Altered Breast Development in Young Girls from an Agricultural Environment

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.

Female reproductive disorders: the roles of endocrine-disrupting compounds and developmental timing

“…We propose that embryonic exposures alter breast architecture, as supported by the discovery that pesticide-exposed girls exhibit breastdevelopment that is associated with adipose deposition and not ductal or glandular growth (208), and that adult exposures alter the initiation or progression of lactation in the same manner as endogenous Es. The limited data in humans comprise a data gap and should be the subject of further research.…”

“…In a study examining breast development in girls exposed both in utero and lactationally to differing amounts of the flame retardant polybrominated biphenyl, there was an increased OR (2.2, 95% CI 0.5-9.8) of early breast development in girls exposed to moderate, but not high or low, concentrations of polybrominated biphenyl (233). Similarly, a study in girls in Sonora, Mexico, indicates that it is possible that fetal, neonatal, or childhood exposure to contemporary pesticides can alter the pattern of breast development (208). The role of peripubertal EDC exposure on female breast development is less clear, but data from rodents show that mammary gland tissue is altered after acute, peripubertal exposure to DES, genistein, or DDT, with these EDCs acting as potent morphogens (234).…”

Estado Actual De La Investigación Sobre Plaguicidas en México

“…En estudios con mujeres en edad reproductiva expuestas a DDT y sus metabolitos, se ha reportado daño genético medido a través del ensayo cometa en muestras de sangre (Yáñez et al 2004). Guillette et al (2006) reportaron un mayor crecimiento de senos, así como una baja relación entre el desarrollo de la glándula mamaria y tamaño del seno en jóvenes de zonas agrícolas del Valle del Yaqui, Sonora, comparadas con jóvenes de zonas serranas con menor exposición. Además, se encontró una asociación significativa entre la exposición a plaguicidas medido a través de la actividad AChE (< 20%) y un retraso en el crecimiento intrauterino (Levario-Carrillo et al 2004).…”

Unsolved Mysteries of the Human Mammary Gland: Defining and Redefining the Critical Questions from the Lactation Consultant’s Perspective

“…Upon further questioning, the mother shared that her own migrant worker mother toiled in the strawberry fields while pregnant with her, and that she herself grew up Bacross the street^from agricultural fields. An intriguing study of Yaqui women in Mexico found troubling anomalies in mammary growth in young girls growing up in a modern agricultural environment versus those from a nearby mountainous traditional ranching environment [73]. While the breasts of the girls appeared the same externally, upon palpation it was discovered that a significant number of those who dwelled in the farm lands had deficiencies in the volume of their glandular tissue.…”