Urinary cadmium and timing of menarche and pubertal development in girls

Background: Cadmium (Cd) is a developmental toxicant that is released into the environment during industrial processes. Previous animal studies suggest that Cd may impact the onset of puberty. Objectives: To determine whether Cd exposure, measured as urinary Cd concentration, was associated with ages at menarche and pubertal development. Methods: A cohort of 211 girls, ages 10-13 years at baseline, was followed for up to two years. Girls completed an interview and self-assessment of Tanner stages of breast development and pubic hair growth. They were followed monthly until menarche. Urinary Cd concentrations were measured in overnight urine specimens. Multivariable Cox regression was used to evaluate the association between urinary Cd and age at menarche and cumulative logit regression was used to evaluate the associations between urinary Cd and breast development and pubic hair growth. Results: The baseline geometric mean creatinine-adjusted Cd concentration was 0.22 mu g/g creatinine (geometric standard deviation = 1.6) and decreased with increasing age (p-trend = 0.04). Cd levels were higher among Asian than White girls or girls of other/mixed race/ethnicity (p = 0.04). In multivariable analyses, girls with urinary Cd >= 0.4 mu g/L were less likely to have attained menarche than girls with urinary Cd < 0.2 mu g/L (hazard ratio = 0.42; 95% confidence interval, 0.23-0.78). Urinary Cd was negatively associated with pubic hair growth (p-trend = 0.01) but not with breast development (p-trend = 0.72) at baseline. Conclusions: These findings suggest that a higher Cd body burden may delay some aspects of pubertal development among girls.