Urinary cadmium and the timing of pubertal development in girls

Abstract

BACKGROUND Cadmium is a reproductive toxin and carcinogen that exhibits estrogen-like activity. In addition to smoking, exposure to cadmium occurs from inhalation of polluted air and diet. Little is known about whether exposure to cadmium affects pubertal development in girls. AIMS Our aim was to determine whether urinary cadmium concentration was associated with the attainment of menarche and Tanner's stages of estrogenic (breast) and androgenic (pubic hair) development. METHODS A total of 211 girls between the ages of 10 and 13 years and primarily non-Hispanic white or Chinese provided an overnight urine specimen and completed an interview and self-assessment of Tanner's stage of breast and pubic hair development at baseline and annually for up to two years. Attainment of menarche was assessed monthly. Urinary cadmium and creatinine concentrations were measured using inductively coupled plasma mass spectrometry and a modified-rate Jaffe method, respectively. Cox proportional hazards regression was used to evaluate whether cadmium was associated with age at menarche and cumulative logit regression to evaluate whether cadmium was associated with stage of breast and pubic hair development. RESULTS The mean creatinine-adjusted cadmium concentration was 0.24 µg/g (SD=0.12 µg/g); it was highest among 10-year olds (0.29 µg/g creatinine) and decreased with age (mean among 13-year olds=0.23 µg/g; Kruskal-Wallis p=0.05). Chinese girls had higher cadmium levels than non-Hispanic white girls (0.30 vs. 0.23 µg/g; p=0.006). Girls with the highest unadjusted cadmium concentrations (? 0.4 vs. <0.2 µg/L) were less likely to have attained menarche (hazard ratio=0.42; 95% confidence interval=0.23-0.78; p-trend=0.007). They also had a lower Tanner stage of pubic hair growth (odds ratio=0.24; 95% confidence interval=0.07-0.81). Breast development stage was not associated with cadmium concentration. CONCLUSIONS These findings suggest that cadmium exposure may delay pubertal development in girls.