Pollution burden and trajectories of pubertal development: Implications for sleep disturbances and depressive symptoms.

Childhood exposure to pollution has been associated with elevated levels of depressive symptoms during adolescence. Epidemiological studies have related exposure to pollution to altered pubertal timing; however, the effects of pollution exposure on levels of pubertal hormones and their developmental trajectories (i.e., pubertal tempo) are not known. Furthermore, how pollution-related alterations in pubertal development influence trajectories of depressive symptoms during adolescence is not well understood. One factor that has been linked to pollution exposure, pubertal development, and depressive symptoms, and that is modifiable, is sleep disturbances; these variables, however, have not been examined together in a single investigation. The current study examined the effects of pollution burden during childhood on trajectories of adrenal and gonadal development and their impact on trajectories of sleep disturbances and depressive symptoms during adolescence. 184 adolescents (109 females) completed four assessments, each approximately 2 years apart, starting at 9-13 years of age (M=11.37, SD=1.06). At each timepoint, participants completed measures assessing pubertal development, sleep disturbances, and depressive symptoms and provided saliva samples, from which levels of DHEA, testosterone, and estradiol (females only) were assayed. We estimated participants' pollution burden at the census tract-level using their residential addresses and publicly available environmental data. We found that female adolescents residing in neighborhoods with greater pollution burden showed delayed adrenarche and gonadarche based on levels of DHEA and estradiol, respectively, followed by faster DHEA and estradiol tempo into middle adolescence. These pollution burden-related increases in DHEA and estradiol tempo interacted with increasing levels of sleep disturbances to predict the highest increase in levels of depressive symptoms. Although pollution burden was associated with altered adrenal development in male adolescents, effects differed for DHEA and self-reported development, and these alterations did not interact with increases in sleep disturbances to predict trajectories of depressive symptoms. Thus, childhood pollution burden appears to affect pubertal development in sex-dependent ways that contribute to sex-differentiated risk for depression in adolescence.