| Altered Breast Development in Young Girls from an Agricultural Environment Elizabeth A. Guillette,1,2 Craig Conard,2 Fernando
Lares,3 Maria Guadalupe Aguilar,3 John
McLachlan,2 and Louis J. Guillette Jr.4 1Department of Anthropology, University of Florida, Gainesville,
Florida, USA; 2Center for Bioenvironmental Research, Tulane-Xavier
Universities, New Orleans, Louisiana, USA; 3Dirección del
Area de Recursos Naturales, Instituto Tecnológico de Sonora, Ciudad
Obregón, Sonora, Mexico; 4Department of Zoology, University
of Florida, Gainesville, Florida, USA Abstract
In several human populations, the age at which female breast development begins is reported to have declined over the last five decades. Much debate has occurred over whether this reported decline has actually occurred and what factors contribute to it. However, geographical patterns reflecting earlier developmental onset in some human populations suggest environmental factors influence this phenomenon. These factors include interactions between genetic makeup, nutrition, and possible cumulative exposure to estrogens, both endogenous as well as environmental beginning during in utero development. We examined the onset of breast development in a group of peripubertal girls from the Yaqui Valley of Sonora, Mexico. We observed that girls from valley towns, areas using modern agricultural practices, exhibited larger breast fields than those of girls living in the foothills who exhibited similar stature [e.g., weight, height, body mass index (BMI) ], and genetic background. Further, girls from valley towns displayed a poorly defined relationship between breast size and mammary gland development, whereas girls from the Yaqui foothills, where traditional ranching occurs, show a robust positive relationship between breast size and mammary size. The differences noted were obtained by a medically based exam involving morphometric analysis and palpation of tissues, in contrast to visual staging alone. In fact, use of the Tanner scale, involving visual staging of breast development for puberty, detected no differences between the study populations. Mammary tissue, determined by palpation, was absent in 18.5% of the girls living in agricultural areas, although palpable breast adipose tissue was present. No relationship was seen between mammary diameter and weight or BMI in either population. These data suggest that future in-depth studies examining mammary tissue growth and fat deposition in breast tissue are required if we are to understand environmental influences on these phenomena. Key words: breast development, mammary gland, Mexico, puberty, thelarche, Yaqui Valley. Environ Health Perspect 114:471-475 (2006) . doi:10.1289/ehp.8280 available via http://dx.doi.org/ [Online 10 November 2005]
Address correspondence to E. Guillette, Department of Anthropology, 1350C Turlington Hall, University of Florida, Gainesville, FL 32611 USA. Telephone: (352) 375-5929. Fax: (352) 392-6929. E-mail: eguillet@anthro.ufl.edu We thank the participating state health clinics in the state of Sonora, Mexico, for their help in this project. Funding was provided, in part, from the Jenifer Altman Foundation and the Center for Bioenvironmental Research. The authors declare they have no competing financial interests. Received 3 May 2005 ; accepted 10 November 2005. The full version of this article is available for free in HTML or PDF formats. |
