Stacy Endres

Comparison of Xenoestrogen Levels Among Prepubertal Females in Urban and Rural Ghrabiah, Egypt

ABSTRACT: Exposure to certain chemicals and hormone mimicking endocrine-disrupting compounds (EDCs) are believed to contribute to increased incidence in breast cancer. Rodent studies indicate that EDCs can alter mammary gland development and cause transient and/or persistent effects depending on the dose and whether exposure was during a critical period of mammary gland growth and differentiation. In humans, there are three phases of mammary gland growth that have been suggested to be critical: in utero, peripubertal, and during pregnancy. The unifying factor in the three critical phases involves breast tissue growth and differentiation which is sensitive to environmental insults. During the peripubertal period, mammary growth is exponential and highly proliferative, making adolescent females especially vulnerable to xenoestrogenic insult.

Several common chemicals have been linked to breast cancer including Bisphenol A (BPA) and phthalates. Every year billions of pounds of BPA are used in the manufacture of epoxy resins, and polycarbonate plastics. BPA is a polar compound commonly found in metal food can linings, plastic food containers (including baby bottles), and eating utensils. Phthalates, commonly used to render plastics soft and pliable, are also considered to be endocrine-disrupting chemicals. Phthalates are found in soft plastics sold specifically for infants, a variety of nail polishes, perfumes, solvents, skin moisturizers and flavorings. Research has shown that BPA and phthalates disrupt hormonal processes and therefore may increase breast cancer risk.

Exciting new research from Egypt shows that urban incidence of breast cancer is 3-4 times than rural incidence. However, when the serum organochlorine load was quantified, rural women had higher circulating levels than urban women. Since organochlorines are non-polar, lipophilic substances which can be sequestered in adipose tissue, it seems plausible that urban women (having higher BMIs than rural) would have lower circulating levels. Around puberty body fat and sequestration of endocrine-disrupting chemicals will not be a factor, thus circulating levels will be more reflective of any risk that is present. My research proposal entails the comparison of polar (BPA and Phthalate) xenoestrogen levels among prepubertal females aged 9-12 years in urban and rural Ghrabiah, Egypt. My hypothesis is that urban adolescent females will have higher urinary BPA and Phthalate concentrations than rural adolescents due to increased environmental exposure.

Tanta University Medical School conducts routine health checks, built on a census developed for each city, of children in both urban and rural areas in Ghrabiah, Egypt. Approximately 30 girls will be recruited from the rural and urban health centers participating in the routine health checks. Urine and saliva samples will be collected from each participant and analyzed for chemical concentration and genetic polymorphisms. To get a more accurate estimation of each subjects exposure, a questionnaire will also be given to assess exposure risk and potential sources of contamination. The questionnaire is designed to elicit lifestyle risk factors including environmental exposures to endocrine disrupting chemicals (specifically BPA and phthalates).