BMC Public Health 2008, 8:72 http://www.biomedcentral.com/1471-2458/8/72 Table 2: Adjusted geometric means (95% confidence interval) by quartile of creatinine corrected urinary cadmium Quartile 1 < 0.18 µg/g Quartile 2 0.18–0.33 µg/g Quartile 3 0.34–0.62 µg/g Quartile 4 ≥ 0.63 µg/g p-trend Total testosterone, ng/mL Age and race-ethnicity adjusted Multivariable model 1† Multivariable model 2‡ Total estradiol, pg/mL Age and race-ethnicity adjusted Multivariable model 1† Multivariable model 2‡ SHBG, nmol/L Age and race-ethnicity adjusted Multivariable model 1† Multivariable model 2‡ Androstanediol glucuronide, ng/mL Age and race-ethnicity adjusted Multivariable model 1† Multivariable model 2‡ Estimated free testosterone, ng/mL Age and race-ethnicity adjusted Multivariable model 1† Multivariable model 2‡ Estimated free estradiol, pg/mL Age and race-ethnicity adjusted Multivariable model 1† Multivariable model 2‡ Estradiol*1000/total testosterone Age and race-ethnicity adjusted Multivariable model 1† Multivariable model 2‡ Total testosterone/SHBG Age and race-ethnicity adjusted Multivariable model 1† Multivariable model 2‡ Estradiol*1000/SHBG Age and race-ethnicity adjusted Multivariable model 1† Multivariable model 2‡ 4.69 (4.40, 4.99) 5.06 (4.78, 5.36) 5.10 (4.85, 5.35) 32.1 (29.6, 34.8) 34.4 (32.2, 36.8) 34.3 (32.3, 36.4) 34.2 (31.4, 37.2) 35.2 (32.1, 38.6) 35.5 (32.7, 38.5) 13.0 (12.2, 13.8) 12.9 (12.1, 13.8) 12.9 (12.1, 13.7) 0.092 (0.087, 0.097) 0.099 (0.094, 0.105) 0.100 (0.094, 0.105) 0.81 (0.75, 0.89) 0.87 (0.81, 0.94) 0.87 (0.81, 0.93) 7.24 (6.57, 7.99) 7.20 (6.55, 7.91) 7.12 (6.60, 7.69) 0.476 (0.445, 0.510) 0.498 (0.461, 0.538) 0.498 (0.461, 0.538) 3.45 (3.03, 3.92) 3.59 (3.14, 4.09) 3.55 (3.16, 3.99) 4.85 (4.45, 5.27) 5.06 (4.71, 5.44) 5.07 (4.72, 5.45) 34.6 (33.1, 36.1) 36.1 (34.6, 37.7) 36.0 (34.5, 37.6) 33.1 (30.9, 35.4) 33.9 (31.6, 36.3) 34.0 (31.7, 36.4) 11.8 (10.9, 12.9) 11.8 (10.8, 12.9) 11.7 (10.8, 12.8) 0.098 (0.091, 0.105) 0.102 (0.095, 0.108) 0.102 (0.095, 0.109) 0.89 (0.84, 0.93) 0.92 (0.87, 0.97) 0.92 (0.87, 0.97) 7.56 (6.81, 8.39) 7.55 (6.83, 8.34) 7.52 (6.80, 8.31) 0.508 (0.475, 0.543) 0.518 (0.488, 0.551) 0.518 (0.485, 0.554) 3.84 (3.52, 4.20) 3.91 (3.56, 4.30) 3.90 (3.55, 4.28) 5.13 (4.78, 5.52) 5.03 (4.68, 5.41) 5.00 (4.67, 5.35) 37.5 (35.8, 39.2) 36.9 (35.2, 38.6) 37.1 (35.4, 38.8) 34.6 (32.6, 36.7) 34.4 (32.3, 36.7) 34.3 (32.4, 36.3) 10.9 (9.5, 12.5) 10.9 (9.5, 12.5) 10.9 (9.5, 12.5) 0.104 (0.095, 0.113) 0.101 (0.093, 0.111) 0.101 (0.092, 0.110) 0.96 (0.91, 1.02) 0.95 (0.90, 1.00) 0.95 (0.90, 1.01) 7.74 (7.18, 8.34) 7.75 (7.14, 8.42) 7.85 (7.23, 8.53) 0.514 (0.469, 0.564) 0.507 (0.460, 0.558) 0.505 (0.458, 0.555) 3.98 (3.66, 4.32) 3.93 (3.60, 4.28) 3.97 (3.66, 4.30) 5.64 (5.27, 6.04) 5.09 (4.69, 5.53) 5.08 (4.68, 5.51) 39.8 (37.9, 41.8) 36.2 (33.8, 38.7) 36.1 (33.7, 38.8) 37.5 (34.6, 40.7) 35.6 (32.7, 38.8) 35.4 (32.5, 38.5) 11.2 (9.7, 13.0) 11.3 (9.8, 13.1) 11.4 (9.8, 13.2) 0.109 (0.102, 0.118) 0.100 (0.091, 0.109) 0.100 (0.090, 0.110) 1.00 (0.94, 1.07) 0.91 (0.84, 0.99) 0.91 (0.83, 1.00) 7.47 (6.98, 8.00) 7.52 (6.90, 8.20) 7.54 (6.86, 8.28) 0.522 (0.480, 0.566) 0.495 (0.444, 0.553) 0.497 (0.442, 0.559) 3.90 (3.49, 4.35) 3.72 (3.29, 4.22) 3.75 (3.29, 4.27) < 0.001 0.88 0.99 < 0.001 0.42 0.41 0.009 0.57 0.71 0.23 0.33 0.40 < 0.001 0.89 0.85 < 0.001 0.69 0.69 0.80 0.70 0.61 0.05 0.71 0.79 0.15 0.98 0.87 SHBG = Sex hormone-binding globulin †Adjusted for age (continuous) and race-ethnicity (non-Hispanic white, non-Hispanic black, Mexican-American, and other), smoking status (never, former, and current), and serum cotinine (continuous) ‡Adjusted for variables in model 1 and household income (< $20,000 and ≥ $20,000), physical activity (none, 1–2, and ≥ 3 times a week), alcohol consumption (< 12 and ≥ 12 drinks in the past year), percent body fat (continuous), blood lead (log-transformed, continuous), and serum selenium (continuous) icant, positive association between urinary cadmium and free testosterone concentrations (p-trend = 0.09). Discussion In this large, representative sample of US adult men, uri- nary cadmium levels were not associated with sex steroid hormone levels after adjustment for confounders. In our analysis, smoking was an important confounder of the association between cadmium and sex steroid hormone levels. The lack of association between cadmium and sex steroid hormones was also evident after stratifying by smoking status, although we identified a marginally sig- nificant association between cadmium and total testoster- one among never smokers and free testosterone among current smokers. These findings may be explained as chance findings or a result of residual confounding, although we cannot exclude a modest association. Four previous studies have evaluated the association of urine or blood cadmium with sex steroid hormone levels in men [10-13]. In a cross-sectional study of Chinese men with environmental exposure to cadmium, blood and urine cadmium did not meet the criteria for inclusion in stepwise models predicting testosterone levels [10]. Blood cadmium was positively associated with testosterone in two separate studies of Croatian men who had never been occupationally exposed to cadmium [11,12] and in a study of Chinese male smelter workers [13]. These studies Page 4 of 7 (page number not for citation purposes)