Role of Environmental Factors in the Timing of Puberty

Abstract

Puberty-timing measures have historically been used as indicators of adequate nutrition and growth. More recently, these measures have been examined in relation to exposure to estrogenic or antiandrogenic agents, as well as other environmental factors. The scientific community has debated whether puberty timing is occurring earlier today than in the mid-1900s in the United States and, if so, whether environmental factors play a role; however, no one has asked a multidisciplinary panel to resolve this question. Thus, a multidisciplinary expert panel jointly sponsored by the US Environmental Protection Agency, the National Institute of Environmental Health Sciences, and Serono Symposia International was convened to examine the evidence of a secular trend, identify potential environmental factors of concern, and identify research needs regarding environmental factors and puberty timing at "The Role of Environmental Factors on the Timing and Progression of Puberty" workshop. The majority of the panelists concluded that the girls' data are sufficient to suggest a secular trend toward earlier breast development onset and menarche from 1940 to 1994 but that the boys' data are insufficient to suggest a trend during this same period. The weight-of-the-evidence evaluation of human and animal studies suggest that endocrine-disrupting chemicals, particularly the estrogen mimics and antiandrogens, and body fat are important factors associated in altered puberty timing. A change in the timing of puberty markers was considered adverse from a public health perspective. The panel recommended research areas to further our understanding of the relationships among environmental factors, puberty-timing outcomes, and other reproductive and adult disease at the individual and population levels.T HE AGE OF puberty has historically been used as a measure of health status of particular populations. From as early as the 1800s, data on the age of menarche have been collected and recorded in health records among specific populations in the United States 1 and Europe. 2 Declines in the age at menarche have been reported from the late 1800s to the mid-1900s, and these declines have been attributed to improvements in nutrition occurring over the same period (Fig 1). 3,4 Contemporary and historical studies of puberty timing have focused on girls' age at menarche, in part because it is relatively easy to collect either retrospectively or prospectively. Puberty-timing measures used in studies have expanded in the past century to include measures that capture onset and progression of puberty (eg, Tanner stages) as well as completion. [5][6][7][8][9] Although researchers disagree about whether children are entering and/or progressing through puberty earlier today than in the mid-1900s, some recent analyses of US cross-sectional data concluded that girls are reaching puberty earlier over this time span, as measured by age at breast development stage, pubic hair development stage, and/or age of menarche. [10][11][12][13][14] Conversely, other...

Effects of growth environments and two environmental endocrine disruptors on children with idiopathic precocious puberty

“…The weight-of-the-evidence evaluation of human and animal studies suggest that EDCs, particularly the estrogen mimics and antiandrogens, are an important factor associated with a secular trend toward earlier breast development onset and menarche (24). Many EDCs are estrogen agonists and/or androgen antagonists.…”

Age, sex and ethnic differences in the prevalence of underweight and overweight, defined by using the CDC and IOTF cut points in Asian children

“…Second, differences in maturational timing across populations might contribute to the ethnic difference. As there is a trend of decreased maturational age with an increase in BMI, body fat or socioeconomic status (Wyshak and Frisch, 1982;Kaplowitz, 2006;Euling et al, 2008aEuling et al, , 2008b, which advances from Vietnam, Indonesia, China, to the US (World Bank, 2008), Chinese adolescents might reach maturation age earlier compared with the Vietnamese and Indonesians, but latter compared with Americans. An adjustment for maturation age in these populations would lead to an increase in ageand sex-specific mean BMI (Daniels et al, 1997;Wang and Adair, 2001), and thus an increase in the consistency between the CDC and IOTF cut points.…”

Pubertad precoz: no solo una cuestión de edad

“…Y si bien varios estudios encuentran asociación entre el aumento del índice de masa corporal (IMC) y la presentación temprana de la pubertad (50,55,56) , otros tantos han reportado el avance en la edad de la pubertad sin cambios significativos en el índice de masa corporal (3) . Se plantea de esta manera que otros factores ambientales, como los cambios en el estado físico (51) , la nutrición, la exposición a productos químicos de disrupción endocrina (5,6,52) , entre otros, pueden modificar la biodisponibilidad de esteroides sexuales y la sensibilidad a ellos.…”

“…Así, factores nutricionales desde la vida fetal o posnatal (como la obesidad, en especial en el sexo femenino) y medioam-bientales (5) (incluidos los disrruptores endocrinológicos (6) ) han sido asociados con el inicio precoz de la pubertad en diversas poblaciones del mundo.…”