (Fruits) from Markets in Dar es Salaam, Tanzania
(University of Port Harcourt, 2017) Mahugija, John A.M.; Khamis, Farhat A.; Lugwisha, Esther H.J.
This study investigated the levels of pesticide residues in selected fruits from major markets in Dar es Salaam city. Samples of tomatoes and watermelons were analysed for eighteen organochlorine, organophosphorus and pyrethroid pesticide residues. Extraction was performed using acetone followed by dichloromethane: cyclohexane mixture and the extracts were cleaned-up using florisil. The compounds were determined by gas chromatography–mass spectrometry (GC–MS). Pesticides and metabolites were detected in 95.8% of the samples. The compounds detected included chlorpyrifos, α-endosulfan, β-endosulfan and cypermethrin and their highest concentrations were 3810 ± 50, 370 ± 20, 120 ± 6 and 50 ± 4 ng/g, respectively. Others were p,p'-DDD, o,p'-DDD, p,p'-DDE and α-HCH with highest concentrations varying from 1 ± 0.5 to 20 ± 1.2 ng/g. There were no significant variations in concentrations of the pesticide residues between the fruits and among the sampling sites, indicating similarities in contamination patterns. The concentrations of the contaminants were above the maximum residue limits (MRLs) in 41.7% to 50% of the tomatoes and watermelons indicating risks and concerns for public health. The Tanzanian agrochemicals and food regulatory agencies (e.g. TPRI, TFDA and TBS) and the government in general should ensure strict applications of laws that regulate pesticides in the country and develop effective educational programmes for farmers to apply good agricultural practices such as reducing the use of pesticides, applying appropriate pesticides and doses, and restrict the spray before harvesting. The consumers should thoroughly wash or process the fruits to reduce the levels.
Concentrations of pesticide residues in grasses and sedges due to point source contamination and the indications for public health risks, Vikuge, Tanzania
(Elsevier, 2005) Mahugija, John A.M.; Kishimba, Michael A.
The concentrations of organochlorine pesticide residues were determined in roots and leaves of giant sedges (Cyperus exaltatus), fresh leaves and dry hay of guinea grasses (Panicum maximum), and in stems and leaves of elephant grasses (Pennisetum purpureum) in the vicinity of a point source of contamination, an old storage site at Vikuge farm in Tanzania. The GPC-cleaned extracts were analyzed by GC-ECD and GC/MS. The concentrations of total DDT ranged from 83 – 18274 ng/g, 166 – 7922 ng/g, and 68 – 405 ng/g, on fresh weight bases, in C. exaltatus, P. maximum and P. purpureum, respectively. The concentrations of total HCH were up to 74 ng/g fw in leaves of C. exaltatus, 43 ng/g dw in dry hay of P. maximum, and 10 ng/g fw in stems of P. purpureum. Aldrin and dieldrin were only detected in C. exaltatus and their concentrations were up to 11 and 8 ng/g fw, respectively. The strong positive correlations between the concentrations of the detected compounds suggest a common source. The concentrations of total DDT were far above the Australian extraneous maximum residue limit in primary animal feedstuffs. These findings indicate potential risks and concerns for livestock and public health. The concentrations of aldrin, dieldrin and lindane were lower than the Australian limits. 2005 Elsevier Ltd. All rights reserved.
Concentrations of polar pesticide residues in the surface waters of selected areas of Coast region, Tanzania
(Makerere University, Kampala-Uganda, 2005-01-20) Mahugija, John A.M.; Kishimba, Michael A.
The concentrations of 60 polar pesticide residues were investigated in surface waters from eleven sites in two rivers, a pond and four drinking water wells in Coast region, Tanzania. The extracts were analyzed by Gas Chromatography-Nitrogen Phosphorus Detection (GC-NPD) and confirmed by high-performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS). Quantification of analytes was done by using the peak heights with two different m/z for each analyte. The compounds detected were atrazine, isoproturon and diuron. The highest concentrations of atrazine were 13 ng/l in drinking water, 16 ng/l in pond water and 172 ng/l in river water. The highest concentrations of isoproturon and diuron in river water were 18 ng/l and 12 ng/l, respectively. Atrazine was the most predominant pollutant in water. The results indicate that the source of contamination is due to the agricultural use of these pesticides in the nearby areas. The concentrations of atrazine, isoproturon and diuron in drinking water were far below the WHO guidelines for drinking-water quality.
Contamination of Surface Waters by Obsolete Pesticides Emanating from a Point Source in Coast Region, Tanzania
(University of Nairobi, 2007) Mahugija, John A.M.; Kishimba, Michael A.
This paper reports on the concentrations of organochlorine pesticide residues in water samples collected from 1 – 25 km away from a highly obsolete pesticides contaminated site at Vikuge farm in Coast region -Tanzania. GPC-cleaned extracts analyzed by GC-ECD and confirmed by GC-MS showed the presence of twelve compounds namely p,p’-DDT, o,p’-DDT, p,p’-DDE, o,p’-DDE, p,p’-DDD, o,p’-DDD, pentachloroanisole, a-HCH, b-HCH, g-HCH, aldrin and dieldrin. The concentrations of total DDT ranged from 819 – 1764 ng/l in pond water, below detection limit (bdl) – 1076 ng/l in river water, and bdl – 572 ng/l in drinking water. The concentrations of total HCHs were up to 23 ng/l in pond water, 1167 ng/l in river water, and 12 ng/l in drinking water. The highest concentrations for other compounds were 29.2 +/- 0.1 ng/l for pentachloroanisole, 8+/- 0.7 ng/l for aldrin and 6+/- 0.6 ng/l for dieldrin. There are strong positive correlations in the concentrations of most of the detected compounds suggesting a common source. Some concentrations were higher than the respective maximum residue limits and guidelines for aquatic ecosystems indicating potential risks and concerns for public health and the environment at large.
Determination of Dichlorodiphenyltrichloroethane (DDT) and Metabolites Residues in Fish Species from Eastern Lake Tanganyika
(South African Chemical Institute, University of KwaZulu-Natal, 2018) Mahugija, John A.M.; Nambela, Lutamyo; Mmochi, Aviti J.
In this study, the levels and status of dichlorodiphenyltrichloroethane (DDT) residues in fish samples collected from Eastern Lake Tanganyika were investigated. The analytes were determined using gas chromatography equipped with an electron capture detector (GC–ECD) and by gas chromatography-mass spectrometry (GC-MS). The compounds p,p’-DDE (4,4’-DDE), p,p’-DDD (4,4’-DDD), o,p’-DDT (2,4’-DDT) and p,p’-DDT (4,4’-DDT) were detected in all the samples, with total DDT concentrations ranging from 23 ± 8.3 to 339 ± 27 μg kg–1 fresh weight and 1736 ± 1388 μg kg–1 to 25 552 ± 4241 μg kg–1 lipid weight. The highest concentrations of total DDT were detected in Lates stappersii species. The ratios of the metabolites (DDD + DDE) to the parent compound (p,p’-DDT) were low (< 1) in all the fish samples, indicating exposure to fresh DDT. The concentrations of the DDT residues exceeded the extraneous maximum residue limit of 1.0 μg kg–1, indicating risks and concerns for public health and the environment because of the indication of fresh application of banned pesticides and bioaccumulation. There is need for continued monitoring of the residues in Lake Tanganyika environs and controlling the pesticides used in the area.
Determination of Levels of Organochlorine, Organophosphorus, and Pyrethroid Pesticide Residues in Vegetables from Markets in Dar es Salaam by GC-MS
(Hindawi, 2017) Mahugija, John A.M.; Khamis, Farhat A.; Lugwisha, Esther H.J.
This study investigated the levels of pesticides and metabolites in vegetables from major markets in Dar es Salaam city, Tanzania. Samples of fresh cabbage, spinach, and onions from the markets were analysed for pesticide residues. Extraction was performed using acetone followed by dichloromethane : cyclohexane mixture and the extracts were cleaned up using Florisil. The compounds were determined by gas chromatography-mass spectrometry (GC-MS). Pesticides and metabolites were detected in 72.2% of the samples. The detected pesticide residues and their highest mean concentrations were p,p′-DDT 4.00 × 10−3 mg/kg, p,p′-DDD 6.40 × 10−1 mg/kg, o,p′-DDD 1.00 × 10−2 mg/kg, α-endosulfan 6.00 × 10−1 mg/kg, β-endosulfan 2.10 × 10−1 mg/kg, chlorpyrifos 3.00 mg/kg, and cypermethrin 4.00 × 10−2 mg/kg. The most frequently detected compounds were p,p′-DDD and chlorpyrifos. The order of contamination was spinach > cabbage > onions. Generally, there were no significant variations in concentrations of pesticide residues among samples and sampling sites, which indicated similarities in contamination patterns. The concentrations of contaminants were above the maximum residue limits (MRLs) in 33.3–50% of the samples. The findings indicated risks and concerns for public health.
Determination of toxic diethylene glycol in toothpastes in Dar es Salaam by high performance thin layer chromatography and colorimetric methods
(College of Natural and Applied Sciences, University of Dar es Salaam, 2018) Mahugija, John A.M.
The aim of this study was to determine the presence and the levels of diethylene glycol (DEG) in toothpaste products commonly used in Dar es Salaam. Forty five samples of different brands of imported and locally manufactured toothpastes were collected and processed prior to analysis. High performance thin layer chromatography (HPTLC) method was used for the qualitative detection of diethylene glycol in the toothpastes. In quantitative analysis, a colorimetric method that involved ultraviolet–visible (UV-Vis) spectrophotometric measurements of absorbances of prepared coloured samples and standards was used. DEG was found in 37.8% of the tested samples. The concentrations of the DEG detected in the samples varied from 0.106 to 7.71 mg/g. The results indicated that 88.2% of the samples found with DEG were obtained from imported toothpastes and 11.8% of the samples found with DEG were from local pharmaceutical industries. The findings indicate public health risks because, according to the WHO standards, toothpastes should have no traces of DEG as it is toxic. There is a need for regular checking of the composition of both imported and locally manufactured toothpastes by the regulatory authorities.
Distribution of Pesticide Residues in Soil and Sediments from Areas of Coast Region Near a Heavily Contaminated Site in Tanzania
(University of Nairobi, 2007) Mahugija, John A.M.; Kishimba, Michael A.
Soil and sediment samples collected from 0.1 to 25 km away from a heavily contaminated site at Vikuge farm in Coast region were extracted, cleaned by GPC and analyzed using GC-ECD and GC-MS. Ten compounds namely p,p’-DDT, o,p’-DDT, p,p’-DDE, o,p’-DDE, p,p’-DDD, o,p’-DDD, pentachloroanisole, a-HCH, b-HCH and g-HCH were detected in the samples. In general, contaminants during this round of sampling were widespread. The compounds o,p’- and p,p’-DDT, DDD and DDE were detected in 64.3% - 100% of the samples. Pentachloroanisole was detected in 95.5% of the soil and 50% of the sediment samples, while for the HCH isomers, the highest frequency was for b-HCH (57.1%) in sediments. The concentrations of total DDT were up to 534 ng/g dry weight (dw) in soil and 1945 ng/g dw in sediments. The highest concentrations for total HCH were 3.8 ng/g dw in soil and 24.6 ng/g dw in sediments. The very strong positive correlations in the concentrations of the detected compounds suggest a common source. The low DDE/DDT ratios (0.01 - 0.83) in all but one sample indicate input of significantly non-degraded DDT from the source. The high DDE/DDT ratio (1.35) in one soil sample indicates significant degradation. The low a-HCH/g- HCH ratios in the samples indicate inputs of lindane. There is an urgent need for remedial actions to solve the problem at the source.
Distribution of Pesticide Residues in Soil and Sediments from Areas of Coast Region Near a Heavily Contaminated Site in Tanzania
(University of Nairobi, 2007-12) Mahugija, John A.M.; Kishimba, Michael A.
Soil and sediment samples collected from 0.1 to 25 km away from a heavily contaminated site at Vikuge farm in Coast region were extracted, cleaned by GPC and analyzed using GC-ECD and GC-MS. Ten compounds namely p,p’-DDT, o,p’-DDT, p,p’-DDE, o,p’-DDE, p,p’-DDD, o,p’-DDD, pentachloroanisole, a-HCH, b-HCH and g-HCH were detected in the samples. In general, contaminants during this round of sampling were widespread. The compounds o,p’- and p,p’-DDT, DDD and DDE were detected in 64.3% - 100% of the samples. Pentachloroanisole was detected in 95.5% of the soil and 50% of the sediment samples, while for the HCH isomers, the highest frequency was for b-HCH (57.1%) in sediments. The concentrations of total DDT were up to 534 ng/g dry weight (dw) in soil and 1945 ng/g dw in sediments. The highest concentrations for total HCH were 3.8 ng/g dw in soil and 24.6 ng/g dw in sediments. The very strong positive correlations in the concentrations of the detected compounds suggest a common source. The low DDE/DDT ratios (0.01 - 0.83) in all but one sample indicate input of significantly non-degraded DDT from the source. The high DDE/DDT ratio (1.35) in one soil sample indicates significant degradation. The low a-HCH/g- HCH ratios in the samples indicate inputs of lindane. There is an urgent need for remedial actions to solve the problem at the source.
Effects of washing on the polycyclic aromatic hydrocarbons (PAHs) contents in smoked fish
(Elsevier Ltd., 2018) Mahugija, John A.M.; Njale, Emmanuel
This study investigated the effects of washing on the contents of the polycyclic aromatic hydrocarbons (PAHs) in smoked fish. Portions of smoked fish samples were washed with warm water (60 °C). The unwashed and washed fish samples were separately homogenized, extracted, cleaned-up and screened for thirteen PAHs. The PAHs were determined using gas chromatography-mass spectrometry (GC-MS). Washing of the fish samples reduced the concentrations of the individual PAHs by 35.8%–100% in almost all S. victoria samples, 0.6%–100% in most L. niloticus samples and 2.9%–100% in some Haplochromis spp samples. The concentrations of total PAHs in S. victoriae samples were reduced by 77.4%–99.5% in washed samples compared to the concentrations in the unwashed samples. The concentrations of the total PAHs in most washed L. niloticus samples were less by 5.8%–77.4% than the concentrations in the unwashed samples. The concentrations of total PAHs in washed samples of Haplochromis spp were reduced by 7.2% in one third of the washed samples but were not reduced in other samples. Therefore, washing reduced or eliminated the PAHs in smoked fish depending on the fish species, although the levels still exceeded the permissible levels.
Levels and distribution of pesticide residues in soil and sediments in Eastern Lake Tanganyika environs
(International Formulae Group (IFG), University of Dschang, Cameroon, 2017) Mahugija, John A.M.; Nambela, Lutamyo; Mmochi, Aviti J.
The aim of this study was to investigate the types, levels and distribution of pesticide residues in Eastern Lake Tanganyika basin in Tanzania. Soil and sediments samples were collected from various sites in Kigoma region. Analyses of cleaned sample extracts were performed using gas chromatographyelectron capture detection (GC-ECD) and gas chromatography-mass spectrometry (GC-MS). Six pesticide residues and metabolites were detected, namely, p,p'-DDT, o,p'-DDT, p,p'-DDE, p,p'-DDD, diazinon and chlorpyrifos. DDT, DDD and DDE were the predominantly detected compounds in all of the samples. Diazinon and chlorpyrifos were detected in soil samples only. The highest concentrations of total DDT in sediments and soil ranged from 10.02 to 116 μg/kg dry weight (dw) and 7.5 to 564.2 μg/kg dw, respectively. Chlorpyrifos and diazinon had concentrations up to 36 and 184 μg/kg dw, respectively. The concentrations of DDT residues were greater in soil samples than in sediments. The highest concentrations of DDT residues were detected in soil samples. The ratios of (p,p'-DDE + p,p'-DDD)/p,p'-DDT indicated recent inputs in most samples. The study reveals that there were recent uses of DDT, diazinon and chlorpyrifos in the region. Continued use of DDT indicates risks and may result into serious environmental problems. The area therefore needs serious environmental monitoring.
Levels and patterns of organochlorine pesticides and their degradation products in rainwater in Kibaha Coast Region, Tanzania
(Elsevier, 2015) Mahugija, John A.M.; Henkelmann, Bernhard; Schramm, Karl-Werner
The levels and patterns of organochlorine pesticides and degradation products in rainwater samples collected in relation to a contaminated site in Kibaha district, Tanzania were investigated. The compounds detected in the samples by GC–MS and isotope dilution methodology included DDT, DDE, DDD, HCHs, dieldrin, heptachlor, chlordane, endrin and hexachlorobenzene. The concentrations of total DDT and total HCH ranged 0.005–3200 µg L–1 and 0.01–170 µg L–1, respectively and they indicated input of significantly non-degraded technical mixtures. The highest concentrations for other compounds ranged 0.001–1.3 µg L–1. The highest concentrations were found in samples collected in the vicinity of the contaminated site and the concentrations at other points showed a general even distribution suggesting repeated volatilization and deposition mechanisms. The strong positive correlations in the concentrations of the compounds indicated a common source. A decrease in concentrations with time was indicated, although the decrease was not significant during the period of sampling. The findings indicate risks and concerns for public and environmental health.
LEVELS AND PROFILES OF POLYCYCLIC AROMATIC HYDROCARBONS AND POLYCHLORINATED BIPHENYLS IN SOIL AT AN INDUSTRIAL AREA IN DAR ES SALAAM, TANZANIA
(Best Journals, 2015) Mahugija, John A.M.
This study investigated the levels and profiles of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in soil from an urban/industrial area in Dar es Salaam, Tanzania. Analysis was performed using a high resolution gas chromatograph coupled to a high resolution mass spectrometer (GC–MS). The results indicated that the contents of total PAHs (16 US EPA priority PAHs) ranged from 104 ng/g to 35890 ng/g and the pollution level is classified as a moderate level with some spots of high and very high pollution levels. The composition profiles of PAHs were dominated by high molecular weight (4-6 rings) PAHs. The ratios of phenanthrene/anthracene and fluoranthene/pyrene indicated that the concentrations of PAHs in the area were influenced by pyrogenic (combustion) sources and petrogenic (petroleum) sources. The total concentrations of 18 PCBs in soil varied from 0.4 ng/g to 282 ng/g. Most of the PCBs concentrations were generally low. PCB 138, PCB 153, PCB 180, PCB 101 and PCB 118 accounted largely among the contaminants of PCBs.
Levels of formaldehyde and acetaldehyde in selected bottled drinking water sold in urban areas in Tanzania
(College of Natural and Applied Sciences, University of Dar es Salaam, 2016) Lugwisha, Esther H.J.; Mahugija, John A.M.; Mwankuna, Christopher
The levels of formaldehyde and acetaldehyde in bottled drinking water and the effect of storage time and storage conditions on their levels were determined. A total of 144 samples of six brands of bottled drinking water were purchased from Dar es Salaam, Iringa, Mwanza and Arusha regions in Tanzania. Analysis was performed using HPLC on the 1st day and after 14 and 42 days of storage in a refrigerator, at room temperature and exposure to sunlight. The levels of formaldehyde and acetaldehyde in the refrigerated samples ranged from 2.46 to 19.25 μg/L and from not detected (ND) to 58.70 μg/L, respectively. In samples stored at room temperature, the levels of formaldehyde and acetaldehyde were up to 23.26 μg/L and 36.10 μg/L, respectively. The highest levels of formaldehyde and acetaldehyde in samples exposed to sunlight were 46.0 μg/L and 187.0 μg/L, respectively. The lowest levels of the aldehydes were found in refrigerated samples and the highest levels were in samples exposed to sunlight. The levels of these aldehydes increased with increased storage time. The levels were below the WHO acceptable limits; however, the findings indicate that the levels could be elevated with increased storage time and exposure to sunlight.
Levels of heavy metals in drinking water, cosmetics and fruit juices from selected areas in Dar es Salaam, Tanzania
(College of Natural and Applied Sciences, University of Dar es Salaam, 2018) Mahugija, John A.M.
Heavy metals were determined in samples of drinking water, cosmetics (nail polish, lip glosses and hair dye) and fresh fruit juices in Dar es Salaam. The samples were analyzed using Atomic Absorption Spectrometry (AAS) after digestion with concentrated acids, filtration and dilution. Lead, zinc and iron were detected in the water samples and the concentration ranges were below detection limit (BDL) to 0.114, 0.01 to 1.47 and 0.027 to 0.39 mg/L, respectively, whereas cadmium was not detected. The concentrations of lead in 70.83% of the samples exceeded the WHO permissible limit, implying that the water in most of the areas was not suitable for human consumption. Lead, zinc, and cadmium were detected in all the cosmetics at concentrations ranging from 6.6 to 37400, 21.5 to 2600, and up to 0.25 mg/kg, respectively. Most of the concentrations of lead in cosmetics exceeded the EU/US permissible limits. The continued use of products containing such heavy metals may increase the body intake of the metals and cause harmful effects. Only copper was detected in the fruit juices and the water used for their preparations at concentrations ranging from 0.008 ± 0.003 to 0.215 ± 0.014 mg/L, which were below the WHO permissible limit.
Levels of heavy metals in urine samples of school children from selected industrial and non-industrial areas in Dar es Salaam, Tanzania
(Makerere University Medical School, 2018-12) Mahugija, John A.M.; Kasenya, Zainab S.; Kilulya, Kessy F.
Objectives: The levels of lead, zinc, iron, copper and cadmium metals in the urine samples of selected school children in industrial and non-industrial areas in Dar es Salaam were investigated. Methods: Urine samples were collected from 120 children in industrial areas and 120 children in non-industrial areas then digested in concentrated acids and analysed using atomic absorption spectrophotometry (AAS). Results: The concentrations of the heavy metals in the urine samples ranged from below detection limit/non-detectable (ND) to 1.92 mg/L for lead, ND to 2.55 mg/L for zinc, ND to 8.98 mg/L for iron and ND to 0.05 mg/L for copper. Cadmium was not detected. Significant differences were found between the concentrations of heavy metals in urine of pupils from the industrial areas and those from non-industrial areas. The mean concentrations of lead and copper in samples from industrial areas were significantly higher than those found in non-industrial areas (p < 0.002), while the mean concentrations of zinc and iron found in samples from non-industrial areas were significantly higher than those found in industrial areas (p < 0.0001). Conclusion: The contamination levels were generally high in samples from both areas indicating exposure from various sources. The findings indicate public health risks.
Levels of polycyclic aromatic hydrocarbons (PAHs) in smoked and sun-dried fish samples from areas in Lake Victoria in Mwanza, Tanzania
(Elsevier Ltd., 2018) Mahugija, John A.M.; Njale, E.
This study investigated the concentrations of 13 polycyclic aromatic hydrocarbons (PAHs) in smoked and sundried fish samples of three species (Synodontis victoriae, Haplochromis spp and Lates niloticus) from areas in Lake Victoria in Mwanza region, Tanzania. The PAHs in cleaned extracts were determined using gas chromatography-massspectrometry (GC–MS). The concentrations of total PAHs in sun-dried fish samples were up to 0.13 mg/kg in S. victoria and Haplochromis spp and ranged from 0.08 to 0.3 mg/kg in L. niloticus. The concentrations of total PAHs in smoked fish samples ranged from 12.1 to 31.4, 21.8 to 27.4 and 19.5 to 33.9 mg/kg in S. victoriae, Haplochromis spp and L. niloticus, respectively. The concentrations of benzo[a]pyrene in all the smoked fish samples exceeded the European Union (EU) maximum permissible level (0.002 mg/kg) and the sum of the concentrations of benzo[a]pyrene, benz[a]anthracene, benzo[b]fluoranthene and chrysene in all the smoked fish samples exceeded the EU maximum permissible level (0.012 mg/kg), but were generally below these limits in the sun-dried fish samples. The concentrations of the PAHs in smoked fish samples were significantly greater than in the sun-dried samples.
Levels, compositions and distributions of organochlorine pesticide residues in soil 5–14 years after clean-up of former storage sites in Tanzania
(Elsevier, 2014) Mahugija, John A.M.; Henkelmann, Bernhard; Schramm, Karl-Werner
The levels, compositions and distributions of organochlorine pesticides and metabolites were determined in soil samples collected 5–14 years after clean-up was carried out at seven contaminated sites in Tanzania. Samples were collected from various depths (5–10 cm, 30 cm, and 50 cm for most sites and up to 300 cm for one site. Determination of the analytes was performed using a high resolution GC–MS and isotope dilution technology. DDT, DDD, DDE, HCH isomers, aldrin, dieldrin, endrin, endosulfans, chlordanes and heptachlor were the major compounds detected. The concentrations of total DDT and total HCH were up to 250000 and 164000 mg kg–1, respectively, while the highest concentrations for other compounds ranged from 29 to 3300 mg kg–1. The results indicated that there were no significant degradations/transformations of the pesticides for most of the sites. The highest concentrations of the compounds were mostly found in surface soil samples and there were variations in distribution among the sampling depths. The results indicate risks and concerns for public health and the environment.
Occurrence of organochlorine and organophosphorus pesticide residues in poultry feeds, raw and cooked eggs from selected farms in Ilala and Kibaha Districts, Tanzania
(University of Port Harcourt, 2018) Mahugija, John A.M.; Chibura, Patrick E.; Lugwisha, Esther H.J.
This study assessed the levels of seventeen pesticides and metabolites residues in chicken feeds and raw eggs as well as the effects of processing methods on the levels in eggs in samples obtained from six poultry farms in Ilala and Kibaha districts, Tanzania. Extraction was performed by solid dispersion method and the extracts were cleaned-up by adsorption column chromatography. The analytes were determined by Gas Chromatography–Mass Spectrometry (GC–MS). The highest mean concentrations of the contaminants in feeds and eggs were as follows, respectively: aldrin 0.62 and 2 mg/kg, dieldrin 0.71 and 1.3 mg/kg, total DDT 6.68 and 8.14 mg/kg, total endosulfan 3.53 and 3.74 mg/kg, total HCHs 0.91 and 1.21 mg/kg, chlorpyrifos 12.2 and 0.59 mg/kg, fenitrothion 4.9 and 0.64 mg/kg and pirimiphos methyl 22.11 and 1.6 mg/kg. Chicken feeds were found to be the most contaminated followed by raw eggs and finally cooked eggs. Most of the concentrations were above the maximum residue limits (MRLs) indicating risks and concerns. Proper selection and preparation of poultry feeds could reduce the levels in the feeds and eggs.
ORGANOCHLORINE PESTICIDES AND DEGRADATION PRODUCTS IN SOIL AROUND A FORMER FORMULATION PLANT IN MOROGORO MUNICIPALITY, TANZANIA
(College of Natural and Applied Sciences, University of Dar es Salaam, 2012) Mahugija, John A.M.
The levels and compositions of organochlorine pesticides and degradation products in soil samples collected from a former formulation plant in Morogoro municipality, Tanzania, were determined. Extraction was performed by pressurized fluid extraction using n-hexane:acetone (75:25) mixture. Clean-up of extracts was conducted by using silica gel and alumina with 3% H2O and the extracts were eluted with hexane and dichloromethane (1:1). Additional clean-up was performed by using C18 SPE cartridges using acetonitrile as the eluting solvent. The samples were spiked with labelled internal standards for identification and quantification. Analysis of the analytes was performed using a high resolution gas chromatograph coupled to a high resolution mass spectrometer (GC–MS). 27 organochlorine pesticides and degradation products were detected. The concentrations of total DDT and total HCH ranged 300–152000 and 2–8300 mg/kg dry weight (dw), respectively. The concentrations for other compounds were up to 1400 mg/kg dw. The results indicated old contamination by technical mixtures and lack of significant degradation. It is recommended that clean-up and proper disposal of contaminated soil should be carried out.

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