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

Abstract

Respirable crystalline silica exposure more than 4 mg/m-years (cumulative) or more than 0.15 mg/m (average) were strongly associated with silicosis, but unrelated to lung cancer risks.

Differences in gene expression and cytokine production by crystalline vs. amorphous silica in human lung epithelial cells

“…With increasing numbers and compositional heterogeneity of potentially harmful natural and synthetic particulates, there is a vital need for screening assays to determine their potential pathogenicity. Crystalline silica particles are known to cause silicosis (a pneumoconiosis) and have other detrimental respiratory effects when inhaled in excessive amounts [1]. Airborne exposures are also associated with lung inflammatory diseases, increased susceptibility to infection, as well as lung cancers, especially in smokers [2,3].…”

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.…”

Extended follow-up of lung cancer and non-malignant respiratory disease mortality among California diatomaceous earth workers: Table 1

“…Assuming an average duration of employment of 10 years, average exposure intensity can be estimated at 1.0–1.2 and 0.38–0.45 mg/m 3 for the highest exposure groups, respectively. In a study of German porcelain workers,3 an excess of silicosis (International Labour Organization ≥1/1) was demonstrated among those exposed to >4.0 mg/m 3  years, or with average intensity of 0.15 mg/m 3 , and possibly as high as 0.25 mg/m 3 . 4…”

“…Some recent reports suggest exposure thresholds for both lung cancer and silicosis;3 8 9 others demonstrate a linear or other monotonic risk 10 11. Determining precisely where any exposure threshold lies will require additional studies that quantify crystalline silica exposures, and have individual smoking history data.…”