Table 2 Comparison of the possible confounding factors among the different exposure categories.
| Control | Exposed | |||||||
|---|---|---|---|---|---|---|---|---|
| Total | Current work type* | Cumulative exposure length, years† | ||||||
| Production | Development | Maintenance | 1–10 | 11–20 | 21+ | |||
| Surveyed, n | 212 | 600 | 142 | 114 | 344 | 271 | 295 | 27 |
| Age (years) | 38 (9) | 35§ (8) | 39 (11) | 36§ (6) | 32§ (5) | 33§ (9) | 35§ (5) | 44§ (5) |
| Height (cm) | 170 (6) | 171 (6) | 170 (6) | 171 (5) | 172§ (6) | 171 (6) | 171 (6) | 170 (6) |
| BMI (kg/m2) | 23 (3) | 23 (3) | 23 (3) | 23 (3) | 23 (3) | 23 (3) | 23 (3) | 23 (4) |
| Smoking habit‡ | ||||||||
| Never | 58 (27) | 157 (26) | 32 (23) | 45 (40) | 80 (23) | 84 (31) | 64 (22) | 7 (26) |
| Former | 27 (13) | 71 (12) | 17 (12) | 21 (19) | 33 (10) | 31 (12) | 36 (13) | 3 (11) |
| Current | 127 (60) | 371 (62) | 93 (65) | 47 (41) | 231 (67) | 155 (57) | 195 (66) | 17 (63) |
*Production: toner production; development: machine development; maintenance: machine maintenance.
†Excluding seven subjects with unverified exposure length.
‡One machine development worker with a duration of exposure of 1–10 years was excluded because of unspecified smoking history.
§Significant difference from the mean value in the control group by analysis of variance.
The figures show the means (standard deviation) for age, height, and body mass index (BMI), and the number of subjects (% of the column total) with a current smoking habit.