• Ice sheet mass balance in central West Greenland

      Greuell W; Denby B; NOP (Institute for Marine and Atmospheric ResearchUtrecht University, 2001-05-21)
      Volume changes of the Greenland ice sheet in response to climate change may form a significant contribution to variations in sea level. However, still the sign of the present volume change is unknown. The aim of this project was to increase our understanding of present state of the Greenland ice sheet and of its sensitivity to climate change, with emphasis on the Kangerlussuaq transect (West Greenland, 67 uN). We have performed mass-balance, meteorological and ice-velocity measurements along the transect. With a record length of 10 years, the mass-balance measurements constitute the longest series of this kind on the Greenland ice sheet. A crucial parameter for the determination of the amount of melt is the albedo (this is the fraction of the solar radiation reflected by the surface). Therefore, we have improved the retrieval methods used to estimate the surface albedo from satellite data. For that purpose we have, among others, measured the albedo from a helicopter. The resulting data were used for validation of the satellite-derived albedos. With the satellite-derived albedos and the mass-balance data we have developed a method for estimating the surface mass balance of the Greenland ice sheet from satellite data. Furthermore, we have developed an atmospheric boundary-layer model, specifically designed for glaciers and ice sheets. The model was used to study the relation between the climate of the free atmosphere and conditions near the surface of the ice sheet, which determine the amount of melt.
    • De ICRU dosisequivalent grootheden in de stralingshygiene

      Grimbergen TWM (1990-09-30)
      The definitions and application of the new ICRU radiation protection quantities have been reviewed and studied in literature. Special emphasis was laid on the consequences of the use of the new quantities by personnel dosimetry services, and on the consequences of the use of the new quantities during an intercomparison programme for dosimetry services. The study shows that the recommendations of the ICRU are not yet complete and not fully realizable. This means that the dosimetry services always have to make certain approximations, when they use the new quantities. In literature, several approaches have been proposed. The feasibility of an approach depends on the characteristics of the dosimeters used. The use of different approaches by the dosimetry services is thought to be of possible influence on the results of an intercomparison programme.
    • Identificatie en kwantificering van Escherichia coli door bepaling van de beta-glucuronidase-activiteit

      Schets FM; Havelaar AH (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1990-09-30)
      The determination of E.coli as a fecal indicator for surface- and drinking water according to NEN 6261 is based on the ability of E.coli to produce indole from tryptophane. E.coli is also able to use the constitutive enzyme beta-glucuronidase to produce the fluorescent methylum-belliferyl from the substrate 4-methylumbelliferyl-beta-D- glucuronide (MUG). This report describes research on the possibility to use the beta-glucuronidase-activity as an identification- characteristic for E.coli. 14% of the isolated E.coli strains was found to be beta-glucuronidase-negative at 44 degr. C. 24% of these strains showed a positive beta-glucuronidase-reaction at 37 degr. C. Two percent of the isolated E.coli strains was indole-negative and four percent of strains other than E.coli gave false positive reactions in this test. There were no false-positive beta-glucuronidase reactions. It is concluded that the indole-reaction gives better results than the beta-glucuronidase-reaction. The interpretation of the beta- glucuronidase- reaction is more difficult and it gives more false- negative results.<br>
    • Identificatie van belangrijke beroepsgroepen en stoffen bij het ontstaan van gezondheidseffecten en ziektelast door blootstelling aan stoffen onder arbeidsomstandigheden

      Dekkers S; Preller EA; Baars AJ; Marquart J; Raaij MTM van; SIR (TNO Kwaliteit van Leven, 2006-12-18)
      In a previous RIVM report the burden of disease due to exposure to chemicals at the workplace was estimated for nine investigated diseases. This follow-up study further investigates the determinants occupation and chemicals. For the diseases asthma, COPD, contact dermatitis and lung cancer (excluding lung cancer caused by asbestos) the most important occupations in which the diseases occurs relatively often are determined first. Then the most relevant chemicals associated with each of these diseases are identified. Finally, the occupation and chemical combinations that are actually present in meaningful magnitude in the Netherlands are selected. In spite of many uncertainties in the selection of important occupational-substance combinations, it is nevertheless predicted from which occupational-substance combinations it can probably be expected that a reduction in occupational exposure may lead to substantial health profit for each of investigated diseases. For asthma, the following occupational-substance combinations are probably important: flour dust at bakers, isocyanates in the construction industry, latex in health care, and animal allergens in agriculture. For COPD, inorganic dust in the construction industry, flour dust at bakers and workers in food production, and organic dust in the agriculture are relevant. Wet work, grease removers, soaps and detergents in several professions in the health care, cleaners, hairdressers and beauty specialists play an important role in the development of occupational contact dermatitis. For lung cancer, quartz dust in construction work and passive smoking in the hotel- and catering industry are likely to be relevant. However, this does not mean that there is no risk to develop the diseases due to occupational exposures within occupations and branches which are not mentioned in this inventory. But the occupational-substance combinations mentioned above do give an indication of the most important combinations within the entire businesses activities of the Netherlands.
    • Identificatie van belangrijke beroepsgroepen en stoffen bij het ontstaan van gezondheidseffecten en ziektelast door blootstelling aan stoffen onder arbeidsomstandigheden

      Dekkers S; Preller EA; Baars AJ; Marquart J; Raaij MTM van; TNO Kwaliteit van Leven; SIR (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 2006-12-18)
      De ziektelast als gevolg van astma, chronische bronchitis en longemfyseem (COPD), contact-eczeem en longkanker zal naar verwachting afnemen, wanneer arbeidsgerelateerde blootstelling aan een aantal stoffen (chemicalien) binnen bepaalde beroepsgroepen wordt teruggedrongen. In een eerder RIVM-rapport werd voor negen aandoeningen de ziektelast als gevolg van blootstelling aan stoffen op de werkplek geschat. In dit vervolgonderzoek is voor de vier genoemde aandoeningen onderzocht bij welke combinaties van beroepsgroep en stof een relevante gezondheidswinst zou kunnen worden bereikt bij vermindering van de blootstelling. Relevante gezondheidswinst lijkt met name te behalen in de volgende combinaties van beroepsgroep en stof: - meelstof bij bakkers, isocyanaten in de bouwnijverheid, latex in de gezondheidszorg, en dierlijke allergenen in de landbouw voor astma; - anorganisch stof in de bouwnijverheid, meelstof bij bakkers en werkers in de voedselproductie, en organisch stof in de landbouw voor COPD; - nat werk, ontvetters, zepen, en detergentia bij diverse beroepen in de gezondheidszorg, schoonmakers, kappers en schoonheidsspecialisten voor contact-eczeem; en - kwartsstof in de bouw en passief roken in de horeca voor longkanker (uitgezonderd asbest als oorzaak van longkanker). De bovengenoemde opsomming geeft een indicatie van de belangrijkste combinaties van beroepsgroepen en stoffen in het Nederlandse bedrijfsleven. Echter, ook in andere beroepsgroepen en branches kunnen werknemers genoemde aandoeningen ontwikkelen door blootstelling aan bepaalde stoffen op de werkplek.
    • Identificatie van chloorpyreenisomeren met vloeistof chromatografie-Fourier Transform infrarood spectrometrie

      Visser T; Stee LPP van; Somsen GW (1993-12-31)
      Liquid chromatography coupled with Fourier transform infrared specrometry (FT-IR) was applied to the analysis of impurities in a sample of synthesized 1-choropyrene. The method was used to identify compounds with closely related structures in addition to gas chromatography-mass spectrometry. All previously detected components were separated and the corresponding FT-IR spectra were recorded. The presence of pyrene and 1-chloropyrene was confirmed by comparison with reference spectra. 1,3,6-trichloropyrene and the isomers 1,3-, 1,6- and 1,8-dichloropyrene were identified by interpretation of the spectra.
    • Identificatie van polycyclische aromatische koolwaterstoffen met behulp van gaschromatografie-Fourier transform infraroodspectrometrie

      Vredenbregt MJ; Londo M; Visser T; Jong APJM de (1993-05-31)
      A study has been carried out on the applicability of cryotrapping gas chromatography-Fourier Transform infrared spectrometry (GC-FTIR) for the identification and isomer discrimination of polycyclic aromatic hydrocarbons (PAHs). Method development has been performed by means of a standard mixture of 24 PAHs of the series from naphthalene to benzo(ghi)perylene. All compounds including structural isomers have been identified on the basis of spectral differences. Detection limits were established as 250-500 picogram per microliter injected on-column. The applicability of the method has been tested on the analysis of sediment, soil and river clay extracts, which had been analysed previously by means of HPLC with fluorescence detection. The presence of the majority of the PAHs was unequivocally confirmed while previously undetermined PAHs could be identified. Moreover essential additional information was obtained on the identity of two coeluting structural isomers. As such cryotrapping GC-FTIR forms an important additional tool in the analysis of PAHs by means of GC-FID, GC-MSD and HPLC with fluorescense detection. Cryotrapping spectra of PAH appear to be quite similar to conventionally recorded spectra. Absorption frequencies are found within the data point resolution although minor intensity differences may occur. For that reason existing interpretation and library search systems remain useful for structural elucidation.
    • Identification and Characterization of Proteins based on Mass Spectrometric Mapping of Tryptic Peptides and On-line Internet Database Searches

      Meiring HD; ten Hove GJ; de Jong APJM; LOC (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1997-11-30)
      A method described for the identification and characterization of proteins isolated on primary one- or two-dimensional polyacrylamide gel electrophoresis has been adapted to recently developed concentration/desalinization techniques (electrotransferation of proteins to a secondary gel and reversed-phase micro-capillary column switching trapping system), and mass spectrometric techniques like nano-electrospray ionization in combination with quadrupole ion-trap mass spectrometry. Model studies were performed with Bovine Serum Albumin. It was found using this method that concentration factors of at least 50-fold can be easily obtained by electro-transfering the isolated proteins on a secondary gel. Low femtomole amounts can be sequenced when spots from multiple primary gels are combined on a single secondary gel. On-line Internet database searches are used to identify the protein by using (partial) sequence information obtained from MS(n) experiments of the peptides after tryptic proteolysis. Different aspects of the applicability of the method, like sample matrices and chemical modifications of the tryptic peptides to the MS analysis, were also considered.<br>
    • Identification and handling of uncertainties in dietary exposure assessment

      Ooijen HJ van; van der Voet H; Bakker MI; SIR (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 2009-10-15)
      The RIVM and the RIKILT-Institute of Food Safety estimate the intake of chemical substances via food at the population level. The method presently used for dietary exposure assessments should be adapted to allow more insight into the extent of the uncertainties in such exposure estimates. The quantification of uncertainties is in line with international scientific endeavors that are currently being carried out in the field of uncertainty analysis of exposure assessment. In addition to the quantification of uncertainties, it is important to consider the expected impact of the (remaining) non-quantified uncertainties on the dietary exposure estimate. These are the conclusions drawn by the RIVM and Wageningen University and Research Centre (WUR) based on a study carried out by these institutes by order of the Dutch Food and Consumer Product Safety Authority (VWA). This report contains a proposal for adapting the current software program (Monte Carlo Risk Assessment) as well as two examples that illustrate the use of the Guideline of the European Food Safety Authority for describing non-quantified uncertainties. An analysis of the uncertainties in an exposure assessment is necessary to enable a proper interpretation of the assessment results. Uncertainty analysis can also highlight those factors that are the major sources of uncertainty in the dietary exposure assessment. By decreasing (the impact of) the most important sources of uncertainties (e.g. by collecting additional data), (future) exposure assessments can be improved. The software program currently used by the RIVM and the RIKILT is able to perform a limited quantitative uncertainty analysis. This program could be expanded in a relatively simple manner by including the quantification of a number of other sources of uncertainty.
    • Identification of allergenic potency of Latex-chemicals in the auricular lymph node assay in the mouse

      de Jong WH; Tentij M; Legtenberg RJ; van de Vliet H; Vandebriel RJ; van Loveren H; LPI (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1997-10-31)
      In recent years the occurence of latex allergy has been increased due to the preventive use of latex gloves. The use was studied of the ALNA as a detector of allergenic properties of chemicals in latex gloves. In this so called auricular lymph node assay (ALNA) a test compound is administered epicutaneously at the dorsum of the ears for three consecutive days. Several days after administration, the draining (auricular) lymph node was removed and weight, cell number and lymphocyte proliferation were determined as parameters for activation. An increased value of these parameters indicates interaction with the immune system and hence immunogenic cq. allergenic potential. Generally an increase in activity as compared to vehicle treated control lymph nodes, expressed as stimulation index, with a factor of 3 or more is considered a positive reaction. Several chemicals used in the latex production process and known to induce Type IV allergy were tested, including tetramethylthiuramdisulfide (TMTD) , zincdimethyldithiocarbamate (ZDMC), 2-mercapto-benzothiazole (MBT) and diethylamine (DEA). For the evaluation of the ALNA, dinitrochlorobenzene (DNCB) and trimellitic anhydride (TMA) were used as model compounds. Latex allergy is not only caused by chemicals but also by proteins. In pilot experiments with ovalbumin as a model protein, it was investigated whether the ALNA assay can be used for the detection of allergenic properties of proteins. The results show that, using the ALNA, sensitizing activity of TMA and DNCB and also of the rubber additives TMTD, ZDMC, MBT and DEA can be identified. Preliminary data indicate that it might be possible to use the ALNA to identify sensitizing activity of proteins and glove extracts. However, these results need further confirmation.<br>
    • Identification of Beta-agonists in animal samples by means of cryotrapping gas chromatography-fourier transform infrared spectrometry

      Visser T; Vredenbregt MJ; Jong APJM de; Ginkel LA van; Rossum HJ van; Stephany RW (1993-01-31)
      The usefulness of cryotrapping gas chromatography-Fourier transform infrared spectrometry (GC-FTIR) for the residue analysis of the beta-agonists clenbuterol, mabuterol and salbutamol in bovine urine and tissues has been evaluated. It is demonstrated that the technique is able to detect and identify the trimethylsilyl derivatives of these compounds in urine and liver extracts of veal calves and cattle. The obtained limit of identification is approximately 1 nanogram per microliter extract injected on column which is equivalent to 2.5 microgram per liter or kilogram of the original sample. It is anticipated that the technique may develop as a valuable method for univocal confirmation of the presence of residues, particularly in addition to gas chromatography-mass spectrometry (GC-MS).
    • Identification of Endocrine Disruptive Effects in the Aquatic Environment - a Partial Life Cycle Study in Zebrafish

      Wester PW; Brandhof EJ van den; Vos JH; Ven LTM van der; TOX; LER (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 2003-12-12)
      In dit project is een testmodel ontworpen en toegepast voor de identificatie van hormoonactieve stoffen in het aquatisch milieu. In het laboratorium zijn zebravissen gedurende de reproductie en ontwikkelingsfase blootgesteld aan een reeks bekende hormoonactieve stoffen, te weten een oestrogeen (17 beta-oestradiol) , een anti-oestrogen (tamoxifen), androgeen (methyldihydro-testosteron), anti-androgeen (flutamide), een schildklierremmer (propylthiouracil); tenslotte is een veldmonster getest in het kader van het landelijk onderzoek oestrogene stoffen (LOES). Onderzocht zijn parameters voor eiproductie, vruchtbaarheid en ontwikkeling van het eieren en nageslacht. Daarnaast is het plasmaeiwit vitellogenine bepaald, dat een maat is oestrogene activiteit. Hiervoor zijn (immuno)histochemische bepalingsmethoden ontwikkeld als alternatief voor de klassieke ELISA. Voorts zijn dieren histopathologisch onderzocht op afwijkingen in (ontwikkeling van) geslachtsorganen en endocriene organen. Uit de resultaten blijkt dat met het testsysteem binnen een betrekkelijk korte blootstellingsperiode (9 weken) inzicht verkregen kan worden in effecten van hormoonverstoring op het niveau van reproductie en ontwikkeling, waarbij met name het histopathologisch onderzoek een cruciale rol speelt, zowel betreffende gevoeligheid als specificiteit voor alle geteste referentiestoffen. Verstoring in de geslachtsverhouding blijkt het meest gevoelige voor de voortplanting relevante effect te zijn. De histopathologische bevindingen staan in de vorm van een educatieve atlas op Internet (http://www.rivm.nl/fishtoxpat/).
    • Identification of Endocrine Disruptive Effects in the Aquatic Environment - a Partial Life Cycle Study in Zebrafish

      Wester PW; van den Brandhof EJ; Vos JH; van der Ven LTM; TOX; LER (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 2003-12-12)
      In this project, an assay was developed and applied to identify hormone active substances in the aquatic environment. Laboratory fish were exposed during the reproductive and development phase to a range of established endocrine active compounds; these were estrogen (17 beta-estradiol), anti-estrogen (tamoxifen), androgen (methyldihydrotestosterone), anti-androgen (flutamide), and an antithyroid compound (propylthiouracil); also a field sample from a national field study (LOES) was tested. Parameters were fecundity, fertility, development, plasma vitellogenin, and histopathology with emphasis on gonads; for vitellogenin, (immuno)histochemistry detection methods were developed, as an alternative for the common ELISA methods. This approach enables the identification of a variety of endocrine effects within a relatively short period (9wk); histopathology is the most specific and sensitive parameter for the reference compounds used. Changes in sex ratio of offspring appears the most sensitive endpoint with relevance for reproduction fitness. The educational histopathology database from this project is available on the Internet (http://www.rivm.nl/fishtoxpat/).<br>
    • Identification of MHC class I associated peptides. Development of sensitive mass spectrometric sequence analysis techniques

      de Jong APJM; van der Heeft E; ten Hove GJ; van Gaans-van den Brink JAM; van Els CACM; LOC; LVM (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1996-03-31)
      The development of methods and techniques for the sensitive analysis of MHC class I associated peptides has been described. Analysis concerns the identification and sequence determination of specific T-cel stimulating antigenic peptides in complex mixtures derived from cell cultures. Such mixtures comprise a few hundreds to thousand different class I peptides present at femtomol (10 exp. -15) to picomol (10 exp. -12) level per billion cells. Liquid chromatography-electrospray ionisation mass spectrometry has emerged as the most appropriate technique for such analysis. For this purpose, a micro-column switching technique has been developed; conditions were optimised directed to large volume sample introduction, concentration and separation for their sensitive analysis at suitable ESI conditions. The sensitivity of the method for molecular weight determination (identification) range between 10 and 50 fmol for individual peptides. Sequence analysis required a ten-fold higher amount of peptide, but is sufficiently low for application to amounts that can be made available from medium size cell cultures of typically 10 exp. 10 cells.<br>
    • Identification of polycyclic aromatic hydrocarbons in combustion effluents by gas chromatography-infrared spectrometry

      Visser T; Sarobe M; Jenneskens LW; Wesseling J (1996-11-30)
      A pilot study has been carried out on the potentials of gas chromatography (GC) with infrared (IR) spectrometric detection for the structure elucidation of polycyclic aromatic hydrocarbons (PAHs), ethynyl-substituted PAH's and cyclopenta-fused PAHs (CP-PAHs). Experiments have been carried out on standard compounds and on products generated by in situ pyrolysis (T 600-1100oC) of ethynyl-substituted PAHs as models for mimicking combustion processes. The results have been compared with the data obtained by GC with mass spectrometry (GC-MS), the current method for the analysis of PAHs in complex combustion effluents. GC-IR proves to be a valuable and complementary addition to GC-MS. Conclusions from GC-MS have been confirmed and, additionally, the molecular structures of previously unidentified constituents have been elucidated. The combination of GC-IR and GC-MS is a prerequisite for unequivocal structural elucidation of isomeric PAHs.
    • Identification of specific intrinsic liver clearance from a precision-cut liver-slice experiment

      Eijkeren JCH van; LBM (2000-06-20)
      A model describing metabolism experiments with precision-cut liver-slices incubated in a culture medium is developed. Formal mathematical techniques are presented that solve the problem of identifying the specific intrinsic liver clearance from the experimental data. The formal solution is discussed from the perspective of experimental practice. A necessary condition for identification is sampling parent compound in slice or culture medium. However, sampling parent compound in slice and additionally metabolite pooled from medium and slice is required by experimental limitations. Moreover it appears that identification is unreliable when the value of the slice's intrinsic clearance exceeds the diffusion rate of transport of the parent compound from the culture medium to the slice, a condition to be verified only afterwards.
    • Identification of specific intrinsic liver clearance from a precision-cut liver-slice experiment

      Eijkeren JCH van; LBM (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 2000-06-20)
      Er wordt een model ontwikkeld dat metabolisme experimenten met liver-slices beschrijft die geincubeerd worden in een kweekmedium. Er worden formele wiskundige technieken geintroduceerd die het probleem van de identificatie van de specifieke intrinsieke leverklaring oplossen. Deze formele oplossing wordt bediscussieerd vanuit het oogpunt van de experimentele praktijk. Een nodige voorwaarde voor identificatie is de bemonstering van de moederstof in de slice of het kweekmedium. Maar door de experimentele limitaties is het vereist de moederstof in de slice te bemonsteren en daarnaast ook de metabolieten samengevoegd uit slice en kweekmedium. Bovendien blijkt dat de gevonden waarde voor de klaring onbetrouwbaar is als deze groter is dan de diffusiesnelheid van transport van moederstof van kweekmedium naar slice.
    • Identification of the gestagenic steroid Algestone acetophenide in slaughter cattle. A possible misuse for illegal growth promoting purposes

      van Ginkel LA; Stephany RW; Sterk SS; van Rossum HJ; Schwillens PLWJ; Evers EAJM; Visser T; de Jong APJM; Jacquemijns M; Zomer G; ARO; LOC; BFT (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1993-12-31)
      The identity was elucidated of a compound detected in an application site and not identical to any compound known to be used as an anabolic agent or veterinary drug. The compound was identified as Algestone acetophenide (dihydroxyprogesterone acetophenide (DHPA)). For complete identification information obtained with a number of molecular spectroscopic techniques was combined. The identity was confirmed by comparing the spectroscopic data obtained with those of the reference compound. For meat inspection purposes diagnostic ions for the compound as HFB-derivative were established. Within the Netherlands the standard was made available to the appropriate government laboratories for regulatory purposes. The extent of the use of DHPA remains to be established.<br>
    • Identifying potential POP and PBT substances : Development of a new Persistence/Bioaccumulation-score

      Rorije E; Verbruggen EMJ; Hollander A; Traas TP; Janssen MPM; SEC ; LER; mev (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 2011-04-01)
      RIVM has screened the potential for long-term fate in the environment of a large number of substances. For this purpose a new methodology has been developed which indicates whether substances will persist in the environment and/or bioaccumulate in biological organisms. The results are a first step towards selection of substances which have inherent chemical properties that potentially make them a long-term hazard for the environment. Further research into the actual persistence and bioaccumulation of these substances in the environment will be needed. This information is necessary for proposing selected substances under REACH as Persistent, Bioaccumulative and Toxic substances (PBTs) or very Persistent and very Bioaccumulative substances (vPvBs), or when they are proposed within the Stockholm Convention as Persistent Organic Pollutants (POPs). Once identified as PBT, vPvB or POP, further risk management measures or even a ban on production and use of such chemicals may follow. REACH (Registration, Evaluation and Authorization of Chemicals) is the European chemical substances regulation, in force since June 2007, which aims to evaluate and minimize all risks of chemicals produced and/or used in the European Union. The international Convention of Stockholm, in force since May 2004, aims to minimize or eliminate the presence of POPs in the world. In many cases, the harmful potential of substances that were later identified as POPs and PBTs only became apparent after scientists were alarmed by monitoring results looking for these substances in the environment. Nowadays, most new substances are screened on potential long term hazard to the environment before they are introduced to the market. However, for a large number of existing substances on the (European) market their potential hazard has never been evaluated, since such an evaluation was not required in the past, or because their market volumes were so small. The Persistence/Bioaccumulation score presented in this report can be used as a tool to quickly screen data-poor substances for their potential environmental persistence and bioaccumulation in the food chain.
    • Identifying prevalent carcinogens at the workplace in Europe

      Puts C; ter Burg W; NAT; M&V (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 2015-06-02)
      The RIVM compiled a shortlist of substances, mixtures and processes identifying carcinogens with the most occupational exposure across Europe. The list also includes processes such as welding, painting and processing mineral oils. Those substances, mixtures and processes ranking highest can be selected at a European level for risk reduction by setting binding occupational exposure limit values. The highest ranking substances, mixtures and processes are, among others, benzene, formaldehyde, engine exhaust, and wood dust. These belong to the top 30 of 175 ranked substances, mixtures and processes for which information was available. These substances, mixtures and processes are considered the most prevalent carcinogens at the workplace based on the available data, contributing most to exposure. The report focuses specifically on non-threshold carcinogens. Nonthreshold carcinogens are without a safe level of use. European worker legislation prescribes that those substances should be substituted wherever possible. If this is not possible, employers must ensure that exposure is as low as reasonable achievable. At this moment, the approaches to derive occupational limit values for carcinogens differ among Member States. The Dutch Ministry of Social Affairs and Employment requested the RIVM to compile the shortlist aiming to increase worker safety. Data from six European databases were used, containing information on the number of workers exposed and other indicators. These range from specific worker tasks such as mixing of fluids to uses in chemical industries.