Archives for category: Journal Articles

From Today’s New York Times: “Study: Human Exposure to BPA ‘Grossly Underestimated’” (by Gayathr Vaidyanathan), here is the introduction to an article discussing an important new study (by Julia Taylor, a biologist at the University of Missouri, and her co-authors):

Americans are likely to be exposed at higher levels than previously thought to bisphenol A, a compound that mimics hormones important to human development and is found in more than 90 percent of people in the United States, according to new research.

U.S. EPA says it is OK for humans to take in up to 50 micrograms of BPA per kilogram of body weight each day. The new study, published in the journal Environmental Health Perspectives, suggests that we are exposed to at least eight times that amount every day.

“Our data raise grave concern that regulatory agencies have grossly underestimated current human exposure levels,” states the study.

The study also gives the first experimental support that some BPA is likely cleared at similar rates in mice, monkeys and humans, making it possible to extrapolate health studies in mice to humans.

Despite decades of research, questions about BPA have lingered and recently become politicized. Sen. Dianne Feinstein (D-Calif.) hopes to add an amendment to the “FDA Food Safety Modernization Act,” currently under consideration in the Senate, banning the chemical from children’s food and drink packaging. Republicans and industry representatives have been averse, saying that research has not shown conclusively that the chemical is harmful.

Hormones are essential during development and can determine, among other things, a child’s gender. BPA, since it mimics estrogen, is an “endocrine disrupter,” according to Thomas Zoeller, a biology professor at the University of Massachusetts, Amherst. And amazingly, BPA has the ability to bind to not one, but three receptors — the estrogen, the male hormone and the thyroid hormone receptors, Zoeller said.

You can read the entire Times article here.

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Here are excerpts from the University of Missouri press release:

COLUMBIA, Mo. – Researchers have discovered that women, female monkeys and female mice have major similarities when it comes to how bisphenol A (BPA) is metabolized, and they have renewed their call for governmental regulation when it comes to the estrogen-like chemical found in many everyday products.

A study . . .  ties rodent data on the health effects of BPA to predictions of human health effects from BPA with the use of everyday household products. . . .

“This study provides convincing evidence that BPA is dangerous to our health at current levels of human exposure,” said Frederick vom Saal, Curators’ professor of biological sciences at the University of Missouri. “The new results clearly demonstrate that rodent data on the health effects of BPA are relevant to predictions regarding the health effects of human exposure to BPA. Further evidence of human harm should not be required for regulatory action to reduce human exposure to BPA.”

BPA is one of the world’s highest production-volume chemicals, with more than 8 billion pounds made per year. It can be found in a wide variety of consumer products, including hard plastic items such as baby bottles and food-storage containers, the plastic lining of food and beverage cans, thermal paper used for receipts, and dental sealants. The findings in the current study suggest that human exposure to BPA is much higher than some prior estimates and is likely to be from many still-unknown sources, indicating the need for governmental agencies to require the chemical industry to identify all products that contain BPA.

Several states, including Connecticut, Massachusetts, Washington, New York and Oregon, have passed bills to reduce exposure to BPA, and similar legislation is pending in the U.S. Congress.

“For years, BPA manufacturers have argued that BPA is safe and have denied the validity of more than 200 studies that showed adverse health effects in animals due to exposure to very low doses of BPA,” said Julia Taylor, lead author and associate research professor at the University of Missouri. “We know that BPA leaches out of products that contain it, and that it acts like estrogen in the body.”

“We’ve assumed we’re getting BPA from the ingestion of contaminated food and beverages,” said co-author Pat Hunt, a professor in the Washington State University School of Molecular Biosciences. “This indicates there must be a lot of other ways in which we’re exposed to this chemical and we’re probably exposed to much higher levels than we have assumed.”

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You can read the abstract and download the study here or download a pdf of the study directly here. (Citation: Taylor JA, vom Saal FS, Welshons WV, Drury B, Rottinghaus G, Hunt PA, et al. 2010. Similarity of Bisphenol A Pharmacokinetics in Rhesus Monkeys and Mice: Relevance for Human Exposure. Environ Health Perspect.)

Tomorrow, I will post the portion of my interview with Drs. Carlos Sonnenschein and Ana Soto when I asked them about their pathbreaking work on BPA.


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From Environmental Health News:

After his first child was born, black and blue marks started showing up on Stanley Finger’s body. Jolted awake most nights by his crying infant, Finger would stumble half asleep toward her room, bumping into walls and furniture in the dark. “My wife and I would joke about it,” says Finger, a chemical engineer from Bluffton, South Carolina. But during a routine checkup, Finger learned his easy bruising was caused by a precipitous drop in blood platelets. The body relies on these cell fragments for clotting, and Finger’s platelet count had dropped to nearly a third its normal value. After ruling out cancer and other illnesses, Finger’s doctor eventually arrived at a diagnosis:  .

ITP is an autoimmune disease, a condition that occurs when the immune system attacks the body’s own cells and tissues. When Finger was diagnosed in 1974, autoimmune illnesses weren’t yet perceived as the public health menaces they’re often seen as today. But according to Fred Miller, director of the Environmental Autoimmunity Group at the National Institute of Environmental Health Sciences, autoimmune diseases are now recognized as among the leading causes of death among young and middle-aged women in the United States.

What’s more, prevalence rates for some of these illnesses are rising for what Miller says must largely be environmental reasons. “Our gene sequences aren’t changing fast enough to account for the increases,” Miller

says. “Yet our environment is—we’ve got 80,000 chemicals approved for use in commerce, but we know very little about their immune effects. Our lifestyles are also different than they were a few decades ago, and we’re eating more processed food.” Should prevalence rates for heart disease and cancer continue their decline, Miller says, autoimmune diseases could become some of the costliest and most burdensome illnesses in the United States.

More.

From All Things Considered (portions of a radio news story discussing a recent Nature article challenging the conventional wisdom about genetic inheritance):

We can’t change the genes we received from our parents. But our genes are controlled by a kind of instruction manual made up of billions of chemical markers on our DNA, and those instructions can be rewritten by our circumstances — for instance, by obesity. According to the new research, they can even be passed along to children.

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The Grammar Of DNA

[Andy] Feinberg thinks he knows how this may be happening. It’s an example of an “epigenetic” effect, which is his specialty.

This field — epigenetics — is getting a lot of attention these days. It refers to things in and around our DNA, such as billions of chemical markers that attach to it. Those markers are signals that turn genes on and off. They tell the genes of a liver cell to behave differently from genes in a blood cell, for instance.

The sequence of our DNA — the human genome — has been called the book of life. Feinberg has his own metaphor for the billions of added signals that he studies. If the genetic sequence is the words of the book, the epigenome is the grammar, he says. “It helps to tell what the genes are actually supposed to do, and puts them in context.”

Our genes don’t change, or if they do, it’s a rare and random event. But the grammar of the epigenome is changing all the time. It can also be disrupted by chemicals we eat or breathe.

Apparently it can also be disrupted by obesity, because Feinberg thinks those fat dad rats in Australia created sperm cells with a different pattern of epigenetic marks on their DNA; that’s how the effect showed up in their children.

Michael Skinner at Washington State University in Pullman says epigenetic effects are swinging the pendulum of scientific attention from the genetic code back toward the impact of environment.

“I think that we’re eventually going to have sort of a merger of this,” he says. “I think that we’re going to have an appreciation of the fact that there is an environmental influence on biology that probably through more epigenetic mechanisms. There’s also a baseline genetic element of biology. And the two combined will actually give us more information about how things work.”

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The entire story, the podcast, and related links can all be found here.

A new study published online by the Annals of Medicine reports a significant increase in people with celiac disease — particularly in the elderly.  The results were a surprise to researchers.   According to the study’s abstract: “During a 15-year period [celiac disease] prevalence increased 2-fold in the CLUE cohort and 5-fold overall in the US since 1974. The CLUE study demonstrated that this increase was due to an increasing number of subjects that lost the immunological tolerance to gluten in their adulthood.”

Of course, that raises the important question:  why did so many subject lose their immunological tolerance to gluten?

Here is what the study’s lead author had to say:

NPR:

“It may be the environment that has made this change over time.  Grains now are more refined and therefore have more gluten. It could also be the quantity of grains that we eat. It could be the composition of the bacteria that live in our intestines that can trick our immune system differently now than the past. These are all obvious — but not solid — guesses.”

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“We’re in the midst of an autoimmunity epidemic, and celiac disease is not an exception. . . .”

Los Angeles Times :

What causes late onset of celiac disease isn’t known. People must have a genetic predisposition to it, but scientists aren’t sure why gluten intolerance would develop after so many trouble-free years.

Fasano said environmental factors may trigger changes in the immune system that could activate anti-gluten gene. But identifying those factors won’t be easy.

“What has changed in the environment in the last 30 years?” Fasano said. “We have more antibiotics, more vaccinations, bioengineered foods, chemicals we haven’t been exposed to, and pollutants that haven’t been around in the concentrations we have now.”

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