Djien Liem - Academia.edu (original) (raw)
Papers by Djien Liem
EFSA Journal, 2016
The EFSA 2nd Scientific Conference ‘Shaping the Future of Food Safety, Together’ gathered an inte... more The EFSA 2nd Scientific Conference ‘Shaping the Future of Food Safety, Together’ gathered an international audience composed of scientists, risk assessors, risk managers, as well as non-governmental organisations and industry representatives. This article summarises the final plenary session where a panel was asked to draw out overall impressions and conclusions for the EFSA to take away for its strategic planning into the future. The main conclusions of the conference are presented under five major themes. With new methodologies, technologies, big data and the increased societal demand for enhanced engagement in the risk assessment process, there is a clear need to maintain levels of expertise from traditional areas and to consider the inclusion of new areas and sources of expertise to perform scientific assessments. Academia, industry, research and regulatory science should work together to achieve this goal. As science progresses at pace, the continued development of assessment methodologies to deal with increasingly complex assessment questions is necessary, as is the need for applied research to underpin the support to policy development that EFSA provides. Greater collaboration is needed to reach agreement on best methods and practices for scientific assessment not just internationally, but also, equally importantly, across legislative areas and scientific disciplines, and in consultation with society at large. The communication of complex science, including important concepts such as uncertainty and risk perception, is not a trivial task, and must be integrated into the scientific process. As such, the relationship between risk assessment and risk management must continue to mature, remaining close, yet independent.
EFSA Journal
... Barlow, Sue. Schlatter, Josef. Öberg, Tomas (Linnaeus University, Faculty of Science and Engi... more ... Barlow, Sue. Schlatter, Josef. Öberg, Tomas (Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences). ... Publication type: Article in journal (Refereed). Language: English. Place of publ.: Parma, Italy Publisher: European Food Safety Authority. Status: ...
Food Additives and Contaminants, 2000
J Chromatogr a, 1992
A comparison is made of supercritical fluid extraction (SFE) with two other techniques widely use... more A comparison is made of supercritical fluid extraction (SFE) with two other techniques widely used for the extraction of polychlorinated biphenyls (PCBs) and organochlorine pesticides in soil. Extraction conditions for the SFE of PCBs and pesticides were first determined. An experimental approach was set up to determine the influence of different extraction parameters such as pressure, extraction time, static and dynamic extraction, restrictor type and collection solvent for off-line SFE. The use of carbon dioxide at 50 degrees C and 20 MPa, 10 min static followed by 20 min dynamic extraction with collection in iso-octane were been found to be the optimum conditions. Two types of soil, with a low and high content of organic carbon, respectively, spiked with 16 PCBs and organochlorine pesticides with a wide range of volatility and polarity at a level of 5 ng/g dry matter, were used as test materials. Conventional solvent extraction gives a good extraction yield for soil with a low content of organic carbon, but for peat soil the recoveries decrease dramatically to 30% for DDE, DDT and PCB 138 and 153. The recoveries with Soxhlet extraction are good, but an extra clean-up step before analysis is necessary. SFE gives good extraction yields for PCBs and organochlorine pesticides, varying between 85 and 105% with a reproducibility of 5% for each component for both types of soil. SFE is a fast, clean and reproducible method for the extraction of PCBs and organochlorine pesticides from these two soil matrices.
... 2,3,7,8-TCDD-equivalenten (I-TEQ) in Nederlandse paling, uitgedrukt per gram vet 15 5 ... bed... more ... 2,3,7,8-TCDD-equivalenten (I-TEQ) in Nederlandse paling, uitgedrukt per gram vet 15 5 ... bedrijven), verbranding van chemisch afval, gebruik vanbestrijdingsmiddelen (waaronder houtverduurzamingsmiddelen), industríele processen (metaalindustrie), branden van houtkachels ...
In melk van het Lickebaertgebied zijn PCDD's en PCDF's aangetoond op een gemiddeld niveau... more In melk van het Lickebaertgebied zijn PCDD's en PCDF's aangetoond op een gemiddeld niveau van 8,6 pg TEQ/g melkvet (n=11). Het landelijk achtergrondniveau hiervan is vastgesteld op een niveau van 0,8-2,5 TEQ/g melkvet aan de hand van melkmonsters afkomstig uit 5 over het land verspreide gebieden. De bijdrage van stedelijke achtergrond aan het TEQ-gehalte in melk wordt gering geacht. Bij een normale consumptie van melk en kaas, afkomstig van koeien uit het Lickebaertgebied wordt de toegestande dagelijkse dosis van 4 pg TEQ per kg lichaamsgewicht overschreden. Hoewel de overschrijding niet tot acute gezondheidseffecten leidt, kunnen bij voortdurende consumptie op de lange termijn gezondheidseffecten niet worden uitgesloten.
In order to evaluate the quality of data resulting from analyses of polychlorinated dibenzo-p-dio... more In order to evaluate the quality of data resulting from analyses of polychlorinated dibenzo-p-dioxins and dibenzofurans in soil, two Dutch laboratories have participated in a RIVM-coordinated interlaboratory comparison study, i.e. the Laboratory of Environmental and Toxicological Chemistry of the University of Amsterdam (UVA) and TAUW Infra Consult B.V. Subsamples of a sandy soil have been fortified with standards of 2,3,7,8-chlorine substituted PCDDs and PCDFs at three different levels (20-8600 ng/kg of soil). Each participant has determined the levels of the seventeen toxic congeners of PCDDs and PCDFs using the own methodology and reference standards. The subsamples have also been analysed by the RIVM. The accuracy and repeatability of the analysis has been examined by using the reported data from the complete analysis of three separate subsamples. Reported levels were generally higher than the actual levels of fortification. This was partly caused by background concentrations in...
Thirty-two grassland sites, distributed over the Netherlands, were sampled to determine 'back... more Thirty-two grassland sites, distributed over the Netherlands, were sampled to determine 'background" concentrations of dioxins. The sites were chosen on the basis of calculations using a model for a large-scale distribution and deposition of dioxins from especially waste incinerators. Sampling procedure, sample processing and physico chemical analyses are described. Special attention is given to the analytical procedure, the recoveries and the repeatability. 'Background' concentrations from 1.8 to 16.4 ng I-TEQ kg-1 were determined for the layer 0-5 cm below surface level. These concentrations reflect the concentrations to be expected as 'background' concentrations in Dutch soils. It appeared appropriate to predict the concentrations in the soil from the deposition data, not only for 'background' sites but also for sites in the vicinity of waste incinerators. From the viewpoint of policy-making further research was not recommended. Additional studies...
This report describes the results of analyses of dioxin levels in soil of five pastures in the vi... more This report describes the results of analyses of dioxin levels in soil of five pastures in the vicinity of the municipal waste incinerator of Zaandam. Isomer specific analysis of dioxins were conducted by high resolution gas chromatography-mass spectrometry using a polar chromatographic capillary column. Dioxin levels are expressed in toxic equivalence per kg of dry soil, per kg of organic carbon as well as per unit of volume of soil using the international toxicity equivalence factors (ITEF) of individual congeners. Samples consisted of blends of frequent samplings of five pastures in the layer at 0-2 cm and 2-10 cm, respectively and of two pastures also in the layer at 10-50 cm below the surface. Dioxin levels in the layer of 10 - 50 cm were 2 and 5 ng/kg dry soil, respectively. Levels in the layer of 2-10 cm were between 12 and 48 ng TEQ/kg dry soil and in the surface layer of 0-2 cm between 13 and 252 ng TEQ/kg dry soil. The lower surface values (13, 60 and 82 ng TEQ/kg dry soil...
Koemelk uit de omgeving van negen afvalverbrandingsinstallaties in Nederland is onderzocht op de ... more Koemelk uit de omgeving van negen afvalverbrandingsinstallaties in Nederland is onderzocht op de aanwezigheid van dioxinen en furanen. de gehalten voor Dordrecht, 's Gravenhage, Leeuwarden, Roosendaal en Rotterdam (Roteb) lagen binnen het landelijke achtergrondniveau van 0,8-2,5 pg TEQ/g melkvet. In koemelk uit de omgeving van de AVI te Leiden (2,4 +/- 0,1 tot 4,2 +/- 0,2 pg TEQ/g melkvet), Alkmaar (1,6 +/- 0,1 tot 5,1 +/- 0,3 pg TEQ/g melkvet) werden licht verhoogde waarden gevonden. De mengmonsters uit de omgeving van de AVI's te Duiven (4,4 +/- 0,2 pg TEQ/g melkvet) en Zaandam (5,4 +/- 0,3 pg TEQ/g melkvet) bevatten verhoogde gehalten aan dioxinen. Tevens werden individuele monsters geanalyseerd uit de omgeving van Oudenhoorn en een bedrijf bij Vlaardingen , 2 km N.O. van het Lickebaertgebied.
Six laboratories in four European countries (GER, GB, S, NL) have conducted an interlaboratory co... more Six laboratories in four European countries (GER, GB, S, NL) have conducted an interlaboratory comparison study on the analysis of dioxins in cow's milk. The study comprised a cross comparison of standards and the analysis of the 2,3,7,8-substituted congeners of PCDD/Fs in three different milk pools (no spiking). Participants have used their own procedures and methods for fat and dioxin determination in biological samples, all using non-polar gas chromatography and medium to high resolution mass spectrometry (RP=3.000-10.000). Quantification was performed by the use of a common quantification standard mixture of the native PCDD/Fs (4 labs) or the own quantification standards (2 labs). Within-laboratory reproducibilities for the determination of the major toxic isomers and the total TCDD toxicity equivalence (TE) level were between 2 and 16% (relative standard deviation (RSD)) with a mean of 8%. The interlaboratory variabilty in TE values was less than 12% (RSD) for TE values bet...
British Journal of Cancer, 1997
Organohalogen …, 1995
ABSTRACT Results are presented of a survey on levels of organochlorine pesticides (OCRs), polychl... more ABSTRACT Results are presented of a survey on levels of organochlorine pesticides (OCRs), polychlorinated biphenyls (PCBs), dibenzodioxins (PCDDs) and dibenzofurans (PCDFs) in Individual human milk samples from the Netherlands collected in June 1993. Observed data indicate that since 1972 levels of OCRs (except for p,p'-DDE) are declining to levels around the limits of determination (0.01-0.03 mg/kg of fat). A decline (of approximately 30%) is also observed for the PCDDs and PCDFs in the period 1988-1993. However, no significant decrease could be found for tlie predominant PCB congeners with lUPAC nos. 118,138,153 and 180 in the period 1983-1993.
EFSA Journal, 2016
The EFSA 2nd Scientific Conference ‘Shaping the Future of Food Safety, Together’ gathered an inte... more The EFSA 2nd Scientific Conference ‘Shaping the Future of Food Safety, Together’ gathered an international audience composed of scientists, risk assessors, risk managers, as well as non-governmental organisations and industry representatives. This article summarises the final plenary session where a panel was asked to draw out overall impressions and conclusions for the EFSA to take away for its strategic planning into the future. The main conclusions of the conference are presented under five major themes. With new methodologies, technologies, big data and the increased societal demand for enhanced engagement in the risk assessment process, there is a clear need to maintain levels of expertise from traditional areas and to consider the inclusion of new areas and sources of expertise to perform scientific assessments. Academia, industry, research and regulatory science should work together to achieve this goal. As science progresses at pace, the continued development of assessment methodologies to deal with increasingly complex assessment questions is necessary, as is the need for applied research to underpin the support to policy development that EFSA provides. Greater collaboration is needed to reach agreement on best methods and practices for scientific assessment not just internationally, but also, equally importantly, across legislative areas and scientific disciplines, and in consultation with society at large. The communication of complex science, including important concepts such as uncertainty and risk perception, is not a trivial task, and must be integrated into the scientific process. As such, the relationship between risk assessment and risk management must continue to mature, remaining close, yet independent.
EFSA Journal
... Barlow, Sue. Schlatter, Josef. Öberg, Tomas (Linnaeus University, Faculty of Science and Engi... more ... Barlow, Sue. Schlatter, Josef. Öberg, Tomas (Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences). ... Publication type: Article in journal (Refereed). Language: English. Place of publ.: Parma, Italy Publisher: European Food Safety Authority. Status: ...
Food Additives and Contaminants, 2000
J Chromatogr a, 1992
A comparison is made of supercritical fluid extraction (SFE) with two other techniques widely use... more A comparison is made of supercritical fluid extraction (SFE) with two other techniques widely used for the extraction of polychlorinated biphenyls (PCBs) and organochlorine pesticides in soil. Extraction conditions for the SFE of PCBs and pesticides were first determined. An experimental approach was set up to determine the influence of different extraction parameters such as pressure, extraction time, static and dynamic extraction, restrictor type and collection solvent for off-line SFE. The use of carbon dioxide at 50 degrees C and 20 MPa, 10 min static followed by 20 min dynamic extraction with collection in iso-octane were been found to be the optimum conditions. Two types of soil, with a low and high content of organic carbon, respectively, spiked with 16 PCBs and organochlorine pesticides with a wide range of volatility and polarity at a level of 5 ng/g dry matter, were used as test materials. Conventional solvent extraction gives a good extraction yield for soil with a low content of organic carbon, but for peat soil the recoveries decrease dramatically to 30% for DDE, DDT and PCB 138 and 153. The recoveries with Soxhlet extraction are good, but an extra clean-up step before analysis is necessary. SFE gives good extraction yields for PCBs and organochlorine pesticides, varying between 85 and 105% with a reproducibility of 5% for each component for both types of soil. SFE is a fast, clean and reproducible method for the extraction of PCBs and organochlorine pesticides from these two soil matrices.
... 2,3,7,8-TCDD-equivalenten (I-TEQ) in Nederlandse paling, uitgedrukt per gram vet 15 5 ... bed... more ... 2,3,7,8-TCDD-equivalenten (I-TEQ) in Nederlandse paling, uitgedrukt per gram vet 15 5 ... bedrijven), verbranding van chemisch afval, gebruik vanbestrijdingsmiddelen (waaronder houtverduurzamingsmiddelen), industríele processen (metaalindustrie), branden van houtkachels ...
In melk van het Lickebaertgebied zijn PCDD's en PCDF's aangetoond op een gemiddeld niveau... more In melk van het Lickebaertgebied zijn PCDD's en PCDF's aangetoond op een gemiddeld niveau van 8,6 pg TEQ/g melkvet (n=11). Het landelijk achtergrondniveau hiervan is vastgesteld op een niveau van 0,8-2,5 TEQ/g melkvet aan de hand van melkmonsters afkomstig uit 5 over het land verspreide gebieden. De bijdrage van stedelijke achtergrond aan het TEQ-gehalte in melk wordt gering geacht. Bij een normale consumptie van melk en kaas, afkomstig van koeien uit het Lickebaertgebied wordt de toegestande dagelijkse dosis van 4 pg TEQ per kg lichaamsgewicht overschreden. Hoewel de overschrijding niet tot acute gezondheidseffecten leidt, kunnen bij voortdurende consumptie op de lange termijn gezondheidseffecten niet worden uitgesloten.
In order to evaluate the quality of data resulting from analyses of polychlorinated dibenzo-p-dio... more In order to evaluate the quality of data resulting from analyses of polychlorinated dibenzo-p-dioxins and dibenzofurans in soil, two Dutch laboratories have participated in a RIVM-coordinated interlaboratory comparison study, i.e. the Laboratory of Environmental and Toxicological Chemistry of the University of Amsterdam (UVA) and TAUW Infra Consult B.V. Subsamples of a sandy soil have been fortified with standards of 2,3,7,8-chlorine substituted PCDDs and PCDFs at three different levels (20-8600 ng/kg of soil). Each participant has determined the levels of the seventeen toxic congeners of PCDDs and PCDFs using the own methodology and reference standards. The subsamples have also been analysed by the RIVM. The accuracy and repeatability of the analysis has been examined by using the reported data from the complete analysis of three separate subsamples. Reported levels were generally higher than the actual levels of fortification. This was partly caused by background concentrations in...
Thirty-two grassland sites, distributed over the Netherlands, were sampled to determine 'back... more Thirty-two grassland sites, distributed over the Netherlands, were sampled to determine 'background" concentrations of dioxins. The sites were chosen on the basis of calculations using a model for a large-scale distribution and deposition of dioxins from especially waste incinerators. Sampling procedure, sample processing and physico chemical analyses are described. Special attention is given to the analytical procedure, the recoveries and the repeatability. 'Background' concentrations from 1.8 to 16.4 ng I-TEQ kg-1 were determined for the layer 0-5 cm below surface level. These concentrations reflect the concentrations to be expected as 'background' concentrations in Dutch soils. It appeared appropriate to predict the concentrations in the soil from the deposition data, not only for 'background' sites but also for sites in the vicinity of waste incinerators. From the viewpoint of policy-making further research was not recommended. Additional studies...
This report describes the results of analyses of dioxin levels in soil of five pastures in the vi... more This report describes the results of analyses of dioxin levels in soil of five pastures in the vicinity of the municipal waste incinerator of Zaandam. Isomer specific analysis of dioxins were conducted by high resolution gas chromatography-mass spectrometry using a polar chromatographic capillary column. Dioxin levels are expressed in toxic equivalence per kg of dry soil, per kg of organic carbon as well as per unit of volume of soil using the international toxicity equivalence factors (ITEF) of individual congeners. Samples consisted of blends of frequent samplings of five pastures in the layer at 0-2 cm and 2-10 cm, respectively and of two pastures also in the layer at 10-50 cm below the surface. Dioxin levels in the layer of 10 - 50 cm were 2 and 5 ng/kg dry soil, respectively. Levels in the layer of 2-10 cm were between 12 and 48 ng TEQ/kg dry soil and in the surface layer of 0-2 cm between 13 and 252 ng TEQ/kg dry soil. The lower surface values (13, 60 and 82 ng TEQ/kg dry soil...
Koemelk uit de omgeving van negen afvalverbrandingsinstallaties in Nederland is onderzocht op de ... more Koemelk uit de omgeving van negen afvalverbrandingsinstallaties in Nederland is onderzocht op de aanwezigheid van dioxinen en furanen. de gehalten voor Dordrecht, 's Gravenhage, Leeuwarden, Roosendaal en Rotterdam (Roteb) lagen binnen het landelijke achtergrondniveau van 0,8-2,5 pg TEQ/g melkvet. In koemelk uit de omgeving van de AVI te Leiden (2,4 +/- 0,1 tot 4,2 +/- 0,2 pg TEQ/g melkvet), Alkmaar (1,6 +/- 0,1 tot 5,1 +/- 0,3 pg TEQ/g melkvet) werden licht verhoogde waarden gevonden. De mengmonsters uit de omgeving van de AVI's te Duiven (4,4 +/- 0,2 pg TEQ/g melkvet) en Zaandam (5,4 +/- 0,3 pg TEQ/g melkvet) bevatten verhoogde gehalten aan dioxinen. Tevens werden individuele monsters geanalyseerd uit de omgeving van Oudenhoorn en een bedrijf bij Vlaardingen , 2 km N.O. van het Lickebaertgebied.
Six laboratories in four European countries (GER, GB, S, NL) have conducted an interlaboratory co... more Six laboratories in four European countries (GER, GB, S, NL) have conducted an interlaboratory comparison study on the analysis of dioxins in cow's milk. The study comprised a cross comparison of standards and the analysis of the 2,3,7,8-substituted congeners of PCDD/Fs in three different milk pools (no spiking). Participants have used their own procedures and methods for fat and dioxin determination in biological samples, all using non-polar gas chromatography and medium to high resolution mass spectrometry (RP=3.000-10.000). Quantification was performed by the use of a common quantification standard mixture of the native PCDD/Fs (4 labs) or the own quantification standards (2 labs). Within-laboratory reproducibilities for the determination of the major toxic isomers and the total TCDD toxicity equivalence (TE) level were between 2 and 16% (relative standard deviation (RSD)) with a mean of 8%. The interlaboratory variabilty in TE values was less than 12% (RSD) for TE values bet...
British Journal of Cancer, 1997
Organohalogen …, 1995
ABSTRACT Results are presented of a survey on levels of organochlorine pesticides (OCRs), polychl... more ABSTRACT Results are presented of a survey on levels of organochlorine pesticides (OCRs), polychlorinated biphenyls (PCBs), dibenzodioxins (PCDDs) and dibenzofurans (PCDFs) in Individual human milk samples from the Netherlands collected in June 1993. Observed data indicate that since 1972 levels of OCRs (except for p,p'-DDE) are declining to levels around the limits of determination (0.01-0.03 mg/kg of fat). A decline (of approximately 30%) is also observed for the PCDDs and PCDFs in the period 1988-1993. However, no significant decrease could be found for tlie predominant PCB congeners with lUPAC nos. 118,138,153 and 180 in the period 1983-1993.