We have studied cross-shift respiratory responses of several individual bioaerosol components of ... more We have studied cross-shift respiratory responses of several individual bioaerosol components of the dust in the grain and feed industry in Norway. Cross-shift changes in lung function and nasal congestion, as well as in respiratory and systemic symptoms of 56 exposed workers and 36 referents, were recorded on the same day as full-shift exposure to the inhalable aerosol fraction was assessed. Exposure-response associations were investigated by regression analysis. The workers were exposed on average to 1.0 mg/m(3) of grain dust, 440 EU/m(3) of endotoxin, 6 µg/m(3) of β-1,3-glucans, 17×10(4)/m(3) of bacteria and 4×10(4)/m(3) of fungal spores during work. The exposure was associated with higher prevalence of self-reported eye and airway symptoms, which were related to the individual microbial components in a complex manner. Fatigue and nose symptoms were strongest associated with fungal spores, cough with or without phlegm was associated with grain dust and fungal spores equally strong and wheeze/tight chest/dyspnoea was strongest associated with grain dust. Bioaerosol exposure did not lead to cross-shift lung function decline, but several microbial components had influence on nose congestion. Exposure to fungal spores and dust showed stronger associations with respiratory symptoms and fatigue than endotoxin exposure. The associations with dust suggest that there are other components in dust than the ones studied that induce these effects.
Journal of Occupational and Environmental Hygiene, 2016
We aimed to characterize bakers' personal exposure to airborne flour dust in respect to t... more We aimed to characterize bakers' personal exposure to airborne flour dust in respect to the health-related aerosol fractions inhalable, extrathoracic and thoracic dust, and to examine possible production-related determinants of dust exposure. Sixty-eight bakers from 7 bakeries in Bergen, Norway (2009-2012) participated in the exposure assessment, comprising full-shift personal samples of inhalable dust (n = 107) and thoracic dust (n = 61). The relation between possible determinants and exposure was estimated using mixed effects models, while associations between the various aerosol fractions across task groups and type of bakeries were described by Pearson's correlation coefficients. Bakers overall geometric mean personal exposure to inhalable, extrathoracic and thoracic dust were 2.6 mg/m(3) (95% CI: 2.0, 3.2), 2.2 mg/m(3) (95% CI: 1.9, 2.7) and 0.33 mg/m(3) (95% CI 0.3, 0.4), respectively. A total of 29% of the measurements of inhalable dust were above the Norwegian Occupational Exposure Limit of 3 mg/m(3). The exposure variability of inhalable dust could not be explained by any of the examined production-related determinants, while the daily production volume explained 18% of the variance in thoracic dust. Overall, the thoracic dust represented 15% of the inhalable dust, being rather stable across the production-related determinants. The overall correlation between inhalable and thoracic dust was nevertheless moderate (r = 0.52, p<0.001), with the highest correlation for craft bakers (r = 0.62) and no correlation during dough forming (r = 0.01). Bakers are exposed to flour dust at a level that most likely represents an excess risk of developing chronic diseases of the respiratory system, and a decrease of present exposure level is imperative. Extrathoracic dust - likely the most relevant sub-fraction in respect to flour-induced sensitization and occupational rhinitis - represented the main proportion of the measured inhalable dust. The variation in correlation coefficients between the dust fractions across bakery types and task groups underlines the need of more knowledge about how these aerosol fractions are distributed across the production process and bakery types.
Airborne levels of microorganisms traditionally have been measured by culture-based methods. Cult... more Airborne levels of microorganisms traditionally have been measured by culture-based methods. Culture-based methods are suitable for the detection of infectious agents, but their suitability for the detection of microorganisms with toxic and allergic effects is less clear, because these effects do not depend on viability of the organisms. During the last 15 years several noncultural methods have been developed for the quantification of airborne microorganisms, including microscopic methods. Microscopy may be expected to provide more valid exposure estimates of microorganisms than culture-based methods, because live and dead microorganisms can be detected. However, their validity may also depend on the ability to differentiate between species. The literature was searched for epidemiological studies in which exposure-response analyses were carried out using culture-based methods and/or microscopy. The influence of several factors on exposure-response associations were considered: design; population size; analytical method; sampling method; exposure levels; outcome; and confounder adjustment. Thirteen studies were found, including a total of 49 exposure-response analyses, and 45% of the analyses showed associations. It was found that the potential of microscopic methods to uncover exposure-response associations was only marginally better than that of culture-based methods (47 and 44%, respectively). Exposure-response associations were more often found with fungi (70%) than with gram-negative bacteria (50%) or total bacteria (22%), perhaps because fungal exposure is more strongly associated to respiratory outcomes than exposure to bacteria. But the shortcomings of the measurement methods may also be important. Further development of measurement methods for bacteria is therefore needed. The complex composition of bioaerosols in many work environments necessitate the assessment of exposure to multiple agents and multivariate statistical analysis of exposure-response associations.
Http Dx Doi Org 10 1080 00028894 1997 10399308, Jun 1, 2011
An inhalation chamber was built to perform experimental studies with hydrogen fluoride (HF), othe... more An inhalation chamber was built to perform experimental studies with hydrogen fluoride (HF), other gases, and particulate matter. The present study sought to describe a new gas delivery system and the distribution and concentration of HF gas in the chamber. The aluminum chamber has a volume of 19.2 m3 and a variable ventilation rate of about 1 to 10 air changes per hour. The negative pressure difference between the chamber and outside air can be regulated from 0 to 300 Pa. HF was fed at concentrations of up to 4000 mg/m3 directly into the ventilation duct feeding the chamber through openings with diameters as small as 50 microns, oriented opposite to the airflow. Gas flow was varied from about 0.1 dm3/min at a pressure of 4 atm. The dilution factor of HF concentration from cylinder to chamber was on the order of 10(3) to 10(4). The standard deviation (SD) of the HF concentrations at a fixed measurement point during a 1-hour test was typically 0.05 mg/m3 at a time-weighted average (TWA) concentration of 2.66 mg/m3. The SD of the TWA HF concentrations at six locations in the chamber was typically 0.05 mg/m3 and 0.29 mg/m3 at 0.61 and 3.46 mg/m3, respectively. Human exposure could be predicted from calculations based on ventilation data, gas flow, and observed ratio between calculated and measured concentrations. When the target exposure concentration was 1.5 mg/m3, the measured mean exposure concentration was typically 1.54 mg/m3 (range: 1.4-1.7 mg/m3, SD 0.09 mg/m3, n = 8). The chamber is well-suited for inhalation studies in humans. Chamber atmosphere was controlled and has proved to be stable and homogeneous, even in tests with HF, a highly reactive gas in the class of superacids.
Journal of Occupational and Environmental Hygiene, Jan 23, 2009
Information was collected on working conditions and personal exposures to dust, bacteria, and fun... more Information was collected on working conditions and personal exposures to dust, bacteria, and fungi in sisal fiber processing factories in Tanzania to identify health hazards and possible needs for preventive measures. Walkthrough surveys were performed in the brushing and decorticating departments of six sisal factories. The number of departments showing adequate scores for ergonomics and work organization, physical working environment, and occupational health items were determined. Personal thoracic dust samples were collected during sisal processing and analyzed for concentration of dust (n = 24) and for fungi and bacteria (n = 32). In both departments, most items considered to be a prerequisite for a good working environment were either missing or inadequate. Ergonomic and physical hazards were observed. Repetitive strenuous tasks, awkward work postures, and high noise levels were found. Visible dust and inadequate ventilation were seen in the brushing departments, and wet floors were observed in the decortication departments. Personal protective equipment was hardly used. The arithmetic mean exposure of sisal processors was 1.2 mg thoracic dust/m(3), 43 x 10(6) bacteria/ m(3), and 2.35 x 10(6) fungal spores/m(3). The highest exposure levels were measured in the decortication departments when machines were cleaned of waste. Significant differences were found for mean thoracic dust exposure and bacteria counts between the brushing and decortication departments and the security guards. Within individual departments, there were no significant differences in exposures between the different work tasks. A linear mixed effect model of thoracic dust including department as fixed effect explained 65% of the between-worker variability for thoracic dust exposure. The study shows that workers in sisal processing in Tanzania are exposed to bioaerosols, and suitable control measures should be implemented. More exposure studies are needed in this type of industry.
International Journal of Occupational and Environmental Health, Apr 1, 2014
The long-term prognosis of repeated acute episodes of hypersensitivity pneumonitis (HP) is not we... more The long-term prognosis of repeated acute episodes of hypersensitivity pneumonitis (HP) is not well described. We report on a 10-year follow-up of a 10-person cluster from a Norwegian sawmill who had all experienced relapsing episodes of HP. To evaluate the health symptoms, work-related sick-leave, and lung function of 10 workers exposed to mold in a Norwegian sawmill. Participants were evaluated at baseline and 10 years later at follow-up. A structured interview, measurement of serum IgG antibodies to Rhizopus microsporus (R. microsporus) antigens, lung function tests, high resolution computed tomography (HRCT) of the chest, and personal measurements of exposure to mold spores and dust were completed for each participant. At baseline, nearly all workers reported acute episodes of HP more than twice a month. At follow-up, both the frequency and intensity of symptoms had declined. Sick-leave was reduced and gas diffusing capacity improved - paralleling the gradually reduced air levels of mold spores. In spite of an initially high occurrence of symptoms, long-term clinical and physiological outcome was good. With reduced exposure to mold spores, symptoms declined and lung function was restored.
Bacterial single cell protein (BSCP) is used as a protein enrichment in livestock and fish feed, ... more Bacterial single cell protein (BSCP) is used as a protein enrichment in livestock and fish feed, and is extracted from dried bacterial mass. In the production of BSCP, workers are exposed to organic dust containing high levels of endotoxins that may induce acute airway inflammation. However, the long term effect on the airways of such exposure is not known, and we have examined inflammatory markers in induced sputum and blood among BSCP exposed workers. We included 21 non-smoking production workers (age 31-42 (range; mean 35)) without respiratory symptoms and 21 healthy non-exposed references (age 21-52 (range; mean 34)). Airborne endotoxin concentrations were measured, and induced sputum samples and blood samples were collected from the workers and non-exposed references. The airborne endotoxin concentration measured in inhaled air during the work shift was 430 EU/m(3) (50-2000) (median (range)). The percentage of neutrophils in induced sputum was 79% (66-93) (median (25th-75th percentiles)) and 31% (25-45) (p < 0.001) for operators and references, respectively. Protein analysis in induced sputum supernatant showed significantly elevated levels of interleukins IL-1beta and IL-12 (p < 0.05), while blood analysis showed significantly elevated levels of PDGF-BB (platelet-derived growth factor-BB) and RANTES (regulated upon activation normally T cell expressed and secreted) (p < 0.05). Workers exposed to BSCP had an airway inflammation characterized by a high level of neutrophils. However, only a few cytokines were elevated in lung and blood, which could imply low inflammatory activity suggestive of possible adaptation mechanisms due to daily exposure to BSCP, or that the inflammation reaction was a dose-related response occurring at higher levels.
Journal of Occupational and Environmental Hygiene, Apr 1, 2012
The objective was to construct a retrospective job-exposure matrix (JEM) for the Norwegian silico... more The objective was to construct a retrospective job-exposure matrix (JEM) for the Norwegian silicon carbide industry. More than 3300 historical total dust measurements were available (1967-2005); however, there were few measurements of other agents. Total dust measurements were therefore used as the basis for the JEM, and a novel method was developed to estimate exposure to other agents. Multiple linear regression models were developed to describe historical exposure to total dust. Exposure estimates were extrapolated backward to periods without exposure data by adjustments for process and work-hour related changes. An exposure assessment study was performed where total dust was sampled in parallel with fibers or respirable dust. The respirable dust was analyzed for the content of quartz, cristobalite, and silicon carbide. Mixed-effect models were developed to estimate the exposure to these agents from total dust exposure, plant, and job group. Exposure to asbestos and polycyclic aromatic hydrocarbons was assigned qualitatively. Multiple linear regression models of total dust described historical exposure best in the furnace department (R(2) (adj) = 0.49-0.74). Models in the other departments explained less variance (R(2) (adj) = 0.12-0.32). Exposure determinants and total dust explained a substantial proportion of the between- (70-100%) and within-worker (8.0-54%) variance in the mixed-effect models. The relative bias between available historical measurements and the estimated exposure to dust components varied between -39% (fiber) and 40% (quartz). However, corrections were not considered necessary due to limitations in the historical data. The component-specific metrices were sufficiently different from each other (r(Pearson) < 0.7), with the exception of total and respirable dust (r(Pearson) = 0.84) and total dust and cristobalite (r(Pearson) = 0.72), and will enable component-specific epidemiologic analyses in the future. Improved and less correlated estimates of exposure levels for the different components in the dust were obtained with the updated exposure assessment. Due to limitations in the measurement data, assumptions had to be made, especially in the period before 1967. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a file containing tables outlining multiple linear regression models for prediction of total dust exposure in the processing departments of Norwegian SiC producing plants, evaluation of the predictive abilities of the reduced total dust models, and mixed models for pedicting exposure to fibers and respirable quartz, cristobalite, non-fibrous silicon carbide and respirable dust from total dust exposure.].
We hypothesised that exposure to workplace aerosols may lead to lung function impairment among ce... more We hypothesised that exposure to workplace aerosols may lead to lung function impairment among cement production workers.Our study included 4966 workers in 24 cement production plants. Based on 6111 thoracic aerosol samples and information from questionnaires we estimated arithmetic mean exposure levels by plant and job type. Dynamic lung volumes were assessed by repeated spirometry testing during a mean follow-up time of 3.5 years (range 0.7-4.6 years). The outcomes considered were yearly change of dynamic lung volumes divided by the standing height squared or percentage of predicted values. Statistical modelling was performed using mixed model regression. Individual exposure was classified into quintile levels limited at 0.09, 0.89, 1.56, 2.25, 3.36, and 14.6 mg·m(-3), using the lowest quintile as the reference. Employees that worked in administration were included as a second comparison group.Exposure was associated with a reduction in forced expiratory volume in 1 s (FEV1), forc...
The aims of this study were to examine the relationships and establish conversion factors between... more The aims of this study were to examine the relationships and establish conversion factors between 'total' dust, respirable, thoracic, and inhalable aerosol fractions measured by parallel personal sampling on workers from the production departments of cement plants. 'Total' dust in this study refers to aerosol sampled by the closed face 37-mm Millipore filter cassette. Side-by-side personal measurements of 'total' dust and respirable, thoracic, and inhalable aerosol fractions were performed on workers in 17 European and Turkish cement plants. Simple linear and mixed model regressions were used to model the associations between the samplers. The total number of personal samples collected on 141 workers was 512. Of these 8.4% were excluded leaving 469 for statistical analysis. The different aerosol fractions contained from 90 to 130 measurements and-side-by side measurements of all four aerosol fractions were collected on 72 workers.The median ratios between obs...
3-Hydroxy acids are constituents of the lipid A part of lipopolysaccharides and may potentially b... more 3-Hydroxy acids are constituents of the lipid A part of lipopolysaccharides and may potentially be used as chemical markers of endotoxin. While commercial enzymatic assays, such as the widely used Limulus amebocyte lysate (LAL) assay, commonly detect merely the water-soluble fraction of the bioactive endotoxin, the chemical approach aims to estimate the total amount of endotoxin present in a sample. Our objective was to develop a simple method for quantitative profiling of 3-hydroxy fatty acids in occupational and environmental samples based on detection with HPLC-MS/MS. We included eleven 3-hydroxy fatty acids (3-hydroxyoctanoic acid to 3-hydroxyoctadecanoic acid) in the HPLC-MS/MS based method, which involved base hydrolysis of filter samples using 1M sodium hydroxide and removal of the base as well as concentration of the fatty acids using solid-phase extraction on a functionalized polystyrene-divinylbenzene polymer. Recovery trials from spiked glass fiber filters, using threo-9,...
A longitudinal study of wood trimmers exposed to mould spores was carried out from 1985 to 1988. ... more A longitudinal study of wood trimmers exposed to mould spores was carried out from 1985 to 1988. Exposure to airborne spores from Rhizopus microsporus ssp. rhizopodiformis and Paecilomyces variotii was measured by scanning electron microscopy of filter samples. Specific IgG antibodies to these moulds were measured by ELISA in serum samples collected at half-year intervals. Antibody levels to R. microsporus and P. variotii were higher in wood trimmers than in other sawmill workers whose jobs had an assumed lower exposure to mould spores. Antibody levels were significantly elevated after periods with high exposure compared to antibody levels in the same wood trimmers after periods with low exposure. Antibodies were also found in newly employed wood trimmers. These wood trimmers were exposed to 1,300 x 10(3) R. microsporus spores/m3 and 130 x 10(3) P. variotii spores/m3 (arithmetic mean exposure). Antibody levels in the newly employed wood trimmers were similar to antibody levels in wood trimmers who had already worked in the trimming department before the start of the study. Antibody levels to R. microsporus and P. variotii in wood trimmers can be regarded as indicators of fairly recent exposure. There were, however, large differences between the individual antibody levels of similarly exposed wood trimmers.
We have studied cross-shift respiratory responses of several individual bioaerosol components of ... more We have studied cross-shift respiratory responses of several individual bioaerosol components of the dust in the grain and feed industry in Norway. Cross-shift changes in lung function and nasal congestion, as well as in respiratory and systemic symptoms of 56 exposed workers and 36 referents, were recorded on the same day as full-shift exposure to the inhalable aerosol fraction was assessed. Exposure-response associations were investigated by regression analysis. The workers were exposed on average to 1.0 mg/m(3) of grain dust, 440 EU/m(3) of endotoxin, 6 µg/m(3) of β-1,3-glucans, 17×10(4)/m(3) of bacteria and 4×10(4)/m(3) of fungal spores during work. The exposure was associated with higher prevalence of self-reported eye and airway symptoms, which were related to the individual microbial components in a complex manner. Fatigue and nose symptoms were strongest associated with fungal spores, cough with or without phlegm was associated with grain dust and fungal spores equally strong and wheeze/tight chest/dyspnoea was strongest associated with grain dust. Bioaerosol exposure did not lead to cross-shift lung function decline, but several microbial components had influence on nose congestion. Exposure to fungal spores and dust showed stronger associations with respiratory symptoms and fatigue than endotoxin exposure. The associations with dust suggest that there are other components in dust than the ones studied that induce these effects.
Journal of Occupational and Environmental Hygiene, 2016
We aimed to characterize bakers' personal exposure to airborne flour dust in respect to t... more We aimed to characterize bakers' personal exposure to airborne flour dust in respect to the health-related aerosol fractions inhalable, extrathoracic and thoracic dust, and to examine possible production-related determinants of dust exposure. Sixty-eight bakers from 7 bakeries in Bergen, Norway (2009-2012) participated in the exposure assessment, comprising full-shift personal samples of inhalable dust (n = 107) and thoracic dust (n = 61). The relation between possible determinants and exposure was estimated using mixed effects models, while associations between the various aerosol fractions across task groups and type of bakeries were described by Pearson's correlation coefficients. Bakers overall geometric mean personal exposure to inhalable, extrathoracic and thoracic dust were 2.6 mg/m(3) (95% CI: 2.0, 3.2), 2.2 mg/m(3) (95% CI: 1.9, 2.7) and 0.33 mg/m(3) (95% CI 0.3, 0.4), respectively. A total of 29% of the measurements of inhalable dust were above the Norwegian Occupational Exposure Limit of 3 mg/m(3). The exposure variability of inhalable dust could not be explained by any of the examined production-related determinants, while the daily production volume explained 18% of the variance in thoracic dust. Overall, the thoracic dust represented 15% of the inhalable dust, being rather stable across the production-related determinants. The overall correlation between inhalable and thoracic dust was nevertheless moderate (r = 0.52, p<0.001), with the highest correlation for craft bakers (r = 0.62) and no correlation during dough forming (r = 0.01). Bakers are exposed to flour dust at a level that most likely represents an excess risk of developing chronic diseases of the respiratory system, and a decrease of present exposure level is imperative. Extrathoracic dust - likely the most relevant sub-fraction in respect to flour-induced sensitization and occupational rhinitis - represented the main proportion of the measured inhalable dust. The variation in correlation coefficients between the dust fractions across bakery types and task groups underlines the need of more knowledge about how these aerosol fractions are distributed across the production process and bakery types.
Airborne levels of microorganisms traditionally have been measured by culture-based methods. Cult... more Airborne levels of microorganisms traditionally have been measured by culture-based methods. Culture-based methods are suitable for the detection of infectious agents, but their suitability for the detection of microorganisms with toxic and allergic effects is less clear, because these effects do not depend on viability of the organisms. During the last 15 years several noncultural methods have been developed for the quantification of airborne microorganisms, including microscopic methods. Microscopy may be expected to provide more valid exposure estimates of microorganisms than culture-based methods, because live and dead microorganisms can be detected. However, their validity may also depend on the ability to differentiate between species. The literature was searched for epidemiological studies in which exposure-response analyses were carried out using culture-based methods and/or microscopy. The influence of several factors on exposure-response associations were considered: design; population size; analytical method; sampling method; exposure levels; outcome; and confounder adjustment. Thirteen studies were found, including a total of 49 exposure-response analyses, and 45% of the analyses showed associations. It was found that the potential of microscopic methods to uncover exposure-response associations was only marginally better than that of culture-based methods (47 and 44%, respectively). Exposure-response associations were more often found with fungi (70%) than with gram-negative bacteria (50%) or total bacteria (22%), perhaps because fungal exposure is more strongly associated to respiratory outcomes than exposure to bacteria. But the shortcomings of the measurement methods may also be important. Further development of measurement methods for bacteria is therefore needed. The complex composition of bioaerosols in many work environments necessitate the assessment of exposure to multiple agents and multivariate statistical analysis of exposure-response associations.
Http Dx Doi Org 10 1080 00028894 1997 10399308, Jun 1, 2011
An inhalation chamber was built to perform experimental studies with hydrogen fluoride (HF), othe... more An inhalation chamber was built to perform experimental studies with hydrogen fluoride (HF), other gases, and particulate matter. The present study sought to describe a new gas delivery system and the distribution and concentration of HF gas in the chamber. The aluminum chamber has a volume of 19.2 m3 and a variable ventilation rate of about 1 to 10 air changes per hour. The negative pressure difference between the chamber and outside air can be regulated from 0 to 300 Pa. HF was fed at concentrations of up to 4000 mg/m3 directly into the ventilation duct feeding the chamber through openings with diameters as small as 50 microns, oriented opposite to the airflow. Gas flow was varied from about 0.1 dm3/min at a pressure of 4 atm. The dilution factor of HF concentration from cylinder to chamber was on the order of 10(3) to 10(4). The standard deviation (SD) of the HF concentrations at a fixed measurement point during a 1-hour test was typically 0.05 mg/m3 at a time-weighted average (TWA) concentration of 2.66 mg/m3. The SD of the TWA HF concentrations at six locations in the chamber was typically 0.05 mg/m3 and 0.29 mg/m3 at 0.61 and 3.46 mg/m3, respectively. Human exposure could be predicted from calculations based on ventilation data, gas flow, and observed ratio between calculated and measured concentrations. When the target exposure concentration was 1.5 mg/m3, the measured mean exposure concentration was typically 1.54 mg/m3 (range: 1.4-1.7 mg/m3, SD 0.09 mg/m3, n = 8). The chamber is well-suited for inhalation studies in humans. Chamber atmosphere was controlled and has proved to be stable and homogeneous, even in tests with HF, a highly reactive gas in the class of superacids.
Journal of Occupational and Environmental Hygiene, Jan 23, 2009
Information was collected on working conditions and personal exposures to dust, bacteria, and fun... more Information was collected on working conditions and personal exposures to dust, bacteria, and fungi in sisal fiber processing factories in Tanzania to identify health hazards and possible needs for preventive measures. Walkthrough surveys were performed in the brushing and decorticating departments of six sisal factories. The number of departments showing adequate scores for ergonomics and work organization, physical working environment, and occupational health items were determined. Personal thoracic dust samples were collected during sisal processing and analyzed for concentration of dust (n = 24) and for fungi and bacteria (n = 32). In both departments, most items considered to be a prerequisite for a good working environment were either missing or inadequate. Ergonomic and physical hazards were observed. Repetitive strenuous tasks, awkward work postures, and high noise levels were found. Visible dust and inadequate ventilation were seen in the brushing departments, and wet floors were observed in the decortication departments. Personal protective equipment was hardly used. The arithmetic mean exposure of sisal processors was 1.2 mg thoracic dust/m(3), 43 x 10(6) bacteria/ m(3), and 2.35 x 10(6) fungal spores/m(3). The highest exposure levels were measured in the decortication departments when machines were cleaned of waste. Significant differences were found for mean thoracic dust exposure and bacteria counts between the brushing and decortication departments and the security guards. Within individual departments, there were no significant differences in exposures between the different work tasks. A linear mixed effect model of thoracic dust including department as fixed effect explained 65% of the between-worker variability for thoracic dust exposure. The study shows that workers in sisal processing in Tanzania are exposed to bioaerosols, and suitable control measures should be implemented. More exposure studies are needed in this type of industry.
International Journal of Occupational and Environmental Health, Apr 1, 2014
The long-term prognosis of repeated acute episodes of hypersensitivity pneumonitis (HP) is not we... more The long-term prognosis of repeated acute episodes of hypersensitivity pneumonitis (HP) is not well described. We report on a 10-year follow-up of a 10-person cluster from a Norwegian sawmill who had all experienced relapsing episodes of HP. To evaluate the health symptoms, work-related sick-leave, and lung function of 10 workers exposed to mold in a Norwegian sawmill. Participants were evaluated at baseline and 10 years later at follow-up. A structured interview, measurement of serum IgG antibodies to Rhizopus microsporus (R. microsporus) antigens, lung function tests, high resolution computed tomography (HRCT) of the chest, and personal measurements of exposure to mold spores and dust were completed for each participant. At baseline, nearly all workers reported acute episodes of HP more than twice a month. At follow-up, both the frequency and intensity of symptoms had declined. Sick-leave was reduced and gas diffusing capacity improved - paralleling the gradually reduced air levels of mold spores. In spite of an initially high occurrence of symptoms, long-term clinical and physiological outcome was good. With reduced exposure to mold spores, symptoms declined and lung function was restored.
Bacterial single cell protein (BSCP) is used as a protein enrichment in livestock and fish feed, ... more Bacterial single cell protein (BSCP) is used as a protein enrichment in livestock and fish feed, and is extracted from dried bacterial mass. In the production of BSCP, workers are exposed to organic dust containing high levels of endotoxins that may induce acute airway inflammation. However, the long term effect on the airways of such exposure is not known, and we have examined inflammatory markers in induced sputum and blood among BSCP exposed workers. We included 21 non-smoking production workers (age 31-42 (range; mean 35)) without respiratory symptoms and 21 healthy non-exposed references (age 21-52 (range; mean 34)). Airborne endotoxin concentrations were measured, and induced sputum samples and blood samples were collected from the workers and non-exposed references. The airborne endotoxin concentration measured in inhaled air during the work shift was 430 EU/m(3) (50-2000) (median (range)). The percentage of neutrophils in induced sputum was 79% (66-93) (median (25th-75th percentiles)) and 31% (25-45) (p < 0.001) for operators and references, respectively. Protein analysis in induced sputum supernatant showed significantly elevated levels of interleukins IL-1beta and IL-12 (p < 0.05), while blood analysis showed significantly elevated levels of PDGF-BB (platelet-derived growth factor-BB) and RANTES (regulated upon activation normally T cell expressed and secreted) (p < 0.05). Workers exposed to BSCP had an airway inflammation characterized by a high level of neutrophils. However, only a few cytokines were elevated in lung and blood, which could imply low inflammatory activity suggestive of possible adaptation mechanisms due to daily exposure to BSCP, or that the inflammation reaction was a dose-related response occurring at higher levels.
Journal of Occupational and Environmental Hygiene, Apr 1, 2012
The objective was to construct a retrospective job-exposure matrix (JEM) for the Norwegian silico... more The objective was to construct a retrospective job-exposure matrix (JEM) for the Norwegian silicon carbide industry. More than 3300 historical total dust measurements were available (1967-2005); however, there were few measurements of other agents. Total dust measurements were therefore used as the basis for the JEM, and a novel method was developed to estimate exposure to other agents. Multiple linear regression models were developed to describe historical exposure to total dust. Exposure estimates were extrapolated backward to periods without exposure data by adjustments for process and work-hour related changes. An exposure assessment study was performed where total dust was sampled in parallel with fibers or respirable dust. The respirable dust was analyzed for the content of quartz, cristobalite, and silicon carbide. Mixed-effect models were developed to estimate the exposure to these agents from total dust exposure, plant, and job group. Exposure to asbestos and polycyclic aromatic hydrocarbons was assigned qualitatively. Multiple linear regression models of total dust described historical exposure best in the furnace department (R(2) (adj) = 0.49-0.74). Models in the other departments explained less variance (R(2) (adj) = 0.12-0.32). Exposure determinants and total dust explained a substantial proportion of the between- (70-100%) and within-worker (8.0-54%) variance in the mixed-effect models. The relative bias between available historical measurements and the estimated exposure to dust components varied between -39% (fiber) and 40% (quartz). However, corrections were not considered necessary due to limitations in the historical data. The component-specific metrices were sufficiently different from each other (r(Pearson) < 0.7), with the exception of total and respirable dust (r(Pearson) = 0.84) and total dust and cristobalite (r(Pearson) = 0.72), and will enable component-specific epidemiologic analyses in the future. Improved and less correlated estimates of exposure levels for the different components in the dust were obtained with the updated exposure assessment. Due to limitations in the measurement data, assumptions had to be made, especially in the period before 1967. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a file containing tables outlining multiple linear regression models for prediction of total dust exposure in the processing departments of Norwegian SiC producing plants, evaluation of the predictive abilities of the reduced total dust models, and mixed models for pedicting exposure to fibers and respirable quartz, cristobalite, non-fibrous silicon carbide and respirable dust from total dust exposure.].
We hypothesised that exposure to workplace aerosols may lead to lung function impairment among ce... more We hypothesised that exposure to workplace aerosols may lead to lung function impairment among cement production workers.Our study included 4966 workers in 24 cement production plants. Based on 6111 thoracic aerosol samples and information from questionnaires we estimated arithmetic mean exposure levels by plant and job type. Dynamic lung volumes were assessed by repeated spirometry testing during a mean follow-up time of 3.5 years (range 0.7-4.6 years). The outcomes considered were yearly change of dynamic lung volumes divided by the standing height squared or percentage of predicted values. Statistical modelling was performed using mixed model regression. Individual exposure was classified into quintile levels limited at 0.09, 0.89, 1.56, 2.25, 3.36, and 14.6 mg·m(-3), using the lowest quintile as the reference. Employees that worked in administration were included as a second comparison group.Exposure was associated with a reduction in forced expiratory volume in 1 s (FEV1), forc...
The aims of this study were to examine the relationships and establish conversion factors between... more The aims of this study were to examine the relationships and establish conversion factors between 'total' dust, respirable, thoracic, and inhalable aerosol fractions measured by parallel personal sampling on workers from the production departments of cement plants. 'Total' dust in this study refers to aerosol sampled by the closed face 37-mm Millipore filter cassette. Side-by-side personal measurements of 'total' dust and respirable, thoracic, and inhalable aerosol fractions were performed on workers in 17 European and Turkish cement plants. Simple linear and mixed model regressions were used to model the associations between the samplers. The total number of personal samples collected on 141 workers was 512. Of these 8.4% were excluded leaving 469 for statistical analysis. The different aerosol fractions contained from 90 to 130 measurements and-side-by side measurements of all four aerosol fractions were collected on 72 workers.The median ratios between obs...
3-Hydroxy acids are constituents of the lipid A part of lipopolysaccharides and may potentially b... more 3-Hydroxy acids are constituents of the lipid A part of lipopolysaccharides and may potentially be used as chemical markers of endotoxin. While commercial enzymatic assays, such as the widely used Limulus amebocyte lysate (LAL) assay, commonly detect merely the water-soluble fraction of the bioactive endotoxin, the chemical approach aims to estimate the total amount of endotoxin present in a sample. Our objective was to develop a simple method for quantitative profiling of 3-hydroxy fatty acids in occupational and environmental samples based on detection with HPLC-MS/MS. We included eleven 3-hydroxy fatty acids (3-hydroxyoctanoic acid to 3-hydroxyoctadecanoic acid) in the HPLC-MS/MS based method, which involved base hydrolysis of filter samples using 1M sodium hydroxide and removal of the base as well as concentration of the fatty acids using solid-phase extraction on a functionalized polystyrene-divinylbenzene polymer. Recovery trials from spiked glass fiber filters, using threo-9,...
A longitudinal study of wood trimmers exposed to mould spores was carried out from 1985 to 1988. ... more A longitudinal study of wood trimmers exposed to mould spores was carried out from 1985 to 1988. Exposure to airborne spores from Rhizopus microsporus ssp. rhizopodiformis and Paecilomyces variotii was measured by scanning electron microscopy of filter samples. Specific IgG antibodies to these moulds were measured by ELISA in serum samples collected at half-year intervals. Antibody levels to R. microsporus and P. variotii were higher in wood trimmers than in other sawmill workers whose jobs had an assumed lower exposure to mould spores. Antibody levels were significantly elevated after periods with high exposure compared to antibody levels in the same wood trimmers after periods with low exposure. Antibodies were also found in newly employed wood trimmers. These wood trimmers were exposed to 1,300 x 10(3) R. microsporus spores/m3 and 130 x 10(3) P. variotii spores/m3 (arithmetic mean exposure). Antibody levels in the newly employed wood trimmers were similar to antibody levels in wood trimmers who had already worked in the trimming department before the start of the study. Antibody levels to R. microsporus and P. variotii in wood trimmers can be regarded as indicators of fairly recent exposure. There were, however, large differences between the individual antibody levels of similarly exposed wood trimmers.
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Papers by Wijnand Eduard