Distribution of covariates among biodosimetry study subjects, mean translocation frequencies, and rate ratios by covariate categories, U.S. Radiologic Technologists Study
| Characteristic . | Subjects (n = 150)* . | Mean number of translocations per 100 CEs . | Translocation rate ratios† (95% CI) . | |||
|---|---|---|---|---|---|---|
| Age at blood draw (y)‡ | ||||||
| 71–74 | 17 (11%) | 0.9 | 0.7 (0.5, 1.0) | |||
| 75–78 | 59 (39%) | 1.4 | 1.0 (reference) | |||
| 79–82 | 31 (21%) | 1.3 | 1.0 (0.8, 1.2) | |||
| 83–86 | 31 (21%) | 1.5 | 1.1 (0.9, 1.4) | |||
| 87–90 | 12 (8%) | 1.9 | 1.5 (1.1, 2.0) | |||
| Gender | ||||||
| Female | 104 (69%) | 1.2 | 1.0 (reference) | |||
| Male | 46 (31%) | 1.7 | 1.3 (1.1, 1.6) | |||
| Race | ||||||
| Caucasian | 147 (98%) | 1.4 | N/A | |||
| African American | 1 (<1%) | N/A | N/A | |||
| Other | 2 (1%) | N/A | N/A | |||
| Former cigarette smoking (number of pack-years) | ||||||
| 0 | 87 (58%) | 1.4 | 1.0 (reference) | |||
| >0–20 | 31 (21%) | 1.2 | 1.1 (0.8, 1.5) | |||
| >20–50 | 17 (11%) | 1.5 | 1.2 (0.9, 1.6) | |||
| >50 | 14 (9%) | 1.6 | 1.7 (0.8, 3.7) | |||
| History of X-ray therapy for benign conditions | ||||||
| Never | 133 (89%) | 1.4 | 1.0 (reference) | |||
| Ever | 17 (11%) | 1.6 | 1.2 (0.9, 1.5) | |||
| In the past, allowed others to take practice X-rays | ||||||
| Never | 88 (59%) | 1.3 | 1.0 (reference) | |||
| 1–24 times | 35 (23%) | 1.4 | 1.0 (0.8, 1.3) | |||
| ≥25 times | 15 (10%) | 1.8 | 1.3 (1.0, 1.7) | |||
| Estimated occupational radiation dose to the RBM§ | ||||||
| ≤10 mGy | 53 (35%) | 1.1 | 1.0 (reference) | |||
| >10–20 mGy | 43 (29%) | 1.3 | 1.1 (0.9, 1.5) | |||
| >20–30 mGy | 27 (18%) | 1.7 | 1.5 (1.2, 2.0) | |||
| >30–40 mGy | 17 (11%) | 1.5 | 1.4 (1.0, 1.8) | |||
| >40 mGy | 10 (7%) | 1.7 | 1.4 (1.0, 2.0) | |||
| Cumulative personal diagnostic RBM radiation dose score∥ | ||||||
| 0–20 | 51 (34%) | 1.2 | 1.0 (reference) | |||
| >20–50 | 51 (34%) | 1.3 | 1.1 (0.9, 1.4) | |||
| >50–100 | 28 (17%) | 1.3 | 1.1 (0.9, 1.4) | |||
| >100 | 20 (13%) | 2.0 | 1.6 (1.2, 2.0) | |||
| Characteristic . | Subjects (n = 150)* . | Mean number of translocations per 100 CEs . | Translocation rate ratios† (95% CI) . | |||
|---|---|---|---|---|---|---|
| Age at blood draw (y)‡ | ||||||
| 71–74 | 17 (11%) | 0.9 | 0.7 (0.5, 1.0) | |||
| 75–78 | 59 (39%) | 1.4 | 1.0 (reference) | |||
| 79–82 | 31 (21%) | 1.3 | 1.0 (0.8, 1.2) | |||
| 83–86 | 31 (21%) | 1.5 | 1.1 (0.9, 1.4) | |||
| 87–90 | 12 (8%) | 1.9 | 1.5 (1.1, 2.0) | |||
| Gender | ||||||
| Female | 104 (69%) | 1.2 | 1.0 (reference) | |||
| Male | 46 (31%) | 1.7 | 1.3 (1.1, 1.6) | |||
| Race | ||||||
| Caucasian | 147 (98%) | 1.4 | N/A | |||
| African American | 1 (<1%) | N/A | N/A | |||
| Other | 2 (1%) | N/A | N/A | |||
| Former cigarette smoking (number of pack-years) | ||||||
| 0 | 87 (58%) | 1.4 | 1.0 (reference) | |||
| >0–20 | 31 (21%) | 1.2 | 1.1 (0.8, 1.5) | |||
| >20–50 | 17 (11%) | 1.5 | 1.2 (0.9, 1.6) | |||
| >50 | 14 (9%) | 1.6 | 1.7 (0.8, 3.7) | |||
| History of X-ray therapy for benign conditions | ||||||
| Never | 133 (89%) | 1.4 | 1.0 (reference) | |||
| Ever | 17 (11%) | 1.6 | 1.2 (0.9, 1.5) | |||
| In the past, allowed others to take practice X-rays | ||||||
| Never | 88 (59%) | 1.3 | 1.0 (reference) | |||
| 1–24 times | 35 (23%) | 1.4 | 1.0 (0.8, 1.3) | |||
| ≥25 times | 15 (10%) | 1.8 | 1.3 (1.0, 1.7) | |||
| Estimated occupational radiation dose to the RBM§ | ||||||
| ≤10 mGy | 53 (35%) | 1.1 | 1.0 (reference) | |||
| >10–20 mGy | 43 (29%) | 1.3 | 1.1 (0.9, 1.5) | |||
| >20–30 mGy | 27 (18%) | 1.7 | 1.5 (1.2, 2.0) | |||
| >30–40 mGy | 17 (11%) | 1.5 | 1.4 (1.0, 1.8) | |||
| >40 mGy | 10 (7%) | 1.7 | 1.4 (1.0, 2.0) | |||
| Cumulative personal diagnostic RBM radiation dose score∥ | ||||||
| 0–20 | 51 (34%) | 1.2 | 1.0 (reference) | |||
| >20–50 | 51 (34%) | 1.3 | 1.1 (0.9, 1.4) | |||
| >50–100 | 28 (17%) | 1.3 | 1.1 (0.9, 1.4) | |||
| >100 | 20 (13%) | 2.0 | 1.6 (1.2, 2.0) | |||
NOTE: In cytogenetic studies of radiation-exposed individuals, it is common to express the translocation frequency as per 100 or per 1,000 CEs as this allows a comparison with other laboratories that may have painted a different combination of chromosomes.
Abbreviation: N/A, not applicable.
Does not always sum to 150 or 100% due to small numbers and percentages in the unknown category: Smoking, n = 1; worked with radioisotopes, n = 2; in the past allowed others to take practice X-rays, n = 12.
Poisson regression adjusted for age; unknowns not included.
Ptrend = <0.001 from Poisson regression with ordinal age categories treated as a continuous variable.
Ptrend = 0.006 from age-adjusted Poisson regression with ordinal estimated occupational RBM dose categories as a continuous variable.
Ptrend = 0.001 from age-adjusted Poisson regression with ordinal estimated personal diagnostic RBM dose score categories treated as a continuous variable. One dose score unit is approximately equivalent to 1 mGy.