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PubMed2002

Contamination of ballistic fractures: an in vitro model.

This study allowed the development of an in vitro model of a high-energy ballistic fracture. Direct fractures are more heavily contaminated than indirect fractures, and the spread of contamination is more extensive than examination of the wounds, particularly the entry wounds, would suggest. The major spread of contamination is along tissue planes, and we would recommend that these are thoroughly lavaged in the management of the fracture. The fracture site is heavily contaminated, with endosteal spread in direct fractures. However, there appears to be relatively little bony contamination beyond the fracture site.

Animals↗

PubMed1992

Mycoplasma contamination in human leukemia cell lines. II. Elimination with various antibiotics.

19 suspension cell lines were treated with antibiotics for elimination of chronic contamination with mycoplasma. We compared the efficiency, cytotoxicity and cross-resistance of the commercially available antibiotics MRA (Mycoplasma Removal Agent, a quinolone derivative and DNA gyrase inhibitor), Ciprobay (ciprofloxacin, also a quinolone derivative and DNA gyrase inhibitor), and BM-cyclin (a combination of tiamulin, a pleuromutilin derivative, and minocycline, a tetracycline derivative, both inhibitors of protein synthesis on ribosomes). Contaminants were eliminated in all 19 cell lines by BM-Cyclin. Only 74% of the cell lines were cleared of contamination by both MRA and Ciprobay. Successful treatment was monitored by three mycoplasma detection assays. Cross-resistance was noted between MRA and Ciprobay in four of the five cell lines not cleared by either reagent. This resistance could, however, be overcome by consecutive exposure to BM-cyclin. Employed at the recommended concentrations, the antibiotics did not cause marked cytotoxicity, but the growth of the cells was affected to various degrees by some antibiotics. The elimination of mycoplasma from chronically contaminated cell lines is an effective alternative to other treatment protocols, but is cost-intensive and time-consuming; lasting damaging effects of the treatments on the eukaryotic cells cannot be excluded. Long-term post-treatment monitoring is mandatory, since contaminants may only be suppressed and then recur.

Anti-Bacterial Agents↗

PubMed2001

Magnetic properties and heavy-metal contents of contaminated seabed sediments of Penny's Bay, Hong Kong.

Magnetic properties and heavy-metal concentrations of vibrocore samples were found to be potential indicators of shipping contamination in seabed sediments in Hong Kong Harbour. Geochemical results of 74 vibrocores located off Penny's Bay on Lantau Island revealed an enrichment of heavy metals in the upper 1-2 m of the cores within the eastern part of the study site. Whole-core magnetic susceptibility measurements also showed a greater concentration of magnetic particles in the surficial layer of these cores. A significant correlation exists between the magnetic susceptibility and the concentrations of Pb, Zn and Cu, as well as the Tomlinson pollution load index (PLI). The proximity of these cores to a major navigation fairway and an anchorage site suggests probable contamination of the surficial seabed sediments by shipping-related wastes. A study of the magnetic properties of one of the cores, VT60, revealed a difference in the magnetic properties between the contaminated and the uncontaminated sediments. Samples from the contaminated zone exhibited relatively stronger magnetic remanence and susceptibility. The two groups of samples also formed distinct trends on the hysteresis ratios plot. A level of unusually high magnetic susceptibility within the contaminated zone was attributable to the presence of strongly magnetized granules, which were probably refuse from shipping-related activities. Geochemical and magnetic results were also conducted on samples of different size-fractions from this core. The < 63 microns fraction was found to contain a relatively higher magnetic susceptibility and greater heavy-metal content.

Environmental Monitoring↗

PubMed2001

Trace contaminant concentrations in the Kara Sea and its adjacent rivers, Russia.

Trace organic (chlorinated pesticides, PCBs, PAHs and dioxins/furans) and trace metal concentrations were measured in surficial sediment and biological tissues (i.e., worms, crustaceans, bivalve molluscs, and fish livers) collected from the Russian Arctic. Total DDT, chlordane, PCB and PAH concentrations ranged from ND to 1.2, ND to <0.1, ND to 1.5 and <20-810 ng g(-1), respectively, in a suite of 40 surficial sediment samples from the Kara Sea and the adjacent Ob and Yenisey Rivers. High sedimentary concentrations of contaminants were found in the lower part of the Yenisey River below the salt wedge. Total dioxins/furans were analysed in a subset of 20 sediment samples and ranged from 1.4 to 410 pg g(-1). The highest trace organic contaminant concentrations were found in organisms, particularly fish livers. Concentrations as high as 89 ng g(-1) chlordane; 1010 ng g(-1) total DDTs; 460 ng g(-1) total PCBs; and 1110 ng g(-1) total PAH, were detected. A subset of 11 tissue samples was analysed for dioxins and furans with total concentrations ranging from 12 to 61 pg g(-1). Concentrations of many trace organic and metal contaminants in the Kara Sea appear to originate from riverine sources and atmospheric transport from more temperate areas. Most organic contaminant concentrations in sediments were low; however, contaminants are being concentrated in organisms and may pose a health hazard for inhabitants of coastal villages.

Animals↗

PubMed2002

A review and assessment of tributyltin contamination in the North Sea, based on surveys of butyltin tissue burdens and imposex/intersex in four species of neogastropods.

It is evident from measures of butyltin tissue burdens and imposex or intersex in neogastropods that tributyltin (TBT) contamination of coastal waters and open parts of the North Sea is now low. It has been declining for at least the past decade. This is probably due to two measures. First, regulations prohibiting the use of TBT-based paints on small boats and fish farms have reduced inputs of TBT from these sources so that they are now negligible (except possibly where the regulations are flaunted). Second, there is evidence from sites, where commercial vessels are the sole source of TBT, that the adoption of TBT SPC paints has been effective in reducing environmental levels of these contaminants. However, poor dockyard practices, allowing TBT-contaminated wastes, including paint flakes, to accumulate in sediments have left a legacy of hot-spots of contamination in some ports. The impact is localised so that TBT contamination is low in coastal areas immediately adjacent to ports.

Animals↗

PubMed2003

Heavy metal sedimentary record in a Galician Ria (NW Spain): background values and recent contamination.

Two long sediment cores were sampled at the Ferrol Ria (Galicia, NW Spain) and the heavy metal (Co, Cr, Cu, Fe, Ni, Pb and Zn) concentrations measured in order to (i) state accurate background values providing baseline relationships with respect to a reference element and (ii) to investigate the recent metal contamination trends. Background values were found to agree well with the world average values for granite/schists-genisses rocks. However, Cu, Co, Pb and Zn were found to be lower than those previously reported as background values for the Galician Rias. Results emphasize the importance of using baseline relationships with respect to a normalizing element in order to reduce the scattering of data and to allow an accurate statement of background values. The distribution of metals in the cores showed an evident enrichment in the surface layers belonging to the industrial era. Normalized enrichment factors (NEF) for copper and zinc are in the order of 3-5 (certain/severe contamination) in the surface sediments, decreasing with depth. Lead contamination has decreased in the recent years from NEF of 3-7 down to a NEF of 2 (i.e. moderate contamination), probably due to the introduction of unleaded gasolines. Chromium, cobalt and nickel NEFs were always in the <1-2 range indicating null/low contamination by these metals.

Environmental Monitoring↗

PubMed2003

Surveillance for previously unmonitored organic contaminants in the San Francisco Estuary.

The San Francisco Estuary Regional Monitoring Program initiated surveillance monitoring to identify previously unmonitored synthetic organic contaminants in the San Francisco Estuary. Organic extracts of water samples were analyzed using gas chromatography-mass spectrometry in full scan mode. The major contaminant classes identified in the samples were fire retardants, pesticides, personal care product ingredients, and plasticizers. Evidence from the literature suggests that some of these contaminants can persist in the environment, induce toxicity, and accumulate in marine biota and in higher food chain consumers. The major sources of these contaminants into the marine environment are the discharge of municipal and industrial wastewater effluents, urban stormwater, and agricultural runoff. As a proactive effort, it is suggested that surveillance studies be used routinely in monitoring programs to identify and prevent potential problem contaminants from harming the marine environment.

Agriculture↗

PubMed1999

Genotoxicity of contaminated soil and shallow well water detected by plant bioassays.

Three major plant bioassays, i.e., the Allium root anaphase aberration (Allium-AA), the Tradescantia-micronucleus (Trad-MCN) and the Tradescantia stamen hair mutation (Trad-SHM) tests, were utilized in soil solutions or shallow well water samples to determine the degree of their genotoxicity. Shallow well water samples were collected from five different farms, and soil solutions were extracted with distilled water or dimethyl sulfoxide (DMSO) from pesticide-contaminated (metolachlor, atrazine, extrazine, and 2, 4-D) and pesticide-free soil samples. Genotoxicity was expressed in terms of anaphase aberration (AA) frequencies in the Allium-AA test, in terms of micronuclei frequencies in the Trad-MCN test, and in terms of pink mutation events in the Trad-SHM test. On average, results of Allium-AA tests showed a 2.78-3.01 fold increase in anaphase aberration frequencies in contaminated soil solution samples and well water samples as compared with the negative control. Results of Trad-MCN tests showed a 1.66-4.75 fold increase of MCN frequencies in contaminated soil solution samples and shallow well water samples as compared with the frequencies of the controls. Results of Trad-SHM tests showed a 2.7-2.86 fold increase of pink mutation events in the contaminated soil solution samples over that of the controls. Control groups of the Allium-AA tests had an average of 0.75/1000 anaphase figures, and control groups of the Trad-MCN tests had an average of 3.2 MCN/100 tetrads, while control groups of the Trad-SHM tests had an average of 1.4 mutation events/1000 hairs. In general, soil solutions of DMSO extracts showed higher genotoxicity than that of distilled water extracts. Among these three plant bioassays, the Trad-MCN test has the highest efficiency. The highest toxicity, based upon the Trad-MCN test results, was found in the pesticide contaminated soil samples from Monroe's farm. Water samples from the Fountain Green/Bushnell area ranked second in genotoxicity.

2,4-Dichlorophenoxyacetic Acid↗

PubMed2002

Simulated formation and flow of microemulsions during surfactant flushing of contaminated soil.

Contamination of groundwater resources by non-aqueous phase liquids (NAPLs) has become an issue of increasing environmental concern. This study investigated the formation and flow of microemulsions during surfactant flushing of NAPL-contaminated soil using the finite difference model UTCHEM, which was verified with our laboratory experimental data. Simulation results showed that surfactant flushing of NAPLs (i.e., trichloroethylene and tetrachloroethylene) from the contaminated soils was an emulsion-driven process. Formation of NAPL-in-water microemulsions facilitated the removal of NAPLs from contaminated soils. Changes in soil saturation pressure were used to monitor the mobilization and entrapment of NAPLs during surface flushing process. In general, more NAPLs were clogged in soil pores when the soil saturation pressure increased. Effects of aquifer salinity on the formation and flow of NAPL-in-water microemulsions were significant. This study suggests that the formation and flow of NAPL-in-water microemulsions through aquifer systems are complex physical-chemical phenomena that are critical to effective surfactant flushing of contaminated soils.

Models, Theoretical↗

PubMed2002

Transport and sources of metal contaminants over the course of tidal cycle in the turbidity maximum zone of the Hudson River estuary.

Transport and source of metal contaminants (Ag, Cd, Cu, Pb and Zn) in the turbidity maximum zone of the Hudson River estuary were studied over the course of a tidal cycle in November 1994 and August 1995. This study showed that the metal/Fe ratios in suspended particles varied more widely than those in the local sediments, implying that sources of metal contaminants to the water column are not only from local sediment resuspension but also from lateral advection. Although the metal/Fe ratios oscillate with time at the anchor stations, a general increasing trend with salinity was found over the course of a tidal cycle, suggesting that the lower estuary could be a source of metal contaminants to the upper estuary regions. These results support that sediment resuspension and lateral advection are important factors responsible for transporting the lower estuary contaminants up river and redistributing metal contaminants in the estuary.

Environmental Monitoring↗

PubMed2002

Predicting runoff-induced pesticide input in agricultural sub-catchment surface waters: linking catchment variables and contamination.

An urgent need exists for applicable methods to predict areas at risk of pesticide contamination within agricultural catchments. As such, an attempt was made to predict and validate contamination in nine separate sub-catchments of the Lourens River, South Africa, through use of a geographic information system (GIS)-based runoff model, which incorporates geographical catchment variables and physicochemical characteristics of applied pesticides. We compared the results of the prediction with measured contamination in water and suspended sediment samples collected during runoff conditions in tributaries discharging these sub-catchments. The most common insecticides applied and detected in the catchment over a 3-year sampling period were azinphos-methyl (AZP), chlorpyrifos (CPF) and endosulfan (END). AZP was predominantly found in water samples, while CPF and END were detected at higher levels in the suspended particle samples. We found positive (p < 0.002) correlations between the predicted average loss and the concentrations of the three insecticides both in water and suspended sediments (r between 0.87 and 0.94). Two sites in the sub-catchment were identified as posing the greatest risk to the Lourens River mainstream. It is assumed that lack of buffer strips, presence of erosion rills and high slopes are the main variables responsible for the high contamination at these sites. We conclude that this approach to predict runoff-related surface water contamination may serve as a powerful tool for risk assessment and management in South African orchard areas.

Agriculture↗

PubMed2003

Remediation of PCE-contaminated aquifer by an in situ two-layer biobarrier: laboratory batch and column studies.

The industrial solvent tetrachloroethylene (PCE) is among the most ubiquitous chlorinated compounds found in groundwater contamination. The objective of this study was to develop an in situ two-layer biobarrier system consisting of an organic-releasing material layer followed by an oxygen-releasing material layer. The organic-releasing material, which contained sludge cakes from a domestic wastewater treatment plant, is able to release biodegradable organics continuously. The oxygen-releasing material, which contained calcium peroxide, is able to release oxygen continuously upon contact with water. The first organic-releasing material layer was to supply organics (primary substrates) to reductively dechlorinate PCE in situ. The second oxygen-releasing material layer was to release oxygen to aerobic biodegrade or cometabolize PCE degradation byproducts from the first anaerobic layer. Batch experiments were conducted to design and identify the components of the organic and oxygen-releasing materials, and evaluate the organic substrate (presented as chemical oxygen demand (COD) equivalent) and oxygen release rates from the organic-releasing material and oxygen-releasing materials, respectively. The observed oxygen and COD release rates were approximately 0.0368 and 0.0416 mg/d/g of material, respectively. A laboratory-scale column experiment was then conducted to evaluate the feasibility of this proposed system for the bioremediation of PCE-contaminated groundwater. This system was performed using a series of continuous-flow glass columns including a soil column, an organic-releasing material column, two consecutive soil columns, and an oxygen-releasing material column, followed by two other consecutive soil columns. Anaerobic acclimated sludges were inoculated in the first four columns, and aerobic acclimated sludges were inoculated in the last three columns to provide microbial consortia for contaminant biodegradation. Simulated PCE-contaminated groundwater with a flow rate of 0.25 L/d was pumped into this system. Effluent samples from each column were analyzed for PCE and its degradation byproducts. Results show that up to 99% of PCE removal efficiency was obtained in this passive system. Thus, the biobarrier treatment scheme has the potential to be developed into an environmentally and economically acceptable remediation technology for the in situ treatment of PCE-contaminated aquifer.

Bacteria, Aerobic↗

PubMed2003

Risk factors contributing to microbiological contamination of shallow groundwater in Kampala, Uganda.

A study of water quality variation in shallow protected springs in Kampala was undertaken over a 12-month period to assess the causes of microbiological contamination. The microbiological quality of water was assessed using thermotolerant coliforms and faecal streptococci. Sanitary inspections and hazard assessments were undertaken to identify faecal sources (hazards), contaminant pathways and contributory factors. Data were collected on rainfall and population as additional factors potentially exerting an influence on microbiological quality. Initial analysis of the data showed a significant relationship between median level of contamination and rainfall, in particular to short-term rainfall events. Total sanitary risk score showed a significant relationship with median level of contamination, but population density may be a confounding factor. The raw microbiological data were transformed into five water quality targets: <1 and < or =10 cfu 100ml(-1) for faecal streptococci; and <1, < or =10 and < or=50 cfu 100 ml(-1) for thermotolerant coliforms. The presence of individual risk factors as well as variables for rainfall and population density were analysed with respect to failure to meet these water quality targets using contingency tables. Logistic regression models were developed for each of the five water quality targets. The analysis strongly suggested that there is rapid recharge of the springs after rainfall and this leads to microbiological contamination. On-site sanitation was less important than other sources of faecal matter, which was consistent with a low sanitation coverage in the study area. The study suggested that improving sanitary completion and local environmental hygiene was more important than controlling on-site sanitation in improving the quality of these springs.

Enterobacteriaceae↗

PubMed2002

Effects of particulate explosives on estimating contamination at a historical explosives testing area.

A historical explosives testing area harbored contamination as unevenly distributed solid particles within a contaminant-stained soil matrix. Particles larger than 3 mm diameter accounted for 96.4% of the explosives contamination. Independent sampling and analysis methods showed significant differences in contaminant estimations due to particulate explosives. We present a solvent-based sample averaging method designed to solve spatial heterogeneity problems resulting from the presence of contaminant particles.

Chromatography, High Pressure Liquid↗

PubMed2002

Setting information priorities for remediation decisions at a contaminated-groundwater site.

Many sites of contamination due to inappropriate disposal of hazardous materials or wastes have been found. These sites have the potential of damaging the environment and human health and thus need to be evaluated as to whether and what actions should be initiated. In the decision on whether a contaminated site should be subject to management, the knowledge concerning important parameters that would influence the decision will be beneficial to planning of data collection to support the decision. This paper presents a case study of contaminated site located in northern Taiwan, where the groundwater is contaminated by chlorinated hydrocarbons including trichloroethylene (TCE) and tetrachloroethylene (PCE). A site-specific multimedia risk assessment is performed to estimate the total risk resulting from the contamination. In addition, Monte Carlo simulation, rank correlation coefficients, and decision criteria are combined to develop a methodology for assessing the important of parameters in terms of their influence on the decision. It is found that TCE concentration, vegetable yield, deposition interception fraction of vegetables, and plant surface loss constant, are the four parameters important to the decision-making of the case problem.

Algorithms↗

PubMed2002

Thyroid status in juvenile alligators (Alligator mississippiensis) from contaminated and reference sites on Lake Okeechobee, Florida, USA.

Exposure to environmental contaminants has been shown to alter normal thyroid function in various wildlife species, including the American alligator (Alligator mississippiensis). Abnormalities in circulating levels of the thyroid hormone thyroxine (T4) have been reported in juvenile alligators from several contaminated lakes in Florida. To further elucidate these functional thyroid abnormalities, this study examines the structure of thyroids and circulating T4 concentrations from juvenile alligators collected from three sites of varying contamination on Lake Okeechobee, Florida. The following variables were used to characterize thyroid morphology: epithelial cell height, width and area, percent colloid, and follicle area. These variables were compared among study sites and between genders. No difference was detected in epithelial cell height, epithelial cell area, or follicle area among the sites, whereas significant differences in epithelial cell width (p = 0.02) and percent colloid (p = 0.008) were found. Animals from the most contaminated site (Belle Glade) had significantly greater epithelial cell widths and significantly less colloid present in their follicles compared to animals from the reference site (West). Gender did not have a significant interaction with site for any variable measured. Thyroxine (T4) concentrations were elevated in the intermediately contaminated site (Conservation Area 3A) compared to the other sites (p < 0.0001). It is proposed that the disruptions seen in Lake Okeechobee alligators are due to disruptions at both the thyroid and extra-thyroidal tissues.

Alligators and Crocodiles↗

PubMed2003

Negative effects of humic acid addition on phytoremediation of pyrene-contaminated sediments by mangrove seedlings.

Vegetated (with Kandelia candel seedlings) and non-vegetated mangrove microcosms were employed to remove pyrene from contaminated sediments, and the effects of adding 6.7% humic acid (HA) on such removal were investigated. At the end of 6-month treatment, residual pyrene concentrations in surface sediments (0-2 cm) of the contaminated microcosms reduced from an initial 5.82 to 0.63 microg g(-1) dw, and the reduction was less in HA amended microcosms with the residual pyrene concentration remained at 3.12 microg g(-1) dw. The pyrene removal percentages in microcosms with HA amendment were 29% for surface aerobic sediments and 41% for bottom (anaerobic) sediments, while the respective removal percentages in microcosms without HA amendment were 89% (surface sediments) and 53% (bottom sediments). Microcosms planted with K. candel seedlings had a significantly higher pyrene removal when compared to the non-vegetated ones, and the average removal percentages were 70.9% and 61.4%, respectively. However, when humic acid was added, no significant difference was found between vegetated and non-vegetated microcosms in pyrene removal, both had less than 40% removal, probably because plant growth in humic acid amended contaminated microcosms, in terms of total biomass, was reduced by 50%. Roots of K. candel could accumulate pyrene from contaminated microcosms, and pyrene concentrations in roots harvested from microcosms with and without humic acid addition were 6.01 and 3.46 microg g(-1) dw, respectively. These results suggest that the addition of HA to contaminated sediments decreased the mangrove microcosm's ability to remove pyrene as pyrene was more tightly bound to the organic matter and plant growth was reduced.

Avicennia↗

PubMed1998

Estimating dermal transfer from PCB-contaminated porous surfaces.

Health risks posed by dermal contact with PCB-contaminated porous surfaces have not been directly demonstrated and are difficult to estimate indirectly. Surface contamination by organic compounds is commonly assessed by collecting wipe samples with hexane as the solvent. However, for porous surfaces, hexane wipe characterization is of limited direct use when estimating potential human exposure. Particularly for porous surfaces, the relationship between the amount of organic material collected by hexane and the amount actually picked up by, for example, a person's hand touch is unknown. To better mimic PCB pickup by casual hand contact with contaminated concrete surfaces, we used alternate solvents and wipe application methods that more closely mimic casual dermal contact. Our sampling results were compared to PCB pickup using hexane-wetted wipes and the standard rubbing protocol. Dry and oil-wetted samples, applied without rubbing, picked up less than 1% of the PCBs picked up by the standard hexane procedure; with rubbing, they picked up about 2%. Without rubbing, saline-wetted wipes picked up 2.5%; with rubbing, they picked up about 12%. While the nature of dermal contact with a contaminated surface cannot be perfectly reproduced with a wipe sample, our results with alternate wiping solvents and rubbing methods more closely mimic hand contact than the standard hexane wipe protocol. The relative pickup estimates presented in this paper can be used in conjunction with site-specific PCB hexane wipe results to estimate dermal pickup rates at sites with PCB-contaminated concrete.

Absorption↗