Table 3.
Incidence rate ratios (RR) of neurodegenerative disease (1992–2018) by self-reported McIntyre Powder (MP) exposure (periods and duration of exposure and time since last exposure) among male miners in the study cohort. [CI=confidence interval.] a
| MP exposure assessment: Self-reports | Alzheimer’s disease | Alzheimer’s with other dementias | Parkinson’s disease | Parkinsonism | Motor neuron disease | |||||
|---|---|---|---|---|---|---|---|---|---|---|
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| Cases | RR (95% CI) | Cases | RR (95% CI) | Cases | RR (95% CI) | Cases | RR (95% CI) | Cases | RR (95% CI) | |
| MP unexposed | 589 | 1.00 (‥) | 3294 | 1.00 (‥) | 393 | 1.00 (‥) | 667 | 1.00 (‥) | 61 | 1.00 (‥) |
| MP exposed | 278 | 0.96 (0.83–1.11) | 1721 | 1.12 (1.06–1.19) | 251 | 1.34 (1.14–1.57) | 364 | 1.19 (1.05–1.36) | 20 | 0.82 (0.49–1.37) |
| Only before 1956 | 44 | 0.90 (0.66–1.23) | 260 | 1.11 (0.98–1.26) | 34 | 1.18 (0.83–1.69) | 45 | 1.08 (0.80–1.48) | <6 | ‥ |
| Ever after 1956 | 234 | 0.97 (0.83–1.13) | 1461 | 1.12 (1.05–1.19) | 217 | 1.36 (1.16–1.61) | 319 | 1.21 (1.06–1.38) | 20 | 0.90 (0.54–1.50) |
| Only after 1956 | 122 | 0.91 (0.75–1.11) | 854 | 1.09 (1.01–1.18) | 125 | 1.34 (1.09–1.64) | 192 | 1.16 (0.99–1.37) | 16 | 1.01 (0.58–1.76) |
| Duration (year) of exposure | ||||||||||
| >0–1 | 39 | 0.70 (0.51–0.97) | 321 | 1.03 (0.92–1.15) | 50 | 1.36 (1.01–1.82) | 73 | 1.17 (0.92–1.49) | 9 | 1.62 (0.81–3.27) |
| >1–5 | 99 | 0.97 (0.79–1.21) | 636 | 1.14 (1.05–1.24) | 90 | 1.34 (1.07–1.69) | 132 | 1.18 (0.98–1.42) | <6 | ‥ |
| >5–10 | 57 | 1.04 (0.80–1.37) | 323 | 1.13 (1.01–1.27) | 48 | 1.35 (1.00–1.83) | 66 | 1.15 (0.89–1.48) | <6 | ‥ |
| >10 | 83 | 1.06 (0.84–1.34) | 441 | 1.15 (1.04–1.27) | 63 | 1.30 (0.99–1.71) | 93 | 1.27 (1.02–1.58) | <6 | ‥ |
| P-value for linear trend | 0.469 | 0.002 | 0.003 | 0.030 | 0.760 | |||||
| Time (year) since last exposure | ||||||||||
| 12–19 | 6 | 0.53 (0.24–1.19) | 73 | 1.26 (0.99–1.60) | 12 | 1.40 (0.78–2.52) | 29 | 1.53 (1.05–2.24) | <6 | ‥ |
| 20–29 | 41 | 0.96 (0.69–1.32) | 266 | 1.20 (1.06–1.37) | 41 | 1.39 (1.00–1.93) | 73 | 1.32 (1.02–1.67) | <6 | ‥ |
| 30–39 | 78 | 0.99 (0.78–1.26) | 500 | 1.17 (1.07–1.29) | 76 | 1.42 (1.11–1.82) | 122 | 1.27 (1.04–1.54) | 9 | 1.07 (0.53–2.17) |
| 40–49 | 95 | 0.98 (0.79–1.22) | 551 | 1.11 (1.02–1.22) | 88 | 1.42 (1.12–1.79) | 106 | 1.15 (0.94–1.42) | <6 | ‥ |
| 50–75 | 59 | 0.95 (0.72–1.26) | 331 | 0.99 (0.88–1.11) | 35 | 1.01 (0.71–1.44) | 35 | 0.82 (0.58–1.17) | <6 | ‥ |
a
All estimates are from Poisson regression models adjusted for age, age2, and birth year throughout the follow-up period. The P-value for linear trend was derived from Poisson regression models.