title: Blood lead levels and delayed onset of puberty in a longitudinal study of Russian boys.
abstract: OBJECTIVE
  We evaluated the association of blood lead levels (BLLs) with pubertal onset in a longitudinal cohort of Russian boys.
  
  
  METHODS
  A total of 489 Russian boys were enrolled in 2003-2005, at 8 to 9 years of age, and were monitored annually through May 2008. Cox proportional-hazards models were used to evaluate the association of BLLs at enrollment with time to pubertal onset during follow-up monitoring.
  
  
  RESULTS
  A total of 481 boys had BLLs, with a median of 3 microg/dL and 28% with values of > or =5 microg/dL. The proportion of pubertal boys increased with age, from 12% at age 8 to 83% at age 12 for testicular volume of >3 mL, from 22% to 90% for genitalia stage 2 or higher, and from 4% to 40% for pubic hair stage 2 or higher. After adjustment for potential confounders including BMI and height, boys with high BLLs (> or =5 microg/dL) had 24% to 31% reduced risk of pubertal onset, on the basis of testicular volume of >3 mL (hazard ratio [HR]: 0.73 [95% confidence interval [CI]: 0.55-0.97]; P = .03), genitalia staging (HR: 0.76 [95% CI: 0.59-0.98]; P = .04), and pubic hair staging (HR: 0.69 [95% CI: 0.44-1.07]; P = .10), compared with those with lower BLLs. Pubertal onset occurred 6 to 8 months later, on average, for boys with high BLLs, compared with those with BLLs of <5 microg/dL.
  
  
  CONCLUSIONS
  Higher BLLs were associated with later pubertal onset in this prospective study of peripubertal Russian boys.
authors.affiliation: Harvard School of Public Health, Department of Biostatistics, Boston, MA 02115, USA. paige@hsph.harvard.edu
authors.forename: Paige L
authors.initials: PL
authors.lastname: Williams
authors.forename: Oleg
authors.initials: O
authors.lastname: Sergeyev
authors.forename: Mary M
authors.initials: MM
authors.lastname: Lee
authors.forename: Susan A
authors.initials: SA
authors.lastname: Korrick
authors.forename: Jane S
authors.initials: JS
authors.lastname: Burns
authors.forename: Olivier
authors.initials: O
authors.lastname: Humblet
authors.forename: Julie
authors.initials: J
authors.lastname: DelPrato
authors.forename: Boris
authors.initials: B
authors.lastname: Revich
authors.forename: Russ
authors.initials: R
authors.lastname: Hauser
mesh_terms: D000293:Adolescent; D049628:Body Size; D002648:Child; D015331:Cohort Studies; D005247:Feeding Behavior; D006306:Health Surveys; D006801:Humans; D007854:Lead / Q000097:blood*; D007855:Lead Poisoning / Q000097:blood* / Q000517:prevention & control; D008137:Longitudinal Studies; D008297:Male; D016016:Proportional Hazards Models; D011628:Puberty, Delayed / Q000097:blood* / Q000139:chemically induced*; D012426:Russia; D012741:Sexual Maturation / Q000187:drug effects; D012959:Socioeconomic Factors
chemical_list: D007854:Lead