BMC Public Health 2008, 8:72 http://www.biomedcentral.com/1471-2458/8/72 steroid hormone concentrations support our findings of no association. Conclusion Cadmium binds with high affinity to the androgen recep- tor, where it inhibits the binding of androgens and induces androgen-like effects [29]. While cadmium itself may exert androgen-like effects, our analysis indicates that urinary cadmium is not an important determinant of sex steroid hormone levels in adult men at the range of expo- sure evaluated in the general US population. Abbreviations AAG – androstanediol glucuronide; SHBG – sex hor- mone-binding globulin; NHANES III – Third National Health and Nutrition Examination Survey Competing interests The author(s) declare that they have no competing inter- ests. Authors' contributions AM, EG, MSS, and EAP were responsible for the concep- tion and design, analysis and interpretation of data. AM drafted the manuscript, that was edited by EG, MSS, and EAP. SR, SB, NR, and WGN were responsible for interpre- tation of the data and revising the manuscript. All authors read and approved the final manuscript. Acknowledgements The Hormone Demonstration Program was supported by the Maryland Cigarette Restitution Fund Research Grant Program at the Johns Hopkins Medical Institutions. References 1. Agency for Toxic Substances and Disease Registry: Toxicological Profile for Cadmium Atlanta, GA, US Department of Health and Human Serv- ices, Public Health Service; 1999. 2. Satarug S, Moore MR: Adverse health effects of chronic expo- sure to low-level cadmium in foodstuffs and cigarette smoke. Environ Health Perspect 2004, 112:1099-1103. 3. Verougstraete V, Lison D, Hotz P: Cadmium, lung and prostate cancer: a systematic review of recent epidemiological data. J Toxicol Environ Health B Crit Rev 2003, 6:227-255. 4. Laskey JW, Phelps PV: Effect of cadmium and other metal cati- ons on in vitro Leydig cell testosterone production. Toxicol Appl Pharmacol 1991, 108:296-306. 5. Zylber-Haran EA, Gershman H, Rosenmann E, Spitz IM: Gonado- trophin, testosterone and prolactin interrelationships in cad- mium-treated rats. J Endocrinol 1982, 92:123-130. 6. Zeng X, Jin T, Zhou Y, Nordberg GF: Changes of serum sex hor- mone levels and MT mRNA expression in rats orally exposed to cadmium. Toxicology 2003, 186:109-118. 7. Apostoli A, Telisman S, Sager PR: Reproductive and Develop- mental Toxicity of Metals. In Handbook on the Toxicology of Metals Volume 12. Third edition. Edited by: Nordberg GF, Fowler BA, Nord- berg M and Friberg LT. Amsterdam, Academic Press Elsevier; 2007:213-249. 8. Akinloye O, Arowojolu AO, Shittu OB, Anetor JI: Cadmium toxic- ity: a possible cause of male infertility in Nigeria. Reprod Biol 2006, 6:17-30. 9. Mason HJ: Occupational cadmium exposure and testicular endocrine function. Hum Exp Toxicol 1990, 9:91-94. 10. Zeng X, Jin T, Buchet JP, Jiang X, Kong Q, Ye T, Bernard A, Nordberg GF: Impact of cadmium exposure on male sex hormones: a population-based study in China. Environ Res 2004, 96:338-344. 11. Jurasovic J, Cvitkovic P, Pizent A, Colak B, Telisman S: Semen qual- ity and reproductive endocrine function with regard to blood cadmium in Croatian male subjects. Biometals 2004, 17:735-743. 12. Telisman S, Cvitkovic P, Jurasovic J, Pizent A, Gavella M, Rocic B: Semen quality and reproductive endocrine function in rela- tion to biomarkers of lead, cadmium, zinc, and copper in men. Environ Health Perspect 2000, 108:45-53. 13. Zeng X, Lin T, Zhou Y, Kong Q: Alterations of serum hormone levels in male workers occupationally exposed to cadmium. J Toxicol Environ Health A 2002, 65:513-521. 14. Satarug S, Baker JR, Urbenjapol S, Haswell-Elkins M, Reilly PE, Wil- liams DJ, Moore MR: A global perspective on cadmium pollu- tion and toxicity in non-occupationally exposed population. Toxicol Lett 2003, 137:65-83. 15. Svartberg J, Midtby M, Bonaa KH, Sundsfjord J, Joakimsen RM, Jorde R: The associations of age, lifestyle factors and chronic dis- ease with testosterone in men: the Tromso Study. Eur J Endo- crinol 2003, 149:145-152. 16. Tamimi R, Mucci LA, Spanos E, Lagiou A, Benetou V, Trichopoulos D: Testosterone and oestradiol in relation to tobacco smoking, body mass index, energy consumption and nutrient intake among adult men. Eur J Cancer Prev 2001, 10:275-280. 17. Plan and operation of the Third National Health and Nutri- tion Examination Survey, 1988-94. National Center for Health Statistics. Vital Health Stat 1994, 1(32):. 18. Chumlea WC, Guo SS, Kuczmarski RJ, Flegal KM, Johnson CL, Heymsfield SB, Lukaski HC, Friedl K, Hubbard VS: Body composi- tion estimates from NHANES III bioelectrical impedance data. Int J Obes Relat Metab Disord 2002, 26:1596-1609. 19. Bernert JT Jr., Turner WE, Pirkle JL, Sosnoff CS, Akins JR, Waldrep MK, Ann Q, Covey TR, Whitfield WE, Gunter EW, Miller BB, Patter- son DG Jr., Needham LL, Hannon WH, Sampson EJ: Development and validation of sensitive method for determination of serum cotinine in smokers and nonsmokers by liquid chro- matography/atmospheric pressure ionization tandem mass spectrometry. Clin Chem 1997, 43:2281-2291. 20. Sassa S, Granick JL, Granick S, Kappas A, Levere RD: Studies in lead poisoning. I. Microanalysis of erythrocyte protoporphyrin levels by spectrophotometry in the detection of chronic lead intoxication in the subclinical range. Biochem Med 1973, 8:135-148. 21. Lewis SA, Hardison NW, Veillon C: Comparison of isotope dilu- tion mass spectrometry and graphite furnace atomic absorption spectrometry with Zeeman background correc- tion for determination of plasma selenium. Anal Chem 1986, 58:1272-1273. 22. Gunter EW LBG Koncikowski SM: Laboratory Procedures Used for the Third National Health and Nutrition Examination Survey (NHANES III). Volume VII-H-1-VII-H-21. Atlanta, GA, US Department of Health and Human Services; 1996. 23. Pruszkowska E, Carnrick GR, Slavin W: Direct determination of cadmium in urine with use of a stabilized temperature plat- form furnace and Zeeman background correction. Clin Chem 1983, 29:477-480. 24. Paschal DC, Burt V, Caudill SP, Gunter EW, Pirkle JL, Sampson EJ, Miller DT, Jackson RJ: Exposure of the U.S. population aged 6 years and older to cadmium: 1988-1994. Arch Environ Contam Toxicol 2000, 38:377-383. 25. Comstock GW, Burke AE, Norkus EP, Gordon GB, Hoffman SC, Hel- zlsouer KJ: Effects of repeated freeze-thaw cycles on concen- trations of cholesterol, micronutrients, and hormones in human plasma and serum. Clin Chem 2001, 47:139-142. 26. Wickings EJ, Nieschlag E: Stability of testosterone and andros- tenedione in blood and plasma samples. Clin Chim Acta 1976, 71:439-443. 27. Rinaldi S, Geay A, Dechaud H, Biessy C, Zeleniuch-Jacquotte A, Akhmedkhanov A, Shore RE, Riboli E, Toniolo P, Kaaks R: Validity of free testosterone and free estradiol determinations in serum samples from postmenopausal women by theoretical calculations. Cancer Epidemiol Biomarkers Prev 2002, 11:1065-1071. Page 6 of 7 (page number not for citation purposes)