Remko Houba

Grouping strategies for exposure to inhalable dust, wheat allergens and α-amylase allergens in bakeries

This paper describes repeated measurements of inhalable flour dust, wheat allergens and alpha-amylase allergens in the bakery industry. A total of 571 full-shift personal dust samples was collected. Wheat allergens and alpha-amylase allergens were measured in 449 and 507 samples, respectively, by the use of recently developed immunoassays. For all three measures of exposure, the main components of exposure variability were determined. Different grouping strategies for studying exposure-response relationships were compared. The specific job of a bakery worker was identified as the most important source of variability in inhalable flour dust concentrations. For exposure to wheat allergens, the job performed was also the most important source of variation, but type of bakery also explained some of the variability. For alpha-amylase allergen exposure, information on type of bakery was more important then job information. For exposure to inhalable dust and wheat allergens, a classification by job title would lead to sufficient contrast in average exposure levels. By contrast, a grouping strategy based on a combination of job and type of bakery appeared to be essential to obtain a useful classification of exposure to alpha-amylase allergens. 1997 British Occupational Hygiene Society.

A cross-sectional study of lung function and respiratory symptoms among chemical workers producing diacetyl for food flavourings.

Objectives: Four diacetyl workers were found to have bronchiolitis obliterans syndrome. Exposures, respiratory symptoms, lung function and exposure–response relationships were investigated. Methods: 175 workers from a plant producing diacetyl between 1960 and 2003 were investigated. Exposure data were used to model diacetyl exposure. Lung function and questionnaire data on respiratory symptoms were compared to a general population sample and respiratory symptoms to an internal reference group. Results: Workers were potentially exposed to acetoin, diacetyl, acetaldehyde and acetic acid. Historic diacetyl exposure ranged from 1.8 to 351 mg/m3, and from 3 to 396 mg/m3 for specific tasks. Diacetyl workers reported significantly more respiratory symptoms compared to the general population sample (continuous trouble with breathing (prevalence ratio (PR) = 2.6; 95% CI 1.3 to 5.1), daily cough (PR = 1.5; 95% CI 1.1 to 2.1), asthma attack (ever) (PR = 2.0; 95% CI 1.2 to 3.4), doctor diagnosed asthma (PR = 2.2; 95% CI 1.3 to 3.8) and asthma attack in the last year (PR = 4.7; 95% CI 1.9 to 11.4)) and to a minimally exposed internal reference group (ever trouble with breathing (PR = 2.8; 95% CI 1.1 to 7.0) and work-related shortness of breath in the last year (PR = 7.5; 95% CI 1.1 to 52.9)). Lung function did not differ between groups. A positive relationship between exposure and FEV1 was found. Conclusion: The excess of respiratory symptoms in this retrospective cohort suggests that diacetyl production poses an occupational hazard. Limited historical exposure data did not support a quantitative individual diacetyl exposure–response relationship, but our findings suggest that preventive measures are prudent.

A cross-sectional study among detergent workers exposed to liquid detergent enzymes

Objectives: To investigate sensitisation and respiratory health among workers who produce liquid detergent products and handle liquid detergent enzymes. Methods: We performed a cross-sectional study among 109 eligible workers of a detergent products plant. 108 were interviewed for respiratory and allergic symptoms and 106 blood samples were taken from them to examine sensitisation to enzymes. Those sensitised to ⩾1 enzymes were referred for clinical evaluation. Workers and representatives were interviewed to characterise exposure qualitatively and estimate exposure semi-quantitatively. Workers were classified into three exposure groups with varying exposure profiles to enzymes, based on frequency, duration, and level of exposure. Results: Workers were exposed to proteases, α-amylase, lipase and cellulase. The highest exposures occurred in the mixing area. Liquid spills with concentrated enzyme preparations and leakage of enzymes during weighing, transportation and filling were causing workplace contaminations and subsequently leading to both dermal and inhalation exposure for workers. Workers with the highest exposures reported significantly more work-related symptoms of itching nose (prevalence ratio (PR) = 4.2, 95% CI 1.5 to 12.0) and sneezing (PR = 4.0, 95% CI 1.5 to 10.8) and marginally significant more symptoms of wheezing (PR = 2.9, 95% CI 0.9 to 8.7) compared with the least exposed group. Fifteen workers (14.2%) were sensitised to ⩾1 enzymes. A marginally statistically significant gradient in sensitisation across the exposure categories was found (p = 0.09). There was a clinical case of occupational asthma and two others with probable occupational rhinitis. Conclusions: Workers exposed to liquid detergent enzymes are at risk of developing sensitisation (14%) and respiratory allergy.

Cost-benefit analysis in occupational health: a comparison of intervention scenarios for occupational asthma and rhinitis among bakery workers

Objectives Use of cost-benefit analysis in occupational health increases insight into the intervention strategy that maximises the cost-benefit ratio. This study presents a methodological framework identifying the most important elements of a cost-benefit analysis for occupational health settings. One of the main aims of the methodology is to evaluate cost-benefit ratios for different stakeholders (employers, employees and society). The developed methodology was applied to two intervention strategies focused on reducing respiratory diseases. Methods A cost-benefit framework was developed and used to set up a calculation spreadsheet containing the inputs and algorithms required to calculate the costs and benefits for all cost elements. Inputs from a large variety of sources were used to calculate total costs, total benefits, net costs and the benefit-to-costs ratio for both intervention scenarios. Results Implementation of a covenant intervention program resulted in a net benefit of €16 848 546 over 20 years for a population of 10 000 workers. Implementation was cost-effective for all stakeholders. For a health surveillance scenario, total benefits resulting from a decreased disease burden were estimated to be €44 659 352. The costs of the interventions could not be calculated. Conclusion This study provides important insights for developing effective intervention strategies in the field of occupational medicine. Use of a model based approach enables investigation of those parameters most likely to impact on the effectiveness and costs of interventions for work related diseases. Our case study highlights the importance of considering different perspectives (of employers, society and employees) in assessing and sharing the costs and benefits of interventions.

A cross-sectional study of exposures, lung function and respiratory symptoms among aluminium cast-house workers

Objectives To investigate exposures, respiratory symptoms, lung function and exposure–response relationships among aluminium cast-house workers. Methods A cross-sectional study was conducted among 182 workers. Exposure data were used to model exposure to irritants. Lung function and questionnaire data on respiratory symptoms were compared to a general population sample and an internal reference group. Blood samples were taken from 156 workers to examine total IgE, eosinophils and sensitisation to common allergens. Results Average daily mean exposure to inhalable dust, metals, hydrogen fluoride, fluoride salts and sulphur dioxide was relatively low compared to reference values. Airflow patterns in the hall were disturbed regularly and resulted in pot emissions with high concentrations of fluorides. Peak exposures to chlorine gas occurred intermittently due to production process disturbances. Workers reported significantly more respiratory symptoms (continuous trouble with breathing (prevalence ratio (PR) 2.5; 95% CI 1.2 to 5.3), repeated trouble with breathing (PR 1.8; 95% CI 1.1 to 3.0), wheezing (PR 1.4; 95% CI 1.1 to 1.8), asthma attack (ever) (PR 2.8; 95% CI 1.7 to 4.6) and doctor diagnosed asthma (PR 2.6; 95% CI 1.5 to 4.4). Regression analysis showed significantly lower FEV1 values (−195 ml) and FVC values (−142 ml) compared to a general population sample. Lung function did not differ between groups. Conclusion This epidemiological study suggests cast-house workers in the aluminium industry are exposed to respiratory hazards. Exposure–response relationships could not be demonstrated but this study supports preventive measures in the work environment with a focus on (peak) exposures to irritants.

Wheat Antigen Content of Inhalable Dust in Bakeries: Modeling and an Inter-Study Comparison

The purposes of this study were (a) to compare wheat antigen content of inhalable bakery dust in Canada and the Netherlands and, (b) to evaluate the validity of dust exposure measurement as a surrogate of specific antigen exposure. Wheat antigen exposure data from the studies of Canadian and Dutch bakeries were used to explore the correlation between dust and antigen levels, and identify factors explaining variability of the antigen content of bakery dust. Direct comparison and pooling of the data were possible because the same antigen assay was used in both studies. Wheat antigen exposure samples totaling 544 were available, all originating from personal full-shift monitoring of bakery workers. The wheat antigen content of bakery dust varied greatly between the two studies and with different products within each study. Bakery dust from the Canadian study had a much higher wheat antigen content. Therefore, the interstudy difference in the wheat antigen content of bakery dust was by far the most significant in undermining the validity of the use of dust levels as a surrogate measures of wheat antigen exposure. The production of croissants, wheat bread and buns, puff pastry, bagels, and cinnamon buns was associated with increased wheat antigen content of bakery dust, while in rye bread production, bakery dust with less wheat antigen content was emitted. Although we can, in part, account for the pattern of variability in the wheat antigen content of bakery dust (explaining 49% of it), we concluded that the effort involved in modeling it accurately would probably exceed that expended in direct measurement of the antigen level. Therefore, for the exposure assessments carried out for the purpose of managing occupational risks of aeroallergen exposure in bakeries, we recommend the use of analytical techniques that can directly measure antigen exposure.

Exposure-response analyses for platinum salt–exposed workers and sensitization: A retrospective cohort study among newly exposed workers using routinely collected surveillance data

BACKGROUND Chloroplatinate salts are well-known respiratory sensitizing agents leading to work-related sensitization and allergies in the work environment. No quantitative exposure-response relation has been described for chloroplatinate salts. OBJECTIVE We sought to evaluate the quantitative exposure-response relation between occupational chloroplatinate exposure and sensitization. METHODS A retrospective cohort study was conducted using routinely collected health surveillance data and chloroplatinate exposure data. Workers who newly entered work between January 1, 2000, and December 31, 2010, were included, and the relation between measured chloroplatinate exposure and sensitization (as determined by skin prick test responses) was analyzed in more than 1000 refinery workers from 5 refineries for whom a total of more than 1700 personal exposure measurements were available. RESULTS A clear exposure-response relation was observed, most strongly for more recent platinum salt exposure. Average or cumulative exposure over the follow-up period was less strongly associated with sensitization risk. The exposure-response relation was modified by smoking and atopy. CONCLUSIONS Indications exist that recent exposure explains the risk of platinum salt sensitization most strongly. The precision of the estimate of the exposure-response relation derived from this data set appears superior to previous epidemiologic studies conducted on platinum salt sensitization and as a result, might have possible utility for the development of preventive strategies.

15 years of monitoring occupational exposure to respirable dust and quartz within the European industrial minerals sector

INTRODUCTION In 2000, a prospective Dust Monitoring Program (DMP) was started in which measurements of workers exposure to respirable dust and quartz are collected in member companies from the European Industrial Minerals Association (IMA-Europe). After 15 years, the resulting IMA-DMP database allows a detailed overview of exposure levels of respirable dust and quartz over time within this industrial sector. Our aim is to describe the IMA-DMP and the current state of the corresponding database which due to continuation of the IMA-DMP is still growing. The future use of the database will also be highlighted including its utility for the industrial minerals producing sector. METHODS Exposure data are being obtained following a common protocol including a standardized sampling strategy, standardized sampling and analytical methods and a data management system. Following strict quality control procedures, exposure data are consequently added to a central database. The data comprises personal exposure measurements including auxiliary information on work and other conditions during sampling. RESULTS Currently, the IMA-DMP database consists of almost 28,000 personal measurements which have been performed from 2000 until 2015 representing 29 half-yearly sampling campaigns. The exposure data have been collected from 160 different worksites owned by 35 industrial mineral companies and comes from 23 European countries and approximately 5000 workers. CONCLUSION The IMA-DMP database provides the European minerals sector with reliable data regarding worker personal exposures to respirable dust and quartz. The database can be used as a powerful tool to address outstanding scientific issues on long-term exposure trends and exposure variability, and importantly, as a surveillance tool to evaluate exposure control measures. The database will be valuable for future epidemiological studies on respiratory health effects and will allow for estimation of quantitative exposure response relationships.

Exposure-response analyses for soluble platinum-salt exposed workers and sensitisation: a retrospective cohort study among newly exposed workers using routinely collected surveillance data

Objectives Soluble platinum salts are well known respiratory sensitising agents leading to work related sensitisation in the work environment. No quantitative exposure response relation has been described for soluble platinum salts. The objective of this study was to explore exposure response relations for soluble platinum salt exposed workers. Method A retrospective cohort study was conducted using routinely collected health surveillance data and soluble platinum exposure data. Workers who newly entered between 1 January 2000 and 31 December 2010 were included and the relation between measured soluble platinum exposure and sensitisation (as determined by skin prick testing) was analysed in more than 1000 refinery workers from 5 refineries from whom a total of more than 1700 personal exposure measurements were available. Exposure response relations were analysed in survival analysis considering changes in exposure over time. Associations were explored for present exposure, cumulative exposure and average exposure. The exposure was lagged by 0.5, 1.0, 1.5, etc. year with a maximum of 5 years. Results A clear exposure response relation was observed, most strongly for present platinum salt exposure. Exposure lagging showed that exposure preceding sensitisation with maximally 1–2 years was most strongly associated with sensitisation risk. The exposure response relationship was modified by smoking and atopy, but relative risks for smoking and atopy were only modestly elevated. Conclusions The precision of estimate of the exposure-response relationship derived from this dataset appears superior to previous epidemiologic studies conducted on platinum salt sensitisation and may as a result have possible utility to occupational exposure standard setting.

Temporal changes in the variability of respirable mineral dust exposure concentrations

In the last decade a lot of evidence with regard to temporal trends in exposure concentrations in predominantly Western industrial countries has become available. In a recent literature review (Creely et al. 2007) overall percentage of yearly declines up to 32% were presented. To what extent these temporal declines also affect the variability in exposure concentrations is unknown. The main reason is lack of longitudinal data including repeated measurements that would allow evaluating trends in personal and temporal components of exposure variability. The recently elaborated exposure database from the Industrial Minerals Association Dust Monitoring Programme provided an opportunity to study these trends for exposure to respirable mineral dust. This database currently contains more than 11,000 measurements from more than 20 companies and 80 sites throughout Europe. About one-third of the measurement data comprised repeated measurements within a specific site-job-survey combination. Linear mixed models were used to estimate variance components. Variance components were consequently plotted against year of measurements. For 377 groups of workers (with number of workers>2, total number of observations >5 and repeats >1.25) the fold range of the total variability (tR.95) appeared to go down significantly with 3% per campaign (half year): from 34 in summer 2002 to 20 in winter 2005/2006. When the variability was teased apart the fold range for the temporal variability (wwR.95) appeared to decrease significantly as well with 3% per campaign (half year): from 17 in summer 2002 to 10 in winter 2005/2006. The between-worker variability did not show a temporal trend and stayed constant with on average a fold-range (bwR.95) of approximately 4. Downward temporal trends in exposure level of respirable (crystalline silica) dust seem to coincide with downward trends in the size of temporal variability. Fold-ranges of average exposure of individual workers within a job at a particular site appear to be stationary. Implications are that attenuation of exposure-response associations in epidemiogical studies will decline and that fewer measurements will have to be collected to arrive at accurate estimates of long-term exposure to respirable mineral dust in this industry.