Characteristics of the Estonian cohort of Chernobyl cleanup workers (exposed cohort) and the unexposed comparison cohort
| Characteristic | Exposed cohort | Unexposed cohort | ||
|---|---|---|---|---|
| N | (%) | N | (%) | |
| Total | 3680 | 100 | 7631 | 100 |
| Vital status on 31 December 2012 | ||||
| Living in Estonia | 3132 | 85.1 | 6795 | 89.0 |
| Dead | 474 | 12.9 | 798 | 10.5 |
| Emigrated | 74 | 2.0 | 38 | 0.5 |
| Age at start of follow-up (full years | ||||
| 35–44 | 1265 | 34.4 | 2645 | 34.7 |
| 45–54 | 1850 | 50.3 | 3738 | 49.0 |
| 55–64 | 536 | 14.6 | 1186 | 15.5 |
| ≥65 | 29 | 0.8 | 62 | 0.8 |
| Person-years in an age group (2004–2012 | ||||
| 35–44 | 4718.4 | 15.4 | 9416.1 | 14.5 |
| 45–54 | 15,513.5 | 50.6 | 32 825.3 | 50.4 |
| 55–64 | 9303.9 | 30.3 | 20 126.9 | 30.9 |
| ≥65 | 1138.6 | 3.7 | 2743.5 | 4.2 |
| Total | 30 674.4 | 100 | 65 111.8 | 100 |
| Ethnicity | ||||
| Estonian | 2036 | 55.3 | 4690 | 61.5 |
| Non-Estonian | 1643 | 44.6 | 2848 | 37.3 |
| Unknown | 1 | 0.0 | 93 | 1.2 |
| Education | ||||
| Higher | 322 | 8.8 | 1159 | 15.2 |
| Secondary | 2446 | 66.5 | 4017 | 52.6 |
| Basic or less | 824 | 22.4 | 1200 | 15.7 |
| Unknown | 88 | 2.4 | 1255 | 16.4 |
| Time of arrival in the Chernobyl area | ||||
| 1986, April–May | 1154 | 31.4 | ||
| 1986, June–December | 1128 | 30.7 | ||
| 1986, month unknown | 13 | 0.4 | ||
| 1987 | 820 | 22.3 | ||
| 1988 | 417 | 11.3 | ||
| 1989–1991 | 67 | 1.8 | ||
| Unknown | 81 | 2.2 | ||
| Duration of stay in the Chernobyl area (days | ||||
| <30 | 220 | 6.0 | ||
| 30–89 | 1487 | 40.4 | ||
| 90–149 | 1163 | 31.6 | ||
| 150–209 | 648 | 17.6 | ||
| ≥210 | 60 | 1.6 | ||
| Unknown | 102 | 2.8 | ||
| Documented dose (cGy | ||||
| <5.0 | 810 | 22.0 | ||
| 5.0–9.9 | 1022 | 27.8 | ||
| 10.0–14.9 | 555 | 15.1 | ||
| 15.0–19.9 | 519 | 14.1 | ||
| 20.0–24.9 | 195 | 5.3 | ||
| ≥25.0 | 21 | 0.6 | ||
| Unknown | 558 | 15.2 | ||