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Table 2 HRs for total and cause-specific mortality associated with silica exposure in the cohort (n = 7,665), 1960–2012

From: Combined effect of silica dust exposure and cigarette smoking on total and cause-specific mortality in iron miners: a cohort study

Cause of death (ICD-10)

Number of deaths

HRs for per 1 mg/m3-y increase in CDE

HRs for silica exposure levels versus unexposeda

Low

Medium

High

p-Valueb

Malignant neoplasm (C00-C97)

789

1.048 (0.962, 1.142)

1.531 (1.241, 1.890)

1.378 (1.137, 1.669)

1.238 (1.025, 1.494)

0.009

 Malignant neoplasm of oesophagus (C15)

66

0.952 (0.693, 1.307)

1.335 (0.648, 2.753)

1.511 (0.795, 2.874)

1.249 (0.644, 2.420)

0.384

 Malignant neoplasm of stomach (C16)

104

1.130 (0.931, 1.373)

1.980 (1.153, 3.401)

1.380 (0.800, 2.379)

1.367 (0.814, 2.295)

0.223

 Malignant neoplasm of liver and intrahepatic bile ducts (C22)

152

0.774 (0.585, 1.025)

1.512 (0.972, 2.353)

1.060 (0.681, 1.648)

0.774 (0.487, 1.229)

0.359

 Lung cancer (C33-C34)

262

1.190 (1.049, 1.349)

1.671 (1.132, 2.466)

1.663 (1.193, 2.318)

1.671 (1.216, 2.298)

0.001

Certain infectious and parasitic diseases (A00-B99, J65)

89

1.204 (1.018, 1.423)

1.073 (0.520, 2.212)

1.560 (0.882, 2.761)

1.790 (1.064, 3.010)

0.020

 Respiratory tuberculosis (A15-A16, J65)

58

1.226 (1.017, 1.477)

0.523 (0.153, 1.785)

1.459 (0.695, 3.061)

2.532 (1.383, 4.635)

0.002

Cardiovascular disease (I00-I52, I70-I99)

372

1.213 (1.117, 1.318)

0.986 (0.672, 1.447)

1.373 (1.030, 1.831)

1.723 (1.345, 2.206)

< 0.001

 Ischaemic heart disease (I20-I25)

219

1.134 (0.990, 1.298)

1.190 (0.738, 1.918)

1.538 (1.063, 2.226)

1.781 (1.281, 2.476)

< 0.001

 Pulmonary heart disease (I26-I27)

66

1.352 (1.197, 1.529)

0.562 (0.168, 1.880)

1.258 (0.615, 2.573)

2.009 (1.160, 3.479)

0.010

Cerebrovascular disease (I60-I69)

388

0.973 (0.859, 1.103)

0.950 (0.670, 1.345)

1.234 (0.945, 1.613)

0.945 (0.724, 1.233)

0.995

Disease of the respiratory system (J00-J99)

324

1.414 (1.329, 1.505)

2.817 (1.927, 4.118)

2.714 (1.954, 3.768)

3.615 (2.718, 4.807)

< 0.001

 Pneumoconiosis (J60-J65)

110

1.384 (1.255, 1.525)

1.000 (reference)

2.245 (0.912, 5.524)

5.312 (2.298, 12.280)

< 0.001

 Chronic lower respiratory disease (J40-J47)

142

1.264 (1.115, 1.434)

2.759 (1.688, 4.507)

2.060 (1.304, 3.253)

1.720 (1.106, 2.675)

0.012

Disease of the digestive system (K00-K93)

95

0.877 (0.635, 1.211)

1.467 (0.831, 2.587)

1.065 (0.605, 1.874)

0.838 (0.468, 1.499)

0.629

 Fibrosis and cirrhosis of liver (K74)

63

0.770 (0.487, 1.218)

1.302 (0.651, 2.601)

1.079 (0.549, 2.121)

0.714 (0.335, 1.524)

0.488

External causes of morbidity and mortality (V01-Y98)

193

0.883 (0.702, 1.110)

2.839 (1.996, 4.038)

1.145 (0.745, 1.761)

0.928 (0.591, 1.458)

0.953

All diseases (A00-Y98)

2814

1.117 (1.074, 1.162)

1.368 (1.218, 1.537)

1.246 (1.121, 1.383)

1.313 (1.192, 1.447)

< 0.001

  1. HRs were calculated by using Cox proportional hazards models, which included the duration of follow-up as time variable and were adjusted for gender, year at hire (five categories: 1955 or earlier, 1956–1960, 1961–1965, 1966–1970, 1971 or later), age at hire (continuous), and smoking intensity (continuous). Pneumoconiosis mortality risks were estimated only among silica-exposed workers
  2. aThe categorical analyses were conducted on the basis of various silica exposure level, i.e. unexposed, low (0.4935 mg/m3-y or below), medium (0.4935 to 0.8423 mg/m3-y), and high level (0.8423 mg/m3-y or above). The reference category was defined as the unexposed level, except pneumoconiosis, which used low level as reference category
  3. bEvaluated by including the median exposure values within each exposure level as a continuous variable in the model
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Environmental Health

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