Serum biochemistry profiles by noise exposure status
| Never exposed (n=5071) | Current exposed (n=1236) | Tertiles of accumulated exposure time | |||
| Short (n=421) | Medium (n=399) | Long (n=416) | |||
| Leukocytes (×109/l), mean (SE) | 7.2 (0.1) | 7.4 (0.1)* | 7.6 (0.1)* † | 7.2 (0.1) | 7.3 (0.1) |
| Platelets (×109/l), mean (SE) | 270.0 (1.3) | 265.8 (1.7)* † | 266.7 (3.6) | 266.6 (3.3) | 263.9 (3.3) |
| Haematocrit (%), mean (SE) | 42.4 (0.1) | 45.0 (0.2)* | 45.0 (0.3)* | 45.0 (0.3)* | 45.1 (0.3)* |
| Fibrinogen (g/l), mean (SE)‡ | 3.52 (0.03) | 3.47 (0.06) | 3.47 (0.07) | 3.40 (0.08) | 3.52 (0.06) |
| CRP (mg/l), median (IQR) | 0.18 (0.06–0.42) | 0.15 (0.07–0.33)* | 0.13 (0.06–0.33)* | 0.14 (0.06–0.31)* | 0.17 (0.08–0.36) |
| Homocysteine (μmol/l), mean (SE) | 8.1 (0.1) | 8.7 (0.1)* | 8.3 (0.1) | 9.0 (0.3)* | 8.9 (0.1)* |
| Total cholesterol (mmol/l), mean (SE) | 5.19 (0.02) | 5.25 (0.05) | 5.08 (0.10) | 5.17 (0.07) | 5.50 (0.08)* |
| HDL-cholesterol (mmol/l), mean (SE) | 1.38 (0.01) | 1.24 (0.01)* | 1.24 (0.02)* | 1.23 (0.02)* | 1.25 (0.02)* |
| LDL-cholesterol (mmol/l), mean (SE)§ | 3.10 (0.03) | 3.15 (0.04) | 2.99 (0.09) | 3.12 (0.07) | 3.31 (0.07)* |
| Triglyceride (mmol/l)§ ¶ | 1.28 (1.02) | 1.40 (1.03) | 1.25 (1.05) | 1.32 (1.06) | 1.61 (1.05)* |
| Plasma glucose (mmol/l)§ ¶ | 5.34 (1.01) | 5.49 (1.01)* | 5.33 (1.01) | 5.41 (1.01) | 5.72 (1.01)* |
| Serum insulin (pmol/l)§ ¶ ** | 42.3 (1.0) | 42.0 (1.1) | 42.5 (1.1) | 40.5 (1.1) | 43.2 (1.1) |
CRP, C-reactive protein; HDL, high-density lipoprotein cholesterol; IQR, interquartile range; LDL, low-density lipoprotein cholesterol; SE, standard error.
↵* p<0.05 compared with the never exposed group in bivariable analysis.
↵† p <0.05 compared with the never exposed group after adjustment for age, sex, ethnicity, BMI, educational level, leisure time physical activity, cigarette smoking and diabetes (model 2).
↵‡ Only available during NHANES 1999–2000, 2001–2002 for participants aged 40 years and older. Four-year weights were incorporated into this analysis. Number of participants in the current/never exposed group: 422/1721.
↵§ This is a morning fasting sample; 6-year fasting weights were incorporated into the analysis. Number of participants in the current/never exposed group: LDL-cholesterol 519/2147, triglyceride 535/2202, plasma glucose 537/2229, serum insulin 533/2197.
↵¶ Geometric mean (SE of the geometric mean).
↵** Serum insulin level was measured using a Pharmacia method during NHANES 1999–2002 but a Tosoh method during NHANES 2003–2004. The Pharmacia values were transferred into the Tosoh values to keep insulin values consistent; two participants with negative transferred values were excluded from the analysis.