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At least 73 records · Page 4Linked to original sources

PubMed2001

Multivariate analysis of U.K. salt marsh sediment contaminant data with reference to the significance of PCB contamination.

A data set acquired to establish an inventory of pollutants in salt marsh sediments has been evaluated using two numerical techniques, principal component analysis and discriminant analysis. Results indicate that sites proximate to the River Thames exhibit a greater degree of contamination, and numerical analysis supports the hypothesis that the river has been the major source of contaminants to the region. The presence of the contaminants within salt marsh sediments may be of concern due to changes in flood defense techniques. The use of managed realignment, where the line of flood defense is moved back to higher ground which requires only a low, minimal cost, sea-wall protected by newly created salt marsh from former farmland, is not free from problems of historical pollution. Mature salt marsh, laid down during previous decades, may be eroded and reworked within the new coastal geomorphology created by breaching existing seawalls and what were previously considered to be sinks of pollutants may have become sources. However, evaluation of the sediment burden of PCB within the salt marshes of the U.K. Essex coast indicates that they are not likely to be a major source of pollutants should sediments be remobilized during managed realignment programs.

Conservation of Natural Resources↗

PubMed1997

Prevention of patient bacterial contamination of anaesthesia-circle-systems: a clinical study of the contamination risk and performance of different heat and moisture exchangers with electret filter (HMEF).

The microbiological contamination of 250 breathing system tubes after use in anaesthesia circle systems with reduced fresh gas flow was investigated. The lungs of 50 patients were ventilated without any filtering device between the endotracheal tube and the Y-piece. A total of 51, 49 and 100 patients, respectively, were given different types of heat and moisture exchanger with electret filters (HMEF). With no filtering device the tubing system was contaminated by microorganisms originating from the patient's tracheal secretion in 13% of the patients. In contrast, no bacterial migration into the tubing system was detected when any of the investigated HMEF-devices were used. We therefore conclude that heat and moisture exchangers with electret filters prevent contamination of the anaesthesia breathing system with microorganisms from the patients airways.

Adult↗

PubMed2001

Evaluation of an automated culture system for detecting bacterial contamination of platelets: an analysis with 15 contaminating organisms.

BACKGROUND: Approximately 1 in 2000 platelet components are bacterially contaminated. The time to detection of 15 seeded organisms in platelets recovered from an automated culture system was studied. STUDY DESIGN AND METHODS: Isolates of Bacillus cereus, Bacillus subtilis, Candida albicans, Clostridium perfringens, Corynebacterium species, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, Propionibacterium acnes, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, Serratia marcescens, Streptococcus pyogenes, and Streptococcus viridans were inoculated into Day 2 apheresis platelet components to obtain a final concentration of approximately 10 and 100 CFU per mL (2 units/organism). Each bag was sampled 10 times (20 mL/sample). Four mL of each sample was inoculated into standard aerobic and anaerobic bottles and into aerobic and anaerobic bottles containing charcoal; 2 mL was inoculated into pediatric aerobic bottles (so as to maintain a 1:10 ratio of sample to media) and 1 mL into thioglycollate broth. RESULTS: With the exception of P. acnes, all organisms were detected in a mean of 9.2 to 25.6 hours. A range of 10 serial dilutions in inoculating concentrations was associated with an overall 10.1-percent difference in detection time. A mean of 74.4 and 86.2 hours (100 and 10 CFU/mL inocula, respectively) was required for the detection of P. acnes in anaerobic bottles. CONCLUSION: Bacteria thought to be clinically significant platelet contaminants can be detected in 9.2 to 25.6 hours when the starting concentration is approximately 10 to 100 CFU per mL. P. acnes required considerably longer incubation times for detection (in either aerobic or anaerobic bottles). However, P. acnes is of questionable clinical significance. Such a detection system could be used in either a blood collection center or a transfusion service to screen platelet concentrates for bacterial contamination. Such testing (with sterile sampling performed so as to maintain a closed-bag system) would be expected to save lives and might allow an extension of platelet storage.

Bacteria↗

PubMed1999

Transfer of contaminants from surface to hands: experimental assessment of linearity of the exposure process, adherence to the skin, and area exposed during fixed pressure and repeated contact with surfaces contaminated with a powder.

Estimation of dermal exposure in the workplace resulting from contact with contaminated surfaces is important in risk assessment. Models have been developed to describe the process of exposure due to transfer, but for major input parameters--that is, contact area surface and adherence--defaults are used. This study examines the effect of one single-hand press contact and repeated contacts with a contaminated glass plate on both skin area exposed and loading of the skin for three volunteers. A fluorescent whitening agent was used to study the process of exposure and to determine the increase of the area exposed as well as the adherence of the compound to the skin surface after 1 to 12 consecutive contacts by a video imaging technique. In addition, loading of the skin after 12 contacts was compared to loading of a cotton glove monitor with similar hand pressures. The results show that after one single-hand contact only 4 to 16 percent of the total surface of the palm of the hand was exposed, whereas after 12 contacts this was increased to about 40 percent. The efficiency of transfer was < or = 2 percent of the contamination of the surface. The adherence to the skin was 1.07 micrograms/cm2 after 12 contacts and tended to increase non-linearly with increase in contacts. Because defaults of adherence for use in exposure models are generally a factor 500 to 5,000 higher, and the area exposed is assumed to be the total surface of the hand, overestimation of dermal exposure due to a single hand-surface contact in workplaces may occur. Therefore, additional studies on multi-contact exposure scenarios are indicated to adjust defaults for hand-surface transfer processes.

Adhesiveness↗

PubMed2002

Lipid metabolism in the moss Rhytidiadelphus squarrosus (Hedw.) Warnst. from lead-contaminated and non-contaminated populations.

Lipid metabolism and the effect of Pb(2+) and Cu(2+) on this process was studied in the moss Rhytidiadelphus squarrosus collected from both a lead-contaminated and a non-contaminated site. Total radiolabelling of lipids from [1-(14)C]acetate was similar in both populations and Cu or Pb (1 microM, 10 microM) did not cause much alteration in acute exposure experiments. However, there were significant qualitative changes. Of the major labelled neutral lipid classes, samples from the lead-polluted site showed a decrease in labelling of triacylglycerols and an increase in wax esters. Acute lead exposure caused similar effects. Cu caused a decrease in the labelling of wax esters and an increase in diacylglycerols. These data suggest that heavy metals cause a change in carbon flux through the acylation reactions associated with the Kennedy pathway. R. squarrosus obtained from the Pb-contaminated site also showed changes in polar lipid labelling compared to the uncontaminated site. The labelling of phosphatidylcholine was more than halved and replaced by increased labelling of other zwitterionic lipids. The chloroplast glycerolipids were also increasingly labelled. Acute exposure to Pb, however, caused little alteration of labelling patterns within 24 h. R. squarrosus contains high levels of polyunsaturated fatty acids (PUFAs), but moss obtained from the Pb-polluted site had significantly less PUFAs containing three or more double bonds. Such samples, when incubated with [1-(14)C]acetate also showed decreased PUFA labelling. By contrast, acute exposure to Pb produced different results. These data provide a foundation for examining lipid metabolism in bryophytes and the effects of pollution in this important class of organism. The results also emphasize that acute and chronic exposure to heavy metals may produce different effects and that caution must be exercised in extrapolating data from one system to another.

Acetates↗

PubMed1997

Contaminated environments in the subsurface and bioremediation: organic contaminants.

Due to leakages, spills, improper disposal and accidents during transport, organic compounds have become subsurface contaminants that threaten important drinking water resources. One strategy to remediate such polluted subsurface environments is to make use of the degradative capacity of bacteria. It is often sufficient to supply the subsurface with nutrients such as nitrogen and phosphorus, and aerobic treatments are still dominating. However, anaerobic processes have advantages such as low biomass production and good electron acceptor availability, and they are sometimes the only possible solution. This review will focus on three important groups of environmental organic contaminants: hydrocarbons, chlorinated and nitroaromatic compounds. Whereas hydrocarbons are oxidized and completely mineralized under anaerobic conditions in the presence of electron acceptors such as nitrate, iron, sulfate and carbon dioxide, chlorinated and nitroaromatic compounds are reductively transformed. For the aerobic often persistent polychlorinated compounds, reductive dechlorination leads to harmless products or to compounds that are aerobically degradable. The nitroaromatic compounds are first reductively transformed to the corresponding amines and can subsequently be bound to the humic fraction in an aerobic process. Such new findings and developments give hope that in the near future contaminated aquifers can efficiently be remediated, a prerequisite for a sustainable use of the precious-subsurface drinking water resources.

Benzene Derivatives↗

PubMed1992

Limiting bacterial contamination of enteral nutrient solutions: 6-year history with reduction of contamination at two institutions.

Running enteral nutrient solution (ENS) bacterial contamination logs that were collected over a 6-year time frame are presented. At hospital A, reconstituted ENS were prepared by the pharmacy department in bulk and were frozen in the final container. These solutions were cultured and counted after 12 hours of storage at room temperature to stimulate this institution's hang time. Major reductions in ENS bacterial counts occurred after improvements in sanitation, a reduction in solution hang time, the conversion to the use of sterile water for dilution and reconstitution of ENS, and most dramatically, after the incorporation of a preservative (potassium sorbate) to reconstituted ENS. At hospital B, ENS usage consisted of canned feedings that were prepared by nursing personnel and were transferred to the feeding container at the bedside. Reductions in final counts of contamination of ENS occurred after procedural changes, which included container changes every 24 hours, use of sterile water for dilution, cleansing of can lids with alcohol swabs before use, rinsing and air drying of intermittent feeding containers between feedings, and limiting feeding container fills to 4-hour hang time quantities. At both institutions, the value of an ongoing three-class enteral quality control program with a defined acceptance/rejection criteria was demonstrated in that ENS contamination was reduced to acceptable levels comparable with federal standards for milk and dairy products.

Enteral Nutrition↗

PubMed2005

Lead contamination in cocoa and cocoa products: isotopic evidence of global contamination.

In this article we present lead concentrations and isotopic compositions from analyses of cocoa beans, their shells, and soils from six Nigerian cocoa farms, and analyses of manufactured cocoa and chocolate products. The average lead concentration of cocoa beans was </= 0.5 ng/g, which is one of the lowest reported values for a natural food. In contrast, lead concentrations of manufactured cocoa and chocolate products were as high as 230 and 70 ng/g, respectively, which are consistent with market-basket surveys that have repeatedly listed lead concentrations in chocolate products among the highest reported for all foods. One source of contamination of the finished products is tentatively attributed to atmospheric emissions of leaded gasoline, which is still being used in Nigeria. Because of the high capacity of cocoa bean shells to adsorb lead, contamination from leaded gasoline emissions may occur during the fermentation and sun-drying of unshelled beans at cocoa farms. This mechanism is supported by similarities in lead isotopic compositions of cocoa bean shells from the different farms (206Pb/207Pb = 1.1548-1.1581; 208Pb/207Pb = 2.4344-2.4394) with those of finished cocoa products (206Pb/207Pb = 1.1475-1.1977; 208Pb/207Pb = 2.4234-2.4673). However, the much higher lead concentrations and larger variability in lead isotopic composition of finished cocoa products, which falls within the global range of industrial lead aerosols, indicate that most contamination occurs during shipping and/or processing of the cocoa beans and the manufacture of cocoa and chocolate products.

Cacao↗

PubMed2006

Genotoxicity of polar fractions from a herbicide-contaminated soil does not correspond to parent contaminants.

Fractionation with biological and chemical analysis has been proposed to characterize the risk associated with complex samples. Thus, we have employed hot pressurized water for fractionating a herbicide-contaminated soil. Genotoxicity was found in polar and midpolarity fractions extracted from a historically herbicide-contaminated soil. However, the parent herbicides as well as organic solvent extracts (consisting of herbicides) were not genotoxic. Thus, polar organics formed by natural degradation of herbicides may be responsible for the genotoxic response. For correct assessment of the toxicity of complex matrices such as soils, both contaminated and uncontaminated samples need to be studied for their toxicological impact.

Escherichia coli↗

PubMed1996

Contamination of central venous catheters. The skin insertion wound is a major source of contamination.

In a prospective controlled trial we compared the rates of catheter-tip contamination in central venous catheters inserted with or without skin contact. The study was designed so that each patient was their own control. All patients had a single-lumen central venous catheter and a Swan-Gantz sheet inserted through the skin. A Swan-Gantz catheter was inserted and retracted through the sheet thus avoiding contact with skin or subcutaneous tissue. Catheter-tip cultures were performed on removal of catheters. Thirty-three Swan-Gantz catheters were cultured and all were sterile. In the corresponding 33 sheets 16 (48.6%) yielded bacterial growth. Four of the sheets showed growth of more than 15 cfu. In the 26 single-lumen catheters, eight (30.8%) catheter-tips grew bacteria, and four of them had more than 15 colonies. The study supports the theory that the skin-insertion wound is a major source of catheter-contamination.

Adult↗

PubMed1986

Contamination of a multiple-use suction catheter in a closed-circuit system compared to contamination of a disposable, single-use suction catheter.

UNLABELLED: Multiple-use (M-U) closed-system endotracheal suction catheters are effective in preventing arterial oxygen desaturation in patients on positive end-expiratory pressure (PEEP) and may lessen the frequency of bradycardia and hypotension in unstable patients who are prone to these complications of suctioning. However, because M-U catheters remain attached to the ventilator circuit and are reintroduced repeatedly into the patient's airway over 24 hours or longer, they could become heavily contaminated with pathogens. We hypothesized a risk of autocontamination to the patient by re-inoculation of the respiratory tract with organisms that flourished on the M-U catheter while it was isolated from the patient's immune defenses or antibiotic therapy. METHODS: We tested this hypothesis in 30 mechanically ventilated adult patients with positive sputum cultures. We measured and compared the amount of bacteria present on an M-U catheter at the end of a 24-hour use period, the amount of bacteria present in the patient's sputum at that time, and the amount of bacteria present on a single-use (S-U) catheter at that time, after it had made one pass into the patient's airway. Organisms recovered and colony counts were also compared to results of a sputum culture obtained before the study began. RESULTS: Fourteen different pathogens or potential pathogens were recovered, in numbers of 2 x 10(1) to 2 x 10(7)colony-forming units. The greatest number of colonies was most often recovered from the sputum specimen, and statistical analysis showed no differences in rate or magnitude of contamination between M-U and S-U catheters.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1996

A study of toothbrush contamination at different time intervals and comparative effectiveness of various disinfecting solutions in reducing toothbrush contamination.

Toothbrush contamination during the procedure of brushing was assessed at different time intervals of usage. A peak value of 100% contamination was found at 1 month interval. Hence, a method suggesting disinfection of the toothbrush was employed by comparing the effectiveness of various disinfecting solutions available in the market so that, the brush does not become a source of potential pathogens.

Adolescent↗

PubMed1991

Effects of mercury, selenium, and organochlorine contaminants on reproduction of Forster's terns and black skimmers nesting in a contaminated Texas Bay.

Mean mercury (0.40 micrograms/g), and geometric mean DDE (1.6 micrograms/g) and polychlorinated biphenyl (PCB) (2.3 micrograms/g) concentrations in Forster's tern (Sterna forsteri) eggs from Lavaca Bay were higher than those in tern eggs from a reference area in San Antonio Bay, but residues were not correlated with hatching success. Nest success was similar between bays. Selenium levels in Lavaca Bay tern eggs (0.71 micrograms/g) were also comparable to those in eggs from the reference area (0.68 micrograms/g). Clutch size (3.1 to 3.4) of Lavaca Bay black skimmers (Rynchops niger) was no different than that (3.4) at a reference colony near Laguna Vista. Nest success was similar among three Lavaca Bay colonies, but success was lower at one Lavaca Bay colony (40%) than at Laguna Vista (65%). Mean mercury (0.46 micrograms/g) and selenium (0.75 micrograms/g) concentrations in skimmer eggs from Lavaca Bay were higher than those (0.19, 0.33 micrograms/g) from Laguna Vista; however, concentrations of neither contaminant were related to hatching success. DDE concentrations in Lavaca Bay skimmer eggs (3.4 micrograms/g) were similar to those from Laguna Vista (3.2 micrograms/g) and DDE was negatively correlated with hatching success. PCBs were higher in eggs from Lavaca Bay (1.3 micrograms/g) than Laguna Vista (0.8 micrograms/g). Organochlorine and metal contaminants in most eggs were below embryotoxic levels. Eggshell thinning in Forster's terns (7%) and black skimmers (5%) was below that associated with lowered reproduction. DDE and PCBs were detected in 9 Caspian tern (S. caspia) eggs; maximum concentrations were 4.7 and 5.4 micrograms/g. Caspian tern and least tern (S. albifrons) eggs contained low (less than or equal to 0.9 micrograms/g) concentrations of mercury and selenium.

Animals↗

PubMed2006

Biotreatment of groundwater contaminated with MTBE: interaction of common environmental co-contaminants.

Contamination of groundwater with the gasoline additive methyl tert-butyl ether (MTBE) is often accompanied by many aromatic components such as benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene (BTEX). In this study, a laboratory-scale biotrickling filter for groundwater treatment inoculated with a microbial consortium degrading MTBE was studied. Individual or mixtures of BTEX compounds were transiently loaded in combination with MTBE. The results indicated that single BTEX compound or BTEX mixtures inhibited MTBE degradation to varying degrees, but none of them completely repressed the metabolic degradation in the biotrickling filter. Tert-butyl alcohol (TBA), a frequent co-contaminant of MTBE had no inhibitory effect on MTBE degradation. The bacterial consortium was stable and showed promising capabilities to remove TBA, ethylbenzene and toluene, and partially degraded benzene and xylenes without significant lag time. The study suggests that it is feasible to deploy a mixed bacterial consortia to degrade MTBE, BTEX and TBA at the same time.

Bacteria↗

PubMed2006

Toxic fluoride and arsenic contaminated groundwater in the Lahore and Kasur districts, Punjab, Pakistan and possible contaminant sources.

The present study is the first attempt to put forward possible sources of As, F- and SO4(2-) contaminated groundwater in the Kalalanwala area, Punjab, Pakistan. Five rainwater and 24 groundwater samples from three different depths were analyzed. Shallow groundwater from 24 to 27 m depth contained high F- (2.47-21.1mg/L), while the groundwater samples from the deeper depth were free from fluoride contamination. All groundwater samples contained high As (32-1900 microg/L), in excess of WHO drinking water standards. The SO4(2-) ranges from 110 to 1550 mg/L. Delta34S data indicate three sources for SO4(2-) air pollutants (5.5-5.7 per thousand), fertilizers (4.8 per thousand), and household waste (7.0 per thousand). Our important finding is the presence of SO4(2-), As and F- in rainwater, indicating the contribution of these elements from air pollution. We propose that pollutants originate, in part, from coal combusted at brick factories and were mobilized promotionally by the alkaline nature of the local groundwater.

Air Pollutants↗

PubMed2026

Leveraging environmental applications and risks of coal gangue: A critical review on authigenic inorganic heavy metals, organic contaminants, and the removal of exogenetic contaminants.

Coal gangue (CG) as bulk solid waste has seriously threatened the ecosystem. Therefore, identifying the key risk drivers and exploring feasible disposal methods for CG are essential for developing a sustainable strategy. However, there is currently a lack of comprehensive information that balances the contamination risks with the valuable constituents present in CG, which hinders its full potential for sustainable use without negative environmental impacts. Given the complex composition and associated risks, we propose that addressing the critical properties related to contamination is crucial for the efficient utilization of CG. On this premise, we summarized several practical resource pathways (ecological multifunctional materials, extraction of rare elements, and soil additives) that are more favorable for sustainable development relative to conventional disposals. Meanwhile, we also propose that coupling disposals could intensely reduce CG's environmental footprints and capital costs. Consequently, regardless of the number of challenges to be solved, we believe the CG has broad application prospects, and we hope this review will promote the conversion of CG into an asset with lower ecological and social impacts.

Metals, Heavy↗

PubMed2003

Cytochrome P4501A expression, chemical contaminants and histopathology in roach, goby and sturgeon and chemical contaminants in sediments from the Caspian Sea, Lake Balkhash and the Ily River Delta, Kazakhstan.

Roach, goby and sturgeon were examined for cytochrome P4501A (CYP1A) expression and histopathology, in relation to contaminant burdens in fish and sediment. Gradients of induction of CYP1A were observed. Roach from the Ural and Ily River Deltas and roach and goby from the two stations nearest the Caspian Sea oil fields displayed higher levels of CYP1A expression in several organs than was observed in fish from further offshore. Great sturgeon and Russian sturgeon showed higher levels of CYP1A expression than was seen in starred sturgeon and gobies in the Ural delta. No fish showed evidence of contaminant-related histopathologies in the organs examined, despite the elevated CYP1A levels. Low levels of polychlorinated biphenyls and elevated levels of inshore and riverine petroleum hydrocarbons from these habitats suggest that this ongoing hydrocarbon exposure, and that from natural sources and long-term oil exploration on the Northeastern Caspian shore, contributed to the CYP1A induction observed.

Animals↗

PubMed1998

Organochlorine pesticides and polychlorinated biphenyls in human milk of mothers living in northern Germany: current extent of contamination, time trend from 1986 to 1997 and factors that influence the levels of contamination.

This study reports the concentration levels of PCB, DDT, HCB and beta-HCH in the human milk of women living in northern Germany over a period of 12 years and determines factors that may influence these levels. From 1986 to 1997 more than 3500 milk samples were analyzed for organochlorine compounds. A questionnaire was used to obtain information regarding personal characteristics, life style factors and eating habits. Descriptive statistics of concentration levels were computed to characterize the current extent of contamination. To follow time trends across the years homogeneous subgroups were compared and multiple regression analyses were used to investigate associations between determining factors and specific contaminants. Between summer 1995 and summer 1997 the median PCB concentration level was 0.502 mg/kg, the median DDT level 0.202 mg/kg, the median HCB level 0.065 mg/kg and the median beta-HCH level 0.036 mg/kg, all values expressed on a fat basis. The median concentration levels decreased by 80-90% during the past 12 years and the median PCB levels by 60%. The concentration levels of all substances were positively correlated with maternal age and negatively associated to parity, to the total period of breast-feeding and to a weight increase of mothers before and after delivery. Post-pregnancy BMI was a significant predictor of the likelihood of having higher concentrations for DDT, HCB and beta-HCH and of having lower concentrations for PCB levels. A balanced diet for at least 3 years was related to lower HCB and beta-HCH levels. Women who ate more than 100 g of fish or more than 700 g of meat per week were more likely to have higher PCB and beta-HCH levels or higher HCB levels, respectively. Higher HCB and beta-HCH concentration levels were associated with lower birth weights of female infants.

Adult↗