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PubMed1990

Fecal contamination of shanty town toddlers in households with non-corralled poultry, Lima, Peru.

We used direct observer techniques to measure the frequency with which toddler-aged children were contaminated by poultry feces in homes in a peri-urban shanty town in Lima, Peru. The mean number of fowl was 5.4 (SD 3.1), with 10.0 (SD 10.7) poultry defecations per 12 hours. Toddlers' hand contact with poultry feces occurred a mean of 2.9 (SD 3.0) times/12 hours. A mean of 3.9 (SD 4.6) feces-to-mouth episodes per household/12 hours occurred both by direct hand-to-mouth contamination and indirectly by handling soiled objects which were then placed in the mouth. There was a strong correlation between feces-to-hand contamination and feces-to-mouth contamination (r = 0.94). There was also an association between feces-to-mouth contamination and the number of stools deposited in the house (r = 0.66). For each additional chicken stool deposited during the day, there was an average increase of 0.27 in feces-to-mouth episodes. We collected feces from 68 infected chickens and found viable Campylobacter jejuni for up to 48 hours after deposition. Yet, a survey of 108 families demonstrated that free-roaming poultry were often not thought of as a health risk for children. An intervention program to reduce oral-fecal contamination should emphasize that all poultry be corralled and not allowed access into the house.

Animals↗

PubMedDate not supplied

Spatial and temporal modeling of microbial contaminants on grazing farmlands.

This paper introduces an integrated spatial and temporal modeling system developed mathematically for assessing microbial contaminants on animal-grazed farmlands. The model uses fecal coliform, specifically Escherichia coli, as an indicator of fecal contamination and describes the sources, sinks, transport processes, and fate of E. coli contaminants in catchments and associated streams. Spatial features include grazing location, land topography, distance to a nearby stream, and distance through the stream network to the outlet. Temporal features are population dynamics on the land surface, in flow, and on streambeds. The model applies the principles of conservation of mass balance on two different types of pools: grid cells on land surfaces and networked stream segments. The model aims to improve the prediction of the effects of different land management strategies on the fecal contamination of waterways. This is achieved by characterizing the movement of fecal contaminants from land to streams and in-stream mobilization. Processes of attenuation, diffusion, and transport govern the movement. Our study site is a hill land catchment with an area of 140 ha and is used exclusively for animal grazing. The model was calibrated with previous research results, and then tested using the data collected at the outlet of the catchment. The sensitivity of the model predictions was analyzed for different scenarios: effect of stock rate, attenuation rate, and flow volumes. The similar pattern between monitored and predicted E. coli concentration proved that the model captures the key features that control the population dynamics of fecal contaminants. Further experiments are required to expand the model's functionality for covering more mitigation options.

Animal Husbandry↗

PubMedDate not supplied

Electron affinity coefficients of nitrogen oxides and biodegradation kinetics in denitrification of contaminated stream water.

During the dry season in Korea, rivers become more vulnerable to contamination by biochemical oxygen demand (BOD) and nitrogen. It is hypothesized that the natural characteristics of the streams in Korea allow the contaminated water to be treated at the tributaries. Down-stream river water quality in Korea may be improved by spraying the contaminated stream water from the tributaries over the surrounding floodplains. The consequent water filtration through the soil could remove the contaminants through aerobic and denitrifying reactions. In this study, the kinetics parameters of the denitrifying reaction in floodplain filtration were determined using contaminated stream water. For the electron donor the Monod kinetics was used, while the competitive Michaelis-Menten model was employed for the electron acceptors. The parameters to the competitive Michaelis-Menten model were found using continuous denitrifying reactions, instead of the batch reactions employed in previous studies, to match the conditions needed to apply the competitive Michaelis-Menten kinetics. From the result, it was found that continuous reactions as well as batch reactions could be used to determine the affinity coefficients in denitrification. The results of this study also showed that the affinity coefficient of NO2, using continuous reactions, was similar to that of other studies in the literature found via batch reactions, whereas the affinity coefficient of N2O was much larger than that acquired with batch reactions. The parameters obtained in this study will be used in future work to simulate the contaminant behaviors during floodplain filtration using a mathematical model.

Biodegradation, Environmental↗

PubMed2006

Distribution of uranium contamination in weathered fractured saprolite/shale and ground water.

The objective of this study was to determine how structure, stratigraphy, and weathering influence fate and transport of contaminants (particularly U) in the ground water and geologic material at the Department of Energy (DOE) Environmental Remediation Sciences Department (ERSD) Field Research Center (FRC). Several cores were collected near four former unlined adjoining waste disposal ponds. The cores were collected, described, analyzed for U, and compared with ground water geochemistry from surrounding multilevel wells. At some locations, acidic U-contaminated ground water was found to preferentially flow in small remnant fractures weathering the surrounding shale (nitric acid extractable U [U(NA)] usually < 50 mg kg(-1)) into thin (<25 cm) Fe oxide-rich clayey seams that retain U (U(NA) 239 to 375 mg kg(-1)). However, greatest contaminant transport occurs in a 2 to 3 m thick more permeable stratigraphic transition zone located between two less permeable, and generally less contaminated zones consisting of (i) overlying unconsolidated saprolite (U(NA) < 0.01 to 200 mg kg(-1)) and (ii) underlying less-weathered bedrock (U(NA) generally < 0.01 to 7 mg kg(-1)). In this transition zone, acidic (pH < 4) U-enriched ground water (U of 38 mg L(-1)) has weathered away calcite veins resulting in greater porosity, higher hydraulic conductivity, and higher U contamination (U(NA) 106 to 745 mg kg(-1)) of the weathered interbedded shale and sandstone. These characteristics of the transition zone produce an interval with a high flux of contaminants that could be targeted for remediation.

Environmental Monitoring↗

PubMed2006

Identifying sources of fecal contamination inexpensively with targeted sampling and bacterial source tracking.

Most bacterial source tracking (BST) methods are too expensive for most communities to afford. We developed targeted sampling as a prelude to BST to reduce these costs. We combined targeted sampling with three inexpensive BST methods, Enterococcus speciation, detection of the esp gene, and fluorometry, to confirm the sources of fecal contamination to beaches on Georgia's Jekyll and Sea Islands during calm and stormy weather conditions. For Jekyll Island, the most likely source of contamination was bird feces because the percentage of Ent. faecalis was high (30%) and the esp gene was not detected. For the Sea Island beach during calm conditions, the most likely sources of fecal contamination were leaking sewer lines and wildlife feces. The leaking sewer lines were confirmed with fluorometry and detection of the esp gene. For the Sea Island beach during stormflow conditions, the most likely sources of fecal contamination were wildlife feces and runoff discharging from two county-maintained pipes. For the pipes, the most likely source of contamination was bird feces because the percentage of Ent. faecalis was high (30%) and the esp gene was not detected. Sediments were also a reservoir of fecal enterococci for both Jekyll and Sea Islands. Combining targeted sampling with two or more BST methods identified sources of fecal contamination quickly, easily, and inexpensively. This combination was the first time targeted sampling was conducted during stormy conditions, and the first time targeted sampling was combined with enterococcal speciation, detection of the esp gene, and fluorometry.

Animals↗

PubMedDate not supplied

Air-quality monitoring and detection of air contamination in an enclosed environment.

We report on the development of an air-quality monitoring and early detection system for an enclosed environment with specific emphasis on manned spacecraft. The proposed monitoring approach is based on a distributed parameter model of contaminant dispersion and real-time contaminant concentration measurements. Kalman filtering is identified as a suitable method for generating on-line estimation of the spatial contamination profile, and an implicit Kalman filtering algorithm is shown to be preferable for rear-time implementation. The identification of the contaminant concentration profile allows for a straightforward solution of the early detection of an air contamination event and provides information that enables potential automatic diagnosis of an unknown contamination source.

Air Pollutants↗

PubMed1995

Studies on the in situ nitrogen degradability corrected for bacterial contamination of concentrate feeds in steers.

Stable 15N was used to evaluate the influence of bacterial contamination on in situ DM and N degradabilities (Dg) of meat and bone meal (MBM), soybean meal (SBM), and wheat bran (WB) in two steers. Bacterial DM and N contamination ranged from 2.4 to 28.6% and 2.1 to 56.8% of residual DM and N, respectively. Effective N degradability increased when bacterial contamination was taken into account (P < .05). The difference was low for MBM (2.4%) and for SBM (3.4%) but high for WB (12.2%). Theoretically, using solid-associated bacteria should give the most accurate correction for bacterial contamination; however, results showed that Dg of N based on liquid-associated bacteria were identical for MBM and SBM (P > .05) and different for WB (P < .05). In a second experiment, five treatments were applied to incubated feeds to remove bacteria fixed to the residues and consequently to determine directly the Dg of DM and N corrected for the bacterial contamination without the need for a marker. These treatments involved chilling for 6 h at 4 degrees C in saline solution alone (T1) or with a commercial detergent (T2), or with sodium dodecyl sulfate (T3) or with methylcellulose (T4), followed by pummeling in a stomacher for 5 min. The last treatment was only machine washing twice (T5). The Dg of DM can be directly determined following the first four treatments, nevertheless their application to MBM and SBM led to higher Dg of N than that corrected for the bacterial contamination determined in the first experiment (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia↗

PubMed1999

Bacillus cereus spores in raw milk: factors affecting the contamination of milk during the grazing period.

Psychrotrophic Bacillus cereus is a limiting factor for the shelf-life of pasteurized milk, particularly during the grazing season. Potential sources of contamination and factors that might affect the spore content of milk were studied in detail for a group of eight cows during three 2-wk study periods from June to September over 2 yr. The spore content of milk was strongly associated with the degree of contamination of the teats with soil. High water content of soil, low evaporation of water and dirty access alloys were the most important factors correlating with high spore concentrations. The spore content of soil varied from < 50 to 380,000/g, depending on time and sampling site. The milking equipment did not contribute significantly to the contamination. The spore contents in air during milking (< 100 cfu/m3) and in feed (silage, hay, fresh grass, and concentrates) were too low to be of importance for contamination. The spore content in dung was also low. Further support that soil was the major contamination source was found by comparison of genetic fingerprints by random amplified polymorphic DNA polymerase chain reaction of isolates of B. cereus from soil and milk and by teat cleansing experiments, which resulted in reduced contamination levels in milk.

Animals↗

PubMed2005

The role of domestic tap water in Acanthamoeba contamination in contact lens storage cases in Korea.

A survey was carried out from August to December 2004 in Pusan, Korea to document the presence of free-living amoeba (FLA), including the genus Acanthamoeba, in both contact lens storage cases and domestic tap water. Acanthamoeba was isolated from 5 (4.2%) in 120 contact lens storage cases. Four house tap water samples from residents, whose contact lens storage cases had been contaminated by Acanthamoeba, were also found to be contaminated with Acanthamoeba. Therefore, the contamination rate of FLA and Acanthamoeba in domestic tap water was investigated in order to examine the role of domestic tap water in Acanthamoeba contamination of contact lens storage cases. FLA and Acanthamoeba were identified in 97 (46.8%) and 16 (7.7%) of the 207 domestic tap water samples, respectively. There were no significant differences between the contamination rates of FLA in tap water according to the filtration plant of origin. No FLA was detected in the tap water directly supplied by the water purification plants. Water storage tanks appear to promote FLA colonization, including Acanthamoeba, in domestic tap water. This increases the risk of Acanthamoeba contamination in contact lens storage cases as well as increasing the risk of Acanthamoeba keratitis.

Acanthamoeba↗

PubMed2005

Bioremediation of contaminated lake sediments and evaluation of maturity indicies as indicators of compost stability.

Land contamination is one of the widely addressed problems, which is gaining importance in many developed and developing countries. International efforts are actively envisaged to remediate contaminated sites as a response to adverse health effects. Popular conventional methodologies only transfer the phase of the contaminant involving cost intensive liabilities besides handling risk of the hazardous waste. Physico-chemical methods are effective for specific wastes, but are technically complex and lack public acceptance for land remediation. iBioremediatio nî, is one of the emerging low-cost technologies that offer the possibility to destroy various contaminants using natural biological activities. Resultant non-toxic end products due to the microbial activity and insitu applicability of this technology is gaining huge public acceptance. In the present study, composting is demonstrated as a bioremediation methodology for the stabilization of contaminated lake sediments of Hyderabad, A.P, India. Lake sediment contaminated with organics is collected from two stratums--upper (0.25 m) and lower (0.5m) to set up as Pile I (Upper) and Pile II (Lower) in the laboratory. Lime as a pretreatment to the lake sediments is carried out to ensure metal precipitation. The pretreated sediment is then mixed with organic and inorganic fertilizers like cow dung, poultry manure, urea and super phosphate as initial seeding amendments. Bulking agents like sawdust and other micronutrients are provided. Continuous monitoring of process control parameters like pH, moisture content, electrical conductivity, total volatile solids and various forms of nitrogen were carried out during the entire course of the study. The stability of the compost was evaluated by assessing maturity indices like C/N, Cw (water soluble carbon), CNw (Cw/Nw), nitrification index (NH4/NO-3), Cation Exchange Capacity (CEC), germination index, humification ratio, compost mineralization index (ash content/oxidizable carbon), sorption capacity index (CEC/oxidizable carbon). Enzyme activities of agricultural interest like urease, phosphatase, P-glucosidase, dehydrogenase and BAA-hydrolyzing protease, which are involved in the nitrogen, phosphorus and carbon cycles, were also assessed. Total content of macro and micronutrients in the final compost was also determined to assess the fertilizer value. The studies revealed that composting could be applied as a remediation technology after removing the top sediment. The maturity indices that are evaluated from the present study can be used to validate the success of the remediation technology.

Arsenic↗

PubMed1997

Airborne bacteria and carcass contamination in slaughterhouses.

Microbiological contamination of air and carcasses was studied in four slaughterhouses by using impactor samples taken at the back-splitting and weighing areas and by sampling carcasses with the swabbing method. Air flow was determined by an air-flow detector, and the movement of workers was observed. The air contamination level in the back-splitting areas (2.25 log CFU/100 liters of air) was generally higher than that in the weighing areas (2.03 log CFU/100 liters of air). Associations between the microbiological contamination of air and carcasses with the movements of workers were found. Layout of the slaughtering line was shown to be important in decreasing airborne contamination. Separation of the clean and unclean parts of the line as well as separation of the weighing area from the other clean parts of the line decreased the contamination level. It appears that airborne bacteria have an important role in carcass contamination.

Abattoirs↗

PubMed2003

Favorable outcome after infusion of coagulase-negative staphylococci-contaminated peripheral blood hematopoietic cells for autologous transplantation.

Bacterial contamination of peripheral blood hematopoietic cells collected for autologous bone marrow transplantation occurs sporadically. Although transfusion of contaminated hematopoietic cells without adverse clinical sequelae has been reported, detailed guidelines for transfusing cells with contamination are not available. We report a case of autologous hematopoietic cell transplantation that necessitated using multiple aliquots of peripheral blood hematopoietic cells known to be contaminated with coagulase-negative Staphylococcus bacteria. Prophylactic intravenous antibiotic therapy was given with the infusion of contaminated hematopoietic cells. The patient had positive results on a blood culture, but engraftment was successful, and serious adverse effects did not occur. With appropriate microbial identification and prophylactic antibiotic therapy, contaminated hematopoietic products can be safely infused when necessary with a good clinical outcome.

Anti-Bacterial Agents↗

PubMed1999

The effect on performance and biochemical parameters when soil was added to aflatoxin-contaminated poultry rations.

The effects of silty clay loam soil on the performance and biochemical parameters of chicks were investigated when the soil was added to aflatoxin B1 (AFB1)-contaminated diets. One hundred 14-d-old White Leghorn chicks were fed a control ration (clean corn), a low aflatoxin-contaminated ration (120 ng AFB1/g), a high aflatoxin-contaminated ration (700 ng AFB1/g), or high aflatoxin-contaminated rations (700 ng AFB1/g) +10% or 25% soil. Body weight, feed consumption and blood samples were monitored weekly. Decreased feed consumption, body weight gain and efficiency of feed utilization, increased SGOT and LDH activities, and cholesterol and triglyceride concentrations, and decreased uric acid concentrations and ALP activity were observed in the chicks fed the high aflatoxin-contaminated ration without soil. Hepatomegaly was prominent in chicks fed the high aflatoxin-contaminated ration without soil, and some livers had extensive hepatocyte vacuolation, hepatocellular swelling, fatty change and hydropic degeneration, and stained positive for fat accumulation. Addition of soil reduced the detrimental effects of AFB1 for some parameters, although the reduction was less when 10% soil was fed compared with the 25% soil feeding.

Aflatoxin B1↗

PubMed1999

Reduction of contamination risks during clinical studies with technegas.

During patient studies with the Technegas equipment in our department, we regularly detected small to considerable contaminations of the operator and in the area surrounding the apparatus. These contaminations were found to be of different origin: residual activity in the tubing from the apparatus to the patient which diffuses after deconnection, residual activity and small particles of the destroyed carbon crucible in the apparatus which are dispersed during opening of the door of the gas preparation chamber, leakage at the patient site during studies in uncooperative patients and a dysfunctioning valve inside the apparatus. To reduce the contamination risks, we made some adaptations to the apparatus. In the first place, the dysfunctioning valve was replaced. In addition, a powerful air exhaust pump with an efficient filter was installed. It was connected with (1) a newly installed transparent box in front of the door of the gas preparation chamber, (2) a dome on a flexible arm which can be positioned above the patient's face during the examination and (3) a nipple on which the mouthpiece can be placed after the study. After these adaptations, a study showed the absence of measurable contamination on the clothing of the personnel handling the apparatus. Occasionally, considerable contamination was still measured on the gloves worn during filling of the carbon boat with generator eluate, but only small contaminations (up to 9.25 kBq) were measured on the mouthmask worn by the operator during administration of the Technegas. This results in a maximum effective dose equivalent from activity deposited in the lungs of 0.008 microSv per study. The total body dose of the operator from external radiation for one Technegas examination was determined to be 2 microSv. The highest dose rate was measured during filling of the crucible (0.2 mSv/h).

Equipment Failure↗

PubMed1999

Use of infrared thermography to detect inflammation caused by contaminated growth promotant ear implants in cattle.

OBJECTIVE: To compare the infrared thermographic appearance of bovine ears that had received contaminated growth promotant implants with ears that had received clean implants and ears without implants. DESIGN: Prospective study. ANIMALS: 32 yearling crossbred beef steers with a mean weight of 322 kg (708 lbs). PROCEDURE: Contaminated (n = 16) and clean (16) implants were placed in the ears of feedlot cattle. Nonimplanted (n = 32) ears served as a within-animal control for thermographic comparisons. Images of rostral and caudal surfaces were obtained during a 21-day period, using an infrared thermal imaging radiometer. Repeated measures ANOVA was used to determine the relationship between mean temperature in a zone on the rostral surface of the ear and at 3 locations (proximal, middle, distal) on the caudal surface of the ear (response variables) with treatment (ears with contaminated implants or clean implants vs control ears with no implants), time (repeated day of measurement), and interactions among these variables. RESULTS: Significant temperature differences existed between ears with contaminated implants and control ears. Temperatures for ears with clean implants were significantly higher than control ears on day 2. At low ambient temperatures when the ears became wet, a greater temperature contrast was detected between ears with contaminated implants and control ears. CONCLUSIONS AND CLINICAL RELEVANCE: Thermal imaging of the ears of feedlot cattle is a noninvasive diagnostic tool that can be used to identify cattle with abscesses caused by contaminated growth-promotant implants.

Administration, Topical↗

PubMed1999

Effect of saliva contamination on micromorphological adaptation of single-bottle adhesives to etched enamel.

This study explored the topography of the interface of composite resin bonded with four single-bottle adhesives and enamel under salivary contaminated conditions. Prime & Bond 2.1, One Step, Tenure Quik and Syntac Single Component were evaluated. Thirty six sound molars were divided into three subgroups for each of the four adhesives. Small flat areas on the buccal and lingual surface were wet ground in enamel. The adhesives were tested under: uncontaminated condition (Group 1), contamination of the bonding site with fresh whole saliva for 20 seconds (Group 2) and rinsing the saliva for 20 seconds before adhesive application and after enamel etching (Group 3). After adhesive application button of composite resin was applied and light cured. The roots of the teeth were removed and the crowns with the bonded composite immersed in HCl acid till the composite resin buttons become free of enamel. The buttons were immersed in NaC10(4) and prepared for SEM examination. The bonding surface of the composite resin buttons revealed the formation of resin tags reflecting the different etching pattern of enamel. Saliva contamination either washed or unwashed did not affected the resin tags formation except for Syntac Single Component with contaminated unwashed enamel. The clinical significance of this in vitro research was that saliva contamination did not affect the resin tags formation of Prime & Bond 2.1, One Step, and Tenure Quick. For Syntac Single Component, only contaminated unwashed enamel decreased resin tags formation.

Acid Etching, Dental↗

PubMed2001

[Effects of chemical agents on the prevention of fungal contamination during household wheat storage in Cixian county].

OBJECTIVE: To evaluate the effectiveness of several commercial chemical agents (DMF, AP and Chumeijing) on the prevention of fungal contamination in household storage of wheat in Cixian county. METHODS: The antifungal agents tested include dimethyl fumarate, DMF, aluminium phosphide, AP and Chumeijing (a Chinese product comprised of propionic acid, formic acid, sorbic acid and fumaric acid). The chemicals were applied in the wheat containers in the rural households. The fungal contamination and the inhibitory effects on fungal growth in wheat were measured by fungal isolation, culture, identification and count. RESULTS: The fungal contamination in the household wheat before using fungicides were quite common, with an overall contamination rate of 67.5% to 100%. The application of the three chemical fungicides effectively reduced fungal contamination in household stored wheat, and the effective rate for DMF, AP, AMF + AP and Chumeijing was 91.2%, 85.2%, 100% and 100% respectively, while the rate of fungi growth inhibition was (61.9 +/- 21.6)%, (64.0 +/- 21.6)%, (72.5 +/- 18.0)% and (63.1 +/- 24.3)% respectively. CONCLUSION: DMF, AP and Chumeijing are all effective in the prevention of fungal contamination for household stored wheat in Cixian county. AP is not recommended owing to its higher toxicity, compared with the other chemicals tested.

Acids, Acyclic↗

PubMed2001

Remediation of metal-contaminated soil and sludge using biosurfactant technology.

Development of environmentally benign approaches to remediation of metal-contaminated soils and sewage sludges are needed to replace currently used techniques of either landfilling or metal extraction using caustic or toxic agents. We report results from four application technologies that use a metal-chelating biosurfactant, rhamnolipid, for removal of metals or metal-associated toxicity from metal-contaminated waste. The four applications include: 1) removal of metals from sewage sludge; 2) removal of metals from historically contaminated soils; 3) combined biosurfactant/phytoremediation of metal-contaminated soil; and 4) use of biosurfactant to facilitate biodegradation of the organic component of a metal-organic co-contaminated soil (in this case the biosurfactant reduces metal toxicity). These four technologies are nondestructive options for situations where the final goal is the removal of bioavailable and leachable metal contamination while maintaining a healthy ecosystem. Some of the approaches outlined may require multiple treatments or long treatment times which must be acceptable to site land-use plans and to the stakeholders involved. However, the end-product is a soil, sediment, or sludge available for a broad range of land use applications.

Biotechnology↗