High Bioavailability of Bisphenol A from Sublingual Exposure
A new experiment with dogs finds that Bisphenol-A (BPA) can be absorbed in the mouth and pass directly into the bloodstream, just as nitroglycerin under the tongue. This way it bypasses detoxification in the liver after absorption in the gut. The result is that much more biologically active BPA is available to possibly cause health effects, with major implications for how much risk BPA may pose for human health.
2013 Study Abstract
Bisphenol A (BPA) risk assessment is currently hindered by the rejection of reported higher than expected BPA plasma concentrations in humans after oral ingestion. These are deemed incompatible with the almost complete hepatic first-pass metabolism of BPA into its inactive glucurono-conjugated form, BPA glucuronide (BPAG).
Using dogs as a valid model, plasma concentrations of BPA were compared over a 24-h period after intravenous, orogastric and sublingual administrations, in order to establish the absolute bioavailability of BPA administered sublingually and to compare it with oral bioavailability. Methods: Six dogs were sublingually administered with BPA at 0.05 mg/kg and 5mg/kg. The time course of plasma BPA concentrations was compared with that obtained in the same dogs after intravenous administration of the same BPA doses and after a 20mg/kg BPA dose administrated by orogastric gavage.
The data indicated that the systemic bioavailability of BPA deposited sublingually was high (70-90%) and that BPA transmucosal absorption from the oral cavity led to much higher BPA internal exposure than obtained for BPA absorption from the gastro-intestinal tract. The concentration ratio of BPAG to BPA in plasma was approximately 100-fold lower following sublingual administration than after oral dosing enabling the two pathways of absorption to be easily distinguished.
These findings demonstrate that BPA can be efficiently and very rapidly absorbed through the oral mucosa by the sublingual route. This efficient systemic entry route of BPA may lead to far higher BPA internal exposures than known for BPA absorption from the gastrointestinal tract.
Bisphenol S Disrupts Estradiol-Induced Nongenomic Signaling in a Rat Pituitary Cell Line: Effects on Cell Functions
Just like the controversial Bisphenol A that it designed to replace, Bisphenol S chemical used in cash register receipts and other consumer products messes with hormones, according to research by University of Texas scientists. The study is the first to link low concentrations of BPS – a BPA alternative – to disruption of estrogen, spurring concern that it might harm human health. Researchers exposed rat cells to levels of BPS that are within the range people are exposed to…. and, just like BPA, the compound interfered with how cells respond to natural estrogen, which is vital for reproduction and other functions.
Women’s Exposures early in Life could unlock Mysteries
” When Ida Washington received a letter inviting her to participate in a women’s health study to explore the environmental roots of breast cancer, she didn’t think twice. Her mother was diagnosed with the disease nearly 40 years ago, and since then, it has been a terrifying mystery she has yearned to unravel.
Washington was just a teenager when the lump was found on her mother’s left breast. In the years that followed, as her mother’s cancer went into remission, she began to wonder what caused it. “My mother didn’t smoke, she didn’t drink. Breast cancer didn’t run in the family,” she said
Ida’s mother, Willie Mae Washington, now 92, participated in the first generation of a scientific study that has endured for more than half a century to investigate whether environmental exposures may trigger breast cancer. Now Ida Washington, 52, is continuing the legacy as part of its second generation.
The two women are among the more than 15,000 mothers, daughters and granddaughters in the San Francisco Bay Area enrolled in a project known as the Child Health and Development Studies, launched in 1959. Tens of thousands of samples of the women’s blood are stored, providing more than 50 years of continuous data on health outcomes and environmental exposures.
Scientists tap into this unique trove as they struggle to figure out what role environmental exposures play in the development of diseases such as breast cancer. ” …
… Continue reading Breast cancer and the environment Part 2: Studied for half a century, these women are ‘a national treasure’, environmentalhealthnews, Feb. 26, 2013.
Studied for half a Century, these Women are “a National Treasure”
” Deep in a laboratory freezer, 100,000 vials of blood have been frozen for the better part of five decades.
For scientist Barbara Cohn, it’s a treasure trove. Collected from more than 15,000 San Francisco Bay Area women after they gave birth in the 1960s, each vial of blood holds a woman’s lifetime of secrets.
Scientists say these vials could help them unravel one of the most enduring medical mysteries: Why do some women, with no family history, develop breast cancer?
The blood bears the chemical signature of environmental pollutants, some long banned, that the women were exposed to decades ago. Cohn, who directs the research in Berkeley, Calif., believes these early-life exposures may hold the key to understanding a woman’s risk of breast cancer today.
The women’s blood is being tested for traces of dozens of pollutants – used by industry and found in many consumer products – that can impersonate estrogen and other hormones. The theory is that early exposure to these chemicals, even before birth, inside the mother’s womb, may fundamentally alter the way that breast tissues grow, triggering cancer decades later.
Cancer patients and their doctors have long puzzled over what factors in a woman’s environment may raise her risk of breast cancer. One of every eight women in the United States is diagnosed with breast cancer during her lifetime, with more than 232,000 new cases diagnosed yearly, according to the American Cancer Society. Only 5 to 10 percent can be accounted for by genetics; other known risk factors include age, obesity and low physical activity. ” …
… Continue reading Breast cancer and the environment Part 1: Women’s exposures early in life could unlock mysteries, environmentalhealthnews, Feb. 26, 2013.