21 research outputs found
Optimising analytical methods for chlorinated paraffins to evaluate their levels in Australia
Full text linkBoer, J. de [Promotor]Muller, J. [Promotor]Gaus, C. [Copromotor]Leonards, P.E.G. [Copromotor
Hap, daar gaat weer zo’n smakelijke orchis; de gevolgen van begrazing door vee voor Rode Lijstsoorten
No full textRuud van der Meijden begon zijn floristische carrière in de duinen van Voorne en deed daar in de jaren voor zijn overlijden waarnemingen over de negatieve gevolgen van begrazing door vee, in het bijzonder voor orchideeën. Dat bleek achteraf het startschot voor een brede discussie over de gevolgen van begrazing door vee voor bijzondere plantensoorten in natuurgebieden. Hij verzette zich vooral tegen het incorrecte ‘oernatuur’-beeld, het jaarrond begrazen, het bijvoederen in de winter en de inadequate wijze van monitoring. Naar aanleiding van deze discussie is in 2005 onderzoek gestart in de duinen van Oostvoorne naar de gevolgen van begrazing voor Rode Lijstsoorten. Na twee jaar zijn er nog geen duidelijke resultaten, alhoewel sommige soorten orchideeën lijken te profiteren van de uitrastering. In de Amsterdamse Waterleidingduinen echter, heeft men al meer dan vijftien jaar ervaring met begrazing en kent men de effecten ervan. Hier blijkt dat de meeste Rode Lijstsoorten zich in de begraasde gebieden over het algemeen goed handhaven. Enkele soorten van algemene vegetaties, zoals duingrasland of bos, worden talrijker of verspreiden zich, maar soorten van beperkt voorkomende vochtige duinvalleien, gaan achteruit of verdwijnen door overbegrazing en/of tred.
Ruud van der Meijden began his career in floristics in the Voorne dunes and it was there, too, in the years prior to his death, that he made a series of observations about the negative impact of cattle grazing on orchids in particular. It was the starting shot for a consciously triggered national debate about the consequences of grazing for valuable species in protected nature areas. There were four things he was particularly opposed to: a flawed notion of ‘primeval nature’, year-round grazing, supplementary winter feeding, and inadequate monitoring. Prompted by this debate, a study was initiated in the Oostvoorne dunes in 2005 to empirically assess the consequences of grazing for Red List species. Two years into the study the results are still not entirely clear, although certain orchid species appear to have benefited from fencing off. As has become clear from fifteen years of grazing in the dunes used for water infiltration (Amsterdamse Waterleidingduinen), most Red List species generally appear to survive well in the areas grazed. Several species of common vegetations like dune grassland and woodland have become more abundant or have colonised new areas. Species of rarer habitats like dune slacks, on the other hand, have declined or disappeared as a result of overgrazing and/or trampling
Developments and interlaboratory study of the analysis of short-chain chlorinated paraffins
Full text linkTo survey the conformity and quality of the results between laboratories for short-chain chlorinated paraffins (SCCPs) determination, we reviewed current and novel analytical methods and organized four worldwide laboratory exercises between 2011 and 2017. Participants were requested to analyse test solutions and extracts of various matrices with their method of choice. Thirty-three laboratories participated (9–22 per round), of which 55–81% were able to submit data. Large differences in results between laboratories were found (CVs 23–137%) but results improved over time, while the levels in the test materials decreased. In the last round acceptable CV values (<25%) were obtained for the test solution. In the last round, results obtained by the GC–ECNI-LRMS technique varied most, which is disconcerting as this technique is most commonly applied. We strongly suggest to continue monitoring comparability of laboratories to assess consensus in SCCP analysis, with a focus on quantification procedures applied
Chlorinated paraffins in the environment: A review on their production, fate, levels and trends between 2010 and 2015
No full textThis review provides an update on information regarding the production volumes, regulations, as well as the environmental levels, trends, fate and human exposure to chlorinated paraffin mixtures (CPs). CPs encompas thousands congeners with varying properties and environmental fate. Based on their carbon chain lengths, CPs are divided into short- (SCCPs;
The underlying challenges that arise when analysing short-chain chlorinated paraffins in environmental matrices
Full text linkAs short-chain chlorinated paraffins (SCCPs) are listed on several monitoring programs, validated methods are essential. However, their complexity and the lack of commercially available certified reference materials (RMs) hinder a proper validation of methods. Instead, one method is usually ‘validated’ by evaluating performances and results of spiked materials with that of one other method, which could easily lead to unreliable results. This study evaluated four analytical methods with different principles (i.e. comprehensive two dimensional GC coupled to a micro electron capture detector, developed for this study, chloride enhanced atmospheric pressure chemical ionization triple quadrupole time of flight MS (APCI-QToF-HRMS), GC coupled to an electron capture negative ion low resolution MS (GC–ECNI–LRMS) and carbon skeleton GC–MS), investigated the comparability in SCCP determination in spiked and naturally contaminated samples and determined SCCP amounts in candidate RMs for possible certification. The results cast doubt on the use of the most commonly applied method (i.e. GC–ECNI–LRMS), as well as using spiked materials for method validation. The APCI-QToF-HRMS method was found most promising as it achieves the required MS resolution (>21,000), is relatively fast and can detect also other CPs. The suitable identified SCCP levels in the candidate RMs and the agreement in results between the methods bring the first certification of a RM for SCCPs within reach
Developments and interlaboratory study of the analysis of short-chain chlorinated paraffins
No full textTo survey the conformity and quality of the results between laboratories for short-chain chlorinated paraffins (SCCPs) determination, we reviewed current and novel analytical methods and organized four worldwide laboratory exercises between 2011 and 2017. Participants were requested to analyse test solutions and extracts of various matrices with their method of choice. Thirty-three laboratories participated (9–22 per round), of which 55–81% were able to submit data. Large differences in results between laboratories were found (CVs 23–137%) but results improved over time, while the levels in the test materials decreased. In the last round acceptable CV values (<25%) were obtained for the test solution. In the last round, results obtained by the GC–ECNI-LRMS technique varied most, which is disconcerting as this technique is most commonly applied. We strongly suggest to continue monitoring comparability of laboratories to assess consensus in SCCP analysis, with a focus on quantification procedures applied
Recent developments in capabilities for analysing chlorinated paraffins in environmental matrices: a review
No full textConcems about the high production volumes, persistency, bioaccumulation potential and toxicity of chlorinated paraffin (CP) mixtures, especially short-chain CPs (SCCPs), are rising. However, information on their levels and fate in the environment is still insufficient, impeding international classifications and regulations. This knowledge gap is mainly due to the difficulties that arise with CP analysis, in particular the chromatographic separation within CPs and between CPs and other compounds. No fully validated routine analytical method is available yet and only semi-quantitative analysis is possible, although the number of studies reporting new and improved methods have rapidly increased since 2010. Better cleanup procedures that remove interfering compounds, and new instrumental techniques, which distinguish between medium-chain CPs (MCCPs) and SCCPs, have been developed. While gas chromatography coupled to an electron capture negative ionisation mass spectrometry (GC/ECNI-MS) remains the most commonly applied technique, novel and promising use of high resolution time of flight MS (TOF-MS) has also been reported. We expect that recent developments in high resolution TOF-MS and Orbitrap technologies will further improve the detection of CPs, including long-chain CPs (LCCPs), and the group separation and quantification of CP homologues. Also, new CP quantification methods have emerged, including the use of mathematical algorithms, multiple linear regression and principal component analysis. These quantification advancements are also reflected in considerably improved interlaboratory agreements since 2010. Analysis of lower chlorinated paraffins
Results of WEPAL-QUASIMEME/NORMANs first global interlaboratory study on microplastics reveal urgent need for harmonization
Full text linkTo survey the conformity and quality of results among laboratories for microplastics determination worldwide, an international laboratory intercomparison and development exercise was organized. The 34 participants were requested to determine the polymer type and number or mass of polymer particles in 12 samples, i.e. six samples containing of pre-production pellets, five dissolvable soda tablets containing different (smaller) polymer particles and one blank soda tablet. A novel method for providing the test materials in aluminium strips was used. Thirty laboratories (88%) submitted data using their own method of choice, resulting in a variety of identification and quantification methods (n = 7). The majority of the labs (53–100%) correctly identified the type of polymer in all samples but one. The performance of the laboratories in quantifying and weighing the pellets was very good. The analysis of the number of the particles in the soda tablets varied considerably between laboratories (29–91%). The results of this study highlight the complexity of microplastics analysis and the need for harmonization of both reporting format and methods. Continued development and assessment of the comparability among analytical methods and laboratories are urgently needed to support monitoring programmes, research and decision-making.</p
Evaluating age and temporal trends of chlorinated paraffins in pooled serum collected from males in Australia between 2004 and 2015
No full textChlorinated paraffins (CPs) are high production volume chemicals of which some show resistance to environmental degradation, long-rang transport, bioaccumulation and toxicity potential. Information regarding their presence in humans is limited, including their human bioaccumulation potential. The present study aimed to evaluate CP levels in human serum from Australia in order to better understand their exposure and current pollution status as well as trends associated with age and time between 2004 and 2015. For this, we selected a male sub-group of the Australian population under 60 years old (n = 16 pools, total 1600 serum samples). While long-chain CP (C18-20) and most short-chain CP (C10-13, SCCPs) levels were below method detection limits (MDL), medium-chain CPs (C14-17, MCCPs) were found in most serum samples (detection frequency 94%) as well as CPs with a carbon chain length of nine (detection frequency 76%). The levels of ΣSCCPs and ΣMCCPs ranged from <MDL−140 and <MDL-520 ng/g lipid weight (lw), respectively, with a median value of 97 ng/g lw for SCCPs and 190 ng/g lw for MCCPs. Analysis by age stratification did not identify any trends but an increase of a factor of 2 in MCCPs levels was observed over time (p < 0.05). Plotting the MCCP/SCCP ratio of all available data in humans over time showed also an increasing trend, including for China. The reported levels are relatively low considering the levels reported in environmental media from Australia such which raises the question to what extent CPs accumulate in humans. Future studies on this aspect are required.</p
Reliability and validity of multicentre surveillance of surgical site infections after colorectal surgery.
Full text linkBACKGROUND: Surveillance is the cornerstone of surgical site infection prevention programs. The validity of the data collection and awareness of vulnerability to inter-rater variation is crucial for correct interpretation and use of surveillance data. The aim of this study was to investigate the reliability and validity of surgical site infection (SSI) surveillance after colorectal surgery in the Netherlands. METHODS: In this multicentre prospective observational study, seven Dutch hospitals performed SSI surveillance after colorectal surgeries performed in 2018 and/or 2019. When executing the surveillance, a local case assessment was performed to calculate the overall percentage agreement between raters within hospitals. Additionally, two case-vignette assessments were performed to estimate intra-rater and inter-rater reliability by calculating a weighted Cohen's Kappa and Fleiss' Kappa coefficient. To estimate the validity, answers of the two case-vignettes questionnaires were compared with the answers of an external medical panel. RESULTS: 1111 colorectal surgeries were included in this study with an overall SSI incidence of 8.8% (n = 98). From the local case assessment it was estimated that the overall percent agreement between raters within a hospital was good (mean 95%, range 90-100%). The Cohen's Kappa estimated for the intra-rater reliability of case-vignette review varied from 0.73 to 1.00, indicating substantial to perfect agreement. The inter-rater reliability within hospitals showed more variation, with Kappa estimates ranging between 0.61 and 0.94. In total, 87.9% of the answers given by the raters were in accordance with the medical panel. CONCLUSIONS: This study showed that raters were consistent in their SSI-ascertainment (good reliability), but improvements can be made regarding the accuracy (moderate validity). Accuracy of surveillance may be improved by providing regular training, adapting definitions to reduce subjectivity, and by supporting surveillance through automation
