Table 1

Characteristics of control participants and mean serum selenium (μg/dl) concentrations

n (%)Mean (SD)Pa,b
Gender0.002a
 Male695 (85)11.49 (1.96)
 Female125 (15)12.09 (2.02)
Race0.006a
 White760 (93)11.63 (1.92)
 Black35 (4)10.53 (3.06)
 Other/Unknown25 (3)11.62 (1.76)
Exposure population0.0001a
 Asbestos269 (33)10.93 (2.06)
 Heavy smoker551 (67)11.90 (1.86)
Treatment arm0.73a
 Active415 (51)11.61 (1.99)
 Placebo405 (49)11.56 (1.98)
Blood draw age group (yr)0.90b
 44–496 (1)12.86 (1.83)
 50–5493 (11)11.46 (2.12)
 55–59182 (22)11.66 (1.70)
 60–64228 (28)11.56 (1.97)
 65–69247 (30)11.52 (2.16)
 70–7456 (7)11.72 (1.75)
 75–798 (1)11.82 (2.67)
Study center0.0001a
 Baltimorec67 (8)9.60 (2.10)
 Irvine83 (10)10.76 (1.57)
 New Havenc55 (7)10.99 (1.93)
 Portland224 (27)11.98 (1.75)
 San Franciscoc47 (6)10.80 (1.57)
 Seattle344 (42)12.11 (1.89)
Blood draw year0.06b
 19856 (1)12.50 (3.11)
 198623 (3)12.43 (1.77)
 198728 (3)12.06 (1.89)
 198989 (11)11.64 (2.04)
 1990116 (14)11.26 (2.43)
 1991136 (17)11.45 (2.09)
 1992191 (23)11.82 (1.80)
 1993156 (19)11.61 (1.67)
 199469 (8)11.00 (1.81)
 19956 (1)11.99 (2.25)
Blood draw visit0.94b
 Baseline491 (60)11.57 (2.07)
 Year 2202 (25)11.67 (1.74)
 Year 315 (2)11.34 (2.17)
 Year 455 (7)11.50 (2.40)
 Year 517 (2)11.38 (1.67)
 Year 617 (2)12.00 (1.35)
 Year 712 (1)11.84 (1.52)
 Year 811 (1)10.77 (1.34)
Blood draw supplemental vitamin used0.81a
 Yes307 (39)11.60 (2.11)
 No487 (61)11.56 (1.92)
Blood draw smoking status0.005a
 Current434 (53)11.40 (1.88)
 Former386 (47)11.79 (2.07)
Years quit smokinge0.0001a
 Current smokers338 (61)11.68 (1.82)
 <128 (5)11.77 (1.67)
 1–227 (5)12.04 (2.02)
 2–327 (5)11.94 (2.07)
 3–430 (5)11.89 (1.80)
 4–529 (5)12.87 (1.79)
 5–627 (5)12.49 (2.07)
 6–716 (3)12.55 (1.67)
 >729 (5)12.54 (1.80)
  • a,b P from test for: aequal means; or bfrom trend test.

  • c Asbestos-exposed participants only; no smoker population.

  • d Twenty-six participants were missing supplemental vitamin usage at blood draw.

  • e Years persons had quit smoking at blood draw for the heavy-smoker-exposure population only (n = 551).