Modelling of occupational respirable crystalline silica exposure for quantitative exposure assessment in community-based case-control studies

Abstract

We describe an empirical model for exposure to respirable crystalline silica (RCS) to create a quantitative job-exposure matrix (JEM) for community-based studies. Personal measurements of exposure to RCS from Europe and Canada were obtained for exposure modelling. A mixed-effects model was elaborated, with region/country and job titles as random effect terms. The fixed effect terms included year of measurement, measurement strategy (representative or worst-case), sampling duration (minutes) and a priori exposure intensity rating for each job from an independently developed JEM (none, low, high). 23,640 personal RCS exposure measurements, covering a time period from 1976 to 2009, were available for modelling. The model indicated an overall downward time trend in RCS exposure levels of -6% per year. Exposure levels were higher in the UK and Canada, and lower in Northern Europe and Germany. Worst-case sampling was associated with higher reported exposure levels and an increase in sampling duration was associated with lower reported exposure levels. Highest predicted RCS exposure levels in the reference year (1998) were for chimney bricklayers (geometric mean 0.11 mg m(-3)), monument carvers and other stone cutters and carvers (0.10 mg m(-3)). The resulting model enables us to predict time-, job-, and region/country-specific exposure levels of RCS. These predictions will be used in the SYNERGY study, an ongoing pooled multinational community-based case-control study on lung cancer.

Evaluation of workplace exposure to respirable crystalline silica in Italy

“…12 Also, multiple national and industry exposure databases from several European countries and Canada were recently used in conjunction with a literature review to empirically model occupational exposure to RCS, resulting in a quantitative job-exposure matrix. 13 We confirmed that construction and manufacturing of non-metallic minerals, which are sectors that are traditionally considered to expose workers to elevated levels of RCS, had the highest number of reported exposures. Mean air RCS concentration measured in these sectors (GM50.045 and GM50.017, respectively) are in line with concentrations reported in recent years in other European countries and in North America.…”

“…[18][19][20] However, the subgroup of workers best characterized in our study, including those engaged in stonework masonry and tunnel construction, can reasonably be considered at high risk for adverse health effects as a result of silica exposure based on their higher mean exposure level (AM50.057, 93% of exposure measurements above the ACGIH limit value). 12,13,18,21 It should also be noted that carpenters and joiners had significant mean RCS exposure levels (AM50.047, 93% of exposure measurements above the ACGIH limit value), comparable with those of miners and quarry workers (AM50.048, 97% of exposure measurements above the ACGIH limit value), likely reflecting an inadequate implementation of preventive measures to control workplace silica dust air concentrations in the Italian construction industry, similar to other economically developed countries. [19][20][21] We estimate that about 30 000 workers are exposed to crystalline silica in the manufacture of non-metallic minerals in Italy (NACE code 26) 12 Similarly, in our study, exposure levels in the manufacture of nonmetallic minerals were found to vary between and within occupations, leading to an overall mean concentration lower than in construction, as well as a smaller percentage of TLV overwhelming values.…”

“…Mean air RCS concentration measured in these sectors (GM50.045 and GM50.017, respectively) are in line with concentrations reported in recent years in other European countries and in North America. [13][14][15][16][17] According to the 2001 industrial activity census, approximately 863 250 Italian workers are employed in construction. 11 Using our data, a reliable estimate of Italian workers exposed to silica was achievable only for a specific subsector of this activity (i.e.…”

Should we share ideas or measurement data?

“…Peters et al 13 collated an immense database with the results of almost 360 000 measurements of five major lung carcinogens across multiple countries and industries. Modelling of part of this database has thus far resulted in a quantitative country-, job- and time period-specific exposure matrix for exposure to crystalline silica 14. Application of this exposure matrix to the almost 38 000 cases and controls resulted in a quantitative monotonic increasing exposure response curve for exposure to respirable crystalline silica and lung cancer risk, which appeared to be comparable with what had been reported within industry-based cohort studies 15.…”

Retrospective benzene exposure assessment for a multi-center case-cohort study of benzene-exposed workers in China

“…1-3 However, to allow more precise risk estimation and extrapolation to lower levels of exposure, quantitative exposure assessment has become more common in retrospective studies in the form of expert assessment and/or statistical modeling of routinely collected measurement data. [4][5][6] Previous epidemiological investigations of benzene and health effects have relied on a variety of approaches for exposure assessment: (i) qualitative assessment, 7 (ii) semi-quantitative assessment sometimes augmented with some measurement data, 8 and (iii) quantitative assessment based on expert judgment and historical exposure measurements. 9 Vlaanderen et al 10,11 recently showed a relation between the quality of benzene exposure assessment and the ability to detect risk of hematolymphopoietic disorders thereby underlining the importance for high-quality exposure assessment in benzene health research.…”