Browsing by Author "Othman, Othman C."
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Item Arsenic: A Toxic Trace Element of Public Health Concern in Urban Roadside Soils in Dar Es Salaam City(JMES, 2014) Luilo, G. B.; Othman, Othman C.; Mrutu, A.Motor vehicles have been associated with high levels of trace metals in urban soils and the metals are mostly emitted though exhaust emissions, brake pad and tire abrasions. This study reports the levels of arsenic in roadside soils obtained from the surface at a depth of 0-5 cm in the Dares Salaam city which has the highest average daily traffic density in the country. The soils samples were collected at 1 m, 5 m, 15 m, 35 m, 50 m and 150 m distances from the road edge at each sampling site. Results showed that roadside soils were contaminated with arsenic and its levels ranged from 0.03 - 0.65 ppm (mean = 0.23 ppm). The amount of arsenic in the soil at each site decreased exponentially with increasing distance up to 35 m distance from the road edge. The Analysis of Variance (ANOVA) test showed that average arsenic levels in the soils varied significantly with study sites (F = 4.14, p = 0.01, n = 5) while the linear regression between average arsenic in all soil samples and average daily traffic density was statistically insignificant (r2 = 0.47, p = 0.21, n = 5). However, the observed spatial distribution of arsenic with increasing distance from the road edge strongly suggests that arsenic levels above background level in the study sites owe its source from traffic emissions.Item Heavy Metal Levels of Pasture Grasses in Metropolitan Area(EDP sciences, 2003) Luilo, G. B.; Othman, Othman C.Urban agriculture is becoming an important lucrative activity in Dar es Salaam City even though the city is subject to traffic and industrial pollution pressures. Poor planning has left only limited spaces, particularly road reserves, for cultivation and foraging animals. While there is increasing road traffic no study bas been conducted determine levels of trace metals in pasture grasses. This study, therefore, reports on the levels of cadmium, manganese, lead and zinc of cynodon grasses in road vicinity in the city. Results show that the trace metal levels (ppm $\pm$ SDE) in Cynodon grass species were: Cd (0.24 $\pm$ 0.06-2.58 $\pm$ 0.15), Mn (41.5 $\pm$ 13.6-345.0 $\pm$ 124.3), Pb (1.15 $\pm$ 0.64-25.53 $\pm$ 1.29) and Zn (25.97 $\pm$ 3.69-95.36 $\pm$ 19.61). The mean levels of lead and zinc varied exponentially with distance off the road up to 15 m distance. Lead and zinc levels correlated with average daily traffic in the roads while cadmium and manganese did not. This suggests that lead and zinc in grasses owe their sources from the passing motor vehicles in agreement with other reported studies. It is recommended that pasture grasses in road vicinities must not be used for foraging dairy cattle and goats for public health reasons.Item Heavy Metals in Green Vegetables and Soils from Vegetable Gardens in Dar Es Salaam, Tanzania.(College of Natural and Applied Sciences (CoNAS) of the University of Dar es Salaam (UDSM), 2001) Othman, Othman C.Edible portions of five varieties of green vegetables, namely amaranth, chinese cabbage, cowpea leaves, leafy cabbage and pumpkin leaves, collected from several areas in Dar es Salaam, were analyzed for lead, cadmium, chromium, zinc, nickel and copper. Except for zinc, the levels of heavy metals in the vegetables grown at Tabata area were much higher than in the vegetables from Ukonga and Kiwalani. Amaranth and pumpkin leaves had more than 60% higher content of heavy metals, especially copper, chromium and lead, than the other vegetables. All vegetables from Tabata, Buguruni and Sinza had lead-levels higher then the FAO/WHO recommended permissible levels in foods. Amaranth, leafy and chinese cabbages had high zinc content. Zinc levels in chinese cabbage and leafy cabbage from Kiwalani, Sinza and Ukonga areas were higher than the permissible FAO levels in foods. The soils from Tabata and Sinza areas had high levels of lead, chromium, zinc and copper while the soils from Kiwalani, Makongo and Ukonga areas had high levels of zinc and copper. There was a direct positive correlation between the zinc and lead levels in soils with the levels in vegetables. Such relation was absent for the other heavy metals. Considering an average daily intake of only 202g of fresh vegetables per person per day, all the vegetables grown at Tabata and Buguruni had lead concentration which would be a health hazard for human consumption.Item Lead Pollution in Urban Roadside Environments of Dar Es Salaam City(College of Natural and Applied Sciences (CoNAS) of the University of Dar es Salaam (UDSM), 2006) Luilo, G. B.; Othman, Othman C.Lead is among the most toxic elements in nature. It is non-biodegradable and its toxicity does not change with time. Use of leaded gasoline in motor vehicles is known as the major source of lead pollution in cities in the world. Dar es Salaam, the main city of Tanzania, has thousands of cars traveling along its roads. The lead contaminating urban roadside environments of Dar es Salaam was determined. Soil and vegetation samples were collected at various distances from the road edges of the New Bagamoyo, Sam Nujoma and Mandela roads in Dar es Salaam and analyzed for lead using Atomic Absorption Spectrophotometric methods. The results show that the soils and grasses along these major highways of Dar es Salaam were contaminated with lead. The highest lead contents (152.5 ppm in soil and 35.7 ppm in couch grass) were found in soils and vegetation within 1 to 5 meters from the road edge. The background lead levels measured at 150 meters from the road side were less than 1.2 ppm in both soil and vegetation. The lead levels along these roads exhibited strong correlation with the average traffic density (r = 0.912 for soil and r = 0.88 for grass). The levels of lead decreased exponentially with increasing distance away from the road. This suggests the major source of lead contamination of these areas was emissions from automobile traffic on these highways. The high levels of lead at 0 – 10 m from the roadside edge also suggest that soil and vegetation close to the roadside were a potential health hazard to both humans and animals.Item Levels of Crude Proteins and Some Inorganic Elements in Selected Green Vegetables of Dar es Salaam(Association of Food Scientists and Technologists, 1997) Raja, T. K.; Othman, Othman C.; Bahemuka, T. E.Eight green vegetables commonly grown in Dar es Salaam were analyzed for their contents of crude proteins, 4 macro minerals (Mg, K, Ca and Na) and 7 heavy metals (Pb, Cd, Zn, Cu, Mn, Cr and Fe). The values of crude proteins ranged between 1.03-5.23% on fresh weight. These vegetables were found to be rich in macro minerals. The levels of Pb and Cd in some vegetables were above the permissible limits recommended by FAO/WHO. Overall data have, however, indicated that consumption of these vegetables is unlikely to pose any health hazard to the consumer, as these vegetables are good sources of some other essential elements.Item Levels of Selected Heavy Metals in Soil, Tomatoes and Selected Vegetables from Lushoto District – Tanzania(2014) Lugwisha, Ester; Othman, Othman C.This study involved the determination of heavy metals of Cd, Cr, Cu, Pb and Zn in cauliflower (Brassica oleracea L. var botrytis L.), carrot root (Daucus carota L.), tomato fruit (Lycopersicum esculentum Mill.), onion bulb (Allium cepa L.) and leafy cabbage (Brassica oleracea L. var capitata L.) and the respective soils from Lushoto District, Tanzania. Samples were collected from eight growing sites. The accumulated heavy metals were quantified and the levels compared to the FAO/WHO CODEX-STAN 179:2003 and TZS 972:2007 contamination limits for such produce. The methodology involved random sampling, extraction of the metals from the vegetable and soil and determination of heavy metals by using ICP-OES and GFAAS. The levels of Cu in all vegetables were below the FAO/WHO limit while levels of Cr and Zn in all vegetables were found to be above this limit therefore advocating a health risk for consumers. Pb was only found in carrots at 2 sites (Montisory and Resource centre) and in onions at the market all at levels above the FAO/WHO limit while Cd was only found in onions and tomatoes at 2 sites (market and Montisory) at above the FAO/WHO limits. Vegetables especially onions from the Mlalo market advocate a health risk to consumers. Levels of heavy metals in the soils were below the limits of the Tanzanian standard (TZS 972: 2007) and were lower than levels found in vegetables. However, the bioconcentration factor for Cr, Pb, Cd and Zn in all vegetables and tomatoes where they were detected except for cabbages at the Garage site were found to be above 1, an indication of high uptake of heavy metals in the vegetables from the soil. Cu at 80% of the sites had a BCF lower than 1 indicating that Cu was more abundant in the soil compared to the vegetables. These results suggest that these vegetables from Lushoto district are not safe for consumption in their raw state.Item Organochlorine Pesticide Residues in Edible Biota from the Coastal Area of Dar Es Salaam City(2002) Mwevura, Haji; Othman, Othman C.; Mhehe, George L.Item Organochlorine Pesticide Residues in Sediments and Biota from the Coastal Area of Dar Es Salaam City, Tanzania(Elsevier, 2002) Mwevura, Haji; Othman, Othman C.; Mhehe, George L.Sediment and biota samples were collected from Msimbazi and Kizinga rivers and from the coastal marine environment of Dar es Salaam during both dry and wet seasons. The samples were analyzed for various organochlorine pesticide residues using GC-ECD and GC-MS. Dieldrin, p,p′-DDT, p,p′-DDE, p,p′-DDD, o,p′-DDT and γ-HCH were detected at significantly greater concentrations above the method detection limits. Recoveries of pesticide residues ranged 86.5–120% in sediments and 62–102% in biota. The average concentrations of total DDT in sediments for the two seasons were almost the same. Biota samples showed significant difference in levels of residues depending on mode of feeding and age of analyzed biota. p,p′-DDT to total DDT ratios in all matrices indicated recent use of DDT. The levels of residues in sediments suggest possible adverse effects to humans consuming biota that are directly exposed to the sediments. This effect, which is associated with bio-concentration of residues in the tissues of edible aquatic biota, should not affect wildlife. In spite of concern on the adverse effect to humans posed by pesticide residues in sediments, edible biota from the examined water bodies were found to be safe for human consumption.Item Organochlorine Pesticides in Residues in Waters from the Coastal Area of Dar es Salaam and Their Effect on Aquatic Biota(College of Natural and Applied Sciences (CoNAS) of the University of Dar es Salaam (UDSM), 2002) Mwevura, Haji; Othman, Othman C.; Mhehe, George L.Water samples from Msimbazi and Kizinga rivers in Dar es Salaam and from the coastal marine environment receiving waters from these rivers were analyzed for various organochlorine pescticide residues using GC-ECD and GC-MS. p,p'-DDE, p,p'-DDT, dieldrin and γ-HCH were the only organochlorine pesticide residues detected at significantly greater concentrations above the detection limits. There was a marked difference in the frequency of pesticide residue detection during the dry and wet seasons. All the wet season samples and 37.5% of the dry season samples revealed presence of p,p-DDE at concentrations ranging from 0.05 to 0.45 mgl-1 and 0.08 to 0.20 mgl-1 respectively. pp'-DDT was detected in 25% of the dry season samples at a concentration range of 0.1-0.4 mgl-1 and in 81% of the wet season samples at concentrations ranging from 0.1 – 0.3 mgl-1. Dieldrin and γ-HCH were only detected during the wet season. Dieldrin amounts ranging between 0.2 and 2.5 mgl-1 were detected in all wet season samples whereas γ-HCH (0.2 mgl-1) was found in only one wet season sample. Recoveries of pesticides ranged from 65 to 108%. The present study suggests that the current levels of pesticides detected in these waters have no acute effects to aquatic biota. However, the levels of total DDT and dieldrin present during the wet season suggest a possibility for chronic effects on aquatic biota.Item Physical and Chemical Composition of Storage-Ripened Papaya (Carica Papaya L.) Fruits Of Eastern Tanzania(College of Natural and Applied Sciences (CoNAS) of the University of Dar es Salaam (UDSM), 2009) Othman, Othman C.The proximate composition (ash, titratable acidity, crude fat, crude fibre, moisture and sugars), soluble solids, ascorbic acid, polyphenol oxidase activity, macro-nutrients and heavy metal contents of storage-ripened papaya (Carica papaya L.) fruits from Mbezi, Dar es Salaam, Tanzania were determined. The determinations were repeated for early, middle and late-season papaya fruits. The fruits were always harvested at the mature green stage and allowed to ripen during room temperature storage. The results showed that papaya fruits had high moisture content (>85.5%), low acidity (<0.18% c.a.), low crude fat (0.10 g/100 g-edible portion), moderate crude fibre (1.45 g/100 g-edible portion), high ascorbic acid content (>84.5 mg/100 gfw), moderate total sugars (>13.0%) and soluble solids (>12.9%) content. Early-season fruits had the highest polyphenol oxidase (PPO) activity while late-season fruits had the lowest PPO activity. During storage-ripening the PPO activity in the papaya fruit decreased. Of the determined macro-nutrients (Ca, K, Mg, Na), potassium content (420 mg/100 g-fw) was the highest. Heavy metals content was very low in the papaya fruits. Variations in moisture content, reducing sugars, total sugars, soluble solids, titratable acidity, ascorbic acid content and PPO activity were observed during the season and during the ripening period.Item Physico-Chemical Characteristics of Storage-Ripened Mango (Mangifera Indica L.) Fruits Varieties of Eastern Tanzania(College of Natural and Applied Sciences (CoNAS) of the University of Dar es Salaam (UDSM), 2009) Othman, Othman C.; Mbogo, G. P.Two mango (Mangifera indica L.) fruit varieties, Dodo and Viringe, from two localities of Eastern Tanzania, (Muheza in Tanga and Ifakara in Morogoro), were harvested as mature green fruits during early, mid and late season and allowed to ripen while stored at room temperature. The fruits were analyzed for their proximate composition (ash, titratable acidity, crude fat, crude fibre, moisture), reducing and total sugars content, ascorbic acid and total soluble solids content, concentration of four macro elements (Ca, Mg, K, Na) and seven heavy metals (Al, Cd, Cu, Fe, Mn, Pb, Zn). The results showed that the mango fruits had high moisture content (>65%), moderate acidity (0.20 - 1.30% c.a.), low crude fat content (0.20 g/100 g-fw), low crude fibre content (0.85 g/100 g-fw), low ash content of 0.55 g/100 g-fw, high reducing sugars amounts (10.5 – 21.3%), high total sugars content (10.5 – 21.3%), high soluble solids content (14.2 – 26.5%) and high ascorbic acid content (15.8-25.1%). Potassium was the major macro element present (209.5 mg/100 g-fw). Heavy metal concentrations in the fruits were very low indicating insignificant pollution of the fruits. Moisture, reducing sugars, total sugars, and soluble solids content in the mango fruits increased within the season and with ripening storage. The ascorbic acid and titratable acidity content increased as the season progressed but decreased during the storage ripening period. Minimal seasonal changes were observed for ash, crude fat and crude fibre contents of the fruits.Item Physicochemical Characteristics and Levels of Inorganic Elements in Off-Vine Ripened Pineapple (Ananas Comosus L.) Fruits of Dar Es Salaam, Tanzania(2011) Othman, Othman C.Several physicochemical characteristics (ash, acidity, crude fat, crude fibre, sugars, moisture, ascorbic acid and soluble solids) and concentration of macro elements (Ca, Mg, Na, K) and trace elements (Al, Cd, Cr, Cu, Fe, Mn, Pb, Zn) were measured in harvested mature, green pineapple (Ananas comosus L.) fruits from Mbezi, Dar es Salaam during their off vine, open air, room temperature storage-ripening period of eight days. Pineapple fruits from early, middle and late fruit-season were studied. The results showed that the Mbezi pineapple fruits had high moisture content (68 – 89%), moderate titratable acidity (0.80 – 1.50% c.a.), low crude fat content (0.12%), low crude fibre amounts (0.40%), low ash content (0.20%), high reducing sugars (14.2 – 22.8%), high total sugars (15.2 – 30.0%), high total soluble solids (15.7 – 29.3%) and high ascorbic acid content (7.9 – 33.4%). Of the four macro elements potassium was highest in concentration. The heavy metals, copper, chromium, iron, manganese and zinc were detected at very low concentrations in the fruits indicating insignificant pollution in the fruits. Ascorbic acid, moisture, titratable acidity, sugars content and total soluble solids amounts varied within the season and with the days of storage-ripening.Item Physicochemical Characteristics of Some Imported Edible Vegetable Oils and Fat Marketed in Dar es Salaam(2012) Othman, Othman C.; Ngassapa, F. N.The physicochemical properties (refractive index, saponification value, Free Fatty Acid content, iodine value, tocopherol content, acid value, peroxide value) of seven imported edible vegetable oils and fat sold in shops in Dar es Salaam were assessed using standard procedures. Also determined were the levels of these properties with respect to shelf storage of the products. When the measurement results were compared with physicochemical properties recommended by the Codex Alimentarius Commission of FAO/WHO and the specification of Tanzania Bureau of Standards, the imported edible vegetable oils and fat were found to be of good quality but of poor storage stability. For long storage life, the edible vegetable oils and fat should be stored in opaque (coloured) bottles, fully filled and tightly sealed.Item Physicochemical Characteristics of Some Locally Manufactured Edible Vegetable Oils Marketed in Dar es Salaam(College of Natural and Applied Sciences (CoNAS) of the University of Dar es Salaam (UDSM), 2001) Ngassapa, F. N.; Othman, Othman C.The physicochemical properties (refractive index, saponification value, Free Fatty Acid (FFA) value, iodine value, acid value, peroxide value and tocopherol content) of seven edible vegetable oils manufactured in Tanzania, were assessed using standard procedures of the Association of Official Analytical Chemists (AOAC). Also determined were the levels of these properties with respect to shelf storage of the products. When compared with standard values recommended by the Codex Alimentarius Commission of FAO/WHO and with other published results, the locally produced vegetable oils were found to be of fair quality but of poor storage stability.Item Polyphenoloxidase and Perioxidase Activity During Open Air Ripening Storage of Pineapple (Ananas comosus L.), Mango (Mangifera indica) and Papaya (Carica papaya) Fruits Grown in Dar es Salaam, Tanzania(College of Natural and Applied Sciences (CoNAS) of the University of Dar es Salaam (UDSM), 2014) Othman, Othman C.Polyphenoloxidase (PPO) and perioxidase (POD), the enzymes responsible for causing browning and change in texture and flavor of fruits and vegetables, were extracted and measured in harvested mature pineapple (Ananas comosus L.), mango (Mangifera indica) (Viringe and Dodo varieties) and papaya (Carica papaya) fruits during off vine, open air, room temperature ripening storage. The initial (at harvest) average PPO activity values in Δ Optical Density (OD) per minute per cm3 of enzyme solution were 0.00074, 0.00083 and 0.0010 for early, mid and late season pineapple fruits respectively. The initial average PPO activity values in ΔOD/min/ cm3 of enzyme solution were 0.00152, 0.00121 and 0.0010 for early, mid and late season ‘Viringe’ mango fruits, respectively and 0.0054, 0.0041 and 0.0024 for early, mid and late season ‘Dodo’ mangoes. For papaya fruits, early, mid and late season fruits had initial average PPO activities of 0.00252, 0.00143 and 0.00085 Δ OD/min/cm3, respectively. The PPO activity decreased continuously during the open air ripening storage of all the fruits while the POD activity increased during ripening storage. Variations in PPO and POD enzyme activity were observed across the season and during the ripening period.Item Post Harvest Physicochemical Properties of Soursop (Annona Muricata L.) Fruits of Coast Region, Tanzania(2014) Othman, Othman C.; Fabian, Christina; Lugwisha, EsterItem Research Trends in Emerging Contaminants on the Aquatic Environments of Tanzania(Hindawi Publishing Corporation, 2016-02-22) Miraji, H.; Othman, Othman C.; Ngassapa, F. N.; Mureithi, E. W.The continuity for discovery and production of new chemicals, allied products, and uses has currently resulted into generation of recent form of contaminants known as Emerging Contaminants (ECs). Once in the aquatic environment ECs are carcinogenic and cause other threats to both human’s and animals’ health. Due to their effects this study was aimed at investigating research trends of ECs in Tanzania. Findings revealed that USA and EU countries were leading in ECs researches, little followed by Asia, South Africa, and then Zambia. Only few guidelines from USA-EPA, WHO, Canada, and Australia existed. Neither published guidelines nor regulations for ECs existed in Tanzania; rather only the occurrence of some disinfection by-products and antibiotics was, respectively, reported in Arusha and Dar es Salaam, Tanzania. As these reports had a limited coverage of ECs, henceforth, these findings constitute the first-line reference materials for ECs research in Tanzania which shall be useful for future monitoring and regulation planningItem Roadside Levels of Ambient Air Pollutants: SO2, NO2, NO, CO and SPM in Dar es Salaam City(2010) Othman, Othman C.Item Seaweeds as Heavy Metal Pollution Indicators(1989) Wekwe, W. W.; Othman, Othman C.; Khan, M. R.Item Urban Dietary Heavy Metal Intake from Protein Foods and Vegetables in Dar es Salaam(College of Natural and Applied Sciences (CoNAS) of the University of Dar es Salaam (UDSM), 2010) Ngassapa, F. N.; Othman, Othman C.; Elisante, EmrodeContamination of food and food products by heavy metals has made dietary intake as one of the major routes of these harmful elements to human beings. The human dietary intake of heavy metals cadmium, copper, lead and zinc from protein-foods (beans, meat, fish, milk) and green vegetables consumed daily from restaurants and street food-vendor kiosks in Dar es Salaam were determined using the Total Diet Study (TDS) method. The cooked food was bought from the restaurants and street food-vendors at several city locations (i.e. Buguruni, Manzese, Mwenge, Temeke and Ubungo) over several months and analyzed. Heavy metal concentrations were determined by Atomic Absorption Spectrophotometry (AAS) after wet digestion of the edible portions of pooled samples of the foodstuff. The results showed significant variation in heavy metal concentration among the foodstuff and at the different locations. The results were compared to the FAO/WHO levels for Acceptable Daily Intake (ADI) and Provisional Tolerable Weekly Intake (PTWI) to estimate risk of toxicity and to the US Recommended Dietary Allowance (RDA) and/or Estimated Safe and Adequate Daily Dietary Intake (ESADDI) for a deficiency in intake. The average weekly dietary intake of cadmium and lead from protein-foods and vegetables ranged from 0.20 - 0.42 µg/kg-bw/week (i.e. 2.82 - 6.00% of PTWI) and 4.77 - 9.83 µg/kg-bw/week (i.e. 68.1 – 140.4% of PTWI) respectively. These dietary intakes were below the ADI values of 0.5 µg/kg-bw/day and 3.6 µg/kg-bw/day of the WHO for cadmium and lead respectively. The daily dietary intake of zinc and copper at all the locations were also below the ADI for these elements, the average being 21.5% for copper and 19.8% for zinc. The results show clearly that the daily urban dietary intake of copper and zinc, from protein foods and vegetables along main streets at the above locations, was acceptable.