Occupational Silica Exposure and Chronic Kidney Disease

Abstract

Introduction Occupational exposure to silica may be associated with chronic kidney disease (CKD). Most studies have been conducted in occupational cohorts with high levels of exposure but small numbers of cases. We analyzed data from a population-based case-control study of occupational silica exposure and CKD. Methods Cases were hospital patients with newly diagnosed CKD and community controls were selected using random digit dialing and frequency matched by age, gender, race and proximity to the hospital. Silica exposure estimates were assigned by industrial hygiene review of lifetime job history data and weighted for certainty and intensity. Conditional logistic regression was used to estimate the odds ratios (ORs) for CKD conditioned on demographic, lifestyle and clinical variables. Results The mean age of participants was 62 years (range, 30-83 years), 56% were male and 54% were white. Any silica exposure (compared to none) was associated with a 40% increased risk of CKD (OR=1.40, 95% confidence interval [CI]: 1.04, 1.89) in a multivariable adjusted model. The mean cumulative duration of silica exposure was significantly higher in exposed cases than in exposed controls (33.4 vs. 24.8 years, respectively). Overall, compared to non-exposed participants, the ORs (95% CI) for those below and above the median duration of silica exposure were 1.20 (95% CI: 0.77, 1.86) and 1.76 (95% CI: 1.14, 2.71), respectively. Conclusions We found a positive relationship between occupational silica exposure and CKD. A dose-response trend of increasing CKD risk with increasing duration of silica exposure was observed and was particularly strong among non-whites.

Health effects of occupational exposure to crystalline silica in the light of current research results

“…Similar values of the OR were assessed for renal insufficiency, 1.74 (95% CI: 1.05-2.87) and for end-stage kidney diseases, 1.75 (95% CI: 0.76-4.01) although the latter value was not statistically significant (59).…”

“…The results of epidemiological studies on the relationship between exposure and various pathological changes in the kidneys are not clear (11,38,39,58,59). The risk of chronic kidney disease assessed by Steenland et al (11) based on pooled analyses of the results of three cohorts was increased in proportion to the exposure to crystalline silica; the OR in the upper quartile of cumulative silica exposure above 1.67 mg/m 3 ×years was 3.93 (95% CI: 1.31-11.76), and the SMR for all the exposed was 1.41 (95% CI: 1.05-1.85).…”

“…Chronic renal disease observed in an increased number of cases among the workers exposed to crystalline silica is supposed to be associated with 3 possible mechanisms of their development: deposition in the kidneys of immune complexes resulting from the inflammatory processes taking place in the lungs; disorders of the immune system leading to autoimmunization; or direct nephrotoxicity of the silica transported by blood from alveoli to the kidneys (3,39,(57)(58)(59).…”

Silicosis and urinary analysis

“…There was no relationship between the duration of silica exposure and the prevalence of kidney disease or elevated creatinine. Vupputuri et al [10] also found a positive relationship between occupational silica exposure and chronic kidney disease. A dose-response trend of increasing chronic kidney disease with increasing silica exposure was also observed in the same study, especially in nonwhites.…”

Selected work-related nephropathies

“…Występowanie PChN związanej z narażeniem na krzemionkę jest często poruszane w piśmiennictwie i dotyczy głównie osób pracujących w narażeniu na nią powyżej 10 lat, z rozpoznaniem pylicy, palących papierosy oraz częściej rasy innej niż kaukaska [59]. W dużym badaniu chorych z pylicą aż 33% spośród 283 osób, z dostępnymi wynikami badań laboratoryjnych, miało kreatyninę powyżej 1,5 mg/dl [60].…”