Exogenous Contamination Research Articles

Using ion-pair reversed-phase HPLC ICP-MS to simultaneously determine Cr(III) and Cr(VI) in urine of chromate workers

Urinary chromium speciation analysis can provide available information of the individual exposure levels of Cr(VI) compounds. An analytical method based on ion-pair reversed-phase HPLC combined with ICP-MS to simultaneously determine Cr(III) and Cr(VI) in human urine has been developed for assessing the occupational exposure to chromate. The separation conditions of the method, including the pH value, the concentrations of ion-pair reagent and methanol in the mobile phase were studied. Specially, a high-speed polyetheretherketone (PEEK) column and a typical sample introduction method were employed to avoid the exogenous chromium contamination during the analysis. The separation of Cr(III) and Cr(VI) could be finished within 4 min with the detection limits as low as 0.03 μg L −1 at 100 μL injections for both of them, providing a convenient method for routine analysis of chromium species. The chromium species in urine of chromate workers were monitored using the developed method. The statistical analysis showed a significant relationship ( n = 32, p < 0.01) between the urinary Cr(VI) and the individual airborne exposure levels, indicating that the urinary Cr(VI) could be used as a convenient and suitable monitor for high level Cr(VI) occupational exposure.

Detection of exogenous contaminants of fingerprints using ToF‐SIMS

AbstractThe aim of this study is to present an application of ToF‐SIMS in forensic research, especially in the imaging of fingerprints and detection of traces of various substances, which do not exist in natural skin excretion, but can be connected with a crime scene. Exemplary ToF‐SIMS images of fingerprints from fingers contaminated with traces of different substances (arsenic, nickel, gunshot residues, amphetamine drugs, etc.) using three kinds of bases (aluminum, stainless steel and brass) are showed. The results of the study show the potential of ToF‐SIMS technique in the analysis of fingerprints with a view to use in forensic science. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Is nasal carriage of Staphylococcus aureus the main acquisition pathway for surgical-site infection in orthopaedic surgery?

The endogenous or exogenous origin of Staphylococcus aureus, responsible for orthopaedic surgical-site infections (SSI), remains debated. We conducted a multicentre prospective cohort study to analyse the respective part of exogenous contamination and endogenous self-inoculation by S. aureus during elective orthopaedic surgery. The nose of each consecutive patient was sampled before surgery. Strains of S. aureus isolated from the nose and the wound, in the case of SSI, were compared by antibiotypes or pulsed-field gel electrophoresis (PFGE). A total of 3,908 consecutive patients undergoing orthopaedic surgery were included. Seventy-seven patients developed an SSI (2%), including 22 related to S. aureus (0.6%). S. aureus was isolated from the nose of 790 patients (20.2%) at the time of surgery. In the multivariate analysis, S. aureus nasal carriage was found to be a risk factor for S. aureus SSI in orthopaedic surgery. However, only nine subjects exhibiting S. aureus SSI had been found to be carriers before surgery: when compared, three pairs of strains were considered to be different and six similar. In most cases of S. aureus SSI, either an endogenous origin could not be demonstrated or pre-operative nasal colonisation retrieved a strain that was different from the one recovered from the surgical site.

DNA Extraction from Pulp Tissue for its Application in PCR. A Study to Extract DNA with High Purity as Quantified by Gel Electrophoresis

ABSTRACT The isolation of human genomic DNA is an important step involved in genetic identity analysis. Also getting optimal quantity and quality of DNA is important as this can alter the results. This consideration is especially important in the field of forensic analysis and genetic identity, where DNA is extracted from extremely small amounts of starting material often recovered from suboptimal storage conditions. Odontological examinations have always been a critical determinant in the search of human identity. Teeth form a natural barrier to exogenous DNA contamination. DNA extraction from dental tissues both hard tissues and dental pulp, has been reported the use of dental pulp, as a source of DNA offers a new paradigm in the process of DNA extraction and its use in forensic analysis.11 The following procedures elucidate a novel method of extraction of DNA using dental pulp, which offers a cost-effective and attractive procedure, which can be replicated and applied in DNA amplification (PCR).

Improved AMS14C Dating of Shell Carbonates Using High-Precision X-Ray Diffraction and a Novel Density Separation Protocol (Cards)

One critical variable in the successful application of radiocarbon dating is the effective removal of carbonaceous contaminants. In the case of marine carbonates, contamination appears usually in the form of secondary low-magnesium calcite, the stable polymorph of calcium carbonate and byproduct of the post-mortem recrystallization or replacement of the autochthonous phase, originally in the form of high-magnesium calcite or aragonite. Depending on the nature of the depositional environment, the secondary phase may be contemporary in age with the original shell carbonate and may have even been derived from it by dissolution-recrystallization processes, or can be an exogenous contaminant of younger or older age. The limited ability of current pretreatment protocols to detect and remove the secondary mineralogical phases prior to dating carbonates has been one of the reasons marine shell and coral14C determinations are often difficult to validate in terms of their reliability. We have developed a new pretreatment protocol designed to achieve greater reliability and accuracy in the dating of this material. The method entails 2 steps. The first one involves the improved detection and quantification of secondary calcite in aragonite using X-ray diffraction, at a precision of ∼0.1% and ∼0.8%, respectively. Next, where this is required, a novel density separation step using non-toxic heavy liquids (CarDS) is applied to the diagenetic sample. This enables the clear separation of calcite and aragonite, with only the latter kept for dating. We have applied the new steps, screening and separation, on standard and archaeological examples and our initial results suggest that it is successful and reproducible. In this paper, we describe the method and initial results.

Factitiously elevated blood chromium

Context. Chromium toxicity is rare in individuals who do not have a history of occupational or deliberate exposure to chromium or chromium-containing compounds. Case report. A 39-year-old female with confirmed bile acid malabsorption had an elevated whole blood chromium concentration of 76.3 nmol/L (normal < 40 nmol/L). There was no history of chromium exposure and no clinical signs of chromium toxicity. Two repeat samples drawn through a butterfly needle, after discarding of an initial blood draw, also revealed an elevated blood chromium concentration (60.1, 122.7 nmol/L). A subsequent sample collected through a plastic intravenous cannula revealed a normal whole blood chromium concentration of 35 nmol/L. Discussion. The elevated chromium concentrations were likely because of exogenous contamination from chromium within the venepuncture and butterfly needles. An appropriate sampling technique involving plastic cannula should be used when measuring blood chromium concentrations.

Accuracy of Whole Blood Glucose Measurement When Venous Catheter Blood Samples Are Used on Glucose Meters

Previous studies have found positive bias and frequent outliers when central venous catheter (CVC) whole blood is used to dose glucose meters. We designed a study to determine whether positive bias and outliers with CVC whole blood glucose samples are due to exogenous glucose contamination of CVC samples, inherent bias and imprecision of glucose meters, or properties of CVC whole blood that interfere with the function of some glucose meters. We studied the relationship between venous whole blood and venous plasma glucose drawn by venipuncture to CVC whole blood and CVC plasma glucose in 50 hospitalized patients. In 27 patients whole blood glucose was measured on both the Accu-Chek Inform (Roche Diagnostics, Indianapolis, IN) and StatStrip (Nova Biomedical, Waltham, MA). By comparing CVC plasma to venous plasma glucose, we determined that contamination of CVC samples with exogenous glucose was uncommon. On the Inform meter outliers were approximately twice as common with CVC whole blood compared to venous whole blood. In 27 patients who had CVC whole blood analyzed by both Inform and StatStrip, outliers occurred approximately twice as often on the Inform compared to the StatStrip. Accounting for CVC samples contaminated with exogenous glucose, outliers on the StatStrip did not occur significantly more often using CVC whole blood compared to venous whole blood. Properties unique to CVC whole blood differentially affect glucose meter bias and imprecision. Device selection is critical in practices that wish to use CVC whole blood to monitor glucose concentration in hospitalized patients.

The Cu, Mn and Zn concentration of sheep wool: Influence of washing procedures, age and colour of matrix

No standard or wholly proven method to determine the trace metal status of human or animal ‘hair’ yet exists. It is well known that hair–metal concentrations are highly influenced by washing procedures applied before analysis. A novel method to determine the efficiency of washing procedures at removing exogenous contaminants was devised. It was shown that suitability of washing procedures was element-specific and increased sonication time during washing progressively removed more Mn and Zn from sheep wool. The efficiency of exogenous contaminant removal by including sonication during washing was also dependant on the efficiency of procedures under study. The Cu, Mn and Zn concentration, and thus exogenous contaminant level, of sheep wool increased in tandem with its age. Additionally, Cu and Zn concentrations of black wool were significantly higher than white wool: a relationship ascribed to melanins. This investigation shows the necessity to standardise procedures used during analysis of ‘hair’ fibres, and to assess each washing procedure for each element before performing routine analysis.

Beyond toxicity: aryl hydrocarbon receptor-mediated functions in the immune system

The aryl hydrocarbon receptor is a ligand-activated transcriptional regulator that binds dioxin and other exogenous contaminants and is responsible for their toxic effects, including immunosuppression. New evidence suggests, however, that the aryl hydrocarbon receptor has a physiological role in the immune system, and the immunosuppressive effects of dioxin may reflect a more subtle disruption of the regulatory interactions between immune cells.

The U, Th and Pb elemental and isotope compositions of mantle clinopyroxenes and their grain boundary contamination derived from leaching and digestion experiments

Minerals from peridotites are known to be affected by trace element contamination on their grain boundaries. In this contribution we investigate the extent and origin of exogenous contamination associated with mantle clinopyroxenes from various localities (Middle Atlas, Beni Bousera [Morocco], Pyrenean Massif, Massif Central [France]) and test the efficacy of different leaching methodologies used to remove this contamination. In doing so we present new U–Th–Pb (double-spike) isotope and trace elemental data of clinopyroxenes and their leachates from spinel-facies sub-continental lithospheric mantle (SCLM, n = 18). Sequential leaching and dissolution of one clinopyroxene separate shows that multiple and short leaching attacks with dilute HCl at moderate temperatures (e.g., 120 °C) interspersed with rigorous ultra-pure water washes do not induce elemental fractionation and are sufficient to remove grain-boundary contamination. Short attacks with very dilute mixtures of HF and HCl induced strong parent/daughter elemental fractionation and significant elemental loss prior to the clinopyroxene digestion with HF/HNO 3. Such leaching is not suitable for studies investigating parent/daughter elemental or isotope ratios of mantle clinopyroxenes. Fluoride co-precipitates that formed in the presence of moderately dilute HF, used during leaching and typical HF/HNO 3 digestions, are an important sink for all trace elements studied here and lock up at least 60% of the trace elements considered. A suite of clinopyroxene–leachate pairs from Moroccan peridotites confirm extreme grain-boundary contamination and show that up to 65% of U, 82% of Th and 91% of Pb, respectively, are of exogenous origin. Pb isotopes of all leachates considered and nearly all reconstructed unleached clinopyroxenes have highly positive Δ7/4 and 207Pb/ 204Pb– 206Pb/ 204Pb systematics reminiscent of enriched mantle (particularly EM II), whereas the corresponding extensively leached clinopyroxenes have very different Pb isotope systematics (verified by replicate digestions). Furthermore, the leachates are often marked by remarkably high 232Th/ 238U (leachate ≫ bulk silicate Earth) in addition to 238U/ 204Pb and 232Th/ 204Pb that are seemingly consistent with depleted mantle (DM) and high 238U/ 204Pb (HIMU) mantle mixing. After leaching, clinopyroxenes may have highly elevated 238U/ 204Pb and 232Th/ 204Pb that are distinct from typical DM- and HIMU mantle, whereas corresponding leachates bear strong resemblance to anthropogenic Pb recovered from rainwater, snow and aerosols. In the light of the great potential of Pb isotope contamination associated with mantle clinopyroxene we have compiled literature data of mantle peridotites. These data seem to suggest that the SCLM is nearly devoid of HIMU signatures but ostensibly represents an important repository for enriched mantle signatures. However, the dominance of enriched mantle is not verified when 87Sr/ 86Sr and 208Pb/ 204Pb ratios for the same database are considered. We highlight that the scarcity of HIMU-like SCLM and the alleged dominance of EM in continental roots may be reconciled if the current Pb isotope database of SCLM contains samples that were insufficiently leached prior to digestion and thus are contaminated by anthropogenic Pb. We stress the importance of replicate digestions, adequate leaching and leachate analysis to verify the U–Th–Pb elemental and isotope systematics of any given mantle (-derived) sample.

Protein markers of algal toxin contamination in shellfish

Filter-feeding bivalve molluscs are often contaminated by algal toxins. We have probed whether proteomic analysis of extracts from the digestive gland (DG) of mussels could be employed to identify biomarkers of contamination due to okadaic acid-group toxins. The protein extracts were obtained from 18 separate mussel samples and were analyzed by two-dimensional gel electrophoresis. When samples were divided into four different classes based on the content of OA-group toxins in the starting material, we found that two proteins varied as a function of OA contamination. By BLAST analysis, the two proteins were identified as a component of photosystem II and a subunit of NADH dehydrogenase. The analysis of peptide homologies showed that the peptide of photosystem II we detected in extracts from the DG of mussels contaminated by OA-group toxins is identical to its counterpart in Dinophysis algae, which are the producers of this group of toxins. We concluded that proteomic analysis can be used for the detection and identification of biomarkers of biotoxin contamination in shellfish, including both proteins expressed by the toxin producers and components that participate to the tissue response to the exogenous bioactive contaminant.

An evaluation of PCR primer sets used for detection of Propionibacterium acnes in prostate tissue samples

Multiple studies have now shown that Propionibacterium acnes can be cultured from post-prostatectomy derived prostate tissue samples. In contrast, both universal eubacterial 16S rDNA PCR and P. acnes-specific 16S rDNA PCR have failed to detect this organism at a frequency similar to that of bacterial culture. A potential explanation for this discrepancy, proposed by Cohen et al., involves mismatches in 16S rDNA primer sets used for bacterial detection. The sensitivity of both a previously published P. acnes-specific primer set containing a potential mismatch and a new primer set with no mismatches was determined. Both primer sets were used to interrogate two sets of DNA samples derived from post-prostatectomy prostate tissues that differed in the level of sterile precautions maintained during tissue collection. The number of P. acnes positive samples was associated with the sterility of the sample collection process. In all instances, positive samples were determined to reflect low cell numbers (<10 CFU). Although the results of previous studies have shown that P. acnes is not the only organism potentially present in the prostates of prostate cancer patients, mismatches in PCR primer sets may have also influenced the sensitivity of P. acnes detection. When using PCR in determining the presence of P. acnes in the human prostate, care should be taken to establish the potential influence of exogenous contamination and, due to the sensitivity of the assay, samples exposed to the urethra during the collection process (prostatic secretions, TURP specimens) should not be used.

Toxicity characterization of waste mobile phone plastics

Waste plastic housing units ( N = 60) of mobile phones (of different models, and brands), were collected and analyzed for lead, cadmium, nickel and silver using atomic absorption spectrophotometry after acid digestion using a 1:1 mixture of H 2SO 4 and HNO 3. The mean (±S.D.) and range of the results are 58.3 ± 50.4 mg/kg (5.0–340 mg/kg) for Pb, 69.9 ± 145 mg/kg (4.6–1005 mg/kg) for Cd, 432 ± 1905 mg/kg (5.0–11,000 mg/kg) for Ni, and 403 ± 1888 mg/kg (5.0–12,500 mg/kg) for Ag. Approximately 90% of the results for the various metals were ≤100 mg/kg. Results greater than 300 mg/kg were generally less than 7% for each metal and could be attributed to exogenous contamination of the samples. These results suggest that there may not be any immediate danger from end-of-life (EoL) mobile phone plastic housing if appropriately treated/managed. However, considering the large quantities generated and the present low-end management practices in most developing countries, such as open burning, there appears a genuine concern over the potential for environmental pollution and toxicity to man and the ecology.

A Comparative Evaluation of Three Washing Procedures for Minimizing Exogenous Trace Element Contamination in Fetal Scalp Hair of Various Obstetric Outcomes

A comparative evaluation of three washing methods for removing exogenous elemental contamination from fetal scalp hair is described. A total of 12 samples, including 6 from normal pregnancies and 6 from abruptio placentae (AP) cases, were used. Each was divided into four subsamples, with one left unwashed for comparison, while three were subjected to one of the three washing methods. The first consisted of agitating hair for 5 min in sequential and equal measures (30 ml) of acetone and water, followed by rinsing with acetone, and the process repeated twice. In the second and third, hair was agitated for 30 min in aqueous solutions of sodium lauryl sulfate (0.5%, w/v), and Triton X-100 (0.5%, v/v), respectively, followed by sequential rinsing with deionized water and acetone. After drying and microwave-assisted digestion in concentrated nitric acid, the subsamples' concentrations of zinc, copper, cadmium, lead, mercury and selenium were determined using inductively coupled mass spectrometry. All washed subsamples, irrespective of washing method used, had lower elemental concentrations than the corresponding, unwashed subsamples. These differences, taken as presumptive indicators of exogenous contamination, showed only small variations (<5%) between the three washing methods, irrespective of element, mode of delivery, and obstetric outcome. However, the contamination levels elicited by each of the three methods varied in magnitude according to individual elements, with those of copper being highest, followed by those of zinc, cadmium, mercury, selenium, and lead. They also varied according to obstetric outcome, being highest in the AP subsamples, while in the normal pregnancy group, copper and zinc contamination levels in the subsamples from neonates delivered by elective caesarean section were higher than in those from normal-delivery neonates. The data from this study suggest that the three washing methods used have comparable efficacies in removing exogenous elemental contamination from fetal hair, further inferring that it is probably a simple biological matrix to decontaminate. Possible contributory factors are discussed and contrasted with those affecting adult hair.

The lead in Beethoven's hair

In the past several years a number of inadequately substantiated reports appeared in the popular media, asserting that lead (Pb) found in Beethoven's hair indicated that he was a victim of Pb poisoning and suggesting that lead played a role in his deafness and illnesses. This article reviews critically a recent report of the longitudinal distribution of Pb along individual hairs belonging to Beethoven by Dr Reiter 1, who interprets the Pb concentration profile of an individual hair in terms of several hypothetical occurrences which might have exposed Beethoven to lead during the last few months of his life and concludes that the resulting Pb poisoning caused his death. This hypothesis is, however, in need of substantiation by additional data since it is at variance with the known kinetics of Pb in blood and because the Pb content of hair is recognized as a problematical and unreliable biomarker of lead absorption, in part, because it is not possible to exclude exogenous Pb contamination in the specimen. In view of Beethoven's extraordinarily well-documented medical history and autopsy report, briefly summarized here, and in the absence of persuasive evidence that Beethoven suffered from lead disease, it is concluded that lead did not contribute significantly to his deafness, illnesses, or death.

Pre-treatment of Dryopteris cristata (L.) A. Gray rhizome as a method of elimination of contaminants and explant browning micropropagation

Micropropagation of Dryopteris cristata (L.) A. Gray by rhizome explants requires a pre-treatment procedure as a &lt;&lt;stage 0&gt;&gt;. Mycological examinations of fungi from fern rhizomes allowed to determine 24 species represented by 66 isolates and a group non-sporulating colonies. Most frequently fungi were represented by Cylindrocarpon destructans and Mycelium radicis atrovirens. The pre-treatment procedure reduces exogenous and endogenous contamination by fungi, actinomycetes and other bacteria in developing adventitious buds. Starvation of rhizomes during pre-treatment significantly reduces starch and phenolic contents and thereby prevents browning of the explants. The present data revealed that in decontaminated, actively growing buds there are less phenolics than in contaminated rhizomes.

Scalp hair as a biomarker in environmental and occupational mercury exposed populations: Suitable or not?

Hair is a well-established and widely used matrix for measuring mercury exposure of an individual. Although a variety of washing procedures to remove external mercury contamination have been proposed, no standardized procedures are available yet. In this study, different washing reagents like l-cysteine (Cys), 2-mercaptoethanol (ME), and disodium diaminoethanetetra acetate (EDTA) were used to find out if it is possible to remove mercury contamination from human scalp hair spiked with HgCl 2 solutions at different concentrations. It was found that the external mercury contamination could not be fully washed off even using reagents with high affinity to mercury like l-cysteine and ME. However, for the well-pulverized CRM hair samples some of the endogenous mercury was washed off. It suggests that hair is not a suitable biomarker for evaluation of total mercury exposure especially in people like mercury miners or gold miners/burners associated with serious external Hg exposure. However, hair still can be used as an indicator for methyl mercury exposure because, generally, there is almost no exogenous contamination of methyl mercury in hair.

Evaluation of viral removal by nanofiltration using real‐time quantitative polymerase chain reaction

Nanofiltration is commonly introduced into purification processes of biologics produced in mammalian cells to serve as a designated step for removal of potential exogenous viral contaminants and endogenous retrovirus-like particles. The LRV (log reduction value) achieved by nanofiltration is often determined by cell-based infectivity assay, which is time-consuming and labour-intensive. We have explored the possibility of employing QPCR (quantitative PCR) to evaluate LRV achieved by nanofiltration in scaled-down studies using two model viruses, namely xenotropic murine leukemia virus and murine minute virus. We report here the successful development of a QPCR-based method suitable for quantification of virus removal by nanofiltration. The method includes a nuclease treatment step to remove free viral nucleic acids, while viral genome associated with intact virus particles is shielded from the nuclease. In addition, HIV Armored RNA was included as an internal control to ensure the accuracy and reliability of the method. The QPCRbased method described here provides several advantages such as better sensitivity, faster turnaround time, reduced cost and higher throughput over the traditional cell-based infectivity assays.

The spectroscopic detection of exogenous material in fingerprints after development with powders and recovery with adhesive lifters

The application of powders to fingerprints has long been established as an effective and reliable method for developing latent fingerprints. The powders adhere to the ridge pattern of the fingerprint only, thus allowing the image to be visualised. Fingerprints developed in situ at a crime scene routinely undergo lifting with specialist tapes to facilitate subsequent laboratory analysis. As with all recovered evidence these samples would be stored in evidence bags to allow secure transit from the scene to the laboratory and also to preserve the chain of evidence. In this paper, the application of Raman spectroscopy for the analysis of exogenous material in latent fingerprints is reported for contaminated fingerprints that had been treated with powders and also subsequently lifted with adhesive tapes. A selection of over the counter (OTC) analgesics were used as samples for the analysis and contaminated fingerprints were deposited on clean glass slides. The application of aluminium or iron based powders to contaminated fingerprints did not interfere with the Raman spectra obtained for the contaminants. In most cases background fluorescence attributed to the sebaceous content of the latent fingerprint was reduced by the application of the powder thus reducing spectral interference. Contaminated fingerprints developed with powders and then lifted with lifting tapes were also examined. The combination of these two techniques did not interfere with the successful analysis of exogenous contaminants by Raman spectroscopy. The lifting process was repeated using hinge lifters. As the hinge lifters exhibited strong Raman bands the spectroscopic analysis was more complex and an increase in the number of exposures to the detector allowed for improved clarification. Raman spectra of developed and lifted fingerprints recorded through evidence bags were obtained and it was found that the detection process was not compromised in any way. Although the application of powders did not interfere with the detection process the time taken to locate the contaminant was increased due to the physical presence of more material within the fingerprint. The presence of interfering Raman bands from lifting tapes is another potential complication. This, however, could be removed by spectral subtraction or by the choice of lifting tapes that have only weak Raman bands.

Randomized clinical trial comparing two options for postoperative incisional care to prevent poststernotomy surgical site infections

Surgical site infection (SSI) remains an important complication of cardiac surgery. Prevention is important, as SSI is associated with high mortality and morbidity rates. Incisional care is an important daily issue for surgeons. However, there is still scant scientific evidence on which guidelines can be based. A randomized clinical trial was performed to compare two options for postoperative incisional care. Patients undergoing sternotomy for cardiothoracic surgery were eligible. To protect an incision from exogenous contamination or direct inoculation by endogenous pathogens, the study group received an adhesive drape, impermeable to water and air. The control group was treated with a water- and air-permeable absorbent dressing. Primary outcome measure was SSI. Between March 2003 and January 2005, 1,185 patients were included. Both groups were comparable for base-line characteristics. No significant difference was found in the incidence of sternal SSI between groups (2.6 vs. 3.3%). In our study, an incisional-care program using a sterile, impermeable adhesive drape did not perform better than an absorbent dressing in reducing SSI after cardiothoracic surgery. In our view, future studies in the field of prevention of SSI should concentrate on other areas of interest.