Incidence RRs of Alzheimer’s disease, ‘Alzheimer’s and other dementias’, Parkinson’s disease, and parkinsonism among workers in mining industries or occupations compared to workers in non-mining industries or occupations in subcohorts for each outcome
| Alzheimer’s disease (2006–2016) | ‘Alzheimer’s and other dementias’ (1999–2016) | Parkinson’s disease (2006–2016) | Parkinsonism (1999–2016) | |||||
| Cases | RR (95% CI) | Cases | RR (95% CI) | Cases | RR (95% CI) | Cases | RR (95% CI) | |
| By mining industry classification (SIC code) | ||||||||
| Workers in non-mining industries | 3696 | 1.00 (–) | 36 186 | 1.00 (–) | 3572 | 1.00 (–) | 8130 | 1.00 (–) |
| Workers in industry of mines (including milling), quarries and oil wells (04) | 88 | 0.99 (0.80 to 1.23) | 814 | 0.95 (0.89 to 1.02) | 87 | 1.06 (0.86 to 1.32) | 174 | 0.95 (0.81 to 1.10) |
| Major industry groups | ||||||||
| Workers of metal mines (09) | 69 | 1.00 (0.79 to 1.27) | 614 | 0.95 (0.87 to 1.03) | 67 | 1.08 (0.85 to 1.38) | 127 | 0.93 (0.78 to 1.10) |
| Workers of non-metal mines (10)* | 5 | 1.27 (0.53 to 3.04) | 44 | 1.17 (0.87 to 1.57) | 6 | 1.62 (0.73 to 3.61) | 16 | 1.95 (1.19 to 3.18) |
| Workers of quarries and sand pits (12) | 9 | 0.98 (0.51 to 1.89) | 81 | 0.83 (0.67 to 1.04) | 8 | 0.86 (0.43 to 1.73) | 16 | 0.73 (0.45 to 1.19) |
| Workers of services incidental to mining (13) | 5 | 0.66 (0.28 to 1.60) | 81 | 0.98 (0.78 to 1.21) | 7 | 0.89 (0.42 to 1.86) | 15 | 0.78 (0.47 to 1.30) |
| Minor industry groups under metal mines | ||||||||
| Workers of gold mines (051 and 052) | 14 | 1.49 (0.88 to 2.52) | 106 | 1.10 (0.91 to 1.33) | 9 | 1.09 (0.57 to 2.10) | 19 | 0.95 (0.60 to 1.49) |
| Workers of uranium mines (057) | <5 | – | 58 | 0.97 (0.75 to 1.25) | 5 | 0.85 (0.35 to 2.04) | 12 | 0.81 (0.46 to 1.43) |
| Workers of miscellaneous metal mines (059)†† | 50 | 0.93 (0.71 to 1.24) | 442 | 0.91 (0.83 to 1.00) | 52 | 1.10 (0.83 to 1.44) | 97 | 0.95 (0.78 to 1.16) |
| By Mining Occupation Classification (CCDO code) | ||||||||
| Workers in non-mining occupations | 3727 | 1.00 (–) | 36 575 | 1.00 (–) | 3613 | 1.00 (–) | 8217 | 1.00 (–) |
| Workers in mining and quarrying including oil and gas field occupations (77) | 57 | 1.28 (0.98 to 1.66) | 426 | 0.95 (0.87 to 1.05) | 46 | 1.08 (0.81 to 1.44) | 88 | 0.90 (0.73 to 1.12) |
| Minor occupation groups | ||||||||
| Foremen (7710) | 7 | 1.18 (0.56 to 2.48) | 50 | 0.93 (0.70 to 1.23) | <5 | – | 6 | 0.56 (0.25 to 1.25) |
| Workers in rock and soil drilling occupations (7713) | 17 | 1.20 (0.74 to 1.93) | 136 | 0.98 (0.83 to 1.16) | 21 | 1.60 (1.04 to 2.45) | 31 | 1.04 (0.73 to 1.48) |
| Workers in cutting, handling and loading occupations (7717) | 22 | 1.28 (0.84 to 1.95) | 166 | 0.94 (0.80 to 1.09) | 16 | 0.93 (0.57 to 1.53) | 34 | 0.86 (0.61 to 1.21) |
| Workers in labouring and other elemental work (7718) | 8 | 1.39 (0.69 to 2.78) | 58 | 0.98 (0.75 to 1.26) | <5 | – | 9 | 0.65 (0.34 to 1.25) |
| Workers in other occupations (7719) | 10 | 1.42 (0.76 to 2.64) | 61 | 0.75 (0.58 to 0.96) | 8 | 1.00 (0.50 to 2.00) | 20 | 1.02 (0.66 to 1.59) |
| Both Mining Industry and Occupation Classification (SIC and CCDO codes) | ||||||||
| Workers in non-mining industries | 3696 | 1.00 (–) | 36 186 | 1.00 (–) | 3572 | 1.00 (–) | 8130 | 1.00 (–) |
| Workers in industry of mines and occupations of mining and quarrying (SIC 04 and CCDO 77) | 50 | 1.20 (0.91 to 1.59) | 383 | 0.93 (0.84 to 1.03) | 42 | 1.08 (0.80 to 1.46) | 79 | 0.90 (0.72 to 1.12) |
| Workers in metal mines and occupations of mining and quarrying (SIC 09 and CCDO 77) | 47 | 1.26 (0.94 to 1.68) | 339 | 0.94 (0.84 to 1.04) | 37 | 1.08 (0.78 to 1.49) | 67 | 0.87 (0.69 to 1.11) |
| Workers in non-metal mines and occupations of mining and quarrying (SIC 10 and CCDO 77) | <5 | – | 9 | 1.10 (0.57 to 2.11) | <5 | – | <5 | – |
| Workers in gold mines and occupations of mining and quarrying (SIC (051 and 052) and CCDO 77) | 8 | 1.26 (0.63 to 2.52) | 69 | 1.05 (0.83 to 1.32) | 8 | 1.43 (0.72 to 2.86) | 17 | 1.25 (0.78 to 2.01) |
| Workers in uranium mines and occupations of mining and quarrying (SIC 057 and CCDO 77) | <5 | – | 33 | 1.02 (0.72 to 1.43) | <5 | – | 5 | 0.59 (0.25 to 1.42) |
| Workers in miscellaneous metal mines and occupations of mining and quarrying (SIC 059 and CCDO 77) | 36 | 1.27 (0.92 to 1.77) | 235 | 0.89 (0.78 to 1.01) | 26 | 1.01 (0.69 to 1.49) | 47 | 0.84 (0.63 to 1.12) |
Follow-up was censored at age 100 years old. All models were adjusted by mean age, age2 and birth year. Results for workers in rotary well-drilling and related occupations (CCDO 7711) and blasting occupations (CCDO 7715) were not presented due to the total number of workers under 500 and small case counts (<5) for most neurodegenerative outcomes.
Alzheimer’s disease: at least one record with one diagnostic code (ICD-10: G30) in any diagnostic field in DAD or NACRS.
Alzheimer’s and other dementias: At least one record with one diagnostic code (ICD-10 F00, F01, F02, F03, G30) in any diagnostic field in DAD or NACRS or at least two physician encounters with at least one diagnostic code in OHIP (OHIP code 290, 331) within 12 months.
Parkinson’s disease: at least one record with one diagnostic code (ICD10: G20) in any diagnostic field in DAD or NACRS.
Parkinsonism: at least one record with one diagnostic code ICD-10 G20, G21.0-0.4, G21.8-9, G22, F02.3) in any diagnostic field in DAD or NACRS or at least two physician encounters with at least one diagnostic code in OHIP (OHIP code 332) within 12 months.
*Workers in non-metal minesinclude those ever employed in Coal Mines, Crude Petroleum and Natural GasIndustry, Asbestos Mines, Peat Extraction, Gypsum Mines and MiscellaneousNon-metal Mine which consists of 66% of saltmines.
†Miscellaneous metal mines consist ofnickel (78%) and zinc mines (13%), and others (9%) in the ODSS cohort.
CCDO, Canadian Classification Dictionary of Occupations; DAD, Hospital Discharge Abstract Database; NACRS, National Ambulatory Care Reporting System; OHIP, Ontario Health Insurance Plan Claims Database; RR, rate ratio; SIC, Standard Industrial Classification.