Hypothesis: exposure to endocrine‐disrupting chemicals may interfere with timing of puberty

Abstract

A recent decline in onset of puberty - especially among girls - has been observed, first in the US in the mid-1990s and now also in Europe. The development of breast tissue in girls occurs at a much younger age and the incidence of precocious puberty (PP) is increasing. Genetic factors and increasing prevalence of adiposity may contribute, but environmental factors are also likely to be involved. In particular, the widespread presence of endocrine-disrupting chemicals (EDCs) is suspected to contribute to the trend of earlier pubertal onset. The factors regulating the physiological onset of normal puberty are poorly understood. This hampers investigation of the possible role of environmental influences. There are many types of EDCs. One chemical may have more than one mode of action and the effects may depend on dose and duration of the exposure, as well as the developmental stage of the exposed individual. There may also be a wide range of genetic susceptibility to EDCs. Human exposure scenarios are complex and our knowledge about effects of mixtures of EDCs is limited. Importantly, the consequences of an exposure may not be apparent at the actual time of exposure, but may manifest later in life. Most known EDCs have oestrogenic and/or anti-androgenic actions and only few have androgenic or anti-oestrogenic effects. Thus, it appears plausible that they interfere with normal onset of puberty. The age at menarche has only declined by a few months whereas the age at breast development has declined by 1 year; thus, the time span from initiation of breast development to menarche has increased. This may indicate an oestrogen-like effect without concomitant central activation of the hypothalamic-pituitary axis. The effects may differ between boys and girls, as there are sex differences in age at onset of puberty, hormonal profiles and prevalence of precocius puberty.

Central precocious puberty: revisiting the diagnosis and therapeutic management

“…The main etiologies of CPP are listed in Table 1 (10)(11)(12)(13)(14)(15). Idiopathic CPP represents 90% of the cases in girls, whereas organic etiologies are more frequent (60% to 70%) in boys.…”

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

“…In addition to the genetic, ethnic, and pediatric obesity explanations for the earlier onset of sexual maturation (5,6), other broad theories have been proposed. These include exposure to environmental toxins that disrupt endocrine function (7), psychosocial stress (8), and possible history of familial precocious puberty or adoption (9,10). 1,1-Dichloro-2,2,bisethylene (p,p 0 -DDE) is the degradation product of DDT (a kind of organochlorine pesticide).…”

Validity of Self-Assessment of Pubertal Maturation

“…4 The age at pubertal onset varies between genders and individuals and is known to be influenced by many factors such as ethnicity, nutrition, genetics, and environment. [5][6][7][8] For clinical or epidemiologic studies in which exact pubertal stages are required, many aspects must be taken into consideration. Some children may feel uncomfortable with the physical examination, and individual assessments are time consuming, logistically challenging, and expensive in large populations.…”