Occupational silica exposure and chronic kidney disease.
BACKGROUND
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 63 years (range 30-83 years); 59% were male and 55% were white. Any silica exposure (compared with 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 with nonexposed participants, the ORs (95% CI) for those below and above the median duration of silica exposure were 1.20 (0.77, 1.86) and 1.76 (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 nonwhites.
The Center for Health Research/Southeast, Kaiser Permanente Georgia, Atlanta, GA 30305, USA. suma.vupputuri@kp.org
Suma
S
Vupputuri
Christine G
CG
Parks
Leena A
LA
Nylander-French
Ashli
A
Owen-Smith
Susan L
SL
Hogan
Dale P
DP
Sandler
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002908:Chronic Disease; D005260:Female; D006801:Humans; D007674:Kidney Diseases / Q000139:chemically induced* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000139:chemically induced* / Q000453:epidemiology; D016273:Occupational Exposure / Q000009:adverse effects*; D012822:Silicon Dioxide / Q000009:adverse effects*
D012822:Silicon Dioxide