World Health Organization Safe Limits Research Articles

Characterization, risk assessment and potential source identification of PM10 in Tehran

This study was performed to investigate the concentration and the health risk of metal(loid)s, polycyclic aromatic hydrocarbons (PAHs) and Water-soluble ions in PM10 during cold and warm seasons in two different stations, rural and an urban area at Tehran. The characterization of the metal(loid)s, PAHs and Water-soluble ions associated to the PM10 were carried out by inductively coupled plasma optical emission spectrometer (ICP-OES), gas chromatography/ mass spectrometry (GC–MS) and ion chromatography (IC), respectively. The average concentrations of ambient PM10 on cold and warm seasons were 79.6 and 67.9 μg/m3 in urban area and 57.3 and 58.8 μg/m3 in rural area, respectively. The elements from crustal source (Na+, Mg2+, Ca2+, Al, Si, Fe and Ti) were the major compositions for PM10 in warm season, and NO3− and SO42− were major component of PM10 in cold season at both sites. The mean concentrations of total PAHs were found to be 103.8 ± 81.2 and 67.1 ± 28.1 ng/m3 on cold and warm seasons for the urban area, and 31.85 ± 18.91 and 26.61 ± 15.72 ng/m3 in cold and warm seasons for the rural area, were indicative of the significance of mobile sources in Tehran.Results from this study indicate that for both sites, the carcinogenic risk caused by inhalation pathway PM10-bound PAHs exceeded the acceptable level of world health organization safe limits, indicating the need for more investigation to reducing potential carcinogenic risk.

Monitoring of arsenic in drinking water of high schools and assessment of carcinogenic health risk in Multan, Pakistan

This study was performed to measure arsenic (As) contents in groundwater/drinking water of high schools and its effects on human health. Chronic daily intake, hazardous quotient (HQ), carcinogenic risk (CR), hazardous index (HI), and carcinogenic indices (CI) for oral and dermal exposure to arsenic were calculated. Samples were taken from high schools in four tehsils of Multan. As contents ranged from 3.25 to 184 µg/l and 99% samples exceeded World Health Organization safe limit (10 µg/l). HQ for Multan city (1.70) and for Multan Saddar (1.38) exceeded USEPA permissible toxic risk value (1.0). CR in four tehsils for oral (0.0001–0.0003) and dermal exposure (0.0000049–0.000011) exceeded USEPA limit (10−6). HI for tehsil Multan city (1.75) and Multan Saddar (1.42) exceeded the limit (1.0). CI for four tehsils ranged from 0.00022 to 0.0008 exceeding USEPA limit (10−6) indicating high chronic and carcinogenic health risk to exposed population. Results indicated that groundwater of district Multan is not fit for human consumption due to excessive arsenic contamination. It invites attention of water supplying agency and educational authorities to take steps for provision of arsenic free safe drinking water to students and local area peoples.

Characterization and Risk Assessment of Atmospheric PM2.5 and PM10 Particulate-Bound PAHs and NPAHs in Rwanda, Central-East Africa.

Exposure to airborne particulates is estimated as the largest cause of premature human mortality worldwide and is of particular concern in sub-Saharan Africa where emissions are high and data are lacking. Particulate matter (PM) contains several toxic organic species including polycyclic aromatic hydrocarbons (PAHs) and nitrated PAHs (NPAHs). This study provides the first characterization and source identification for PM10- and PM2.5-bound PAHs and NPAHs in sub-Saharan Africa during a three-month period that spanned dry and wet seasons at three locations in Rwanda. The 24-h mean PM2.5 and PM10 concentrations were significantly higher in the dry than the wet season. PAH and NPAH concentrations at the urban roadside site were significantly higher than the urban background and rural site. Source identification using diagnostic ratio analysis and principal component analysis (PCA) revealed diesel and gasoline-powered vehicles at the urban location and wood burning at the rural location as the major sources of PAHs and NPAHs. Our analysis demonstrates that PM concentrations and lifetime cancer risks resulting from inhalation exposure to PM-bound PAHs and NPAHs exceed World Health Organization safe limits. This study provides clear evidence that an immediate development of emission control measures is required.

Occurrence and Distribution of Arsenic, Antimony and Selenium in Shallow Groundwater Systems of Ibadan Metropolis, Southwestern Nigerian.

Background.Arsenic, antimony and selenium contamination of groundwater is of great concern due to the potential detrimental effects to human health.Objectives.This study investigates the occurrence and distribution of arsenic, antimony and selenium in the shallow groundwater system of Ibadan metropolis, southwestern Nigeria.Methods.A total of 210 groundwater samples were collected from 35 shallow wells (3.15–7.86 m) within the residential, commercial, industrial and agricultural areas of the metropolis during the dry and wet seasons. The average daily dose intake (ADD), hazard quotient (HQ) and hazard index (HI) of arsenic, antimony and selenium exposure in groundwater were calculated from these four studied areas for children and adults.Results.Average concentrations of arsenic, antimony and selenium in groundwater ranged between 2.17±3.49 to 33.8±37.2 μg/L, 13.5±15.0 to 33.2±36.8 μg/L and 7.33±6.22 to 46.3±22.4 μg/L, respectively. A corresponding analysis relay plot showed the order of occurrence of these trace metals in groundwater to be antimony>selenium>arsenic. The principal component analysis biplot showed that arsenic, antimony and selenium were fairly distributed in all of the study areas, suggesting the influence of geogenic factors. A total of 74.3% of sampling locations had antimony levels slightly above the World Health Organization (WHO) safe limit of 20 μg/L. Statistical t testing (0.05 confidence limit) showed a significant difference in seasonal levels of groundwater antimony concentration, with the dry season recording significantly higher levels with 100% of samples exceeding WHO safe limits. The chemical of highest potential human health concern is antimony, with a non-carcinogenic HQ risk factor >2 for both age groups. The overall non-carcinogenic HI was highest in the commercial area, 4.1989 for adults and 5.2487 for children.Conclusions.Antimony in groundwater within the Ibadan metropolis raises health concerns and a concerted effort is needed to identify its sources to avoid the risk of antimony toxicity.

Physicochemical Analysis of Groundwater Samples in Gezawa Local Government Area of Kano State of Nigeria

The physic-chemical parameters of Groundwater from various locations in Gezawa Local Government Area of Kano State were analyzed using standard methods. The samples taken from ten different locations revealed that the study area has a mean of Alkalinity 79.0 mg/l, temp. 21.64°C, turbidity 5.9NTU, total hardness 65.54 mg/l, pH. 7.13, total dissolved solid 56.54 mg/l, conductivity 111.31 us/cm and total suspended solids 5.2mg/l. As the results indicated all the physicochemical parameters are within the maximum contaminant levels set by standard organization of Nigeria (SON), Nigerian Standard for Drinking Water Quality (NSDWQ) and world health organization (WHO) except for turbidity level in Babawa and Dansarai sampling sites which are close to Wase Dam. However, since some of the results indicate high levels above the standard set by WHO, NSDWQ and SON safe limits there is the tendency of high potential health hazards to the inhabitants of the areas that uses these water sources for drinking and other domestic purpose without treatment. As the results indicated, some of the parameters analyzed showed higher concentration above the WHO, SON and NSDWQ contaminant level especially the sampling sites very closer to Wase Dam which is believed to be contaminated, the following steps are recommended for lowering the concentration, heating the water before used can remove the temporary hardness. Domestic and industrial waste should be properly disposed or recycled. Relevant agencies should make concerted effort to control, regulate and educate the community on indiscriminate waste disposal from domestic and industries within the study area and also further research should be carried out to assess the level of some other parameters.

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Senna alata L. has been ethnobotanically used extensively in traditional medicines for the treatment of a variety of diseases such as skin problems, arthritis, HBP (high blood pressure), and laxative or purgative. The phytochemical, anti-nutritive and antioxidant activities of the leaf and root bark of Senna alata L. grown in Bida Niger State, Nigeria were determined using standard analytical methods. Phytochemical screening of the flower and seed of the plant revealed the presence of flavonoids, phenols, saponins, tannins, alkaloid and anthraquinone. Steroid and cardiac glycosides, were slightly present, while resins were absent. The metabolites present were quantitatively determined with alkaloid contents of 14.09±0.50 and 15.89±0.72, saponin 40.57±0.57 and 33.02±0.07, flavonoid 42.28±0.90 and 36.52±0.38, tannin 59.48±0.50 and 44.38±0.72, and phenol 7.84±0.49 and 9.91±0.68 mg/100 g for leaf and root bark respectively. These results confirm that the metabolites obtained from the two parts of this plant were within the range of toxicity levels according to World Health Organization safe limits. The results of anti-nutritional factors revealed oxalate contents of 7.84±0.74 and 9.91±0.62, cyanide content 13.04±0.09 and 21.69±0.11 and phytate content 15.07±0.58 and 12.44±0.31 mg/100 g for leaf and root bark respectively. The values of anti-nutritional factors obtained from this work show that they may not pose any effects based on their toxicity levels and as recommended by World Health Organization. The major components of the chemical compounds deduced from GC/MS for the two parts of this plant investigated revealed the presence of α-d-mannofuranoside (53.35%), oleic acid (12.30%), β-d-glucopyranoside (12.59%), β-d-mannofuranoside (22.41%), n-hexadecenoic acid (5.73%), 1,2,3- propanetriol (21.54%), α-d-glucopyranoside (16.41%) and oleic acid (14.65%). Thus, if properly domesticated and produced in commercial quantities, this plant will serve as a source of bioactive agents for pharmaceuticals. Key words: Antioxidant, phytochemical, anti-nutritional, leaf, root bark and Senna alata.

Evaluation of Phytochemical, Anti-nutritional and Antioxidant Potentials of Flower and Seed Methanol Extracts of Senna alata L. Grown in Nigeria

Senna alata L., commonly known as Candlestick senna or Wild senna belongs to the family Caesalpiniaceae is widely distributed in Northern Nigeria. It has been used frequently in herbal medicine to treat different kinds of pathogenic conditions, particularly as laxative or purgative and in the treatment of skin infections as such as ring worm, impetigo, syphilis, sores, psoriasis, herpes, scabies, rashes, and itching. The rate at which this plant parts (flowers and seeds) have been frequently used in Nupe ethnomedicine led to the increase interest to determine the phytochemical, anti-nutritive and antioxidant activities of the flower and seed of Senna alata L. grown in Bida Niger State, Nigeria using standard analytical methods. Phytochemical screening of the flower and seed of the plant revealed the presence of flavonoids, phenols, saponins, tannins, alkaloid and anthraquinone, steroid and cardiac glycosides, were slightly present, while resins was absent. The metabolites present were quantitatively determined with alkaloid contents of 10.23±0.35 and 8.41±0.76 saponins 25.72±0.83 and 28.84±0.44, flavonoids 28.52±0.47 and 32.25±0.52, tannins 32.98±0.74 and 39.99±0.37, phenols 4.24±0.76 and 6.31±0.68 mg/100 g for flower and seed respectively. These results confirm that these metabolites obtained from the two parts of this plant were within the range of toxicity levels according to World Health Organization safe limits. The results of anti-nutritional factors revealed the oxalate contents with 4.24±0.12 and 6.31±0.41, cyanide content 8.59±0.71 and 4.89±0.69 and phytate content 17.54±0.63 and 13.72±0.81 mg/100g for flower and seed respectively. The values of anti-nutritional factors obtained from this work show that they may not pose any effects based on their toxicity levels and as recommended by World Health Organization. The major components of the chemical compounds deduced from GC/MS for the two parts of this plant investigated revealed the presence of β-d-mannofuranoside (24.23%), n-hexadecanoic acid (19.20%), oleic acid (28.27%), nonadecanoic acid (5.36%), 3, 11-tetradecadien-1-ol (3.79%) and octadecanal (17.22%), oleic acid (50.21%), octadecanoic acid (7.14), n-hexadecanoic acid (34.16%), pentanoic acid (3.39%) and 2-ethyl-1-decanol (2.21%). Some of these phytoconstituents like n-hexadecanoic and oleic are responsible for the said pharmacological activities. Thus, properly domesticated and utilization of this plant will serve as source of bioactive agents for pharmaceutical industries.

English

This study investigated the spatial distribution, chemistry and subsurface temperatures of geothermal springs in Nkhata Bay, Malawi, which lies in the Western Branch of the East African Rift System. Seventeen geothermal springs were identified and mapped in the District. Eleven of these geothermal springs were purposively sampled for chemistry study on the basis of their spatial distribution representativeness and accessibility for reassessment. Two water types were hydrochemically delineated: sodium-sulfate (Na-SO4) and sodium-sulfate-bicarbonate (Na-SO4-HCO3). Additionally, several mineral species were inferred to have been in contact with the geothermal spring waters in the district: calcite, aragonite, dolomite, gypsum, anhydrite, halite, fluorite, goethite, siderite and haematite. The thermal spring waters were undersaturated with respect to aragonite, calcite, dolomite, gypsum, anhydrite, halite and fluorite. However, four geothermal springs were supersaturated with respect to goethite, haematite and siderite. Although all the geothermal springs were undersaturated with fluorite (CaF2), all contained higher F- concentrations (from 2.21±0.06 to 10.27 ± 0.25 mg/L) than the World Health Organization (WHO) recommended limit for drinking water (1.5 mg/L). This suggests that fluoride does not precipitate as CaF2 in the springs but mobilizes freely in the thermal waters without forming other complexes. The cadmium levels in four thermal springs exceeded the Malawi Bureau of Standards (MBS) and WHO safe limit for human consumption (0.005 mg/L). Furthermore, the iron levels in three springs exceeded the WHO and MBS safe limit (0.20 mg/L). Evidently, the chemistry of geothermal springs in Nkhata Bay shows that their utilization for drinking is not suitable. The Giggenbach Triangle revealed that all but one of the springs had fully equilibrated waters. Hence, chemical geothermometers were used to estimate their original subsurface temperatures. Information about these temperatures is required for the assessment of possible geothermal power stations. Amongst the geothermometers used, the Na/K/Ca and Na/K geothermometers offered better and more robust estimates (P>0.01) of geothermal subsurface temperatures. These geothermometers indicated that the original subsurface temperatures were in the ranges of 85 - 209 and 112 - 280°C, respectively.   Key words: Geothermal springs, spatial distribution, chemistry, subsurface temperatures.

Groundwater Quality Assessment of Arid Regions of Punjab, India with Special Reference to Fluoride

Fluoride (F - ) intake with drinking water is a severe problem in several places in India including arid region of Punjab, North-West, India. Moderate amounts lead to dental fluorosis, but long-term ingestion of large amounts can lead to potentially severe skeletal problems. Keeping in view this fact, a study was planned to know the status of F - content in ground water of south western districts of Punjab and its relationship with other quality parameters. For this purposes, ninety-two ground water samples were collected in October 2009 from shallow aquifers and analyzed for fluoride and various other quality parameters. Fluoride content varied from 0.28 to 14.04 mg L -1 with a mean value of 5.15 mg L -1 . The elevated pH, dissolved salts, alkali metals (Na + , K + ) and anions (Cl - , HCO3 - and SO4 2- ) were accompanied by higher mean, median, 75 th and 90 th percentile fluoride concentration in groundwater. The concentration of fluoride declined with increasing concentration of calcium. Considering the World health organization safe limit of fluoride (1.5 mg L -1 ), 60 % of the total water samples collected were unfit for drinking purposes. From irrigation point of view, our results indicated that 86 % of the water samples are having F - content less than 10 mg L -1 which is the safe limit for all types of crop plants. The exposure doses to fluoride from ground water were also estimated for infants, children and adults. The maximum exposure dose to fluoride for the adults in the study area was 35 times higher than the minimum risk level proposed by Agency for Toxic Substances and Disease Registry's (ATSDR's MRL), indicating need of further research in this area.

Statistical characterization of arsenic contamination in shallow tube wells of western Bangladesh

AbstractA regional assessment of the arsenic (As) contamination scenario in shallow tube wells (depth < 150 m) of western Bangladesh is presented. Comparisons are made in light of bulk geological differences (Pleistocene versus Holocene deposits/northwest versus southwest) and As measurement protocols (field kit (FK) versus atomic absorption spectroscopy (AAS)). Our As database comprised the following: (1) the nationwide As survey completed in 1999 by the British Geological Survey in collaboration with the Department of Public Health Engineering (DPHE); and (2) a regional As survey conducted in southwest Bangladesh by the Japan International Cooperation Agency in collaboration with DPHE in 2002. First, we characterize the error structure of the semi‐quantitative FK As measurements using collocated AAS As measurements as reference from a set of 307 wells located in southwest Bangladesh. The depth distribution of As is identified using a very dense cluster of 2963 wells over a 560 km2 domain. The probability of the FK method for successful detection of a well sample as unsafe (safe) was found to be 96·9% (34·1%) and 95·2% (80·3%) for the World Health Organization (WHO) and Bangladesh safe limits, respectively. Similarly, the probability of false alarms and false hopes for WHO (Bangladesh) safe limits were found to be 3·1% (4·8%) and 87·5% (19·7%), respectively. The depth at which the highest fraction of wells exceeding a given safe limit occurred could still be inferred correctly by FK measurements. A simple bias adjustment procedure on FK As data did not result in a more accurate characterization of depth distribution of As. This indicated that simple error statistics are inadequate for advancing the utility of FKs; rather, an understanding of the complex and multidimensional error structure is required. Regional anisotropy in the spatial dependence of As for the northwest was found to be stronger than the southwest. The correlation length for As concentration in the east–west direction of northwest Bangladesh (i.e. across major river floodplains) was found to be almost twice (158·80 km) that of the north–south direction (along the major axis of Pleistocene deposits) (78·21 km). For the southwest region, the ratio of east–west to north–south correlation lengths ranged from 1·40 to 1·51. For the northwest region, because it is well known to have the lowest concentrations of As countrywide, knowledge of this anisotropy appears to suggest the need for drilling twice as many remediation deep wells in the proximity of an unsafe shallow well in the north–south direction than in the east–west direction. Findings from this study are potentially useful in setting priority areas for emergency testing, distributing remediation resources equitably and formulating a regional water resources strategy for western Bangladesh. Copyright © 2005 John Wiley & Sons, Ltd.