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PubMed1980

An investigation of the effects of impulse noise exposure on man: impulse noise with a relatively low peak level.

The effects of impulse noise of a relatively low peak level were examined to develop damage risk criteria for impulse noise. Eight to 13 normal male students (age: 20-24 years) were exposed to impulse noise. Peak levels of impulse noise were 100 dB (S.P.L.) and 105 dB (S.P.L.), B-duration of impulse noise being 10 ms, 50 ms, and 100 ms, and the repetition rates of impulse noise were 3 per 1 s and 1 per 3 s. Exposure time was 8 h in all exposure conditions. Exposure conditions of long B-duration induced greater TTS2 than those of short B-duration (P less than 0.05). Impulse noise exposure at a high peak level induced slightly larger TTS2 than that at a low peak level. TTS2 increased proportionally to the logarithm of the amount of impulse noise. Exposure to impulse noise induced smaller TTS2 than that of steady-state noise of an equal energy level. In addition, exposure to large amounts of impulse noise induced slightly greater urinary 17 OHCS levels than small amounts of impulse noise, and exposure to impulse noise induced smaller urinary 17 OHCS levels than steady-state noise of an equal energy level (P less than 0.05). The decreasing effect of the acoustic reflex on the acoustic energy of impulse noise was considered to be the reason for the results obtained. This experiment supported the modified CHABA Limit of Damage Risk Criteria of impulse noise proposed by the US Environmental Protection Agency.

17-Hydroxycorticosteroids↗
PubMed1991

Assessment of lawn care worker exposure to dithiopyr.

Eighteen ChemLawn lawn care specialists were monitored for worker exposure by both passive dosimetry and biological monitoring techniques in the performance of normal duties of mixing/loading and application of Dimension herbicide to turfgrass. Passive dosimetry was performed, utilizing cotton gauze patches, silica gel air sampling absorption media, and hand washes as per US Environmental Protection Agency Pesticide Assessment Guidelines. Biological monitoring was performed by analysis of all urine specimens collected from each specialist from initiation until 72 h after application of dithiopyr. The mean body dose estimate from urinalysis of the specimens collected over the 72 h period was 4.60 x 10(-5) mg/kg/lb applied. The passive dosimetry body dose estimates using dermal deposition measurements corrected for skin penetration and simulated inhalation measurements were calculated for the two clothing scenarios observed in the worker tests. The mean body dose estimate for a fully clothed specialist wearing a long-sleeved shirt was 8.09 x 10(-5) mg/kg/lb while for a specialist wearing a short-sleeved shirt the estimate was 3.62 x 10(-4) mg/kg/lb. The lower leg regions, which were protected by long pants and boots, had the highest exposure by passive dosimetry data.

Animals↗
PubMed1991

Detoxification of pentachlorophenol and creosote contaminated groundwater by physical extraction: chemical and biological assessment.

Chemical analyses revealed that polycyclic aromatic hydrocarbons (PAHs) and other organic compounds were present in a perennial freshwater stream that flowed through the abandoned American Creosote Works and into Pensacola Bay, Florida. Moreover, groundwater pumped from a well depth of 21 m at a location adjacent to the site was heavily contaminated with PAHs and other organics. A study was conducted to determine the efficacy of ultrafiltration for removal of organics from groundwater at this U.S. Environmental Protection Agency, Super Fund site. Ultrafiltration reduced the concentration of total identified organics from 210.0 mg/L in groundwater to 1.5 mg/L in the post-filtration permeate. Tests for toxicity/teratogenicity in embryonic inland silversides, Menidia beryllina; and Microtox 15 min EC50's were conducted with: 1) streamwater, 2) untreated groundwater, 3) feedwater used in the ultrafiltration system and 4) permeate water that passed through the ultrafiltration system. A concentration of 100% streamwater caused significant (alpha less than or equal to 0.05) teratogenic responses in fish embryos and larvae; the Microtox EC50 was 3.7% streamwater. Groundwater and feedwater caused significant embryo toxic or teratogenic responses at concentrations of 100, 10, and 1%; the Microtox EC50's were 0.85 and 0.48%, respectively. In contrast, only 100% permeate water caused significant increases in terata, compared to the control response; at 10 and 1% concentrations greater than 90% of hatched larvae appeared normal. The Microtox EC50 was 30% permeate water.

Animals↗
PubMed1980

Evaluating promulgated refinery effluent standards using artificial streams.

Two-week tests on an Artificial Refinery MIxture (ARM) were conducted on periphyton communities on glass slides in laboratory streams. ARM components, which are present in "typical" refinery effluents, approximate maximum allowable concentrations as promulgated by the 1977 U.S. Environmental Protection Agency (USEPA) guidelines for refinery effluents. ARM concentrations tested ranged from approximately 0.25 to 5 times full strength. The nontaxonomic structural parameters--ash-free dry weight, chlorophyll a, and ATP--indicated that ARM concentrations of 1 to 5X stimulated periphyton colonization rates. ARM concentrations of 0.25 to 5X caused a shift in dominant periphytic algae from diatoms in reference streams to green algae in dosed streams; this resulted in higher pH levels in reference streams, apparently related to photosynthetic activity. Changes in nontaxonomic structural parameters of slides precolonized with periphyton were not sensitive water quality indicators. Dry weight was not a useful biomass indicator due to high levels of suspended solids in ARM. The promulgated 1977 guidelines may be adequate to maintain nontaxonomic structural integrity of periphyton communities, while the 1983 guidelines appear to be adequate to maintain taxonomic integrity.

Adenosine Triphosphate↗
PubMed1993

Noise in the ICU.

OBJECTIVE: The growing number of technical devices in ICUs makes noise exposure a major stressor. The purpose of this study was to assess noise levels during routine operation in our ICU. DESIGN: Our ICU is an open ward with four rooms, constructed in the 1960s. During the study period, 4 patients were in the controlled room and were treated by 4 nurses during the day and by 2 at night. A-weighted sound pressure levels (SPL) were measured continuously for 2 days and nights. Also measured were the alarms of various appliances. For gross overall evaluation it is customary to state the Leq, i.e. the energy-averaged level during measurement. The annoyance caused by noise depends more on rare events of high intensity. Therefore, the distribution of SPL values (Ln) over time was also analysed. RESULTS: SPL was roughly the same during the day and at night, with Leq between 60-65 dB(A) and peaks up to 96 dB(A). Most alarms reach an SPL of 60-70 dB(A), but some exceed 80 dB(A). During teaching rounds Leq exceeds 65 dB(A). CONCLUSION: During the day and at night SPL always surpasses the permissible noise exposure for 24 h of 45 db(A) recommended by the US Environmental Protection Agency. Alarms cause the most irritating noise. Hospital management should pay attention to internal noise, and SPL should be measured routinely.

Austria↗
PubMed2001

Scientific analysis of the proposed uses of the T25 dose descriptor in chemical carcinogen regulation.

The uncertainties that surround the methods used for risk assessment of exposure to carcinogens have been highlighted by a recent document advocating an approach based on the T25 dose (the dose giving a 25% incidence of cancer in an appropriately designed animal experiment). This method relies on derivation of the T25 dose then assesses risk at the exposure dose using proportionality provided by a linear extrapolation (T25/linear). To promote discussion of the scientific issues underlying methods for the risk assessment of chemical carcinogens, the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) hosted a one-day workshop in Brussels on 10 November 2000. Several invited presentations were made to participants, including scientists from regulatory authorities, industry and academia. In general, it was felt that there was sufficient basis for using the T25 dose as an index of carcinogenic potency and hence as part of the hazard assessment process. However, the use of the T25 in risk assessment has not been validated. The T25/linear and other extrapolation methods based on metrics such as LED 10 assume linearity which may be invalid. Any risk calculated using the T25/linear method would provide a precise risk figure similar to the output obtained from the Linearised Multistage (LMS) method formerly used by the Environmental Protection Agency (EPA) in the United States of America. Similarity of output does not provide validation but rather reflects their reliance on similar mathematical approaches. In addition to the T25 issue, evidence was provided that using two separate methods (linearised non-threshold model for genotoxic carcinogens; no-observable-effect level with a safety factor (NOEL/SF) method for all other toxicity including non-genotoxic carcinogens) is not justified. Since the ultimate purpose of risk assessment is to provide reliable information to risk managers and the public, there was strong support at the workshop for harmonisation of approaches to risk assessment for all genotoxic and nongenotoxic carcinogens. In summary, the T25 method has utility for ranking potency to focus efforts in risk reduction. However, uncertainties such as the false assumption of precision and non-linearity in the dose-response curve for tumour induction raise serious concerns that caution against the use of T25/linear method for predicting human cancer risk.

Animals↗
PubMed2005

Quantitative determination of organochlorine pesticides in sewage sludges using soxtec, soxhlet and pressurized liquid extractions and ion trap mass-mass spectrometric detection.

A new analytical method is described for the determination of organochlorine pesticides (OCPs) in sewage sludges using GC-ion trap-MS-MS. In this work, 16 organo-chlorine pesticides (OCPs) listed by the US Environmental Protection Agency (US EPA) as priority pollutants were separated and quantified. Sludge samples from three of Kuwait's wastewater treatment plants (WWTPs) were analyzed for organochlorine pesticides (OCPs). Spiked sludge samples were extracted with a mixture of (1:1 v/v) dichloromethane (DCM)/hexane. The extracts were cleaned on a silica/aluminum oxide column, then transferred to a gel permeation chromatography (GPC) column, before undergoing further silica/aluminum oxide clean-up; the presence of OCPs was then confirmed by GC-ion trap-MS-MS. Three extraction techniques, soxtec, soxhlet, and pressurized liquid extractions were utilized, compared and validated using the spiked sludge samples. The methods were validated in term of accuracy (recovery) and precision (RSD). The method recovery values varied from 76.1 to 92.9% for the three extraction techniques.

Aluminum Oxide↗
PubMed2003

Field and laboratory assessment of a coal processing effluent in the Leading Creek Watershed, Meigs County, Ohio.

The U.S. Environmental Protection Agency has not recommended water quality criteria (WQC) to protect aquatic life from elevated sodium and sulfate concentrations, such as those associated with the coal-processing effluent of Meigs County Mine #31. This discharge, received by a tributary of the Leading Creek Watershed (SE Ohio), had a mean specific conductivity (SC) of 8,109 (7,750-8,750) microS/cm and total metal concentrations below acute WQC. The mean 48-h LC(50) for Ceriodaphnia dubia in the effluent was 6,713 +/- 99 microS/cm; mean 48-h survival was 44% for study sites downstream of the effluent. The best indicators of impairment used in this study were Ceriodaphnia fecundity, in situ Corbicula fluminea growth, EPT minus Hydropsychidae (richness and relative abundance), and relative Ephemeroptera abundance. Mayflies, reduced by more than 99% below the effluent, were absent from all but the furthest downstream study site. SC was strongly correlated with Corbicula growth (r = -0.9755, p = 0.0009) and EPT minus Hydropsychidae richness (r = -0.8756, p < 0.0001), suggesting the effluent was primarily responsible for biotic impairment. Our results indicated that SC levels, a measure of dissolved solids, in the Leading Creek Watershed that exceeded approximately 3,700 microS/cm impaired sensitive aquatic fauna.

Animals↗
PubMed2005

Assessing contaminant sensitivity of endangered and threatened aquatic species: part I. Acute toxicity of five chemicals.

Assessment of contaminant impacts to federally identified endangered, threatened and candidate, and state-identified endangered species (collectively referred to as "listed" species) requires understanding of a species' sensitivities to particular chemicals. The most direct approach would be to determine the sensitivity of a listed species to a particular contaminant or perturbation. An indirect approach for aquatic species would be application of toxicity data obtained from standard test procedures and species commonly used in laboratory toxicity tests. Common test species (fathead minnow, Pimephales promelas; sheepshead minnow, Cyprinodon variegatus; and rainbow trout, Oncorhynchus mykiss) and 17 listed or closely related species were tested in acute 96-hour water exposures with five chemicals (carbaryl, copper, 4-nonylphenol, pentachlorophenol, and permethrin) representing a broad range of toxic modes of action. No single species was the most sensitive to all chemicals. For the three standard test species evaluated, the rainbow trout was more sensitive than either the fathead minnow or sheepshead minnow and was equal to or more sensitive than listed and related species 81% of the time. To estimate an LC50 for a listed species, a factor of 0.63 can be applied to the geometric mean LC50 of rainbow trout toxicity data, and more conservative factors can be determined using variance estimates (0.46 based on 1 SD of the mean and 0.33 based on 2 SD of the mean). Additionally, a low- or no-acute effect concentration can be estimated by multiplying the respective LC50 by a factor of approximately 0.56, which supports the United States Environmental Protection Agency approach of multiplying the final acute value by 0.5 (division by 2). When captive or locally abundant populations of listed fish are available, consideration should be given to direct testing. When direct toxicity testing cannot be performed, approaches for developing protective measures using common test species toxicity data are available.

Animals↗
PubMed2005

Evaluation of ionic contribution to the toxicity of a coal-mine effluent using Ceriodaphnia dubia.

The United States Environmental Protection Agency has defined national in-stream water-quality criteria (WQC) for 157 pollutants. No WQC to protect aquatic life exist for total dissolved solids (TDS). Some water-treatment processes (e.g., pH modifications) discharge wastewaters of potentially adverse TDS into freshwater systems. Strong correlations between specific conductivity, a TDS surrogate, and several biotic indices in a previous study suggested that TDS caused by a coal-mine effluent was the primary stressor. Further acute and chronic testing in the current study with Ceriodaphnia dubia in laboratory-manipulated media indicated that the majority of the effluent toxicity could be attributed to the most abundant ions in the discharge, sodium (1952 mg/L) and/or sulfate (3672 mg/L), although the hardness of the effluent (792 +/- 43 mg/L as CaCO3) ameliorated some toxicity. Based on laboratory testing of several effluent-mimicking media, sodium- and sulfate-dominated TDS was acutely toxic at approximately 7000 microS/cm (5143 mg TDS/L), and chronic toxicity occurred at approximately 3200 microS/cm (2331 mg TDS/L). At a lower hardness (88 mg/L as CaCO3), acute and chronic toxicity end-points were decreased to approximately 5000 microS/cm (3663 mg TDS/L) and approximately 2000 microS/cm (1443 mg TDS/L), respectively. Point-source discharges causing in-stream TDS concentrations to exceed these levels may risk impairment to aquatic life.

Animals↗
PubMed2005

Assessing contaminant sensitivity of endangered and threatened aquatic species: part III. Effluent toxicity tests.

Toxicity tests using standard effluent test procedures described by the U.S. Environmental Protection Agency were conducted with Ceriodaphnia dubia, fathead minnows (Pimephales promelas), and seven threatened and endangered (listed) fish species from four families: (1) Acipenseridae: shortnose sturgeon (Acipenser brevirostrum); (2) Catostomidae; razorback sucker (Xyrauchen texanus); (3) Cyprinidae: bonytail chub (Gila elegans), Cape Fear shiner (Notropis mekistocholas) Colorado pikeminnow (Ptychocheilus lucius), and spotfin chub (Cyprinella monacha); and (4) Poecillidae: Gila topminnow (Poeciliopsis occidentalis). We conducted 7-day survival and growth studies with embryo-larval fathead minnows and analogous exposures using the listed species. Survival and reproduction were also determined with C. dubia. Tests were conducted with carbaryl, ammonia--or a simulated effluent complex mixture of carbaryl, copper, 4-nonylphenol, pentachlorophenol and permethrin at equitoxic proportions. In addition, Cape Fear shiners and spotfin chub were tested using diazinon, copper, and chlorine. Toxicity tests were also conducted with field-collected effluents from domestic or industrial facilities. Bonytail chub and razorback suckers were tested with effluents collected in Arizona whereas effluent samples collected from North Carolina were tested with Cape Fear shiner, spotfin chub, and shortnose sturgeon. The fathead minnow 7-day effluent test was often a reliable estimator of toxic effects to the listed fishes. However, in 21 % of the tests, a listed species was more sensitive than fathead minnows. More sensitive species results varied by test so that usually no species was always more or less sensitive than fathead minnows. Only the Gila topminnow was consistently less sensitive than the fathead minnow. Listed fish species were protected 96% of the time when results for both fathead minnows and C. dubia were considered, thus reinforcing the value of standard whole-effluent toxicity tests using those two species. If the responses of specific listed species are important for management decisions, our study supports the value in developing culture and testing procedures for those species.

Animals↗
PubMed2005

Bioassessment of an Appalachian headwater stream influenced by an abandoned arsenic mine.

Recent debate concerning the modification of safe drinking water standards for arsenic (As) has led to increased awareness of the risks As poses to both humans and the environment. However, few studies have examined the effects of As on the diversity and composition of aquatic assemblages in streams. Benthic macroinvertebrate surveys, chemical analysis of water column and sediment, and laboratory toxicity tests were conducted to assess effects of an abandoned As mine on a headwater stream, and to determine the primary component of toxicity. The average 48-hr LC50 value for Daphnia magna was 4316 microg As/L, and the average 96-hr LC50 value for Lepidostoma spp. was 2138 microg As/L. Reproduction was significantly reduced for D. magna at concentrations > or =312 microg As/L in water column laboratory bioassays, and for treatments in bioassays with sediments containing elevated As (> or =2630 mg/kg). These results support the findings of the in-stream benthic macroinvertebrate survey as the density and percent Ephemeroptera + Plecoptera, + Trichoptera (EPT) were substantially lower at sites downstream of the mine compared to upstream reference sites. Results of bioassays comparing the toxicity of As-contaminated site water and upstream reference water spiked with As salts suggest that As is the primary component of toxicity impacting the stream. Measured As concentrations at downstream sites were above the recommended Criterion Maximum Concentration of 340 microg As/L and Criterion Continuous Concentration of 150 microg As/L for protection of aquatic life published by the United States Environmental Protection Agency. At the study site, elevated As concentrations likely prevent recruitment of benthic macroinvertebrates and recovery of the perturbed headwater stream.

Animals↗
PubMed2006

The potential for chromium to affect the fertilization process of Chinook salmon (Oncorhynchus tshawytscha) in the Hanford reach of the Columbia River, Washington, USA.

The Hanford Nuclear Reservation in south central Washington was claimed by the federal government as a site for the production of plutonium. During the course of production and operation of the facilities at Hanford, radionuclides and chromium were discharged directly into the river and also contaminated the groundwater. This study was designed to assess the effects of chromium (Cr) on Chinook salmon (Oncorhynchus tshawytscha) fertilization under exposure conditions similar to those of the Hanford Reach of the Columbia River. Chinook salmon gametes were exposed to aqueous Cr concentrations ranging from 0 to 266 microg Cr l(-1). The current ambient water-quality criteria (AWQC) established for the protection of aquatic life (United States Environmental Protection Agency [USEPA] 1986) is 11 microg Cr l(-1). Cr has been measured in pore water from bottom sediments of the Columbia River at concentrations >600 microg Cr l(-1). Under exposure conditions designed to closely mimic events that occur in the river, the fertilization of Chinook salmon eggs was not affected by concentrations of Cr ranging from 11 to 266 microg Cr l(-1). Data suggest that the instantaneous nature of fertilization likely limits the potential effects of Cr on fertilization success. As a result, the current AWQC of 11 mug Cr l(-1) is most likely protective of Chinook salmon fertilization.

Animals↗
PubMed2000

Evaluating mosquito control pesticides for effect on target and nontarget organisms.

Recent requirements for biomonitoring of urban stormwater runoff have raised the issue of toxic contributions from mosquito control products. A comparison of seven pesticides for their toxicity to target and nontarget organisms was conducted in field and laboratory trials to determine relative impacts in and around Craighead County, Arkansas. Twenty-four and forty-eight-hour acute toxicity tests using Ceriodaphnia dubia, Daphnia magna, Daphnia pulex, and Pimephales promelas were employed with U.S. Environmental Protection Agency (U.S. EPA) suggested procedures as standard test organisms. Additional tests with resident mosquito fish, Gambusia affinis, and mosquito larvae, Anopheles quadrimaculatus, included ditch-receiving waters to compare the somewhat sterile laboratory exposures to actual field conditions. Exposure to as much as 31.4 microg/L of the pesticides Dursban(R), malathion, Permanone(R), Abate(R), Scourge(R), B.t.i, and Biomist(R) were required for effective control of An. quadrimaculatus, whereas as little as 2.7 microg/L resulted in substantial mortality of some nontarget organisms. These data suggest that prevailing application rates for effective mosquito control not only affect nontarget organisms but may also confound stormwater and nonpoint toxicity evaluations that utilize sensitive indicator species.

Animals↗
PubMed2000

Antipredatory behavior as an index of heavy-metal pollution? A test using snails and caddisflies.

The loss of behaviors that organisms use to avoid predation may serve as a sensitive indicator of pollution. We tested the hypothesis that a correlation exists in the field between heavy metal levels and antipredator behaviors. We examined the antipredator behavior of aquatic caddisfly larvae and snails at sites in the Coeur d'Alene basin of Northern Idaho which varied in their levels of heavy metals. We tested the antipredator response of Physella columbiana snails at 10 polluted lakes downstream from the Bunker Hill Environmental Protection Agency (EPA) Superfund cleanup site. We then compared their behavior to snails at 14 reference lakes. We placed the snails in a plastic testing apparatus, exposed them to an extract of crushed snail, and then monitored their movements to a normally preferred shaded area. We also tested the behavior of caddisfly larvae from 36 sites from a total of 6 streams/rivers adjacent to the Superfund site. Sites were located upstream and downstream of abandoned mines. We located active larvae of four genera, simulated predation by grasping the animals between thumb and forefinger (the larvae respond to being grasped by withdrawing into their case), lifted them from the water for 3 s, and then placed them in an adjacent, slower section of the stream. We then recorded how long it took each larvae to partially emerge from its case and attempt to move away. Unlike reference site snails, snails from heavy metal-polluted environments failed to exhibit antipredator behaviors in response to crushed conspecifics. These results are consistent with previous laboratory studies. We found no effect of heavy metals on the antipredatory behavior of caddisfly larvae.

Animals↗
PubMed1999

Decontamination of Fly Ash and Used Lime from Municipal Waste Incinerator Using Thiobacillus ferrooxidans.

/ The purification of incinerator gases produces large quantities of fly ash and used lime [a combination referred to as air pollution control residues (APCR)], both of which contain elevated levels of metals. This paper describes biological solubilization assays utilizing Thiobacillus ferrooxidans to leach metals from APCR to render them nonhazardous. The multistage solubilization process involves an alkaline aqueous phase that removes some Pb. In the second phase, the APCR are acidified to pH 4 with H(2)SO(4), then inoculated with a bacterial culture that has been acclimated in the presence of 2% Fe (FeCl(3)). Several rinses and decantings achieve removal of the leachable metals. The final step involves the addition of Ca(H(2)PO(4))(2) and an increase in the treatment pH prior to the final filtration. Viability of thiobacilli in APCR was poor. Despite this problem, the removal of Pb was 35.9%, 46.0%, and 68.7% (for APCR containing 1594, 3026, and 5038 mg Pb/kg, respectively), which demonstrates greater metal removal with increased APCR contamination. Zn removal varied from 68.2% (8273 mg Zn/kg APCR) to 79.5% (16,873 mg Zn/kg APCR), which was positively correlated to the level of residue contamination, whereas Cu was removed in the proportions of 26.9% (495 mg Cu/kg APCR) to 68.2% (465 mg Cu/kg APCR). Cadmium removal appeared to be independent of the level of Cd in the APCR; Cd was removed to the greatest degree, with a variation of 92.0% (129 mg Cd/kg APCR) to 94.7% (267 mg Cd/kg APCR). The treated APCR were tested using four different leachate tests. The APCR released 43 mg Pb/liter during contact with water, and 7.40 mg Cd/liter during TCLP [the toxicity characterization leaching procedure of the United States Environmental Protection Agency (US EPA)]. After biological treatment, the leachate from TCLP was within the acceptance criteria of the US EPA, if the pH of the APCR was increased to pH 5 after the biological treatment. In the case of the Transport Canada leaching test, a betterment of the process is required in order to satisfy the stringent regulatory level of 0.5 mg Cd/liter (0.68 and 0.57 mg/liter).KEY WORDS: Thiobacilli; Metals removal; Fly ash; Incinerator; Hazardous waste.http://link.springer-ny.com/link/service/journals/00267/bibs/24n4p517.html</HEA

Journal Article↗
PubMed2005

Identification and determination of the viability of Giardia lamblia cysts and Cryptosporidium parvum and Cryptosporidium hominis oocysts in human fecal and water supply samples by fluorescent in situ hybridization (FISH) and monoclonal antibodies.

In the present study, fluorescent in situ hybridization (FISH) and monoclonal antibodies (MAbs) were evaluated for species-specific detection and viability determination of Giardia lamblia, Cryptosporidium parvum, and Cryptosporidium hominis in human fecal and water supply samples. A total of 50 fecal human samples positive for G. lamblia cysts, 38 positive for C. parvum, and 23 positive for C. hominis were studied. Also, 18 water supply samples positive for Giardia spp. and Cryptosporidium spp. by the United States Environmental Protection Agency (USEPA) Method 1623 were studied by FISH and fluorescein isothiocyanate (FITC)-conjugated MAbs. Eighteen percent of the fecal samples parasitologically positive for G. lamblia presented viable and nonviable cysts, and 5% of those positive for Cryptosporidium spp. presented viable and nonviable oocysts. Of the 18 water supply samples analyzed, 6 (33%) presented Giardia spp. viable and nonviable cysts and 2 (11%) presented viable and nonviable Cryptosporidium spp. oocysts. G. lamblia identification was confirmed by polymerase chain reaction (PCR) and sequencing of the beta-giardin gene in the fecal and water samples found positive by FISH and FITC-conjugated MAbs. C. parvum and Cryptosporidium muris were identified, by PCR and sequencing of the small subunit of ribosomal RNA gene, in seven and one water samples, respectively. Our results confirm that this technique enables simultaneous visualization, species-specific identification, and viability determination of the organisms present in human fecal and water supply samples.

Animals↗
PubMed2005

Roadside concentration of gaseous and particulate matter pollutants and risk assessment in Dar-es-Salaam, Tanzania.

This study used manual air sampling method to assess the contribution of road traffic to air pollution level in Dar-es-Salaam City, Tanzania. Samples were collected from 11 different sites. Parameters measured were: sulphur dioxide using pararosaniline method, nitrogen dioxide using saltzman method, particulate matter and particulate lead using filtration method and atomic absorption spectrometric method, respectively. Results showed that hourly average sulphur dioxide concentration range from 127 to 1385 microg/m3. The measured values of sulphur dioxide were above the recommended WHO guidelines with an hourly objective value of 350 microg/m3 at 87% of the sampling sites. The hourly average nitrogen dioxide concentration ranged from 18 to 53 microg/m3. The maximum hourly nitrogen dioxide concentration at 53 microg/m3 was below the WHO guideline value of 200 microg/m3. The hourly average suspended particulate matter (SPM) ranged from 98 to 1161 microg/m3, exceeding the recommended value of 230 microg/m3 by WHO at 87% of the sampling sites. The hourly average lead concentration was found to range from 0.60 to 25.6 microg/m3, exceeding again the WHO guideline value of 1.5 microg/m3 at 83% of the sampling sites. Results predicted by Gaussian model when compared with the measured values were found to have a correlation coefficient of 0.8, signifying a good correlation. The risk assessment was undertaken considering the people who spend a significant portion of their time near the roads, such as the Uhuru primary school pupils and the adult population who reside by the roadside. The unit risk realised was 18.2 x 10(-6) for adult population and 2.2 x 10(-6) for pupils, both scenarios showing risk higher than the United Sates of America Environmental Protection Agency (USEPA) acceptable limit of 1 x 10(-6). Considering the magnitude of the problem at hand, this study recommends an introduction of mandatory emission tests of SPM, lead and sulphur dioxide (SO2). The study further recommends the introduction of continuous and/or regular air quality monitoring and the use non-leaded petrol in Tanzania.

Air Pollutants↗