Male pubertal development: are endocrine-disrupting compounds shifting the norms?

Abstract

Endocrine-disrupting compounds (EDCs) are synthetic or natural compounds that interfere with endogenous endocrine action. The frequent use of chemicals with endocrine active properties in household products and contamination of soil, water, and food sources by persistent chemical pollutants result in ubiquitous exposures. Wildlife observations and animal toxicological studies reveal adverse effects of EDCs on reproductive health. In humans, a growing number of epidemiological studies report an association with altered pubertal timing and progression. While these data are primarily reported in females, this review will focus on the small number of studies performed in males that report an association of polychlorinated biphenyls with earlier sexual maturity rating and confirm subtle effects of lead, dioxins, and endosulfan on delaying pubertal onset and progression in boys. Recent studies have also demonstrated that EDC exposure may affect pubertal testosterone production without having a noticeable effect on sexual maturity rating. A limitation to understand the effects of EDCs in humans is the potential for confounding due to the long temporal lag from early-life exposures to adult outcomes. The complex interplay of multiple environmental exposures over time also complicates the interpretation of human studies. These studies have identified critical windows of vulnerability during development when exposures to EDCs alter critical pathways and affect postnatal reproductive health. Contemporaneous exposures can also disrupt the hypothalamic-pituitary-gonadal axis. This paper will review the normal process of puberty in males and summarize human data that suggest potential perturbations in pubertal onset and tempo with early-life exposures to EDCs.

Timing of Puberty in Overweight Versus Obese Boys

“…There is great concern about the effects of endocrine disrupting compounds, including chemicals such as bisphenol A (BPA), polychlorinated biphenyl, and phthalates, on pubertal timing in boys. 34 Given that BPA binds to estrogen receptors, there is concern that BPA exposure may lead to earlier onset of puberty in girls, 35 but the effects are unknown for boys.…”

Age at spermarche: 15‐year trend and its association with body mass index in Chinese school‐aged boys

“…One study in Poland reported an over 3-month decrease between 2000 and 2010 in the age of initial appearance of pubic hair in boys (12). Another study in Thailand showed that the age at testicular enlargement Tanner exposures, which may be related to the trend of earlier pubertal onset (26)(27).…”

Do Secular Trends in Skeletal Maturity Occur Equally in Both Sexes?

“…Speculations of the origins of such a trend include rapidly changing environmental factors such as chemical exposure [2,4,26] and dietary shifts and a concomitant trend for increased adiposity in children [13].…”