Frank de Vocht

Publications of Frank de Vocht

• The human factor: Re-organisations in public health policy.

  Authors: Kathryn Oliver, Martin Everett, Arpana Verma, Frank de Vocht

  Health policy (Amsterdam, Netherlands). 04/2012;

  INTRODUCTION: Public health policy-making activities are currently split between local authority and NHS organisations. Despite an increasing body of research on evidence-based policy (EBP), fewINTRODUCTION: Public health policy-making activities are currently split between local authority and NHS organisations. Despite an increasing body of research on evidence-based policy (EBP), few studies explore the process of policy-making. Little is known about how policies are made in a local context, or how (scientific) evidence is used. Previous research has ignored the 'human element' in EBP. Social network analysis (SNA) techniques are becoming increasingly important in health policy. This paper describes an innovative study giving a fresh perspective on policy-making processes in public health. METHODS: A social network analysis of public health policy making networks in Greater Manchester based on publicly available data (documents, websites and meeting papers) and an electronic survey, asking actors to nominate those who influenced their own views, those who were powerful, and those who were a source of evidence or information. RESULTS AND CONCLUSIONS: Policy-making networks are described. Formal executive roles are loosely related to perceived influence and power. Evidence-seeking networks are less coherent, with key organisations not represented. These data indicate the importance of collaboration and good relationships between researchers and policy-makers, but few academic researchers with a direct impact on health policy were identified within the networks.

• Comment on: Effects of static magnetic fields on cognition, vital signs, and sensory perception: a meta-analysis.

  Authors: Frank de Vocht, Tobias Stevens, Hans Kromhout

  Journal of magnetic resonance imaging : JMRI. 01/2012; 35(1):235-6; author reply 237.

• Cell phones and parotid cancer trends in England.

  Authors: Frank de Vocht

  Epidemiology (Cambridge, Mass.). 07/2011; 22(4):608-9.

• Authors' reply to Kundi's comments on de Vocht et al. "time trends (1998-2007) in brain cancer incidence rates in relation to mobile phone use in England"

  Authors: Frank de Vocht, Igor Burstyn, John W Cherrie

  Bioelectromagnetics. 05/2011;

• Assessment of dermal exposure to bitumen condensate among road paving and mastic crews with an observational method.

  Authors: Michela Agostini, Wouter Fransman, Frank De Vocht, Berna Van Wendel de Joode, Hans Kromhout

  The Annals of occupational hygiene. 05/2011; 55(6):578-90.

  To assess dermal exposure to bitumen condensate among road pavers and indoor mastic workers in multiple crews using a semi-quantitative observational method [DeRmal Exposure Assessment MethodTo assess dermal exposure to bitumen condensate among road pavers and indoor mastic workers in multiple crews using a semi-quantitative observational method [DeRmal Exposure Assessment Method (DREAM)]. Two skilled observers assessed dermal exposure to bitumen condensate among 85 asphalt workers from 12 crews from nine companies active within four European countries using the DREAM methodology, which produces an estimate of exposure expressed in dimensionless DREAM units. Both observers independently evaluated each crew member's job (N = 14 jobs) for road paving and mastic applications. Potential and actual dermal exposures were estimated for hands and for the rest of the body separately, taking into account the effect of protective clothing. To evaluate the reproducibility of the observational method intra-class correlation coefficients (ICCs) were estimated. The exposures in DREAM units were modelled using linear mixed models to estimate average relative scores for each job. Correlations between dermal exposure parameters were evaluated by estimating Pearson correlation coefficients. A total of 170 observations were completed by two observers independently (n = 118 and n = 52 for 59 road pavers and 26 mastic workers, respectively) in 11 days. The mean ICCs (for potential and actual exposure in DREAM units) varied between 0.74 and 0.80 with values for actual units being slightly higher. Geometric mean potential dermal exposure units of mastic workers were higher than for road pavers (factor 3 for hands and factor 4 for rest of the body). Differences for actual dermal exposure units were smaller for hands (factor 2) and larger for actual exposure units of rest of the body (factor 5). Differences in dermal exposure at the hands between jobs within a paving crew were much larger than between jobs within a mastic crew. Within paving crews, a consistent pattern for all exposure units emerged with 'screed man' and 'raker' as the two highest exposed jobs. Within mastic crews, 'driver dumper truck' and 'spreader of mastic' were scored as the two jobs with the highest exposure units. Potential and actual exposure units were highly correlated. Hands were more profoundly exposed than the rest of the body, with transfer from contaminated surface to the hands as the most important route. DREAM observations were reproducible and showed a consistent dermal exposure pattern among the observed crews. The study provided a clear picture of dermal exposure among road pavers and indoor mastic workers, with the mastic workers being considerably more highly exposed. The most important route of exposure appeared to be transferred from contaminated surfaces to the hands.

• Urinary DAP metabolite levels in Thai farmers and their families and exposure to pesticides from agricultural pesticide spraying.

  Authors: Chalalai Hanchenlaksh, Andrew Povey, Sarah O'Brien, Frank de Vocht

  Occupational and environmental medicine. 03/2011; 68(8):625-7.

  We conducted a biomarker study to characterise exposure to pesticides among farmers and their families in Thailand to assess the relative importance of the dermal exposure route and to identifyWe conducted a biomarker study to characterise exposure to pesticides among farmers and their families in Thailand to assess the relative importance of the dermal exposure route and to identify important factors that determine exposure levels within farmers' families. Sixteen farmers' families (eight vegetable and eight fruit farmers) participated in the study. Three morning spot urine samples were collected during a pesticide spraying week. Spot samples were grouped by individual and analysed for dialkylphosphate (DAP) metabolites and creatinine. Additional information on exposure and lifestyle was collected by means of questionnaires. Dermal exposure was assessed using a semi-quantitative observational method (DREAM). Urinary DAP levels varied 20-fold between farmers, with average (geometric mean) levels of 51.1 μg/g for vegetable and 122.2 μg/g for fruit farmers. A moderate correlation (r(s)∼0.45) was found between log(e)-transformed DREAM scores and DAP levels. Farmers' urinary metabolite levels were not correlated with those of their spouses (r(s)∼-0.30) or children (r(s)∼-0.00) collected on the same days. Detectable spouses' DAP levels were on average (geometric mean) 13.0 μg/g and those of children 7.6 μg/g. Farmers in Thailand as well as their families are exposed to pesticides in the spraying season and dermal exposure is an important route. The main route of exposure for farmers' families seems to be through transfer from the farmer to family members or contamination of the home environment, rather than family members helping or playing on the farm. Showering or washing immediately after pesticide spraying greatly reduces the potential exposure of family members to pesticide residues.

• The influence of seeking God in the association between religiosity and prolonged survival in liver transplant recipients.

  Authors: Frank de Vocht

  Liver transplantation : official publication of the American Association for the Study of Liver Diseases and the International Liver Transplantation Society. 02/2011; 17(2):215-6; author reply 217.

• Health Effects and Safety of Magnetic Resonance Imaging.

  Authors: Frank de Vocht, Jonna Wilén, Kjell Hansson Mild, Lotte E van Nierop, Pauline Slottje, Hans Kromhout

  Journal of medical systems. 01/2011;

• Time trends (1998-2007) in brain cancer incidence rates in relation to mobile phone use in England.

  Authors: Frank de Vocht, Igor Burstyn, John W Cherrie

  Bioelectromagnetics. 01/2011; 32(5):334-9.

  Mobile phone use in the United Kingdom and other countries has risen steeply since the early 1990's when the first digital mobile phones were introduced. There is an ongoing controversy about whetherMobile phone use in the United Kingdom and other countries has risen steeply since the early 1990's when the first digital mobile phones were introduced. There is an ongoing controversy about whether radio frequency (RF) exposure from mobile phones increases the risk of brain cancer. However, given the widespread use and nearly two decades elapsing since mobile phones were introduced, an association should have produced a noticeable increase in the incidence of brain cancer by now. Trends in rates of newly diagnosed brain cancer cases in England between 1998 and 2007 were examined. There were no time trends in overall incidence of brain cancers for either gender, or any specific age group. Systematic increases in rates for cancers of the temporal lobe in men (0.04 new cases/year) and women (0.02/year) were observed, along with decreases in the rates of cancers of the parietal lobe (-0.03/year), cerebrum (-0.02/year) and cerebellum (-0.01/year) in men only. The increased use of mobile phones between 1985 and 2003 has not led to a noticeable change in the incidence of brain cancer in England between 1998 and 2007. The observed increase in the rate of cancers in the temporal lobe, if caused by mobile phone use, would constitute <1 additional case per 100,000 people in that period. These data do not indicate a pressing need to implement a precautionary principle by means of population-wide interventions to reduce RF exposure from mobile phones.

• Incorporating uncertainty in aggregate burden of disease measures: an example of DALYs-averted by a smoking cessation campaign in the UK.

  Authors: Frank de Vocht, James Higgerson, Kathryn Oliver, Arpana Verma

  Journal of epidemiology and community health. 11/2010; 65(9):751-6.

  Summary measures of population health (SMPH) combine information about morbidity and mortality as a means of describing the health of a population and allow for the comparison between otherwiseSummary measures of population health (SMPH) combine information about morbidity and mortality as a means of describing the health of a population and allow for the comparison between otherwise incomparable health problems. Despite the widespread use of SMPHs in global public health policy, the uncertainty in their calculation, inherent due to the variable quality and availability of data from different sources required to calculate SMPHs, is generally ignored. Using the example of the expected effect of a smoking cessation mass-media campaign on ischaemic heart disease in the UK expressed in DALYs (disability adjusted life years)-averted, a transparent and straightforward probabilistic methodology to incorporate uncertainty in the calculation of population impact measures of health, to better inform the public health debate, is described. In addition, a rationale on how this additional information can be utilised to further improve the use of quantitative data for SMPH is presented, and public health policy makers are provided with additional tools for prioritisation of interventions and cost-effective prioritisation of data collection campaigns for the improvement of the calculation of future SMPH. Systematic use of these tools will provide a stronger evidence base for public health policy in the future and will further direct a drive towards the use of quantitative tools.

• Health complaints among nurses working near MRI scanners--a descriptive pilot study.

  Authors: Jonna Wilén, Frank de Vocht

  European journal of radiology. 10/2010; 80(2):510-3.

  A questionnaire-based descriptive pilot study was conducted among all nurses routinely working with MRI in the Northern part of Sweden to provide an indication of the self-reported prevalence ofA questionnaire-based descriptive pilot study was conducted among all nurses routinely working with MRI in the Northern part of Sweden to provide an indication of the self-reported prevalence of health complaints related to working with MRI systems. Fifty-nine nurses (88% response rate), with on average 8 (±6) years experience with MRI scanning procedures, returned the questionnaire. In total, 9 nurses (15%) reported regularly experiencing at least one of the health complaints (1-5% for specific health complaints) attributed to arise or be aggravated by their presence in the MRI scanning room. Stratification of the results indicated that reporting of adverse symptoms was not related to the level of occupational workload/stress. However, reporting of health complaints was related to the strength of the magnet(s) the nurses worked with, with 57% of symptoms reported by those nurses working with the strongest systems (both 1.5 and 3T scanners in this population). Although this descriptive study did not include a control population and was based on self-reporting of health complaints, these data indicate that the prevalence of reported health complaints is not related to perceived work load or occupational stress, but does confirm data from other occupational sectors and indicates that the prevalence of adverse health complaints increases with the strength of the MRI system for nurses as well.

• A case-control study of lung cancer nested in a cohort of European asphalt workers.

  Authors: Ann Olsson, Hans Kromhout, Michela Agostini, Johnni Hansen, Christina Funch Lassen, Christoffer Johansen, Kristina Kjaerheim, Sverre Langård, Isabelle Stücker, Wolfgang Ahrens, Thomas Behrens, Marja-Liisa Lindbohm, Pirjo Heikkilä, Dick Heederik, Lützen Portengen, Judith Shaham, Gilles Ferro, Frank de Vocht, Igor Burstyn, Paolo Boffetta

  Environmental health perspectives. 10/2010; 118(10):1418-24.

  We conducted a nested case-control study in a cohort of European asphalt workers in which an increase in lung cancer risk has been reported among workers exposed to airborne bitumen fume, althoughWe conducted a nested case-control study in a cohort of European asphalt workers in which an increase in lung cancer risk has been reported among workers exposed to airborne bitumen fume, although potential bias and confounding were not fully addressed. We investigated the contribution of exposure to bitumen, other occupational agents, and tobacco smoking to the risk of lung cancer among asphalt workers. Cases were cohort members in Denmark, Finland, France, Germany, the Netherlands, Norway, and Israel who had died of lung cancer between 1980 and the end of follow-up (2002-2005). Controls were individually matched in a 3:1 ratio to cases on year of birth and country. We derived exposure estimates for bitumen fume and condensate, organic vapor, and polycyclic aromatic hydrocarbons, as well as for asbestos, crystalline silica, diesel motor exhaust, and coal tar. Odds ratios (ORs) were calculated for ever-exposure, duration, average exposure, and cumulative exposure after adjusting for tobacco smoking and exposure to coal tar. A total of 433 cases and 1,253 controls were included in the analysis. The OR was 1.12 [95% confidence interval (CI), 0.84-1.49] for inhalation exposure to bitumen fume and 1.17 (95% CI, 0.88-1.56) for dermal exposure to bitumen condensate. No significant trend was observed between lung cancer risk and duration, average exposure, or cumulative exposure to bitumen fume or condensate. We found no consistent evidence of an association between indicators of either inhalation or dermal exposure to bitumen and lung cancer risk. A sizable proportion of the excess mortality from lung cancer relative to the general population observed in the earlier cohort phase is likely attributable to high tobacco consumption and possibly to coal tar exposure, whereas other occupational agents do not appear to play an important role.

• Exposure assessment for a nested case-control study of lung cancer among European asphalt workers.

  Authors: Michela Agostini, Gilles Ferro, Ann Olsson, Igor Burstyn, Frank De Vocht, Johnni Hansen, Christina Funch Lassen, Christoffer Johansen, Kristina Kjaerheim, Sverre Langard, Isabelle Stucker, Wolfgang Ahrens, Thomas Behrens, Marja-Liisa Lindbohm, Pirjo Heikkilä, Dick Heederik, Lützen Portengen, Judith Shaham, Paolo Boffetta, Hans Kromhout

  The Annals of occupational hygiene. 10/2010; 54(7):813-23.

  Development of a method for retrospective assessment of exposure to bitumen fume, bitumen condensate, organic vapour, polycyclic aromatic hydrocarbons, and co-exposures to known or suspected lungDevelopment of a method for retrospective assessment of exposure to bitumen fume, bitumen condensate, organic vapour, polycyclic aromatic hydrocarbons, and co-exposures to known or suspected lung carcinogens for a nested case-control study of lung cancer mortality among European asphalt workers. Company questionnaires and structured questionnaires used in interviews and industry-specific job-exposure matrices (JEMs) were elaborated and applied. Three sources of information were eventually used for exposure assessment and assignment: (i) data obtained in cohort phase, (ii) data from living subjects, next-of-kin, and fellow-workers questionnaires, and (iii) JEMs for bitumen exposure by inhalation and via skin and co-exposures to known or suspected lung carcinogens within and outside cohort companies. Inhalation and dermal exposure estimates for bitumen were adjusted for time trends, time spent in a job, and other determinants of exposure (e.g. oil gravel paving). Clothing patterns, personal protective devices, and personal hygiene were taken into consideration while estimating dermal exposure. Occupational exposures could be assessed for 433 cases and 1253 controls for relevant time periods. Only 43% of work histories were spent inside original asphalt and construction companies. A total of 95.8% of job periods in cohort companies could be coded at a more detailed level. Imputation of work time and 'hygienic behaviour' multipliers was needed for <10% of work history years. Overall, downward trends in exposure were present and differences existed between countries and companies. As expected, correlations were strongest (r > 0.7) among bitumen-related agents, while correlations between coal tar, bitumen-related agents, and established lung carcinogens were weaker (r < 0.4). A systematic and detailed approach was developed to estimate inhalation and dermal exposure for a nested case-control study among asphalt workers.

• Exposure to rubber process dust and fume since 1970s in the United Kingdom; influence of origin of measurement data.

  Authors: Michela Agostini, Frank de Vocht, Martie van Tongeren, John W Cherrie, Karen S Galea, Hans Kromhout

  Journal of environmental monitoring : JEM. 05/2010; 12(5):1170-8.

  The objective of this study was to compare measured concentrations of rubber process dust and rubber fume originating from different sources in the British rubber manufacturing industry. Almost 8000The objective of this study was to compare measured concentrations of rubber process dust and rubber fume originating from different sources in the British rubber manufacturing industry. Almost 8000 exposure measurements were obtained from industry-based survey results collected by the British Rubber Manufacturers' Association (BRMA), and covering the years 1977 to 2002, and from a series of small surveys contained in the Health and Safety Executive's (HSE) National Exposure Database (HSE-NEDB) from 1980 to 2002. The analysis investigated temporal trends in the exposure concentrations and the underlying main factors responsible for these changes. Analyses were carried out using hierarchical linear mixed effects models. Average personal exposures to rubber process dust and rubber fumes were respectively a factor 2 and 4 higher for the HSE-NEDB data when compared to data originating from the industry (BRMA data). Personal exposure to rubber process dust decreased on average by 4.1% (95% CI 4.7-3.6) annually for the BRMA data and slightly less at 2.3% (95% CI 5.2-0.7%) per annum for the HSE-NEDB data. Personal exposure to rubber fume also showed a downward temporal trend of 2.9% (95% CI 3.6-2.3%) and 4.8% (95% CI 7.4-2.1%) annually for the BRMA and HSE-NEDB data, respectively. These trends differed considerably between departments. No major changes in the estimated temporal trends in exposure concentrations were observed after including the presence of local exhaust ventilation in the models for any department in the BRMA and HSE-NEDB datasets. Lack of information on the quality and status of the local exhaust ventilation is the most likely explanation for this. In conclusion, even though there were relatively similar downward time trends in both rubber process dust and fume concentrations in both datasets, the source of exposure data was an important determinant of average exposure concentrations present in the British rubber manufacturing industry. Lack of detailed auxiliary information on company size, reason for sampling, measurement strategy and other potentially important determinants of exposure prevented an explanation for the observed differences in exposure level.

• "Dirty electricity": what, where, and should we care?

  Authors: Frank de Vocht

  Journal of exposure science & environmental epidemiology. 03/2010; 20(5):399-405.

  Environmental exposure to high-frequency voltage transients (HFVT), also termed dirty electricity, has been advocated among electro(hyper)sensitive interest groups as an important biological activeEnvironmental exposure to high-frequency voltage transients (HFVT), also termed dirty electricity, has been advocated among electro(hyper)sensitive interest groups as an important biological active component of standard electromagnetic pollution. A literature search was conducted in PubMed, in which only seven articles were identified. Exposure to HFVT was associated with increased cancer risks, while preferential removal of 4-100 kHz HFVT from 50-60 Hz ELF circuits was linked to a variety of improvements in health (plasma glucose levels in diabetic patients, symptoms of multiple sclerosis, asthma and other respiratory illnesses, and insomnia), well-being (tiredness, frustration, general health, irritation, sense of satisfaction, mood), and student behavior. However, all these published studies were subject to significant methodological flaws in the design of the studies, the assessment of exposure, and the statistical analysis, which prevented valid assessment of a causal link between this exposure metric and adverse effects. Environmental exposure to HFVT is an interesting EMF exposure metric, which might explain the spurious results from epidemiological studies using 'standard' ELF and RF exposure metrics. However, at present, methodological problems in published studies prohibit the valid assessment of its biological activity.

• Historical "evidence" that electrification caused the 20th century epidemic of diseases of civilization and the ecological fallacy.

  Authors: Frank de Vocht, Igor Burstyn

  Medical hypotheses. 12/2009;

• Personal exposure to static and time-varying magnetic fields during MRI system test procedures.

  Authors: Frank de Vocht, Floris Muller, Hans Engels, Hans Kromhout

  Journal of magnetic resonance imaging : JMRI. 11/2009; 30(5):1223-8.

  PURPOSE: To assess personal time-weighted average (TWA) static magnetic field and time-varying magnetic field exposure for several system testing tasks routinely conducted by engineers at an MRIPURPOSE: To assess personal time-weighted average (TWA) static magnetic field and time-varying magnetic field exposure for several system testing tasks routinely conducted by engineers at an MRI manufacturing plant. MATERIALS AND METHODS: Personal exposure was measured using a personal dosimeter that measured B and dB/dt in all three orthogonal directions with a 1 Hz frequency. TWA exposure was calculated and random effects and linear mixed effects models were used to assess exposure levels and variability. RESULTS: Whereas full-body peak (2T) and TWA (200 mT/8 h) exposure limits for the static magnetic field originally proposed by ICNIRP were not exceeded, time-varying magnetic field peaks (dB/dt) did exceed the proposed threshold value (767.9 mT/s) suggested by IEEE on several occasions at the 3.0 Tesla (T) whole-body cylindrical system. CONCLUSION: TWA exposure levels are well below the proposed limit values, but peak exposure limits are exceeded during certain procedures performed on 1.0T to 3.0T systems.

• Cancer mortality and occupational exposure to aromatic amines and inhalable aerosols in rubber tire manufacturing in Poland.

  Authors: Frank de Vocht, Wojciech Sobala, Urszula Wilczynska, Hans Kromhout, Neonila Szeszenia-Dabrowska, Beata Peplonska

  Cancer epidemiology. 09/2009; 33(2):94-102.

  AIM: Most data on carcinogenic risk in the rubber industry are based on data from Western countries. This study assessed cancer risks in a retrospective cohort in a Polish tire manufacturing plant,AIM: Most data on carcinogenic risk in the rubber industry are based on data from Western countries. This study assessed cancer risks in a retrospective cohort in a Polish tire manufacturing plant, relying on quantified exposure to inhalable aerosols and aromatic amines instead of job titles or external comparisons. METHODS: Cumulative exposure for all exposures was assigned to cohort members based on estimates from a company-specific JEM. Cancer risks associated with cumulative exposure adjusted for co-exposures, gender and year of birth were calculated. RESULTS: Exposure levels were higher for women than for men. Aromatic amine exposure was significantly associated with increased urinary bladder cancer risk (RR=7.32-8.27), depending on exposure level, and prostate cancer at low levels only (RR=5.86). In women, increased risks were found for all cancers (RR=2.50) and of the digestive organs and peritoneum (RR=4.54) at low level only, while an exposure-response association with breast cancer risk was found. Inhalable aerosol exposure was associated with cancers of the liver and intrahepatic bile ducts in a dose-dependent manner, while dose-dependent reduced risks were found for respiratory cancers (most notably the larynx) and cancer of the colon. CONCLUSIONS: Increased risks for specific cancer sites in this rubber plant were similar to Western Europe and the US. However, several cancer risks were gender-specific which could relate to higher exposure levels in women or to differences in exposures to chemicals not assessed in this study.

• Bayesian Modeling Of Lung Cancer Risk And Bitumen Fume Exposure Adjusted For Unmeasured Confounding By Smoking.

  Authors: Frank de Vocht, Hans Kromhout, Gilles Ferro, Paolo Boffetta, Igor Burstyn

  Occupational and environmental medicine. 01/2009;

  OBJECTIVES: Residual confounding can be present in epidemiological studies because information on confounding factors was not collected. A Bayesian framework, which has the advantage over frequentistOBJECTIVES: Residual confounding can be present in epidemiological studies because information on confounding factors was not collected. A Bayesian framework, which has the advantage over frequentist methods that the uncertainty in the association between the confounding factor and exposure and disease can be reflected in the credible intervals of the risk parameter, is proposed to assess the magnitude and direction of this bias. METHODS: To illustrate this method, bias from smoking as an unmeasured confounder in a cohort study of lung cancer risk in the European asphalt industry was assessed. A Poisson disease model was specified to assess lung cancer risk associated with career average, cumulative, and lagged bitumen fume exposure. Prior distributions for the exposure strata, as well as for other covariates, were specified as uninformative normal distributions. The priors on smoking habits were specified as a Dirichlet distributions based on smoking prevalence estimates available for a sub-cohort and assumptions about precision of these estimates. RESULTS: Median bias in this example was estimated at 13%, and suggested an attenuating effect on the original exposure-disease associations. Nonetheless, the results still suggested an increased lung cancer risk, especially for average exposure. CONCLUSIONS: This Bayesian framework provides a method to assess the bias from an unmeasured confounding factor taking into account the uncertainty surrounding the estimate and from random sampling error. Specifically for this example, the bias arising from unmeasured smoking history in this asphalt workers' cohort is unlikely to explain the increased lung cancer risk associated with average bitumen fume exposure found in the original study.

• Application of PUF Foam Inserts for Respirable Dust Measurements in the Brick-Manufacturing Industry.

  Authors: Frank De Vocht, Adrian Hirst, Anthony Gardner

  The Annals of occupational hygiene. 11/2008;

  Institute of Occupational Medicine dual-fraction samplers equipped with porous polyurethane foam inserts have been introduced as a cheaper alternative to cyclone pre-selectors for measuringInstitute of Occupational Medicine dual-fraction samplers equipped with porous polyurethane foam inserts have been introduced as a cheaper alternative to cyclone pre-selectors for measuring respirable dust. Initial data from a variety of industries suggested that the dual-fraction sampler yielded similar results as personal cyclones and that the respirable selection of the foam was not adversely affected by particle loading. We conducted a similar study, but specifically in the brick industry to assess the validity of this dual-fraction sampler as an alternative to personal cyclones in this industry. A total of 72 side-by-side samples using Higgins-Dewell cyclones and dual-fraction samplers were taken in seven UK factories manufacturing a variety of bricks. A priori measurements were assigned to any of the three groups based on the dominant source of the particulates in the exposure matrix (clay, sand or mixed) at the location in the factories where the measurements were taken. After log transformation, Higgins-Dewell cyclone-measured concentrations were on average 1.9 times higher than the concentrations measured by the dual-fraction samplers, with a Pearson correlation of 0.78 (95% confidence interval 0.66-0.85). Stratified analysis by main source of exposure suggested that the correlation was best for silica dust-based exposures r(p) = 0.88 (0.63-0.96), but decreased with the relative importance of clay particulates in the exposure matrix to r(p) = 0.82 (0.59-0.93) in the 'mixed-source' group and r(p) = 0.74 (0.55-0.85) in the 'clay particulates' group. Similarly, performance of the dual-fraction sampler relative to the cyclone sampler was negatively associated with increased relative importance of clay particulates in the exposure matrix and ranged from similar measured concentration beta = 0.96 (0.54-1.39) for silica to 50% under sampling beta = 0.50 (0.33-0.67) for clay particulates. These results suggested that the overall performance of the dual-fraction sampler in the brick industry depends on the relative importance of clay particulates in the exposure matrix. As such, results from occupational hygiene compliance surveys close to the occupational exposure limit can lead to erroneous decisions on compliance.