Quantitative Crystalline Silica Exposure Assessment for a Historical Cohort Epidemiologic Study in the German Porcelain Industry

Abstract

A time-dependent quantitative exposure assessment of silica exposure among nearly 18,000 German porcelain workers was conducted. Results will be used to evaluate exposure-response disease risks. Over 8000 historical industrial hygiene (IH) measurements with original sampling and analysis protocols from 1954-2006 were obtained from the German Berufs- genossenschaft der keramischen-und Glas-Industrie (BGGK) and used to construct a job exposure matrix (JEM). Early measurements from different devices were converted to modern gravimetric equivalent values. Conversion factors were derived from parallel historical measurements and new side-by-side measurements using historical and modern devices in laboratory dust tunnels and active workplace locations. Exposure values were summarized and smoothed using LOESS regression; estimates for early years were derived using backward extrapolation techniques. Employee work histories were merged with JEM values to determine cumulative crystalline silica exposures for cohort members. Average silica concentrations were derived for six primary similar exposure groups (SEGs) for 1938-2006. Over 40% of the cohort accumulated <0.5 mg; just over one-third accumulated >1 mg/m(3)-years. Nearly 5000 workers had cumulative crystalline silica estimates >1.5 mg/m(3)-years. Similar numbers of men and women fell into each cumulative exposure category, except for 1113 women and 1567 men in the highest category. Over half of those hired before 1960 accumulated >3 mg/m(3)-years crystalline silica compared with 4.9% of those hired after 1960. Among those ever working in the materials preparation area, half accumulated >3 mg/m(3)-year compared with 12% of those never working in this area. Quantitative respirable silica exposures were estimated for each member of this cohort, including employment periods for which sampling used now obsolete technologies. Although individual cumulative exposure estimates ranged from background to about 40 mg/m(3)-years, many of these estimates reflect long-term exposures near modern exposure limit values, allowing direct evaluation of lung cancer and silicosis risks near these limits without extrapolation. This quantitative exposure assessment is the largest to date in the porcelain industry.

Evaluation of workplace exposure to respirable crystalline silica in Italy

“…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.…”

“…[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. This may be due to the significant decrease of airborne RCS concentrations reported in the ceramic industry over time, 14,22 and to the high variation in whether workers use dry or automated/remotely controlled working methods. 15 A number of female workers were also estimated to be exposed to RCS in this sector, particularly in the ceramic (N52458) and the artistic stone working industry (N5913).…”

Healthy-Worker Effect Led to an Overestimation of the Concentration Threshold Value for Respirable Quartz

“…Also taking into account previous reports on the porcelain worker cohort, [5][6][7] it becomes obvious that the most crucial point in the presented study seems to be the healthy-worker effect. The fixed cohort of workers in the German porcelain industry consists solely of "prevalent" hires, that is, of those employees already at work at the start of the follow-up.…”

Respirable Crystalline Silica Exposure–Response Evaluation of Silicosis Morbidity and Lung Cancer Mortality in the German Porcelain Industry Cohort

“…22 In short, more than 8000 combined static (stationary area) and personal total, respirable and silica dust industrial hygiene measurements were available for about 100 discrete production area or job task code combinations beginning in 1954 and covering all years through the end of folowup. Original sampling and analysis protocols were available for these measurements.…”

“…Extensive industrial hygiene exposure data for this cohort have been obtained and used to derive quantitative exposure estimates for each cohort member. 22 Furthermore, evaluation of a large archive of radiographic examinations obtained as part of a medical surveillance program for German porcelain workers including a substantial proportion of this cohort facilitated radiographic determination of silicosis morbidity. Combining the mortality data, the silicosis morbidity data, and the quantitative exposure assessment allows quantitative evaluation of potential relationships between estimates of respirable crystalline silica exposure and silicosis morbidity and lung cancer mortality.…”