Vesper et al. with non­Hispanic whites [52.6 (95% CI, 50.3–54.9) pmol/g Hb] and MA [57.9 (95% CI, 53.7–62.5) pmol/g Hb]. The HbGA:HbAA ratios were influenced by the variables of age, sex, race/ethnicity, cotinine and BSA. Several interactions were observed between these variables. Therefore covariatea­djusted geometric mean values were calculated for each age group and certain per­ centiles of cotinine levels by race/ethnic group [Supplemental Material, Table 3 (doi:10.1289/ ehp.0901021.S1)] and for certain percentiles of BSA separate for each sex (Supplemental Material, Table 4). The ratios decreased with increasing age in all race/ethnic groups, with levels in the ≥ 60 years group [0.74 (95% CI, 0.63–0.87), 0.63 (95% CI, 0.51–0.79), 0.79 (95% CI, 0.69–0.90) in nonH­ispanic whites, nonH­ispanic blacks, and Mexican Americans, respectively] being approximately half of the levels in the 5–9 years group. Non­ Hispanic blacks had the lowest ratios across all age groups and across all percentiles of cotinine. 14 ) 12 (%10 r ke 8 o m 6 s on 4 N 2 0 14 12 ) 10 % ( r 8 e ok 6 S m 4 2 0 Abbreviations: GM, geometric mean; MA, Mexican American; ND, not determined; NHB, non-Hispanic black; NHW, non-Hispanic white. Group All Sex Female Male 3–11 12–19 20–39 40–59 ≥ 60 NHW NHB MA an < 10. 280 Age group (years) Race/ ethnicity HbAA 49.5 (48.2–50.8) 50.7 (48.4–53.1) 58.7 (56.2–61.2) 52.0 (50.1–54.0) 51.0 (48.5–53.8) 48.6 (46.1–51.2) 50.1 (48.5–51.8) 50.5 (47.5–53.7) 56.3 (53.2–59.6) 44.4 (42.6–46.2) 1,252 41.0 (38.1–44.1) 1,249 3,050 2,636 1,070 1,629 951 784 2,254 1,480 1,582 51.8 (49.1–54.7) 50.2 (48.4–52.0) 73.4 (70.5–76.4) 50.6 (46.7–54.7) 51.7 (48.4–55.3) 49.1 (47.0–51.2) 51.6 (49.2–54.1) 46.3 (43.8–48.9) 60.9 (56.8–65.3) 3,111 2,698 1,138 1,658 972 792 2,287 1,533 1,622 1.04 (0.99–1.09) 0.98 (0.94–1.02) 1.25 (1.20–1.30) 0.97 (0.89–1.05) 1.00 (0.95–1.06) 1.00 (0.95–1.06) 0.92 (0.86–0.98) 1.02 (0.97–1.06) 0.91 (0.83–1.00) 1.08 (1.01–1.15) The relationship between nonH­ispanic blacks and cotinine appears stronger than for the other race/ethnic groups. Women had higher ratios than men across all percentiles of BSA [1.05 (95% CI, 1.00–1.11) in women, 0.92 (0.87–0.97) in men, at the 75th percentile of BSA each]. The ratios decreased modestly with increasing BSA in both men and women. Cotinine levels ranged in the nonsmoker population from 0.01 to 10 ng/mL. The esti­ mated slope for the effect of the logarithm of cotinine levels on HbAA levels was 0.0238 (p = 0.0002) and on HbGA levels was 0.0228 (p = 0.0223), indicating that a 10% increase in serum cotinine would be associ­ ated with a 0.23% (95% CI, 0.10–0.35%) increase in HbAA levels and a 0.22% (95% CI, 0.03–0.41%) increase in HbGA levels. Simulating an increase in cotinine levels from a level equal to the first quartile (0.018 ng/mL) up to a level equal to the third quartile (0.270 ng/mL) would correspond to a 32% increase in HbAA and HbGA levels (assuming a starting point at the 10th percen­ tile). The estimated slope for the effect of BSA in the HbAA model was –0.0399 (p < 0.0001), indicating that an increase in BSA from the median BSA (1.75 m2) to the 75th percentile of BSA (1.97 m2) would be associated with a 2.00% (95% CI, 1.04–2.95%) decrease in HbAA levels. Smokers. In smokers, HbAA and HbGA values were influenced by the variables race/ ethnicity, BSA, age, cotinine, and sex. Several interactions were found between these vari­ ables. Therefore, covariatea­djusted geometric mean HbAA levels were calculated for each race/ethnic group and certain percentiles of BSA levels by sex, and the HbGA:HbAA ratio for certain levels of cotinine by sex [Supplemental Material, Table 5 (doi:10.1289/ ehp.0901021.S1)]. HbAA, HbGA, and the HbAA:HbGA ratios were calculated for spe­ cific ages (20, 40, and 60 years) separately for each race/ethnic group (Supplemental Material, Table 6). Similar to nonsmokers, No. 5,464 2,931 2,533 1,030 1,563 919 753 1,199 2,172 1,405 1,533 10 ) 8 % ( re 6 k o sm 4 n o N 2 0 10 ) 8 % (r 6 e k o 4 m S 2 0 120 (108–133) 108 (97.2–121) NDa 103 (88.1–119) 118 (106–131) 116 (106–127) 93.5 (84.2–104) 114 (103–127) 123 (108–141) 109 (98.5–120) 483 833 240 444 371 252 698 361 190 104 (94.9–115) 87.2 (79.4–95.7) NDa 93.2 (80.4–108) 98.2 (88.5–109) 94.2 (87.1–102) 77.2 (70.1–85.1) 97.8 (88.5–108) 82.1 (72.2–93.5) 92.5 (79.7–107) 496 861 248 464 376 258 714 381 194 0.86 (0.82–0.90) 0.80 (0.76–0.83) NDa 0.89 (0.85–0.93) 0.84 (0.80–0.88) 0.79 (0.75– 0.83) 0.81 (0.76–0.86) 0.84 (0.81–0.87) 0.66 (0.60–0.73) 0.85 (0.77–0.94) 466 816 234 435 362 243 682 350 186 ovlume 118 | number 2 | February 2010 • Environmental Health Perspectives 0.2 0.8 1.4 2.0 2.6 3.2 3.8 4.4 5.0 5.6 6.2 6.8 0.2 0.8 1.4 2.0 2.6 3.2 3.8 4.4 5.0 5.6 6.2 6.8 Log (HbAA) (pmol/g Hb) Log (HbGA) (pmol/g Hb) Figure 1. Frequency distribution of HbAA (A) and HbGA (B) in nonsmokers and smokers. Hb, hemoglobin. Table 1. Geometric mean (95% CI) (pmol/g hemoglobin) and sample size of HbAA, HbGA, and the HbGA:HbAA ratio by sex, age, race/ethnicity, and smoking status in the general U.S. population. Nonsmokers HbGA HbGA:HbAA ratio HbAA Smokers HbGA GM (95% CI) No. GM (95% CI) No. GM (95% CI) 50.0 (48.5–51.7) 5,686 51.1 (49.0–53.2) 5,809 1.01 (0.97–1.06) GM (95% CI) No. GM (95% CI) No. 113 (103–123) 1,316 93.5 (86.5–101) 1,357 0.82 (0.79–0.85) 1,282 HbGA:HbAA ratio GM (95% CI) No.