Carbs and gut microbes fuel colon cancer
July 22, 2014
by Nsikan Akpan
In mouse colons, sugar-loving gut microbes encourage mutations in DNA ..., which elevate cancer-related proteins ..., possibly explaining why Western nations experience more colon cancer.
Magazine issue: August 23, 2014
Westerners' carb-rich diets have long been linked to high levels of cancer, and scientists have begun to work out why. In an experiment with mice, gut bacteria bridged the gap, explaining why sugar-heavy diets can cause cancer, researchers report in the July 17 Cell.
Colorectal cancer ranks third on the list of deadliest cancers, and the disease hits developed countries harder than developing ones. Nearly one of every 15 people in Western nations will suffer from the condition, and doctors suspect that carbohydrate-laden diets contribute to the problem.
In country after country where people have switched to Western-style diets heavy in refined sugars such as high fructose corn syrup, the incidence of colorectal cancer has increased, says geneticist Scott Bultman of the University of North Carolina, Chapel Hill, who was not involved in the study ...
To probe the link between colon tumors and gut microbes, the researchers treated mice engineered to be prone to colon cancer with antibiotics. By reducing intestinal bacteria, the drugs hindered malignant lumps of cells called polyps from growing in the lining of the colon and small intestines. The team then noticed that feeding the rodents a diet low in sugar and starch also reduced the growth of polyps.
The mice had two gene mutations often linked to colon cancer in people, one of which derails a cell's ability to fix errors that arise during DNA replication, known as the mismatch DNA repair system.
A mismatch repair deficiency causes cells in the lining of the colon to divide quickly, explains study leader Alberto Martin, an immunologist at the University of Toronto. Bacteria and carbs speed the process, he says, damaging the genome and leading to tumor growth.
The researchers surmised that when microbes feast on carbohydrates, the bacteria must produce a chemical that pushes colon cells lacking the ability to repair DNA mismatches toward uncontrollably multiplying into tumors.
To find that chemical, they looked to the colon contents of mice that ate low-carb diets or had received antibiotics. Those mice, compared with mice on regular diets, had lower levels of a fatty acid called butyrate, one of the byproducts of microbes' fermentation of carbohydrates.
The researchers then fed mice butyrate-enriched supplements. Those mice had more tumor polyps, suggesting that the path from Western diets to colon cancer relies on this bacterially produced chemical ...
If the mouse experiments mimic human cancers, then shunning high-carbohydrate, Western diets could allay or prevent the disease for many people, says Bultman ...
Editor's Note: This article was updated August 7, 2014, to clarify that antibiotics reduced intestinal bacteria in the mice.
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Compound in red meat, energy drinks linked to heart disease in Cleveland Clinic research
By Brie Zeltner, The Plain Dealer
April 07, 2013
"It's everywhere. The amount of carnitine in many energy drinks is equivalent to a porterhouse steak, or more." -- Dr. Stanley Hazen
A nutrient called carnitine found naturally in red meat products such as beef, venison, pork, duck and lamb appears to lead to hardening of the arteries, according to recent research from the Cleveland Clinic.
CLEVELAND, Ohio -- A dietary compound abundant in red meat and used as a supplement in energy drinks, energy pills and some weight-loss treatments has been found to promote hardening of the arteries, according to a study released Sunday by a research group at the Cleveland Clinic.
The finding may help explain why some people, even when they get their cholesterol under control, still suffer ill effects from a diet high in meats such as beef, venison, lamb, duck and pork.
The research group, led by Dr. Stanley Hazen, section head of preventive cardiology and rehabilitation, has been investigating the link between heart disease and foods, the bacteria in the intestine that digest them, and the substances these bacteria create in the digestion process.
In 2011, the group connected the dietary nutrient lecithin, found naturally in animal products, to heart disease through a byproduct of its metabolism in the gut called TMAO. In those studies TMAO, or trimethylamine N-oxide, proved to be a 10-fold stronger predictor of heart disease than cholesterol, a relationship that has held up in more recent work.
Now Hazen's group has found a similar relationship between TMAO and carnitine, a substance that is found in abundance in red meat and is needed in the body for the production of energy. When carnitine is digested, it drives up TMAO, and TMAO leads to increased plaque buildup in the arteries.
The finding is "fascinating, and starts to build a really interesting story with a lot of important public health implications," said Dr. Daniel Rader, a professor of medicine at University of Pennsylvania who specializes in genetics and heart disease and was not involved in the research.
"It leads to an interesting question that I don't have the answer to: Is there evidence that red meat consumption in people taking statins is still associated with cardiovascular risk? I don't think we know that yet," Rader said.
Rader said that Hazen's paper has changed what he will counsel patients, though.
"What this suggests is that maybe there really is a major mechanism associated with red meat consumption that's associated with cardiac risk factors independent of effects on blood cholesterol. Based on this data it makes sense to eat red meat in moderation at most even if your cholesterol is well-controlled." ...
In this most recent study, published April 7 in Nature, Hazen's group tested the carnitine and TMAO levels of omnivores, vegetarians and vegans to see if there were differences in the levels of the two substances due to diet.
They also took blood samples to test for carnitine and TMAO from more than 2,500 patients undergoing elective heart evaluations, and examined the effects of a carnitine-heavy diet on mice.
One of the study's biggest surprises, Hazen said, was how large an impact vegan and vegetarian diets had on the formation of TMAO from carnitine; people in the study who did not habitually eat red meat did not produce the plaque-forming TMAO even when they were given large doses of carnitine in the form of a steak or a supplement.
"Chronic dietary pattern has a real profound effect on the intestinal flora composition and your ability to make TMAO," Hazen said. Vegans and vegetarians seem to lack the microbes necessary to break down the carnitine, which may help explain the heart-protective benefit of such a diet.
"As far as I'm aware, this is the first time that anyone's really shown such a big dichotomy in metabolism between someone who's a vegetarian or vegan versus an omnivore," Hazen said.
Yet even those who eschew red meat may not be immune to the effects of carnitine, Hazen warned, because of the substance's frequent use as an energy-boosting supplement.
"It's everywhere," he said. "The amount of carnitine in many energy drinks is equivalent to a porterhouse steak, or more. Especially if you're talking about kids who are being targeted with all this advertising, drinking these drinks is like eating steaks every day and they're getting it in a can and don't even realize it."
Carnitine is usually listed on energy drink and supplement labels as L-carnitine, and may be part of a longer list of ingredients as an "energy blend." In the body, carnitine is used to help transport fatty acids, which are used as fuel, into the fuel production chambers of every cell in the body.
While it's long been touted as an energy-booster, there is no consistent evidence that carnitine improves exercise ability, function, or energy levels.
While it's going to take a lot more research to be sure what the long-term effects of supplemental carnitine intake might be, Hazen is concerned.
"It's shifting their [gut] flora to one that's more likely to promote atherosclerosis or hardening of the arteries," he said. "I wouldn't want my family members drinking these."
"I do think that's a second source of carnitine in the diet that people aren't aware of and don't think of being deleterious," Rader said. "This suggests that if you're a habitual consumer of supplemental carnitine you may being putting yourself at higher cardiovascular risk."
The new study also showed that blood levels of carnitine are able to predict cardiac risk. "Even after adjusting for all the traditional cardiac risk factors, blood level of carnitine predicts your future risk of heart attack and stroke death," Hazen said. The findings came from a large group of patients tested while undergoing cardiac evaluation.
Like the group's previous studies on lecithin, though, it was clear from the results that it wasn't the carnitine itself that was dangerous, but its conversion to TMAO that accounted for the elevated risk.
Mice who were given broad-spectrum antibiotics to wipe out their gut bacteria did not produce TMAO even on a high-carnitine diet, confirming the microbes' role in linking the two. The group previously found the same result in their lecithin study.
That doesn't mean anybody should be taking antibiotics to help prevent heart disease [Why?], Hazen said. It does mean that a heart-healthy probiotic or yogurt might be a way of modifying the carnitine-TMAO pathway and reducing heart disease risk.
Therapeutics like these are where Hazen's group is focused, he said.
"The first step is understanding what the components and the participants are, and now that we're getting a better handle on all these things, we're also finding new ways to explain how it's contributing to heart disease," he said. "The most exciting thing is going after a drug or food as a way of blocking it."
The group also continues to work on a diagnostic test for TMAO, which should be available late this year.
Trimethylamine N-oxide (TMAO) is the organic compound with the formula (CH3)3NO. This colorless solid is usually encountered as the dihydrate. It is an oxidation product of trimethylamine and a common metabolite in animals.
It is an osmolyte found in saltwater fish, sharks and rays, molluscs, and crustaceans. It is a protein stabilizer that may serve to counteract urea, the major osmolyte of sharks, skates and rays. It is also higher in deep-sea fishes and crustaceans, where it may counteract the protein-destabilizing effects of pressure.
TMAO decomposes to trimethylamine (TMA), which is the main odorant that is characteristic of degrading seafood.
Treatment of aqueous trimethylamine with hydrogen peroxide affords the dihydrate (Me = CH3):
H2O2 + Me3N => H2O + Me3NO
Trimethylamine-N-oxide is biosynthesized from trimethylamine, which is derived from choline.
A recent study indicates that high levels of TMAO are associated with an increased risk of cardiovascular disease. High levels of TMAO are found in the blood after consuming foods containing carnitine.
High concentrations of carnitine are found in red meat and some energy drinks. Some types of gut bacteria (e.g. some species of Acinetobacter) convert dietary L-carnitine to TMAO. Vegans appear to lack the gut bacteria that convert carnitine to TMAO.
Gut microbes may foster heart disease
Helpful bacteria produce artery-hardening compound
By Tina Hesman Saey
Web edition: April 7, 2011
Even the best of friends can be heartbreakers.
Friendly bacteria living in the intestines may contribute to heart disease just by helping digest dietary fats. Bacteria that break down a fat found in meat, dairy and some fish set off a chain reaction that leads to the buildup of an artery-clogging substance in the blood, say researchers from the Cleveland Clinic and their colleagues. The findings, published in the April 7 Nature, point to a new culprit in the hardening of arteries and may lead to new treatments for heart disease.
"We probably have underestimated the role our microbial flora play in modulating disease risk," says Daniel Rader, a heart disease specialist at the University of Pennsylvania School of Medicine. Rader, who was not involved in the study, says that gut bacteria may not be as big a factor in causing heart disease as diabetes or smoking, but could be important in tipping some people toward sickness.
Researchers led by Stanley Hazen, a cardiologist at the Cleveland Clinic, didn't start out to study gut bacteria. In fact, says Hazen, he had "no clue -- zero," that intestinal microbes were involved in heart disease. "I'd never even considered it or thought of the concept."
Hazen and his colleagues compared blood plasma from healthy people to plasma from people who had had heart attacks, strokes or died to see if substances in the blood could predict who is in danger from heart disease. The researchers found 18 small molecules associated with fat buildup in the arteries. One of the best predictors turned out to be a by-product made when gut bacteria break down a fat called phosphatidylcholine (also known as lecithin).
The more of this by-product, called trimethylamine N-oxide or TMAO, a person or mouse has in the blood, the higher the risk of getting heart disease, the researchers found.
Gut bacteria are actually middlemen in TMAO production. The microbes convert lecithin to a gas that smells like rotten fish. Then an enzyme in the liver changes the foul-smelling gas to TMAO.
Mice genetically prone to get heart disease developed hardened arteries when fed lots of lecithin-rich egg yolks. But if the researchers eliminated most of the mice's gut microbes with antibiotics, the animals didn't get clogged arteries. The researchers don't know exactly which types of gut bacteria make TMAO.
These findings show that the interactions of gut bacteria with diet can influence health, says Rader. The work also suggests that probiotics or drugs might be able to block TMAO production ...
Z. Wang, et al. Gut flora metabolism of phosphatidylcholine promotes cardiovascular disease. Nature, Vol. 472, April 7, 2011, p. 57 doi:10.1038/nature09922
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A. Goho. Our Microbes, Ourselves. Science News, Vol. 171, May 19, 2007, p. 314.
T. Hesman Saey. Antibiotics may make fighting flu harder. Science News, Vol. 179, April 9, 2011, p. 14.
L. Sanders. Identical twins may not be so identical when it comes to gut bacteria. Science News, Vol. 177, April 24, 2010, p. 9.
J. Travis. Gut Check. Science News, Vol.163, May 31, 2003, p. 344
[Fat Lies Exposed]
Omega-3s and More: The Importance of Fat in a Healthy Diet
By Richard Manning
Mother Earth News
December 2015/January 2016
... Think of omega-3s as a ... portal into a bigger, fuller, richer story of fats in general ...
It was ... an oversimplification that persuaded experts to recommend avoiding [fats] for the past 40 years. Consider, for example, how the popular mantra "You get fat because you eat fat" relates to a cornerstone of contemporary medicine: "Cholesterol in our blood derives from eating certain fats, and causes the heart disease that kills us."
None of this is true. Despite prominent critiques over the past decade by writers such as Mary Enig, Ph.D., Gary Taubes, and Nina Teicholz, these anti-fat articles of faith spawned legions of unctuous fat nags, cholesterol screenings, skin-trimmed chicken breasts, Egg Beaters, and margarine. All of this was wrong ...
How Bad Advice Brought Bad Health
The long-recommended health guidelines that demonized all fat ultimately increased the amount of recommended carbohydrates in our diets. Unlike fats, carbohydrates are simple. Some carbohydrates are called "complex" -- such as whole-wheat flour and potato starch -- but all carbohydrates eventually reduce to sugars, which then reduce to glycogen.
An overload of carbohydrates triggers an insulin response, leading eventually to insulin resistance -- one of the markers associated with metabolic syndrome, which underpins obesity, diabetes, heart disease and the related inflammation ...
Fats perform many tasks in your body: They provide energy, wire brain neurons, allow bones to absorb calcium, prevent blood clots, mediate inflammation, and speed nervous-system response -- to name a few ...
For example, a person short on one simple vitamin or nutrient often can't correct the deficiency by taking a vitamin supplement. If the other components of basic transport and chemical reactions aren't present to allow the body to use that vitamin, that person won't absorb its benefits. Fats enable bioavailability for a variety of nutrients, including carotenoids and the fat-soluble vitamins A, D, E and K ...
On some fat-related issues, mainstream consensus has emerged on what is actually good versus bad. Trans fats, for instance, are now understood to be the original Frankenfood ...
Artificial trans fats are found in industrially processed, hydrogenated vegetable oils. Whipped up as a cheaper alternative to lard in the early 20th century, artificial trans fats are the core of shortening and margarine; both are thinly disguised vegetable oils previously touted as healthful substitutes for allegedly harmful animal fats.
Many biochemical processes in your body work by pairing shapes of molecules to receptors, like keys fitting into locks. When your body doesn't recognize a molecular shape, it treats the stranger as an invader, and fights it with the immune response of inflammation. Trans fats have an unrecognizable shape, which is why the U.S. Food and Drug Administration now officially lists trans fats as unsafe to eat. Yet they remain the lubricant in much of fast and processed food.
An advisory committee that guides federal nutrition policy signaled an even bigger shift in February 2015 by reversing long-standing advice to avoid foods high in saturated fats, such as butter and lard, and those high in cholesterol, such as eggs.
Omega-3s and Omega-6s
Many of the fats labeled "essential fatty acids" perform particular, unique, and, yes, essential tasks to keep our bodies running. These fatty acids have no substitutes, and for the most part can't be made within our bodies ...
A lack of a particular omega-3 -- docosahexaenoic acid, or DHA -- undermines the function of our brains. As the British journalist Graham Rose famously wrote, we are in danger of creating "a race of morons" because of the omega-3 deficiency in contemporary diets.
Here's the scary news: Most of us eating modern diets aren't getting enough of these crucial omega-3 fats. Omega-3 is not the name of a single kind of fat molecule, but rather is an umbrella term for a set of five similar fat molecules.
Like omega-3, omega-6 is an umbrella term for a number of fatty acids, and the key one is linoleic acid. Linoleic acid is the primary fat in corn, soy, cottonseed, safflower and sunflower oils. Modern industrial agriculture and food processing have replaced the DHA we once consumed with linoleic acids from vegetable oils ...
A growing number of researchers focus on one specific omega-3 fatty acid, DHA ... it is critical to brain function. A shortage of DHA is linked to a wide range of brain malfunctions, including:
The brain runs on fat, but this is not a brain issue alone. The prevailing advice, to choose vegetable oils rather than animal fats, may also have raised obesity rates by lowering DHA concentrations in red blood cells. It's important to realize that while other omega-3s have particular functions, they can't substitute for DHA. Eating more omega-3s will not stave off these problems unless an adequate amount of DHA is in the mix ...
The best contemporary source of DHA is cold-water fish, such as salmon and tuna. Can we solve these urgent health problems simply by eating more fish? J.T. Winkler, a British researcher of nutrition policy, provided a blunt answer to another key question: "Are there enough fish in the sea to provide the amounts we need? No." ...
The industrial solution to overfishing seems to be aquaculture, or farmed fish. But that "solution" is a dead end, and the reason is illuminated by the term some apply to farmed fish: "floating vegetables." Farmed fish would ideally get omega-3s mostly by eating fish meal and fish oils, but they don't. Farmed fish become "floating vegetables" simply because aquaculture worldwide feeds vegetable oils to farmed fish, a practice that has left them with an unnatural and unhealthful omega-6 to omega-3 ratio -- the same defect of all factory-farmed foods.
The problem is that foods high in omega-6 -- notably soy and corn oils, as well as factory-farmed meat and dairy -- produce such a surplus of omega-6 fatty acids that the beneficial omega-3 fats can't compete.
When omega-6s flood your system, they use up all the molecular sockets needed by omega-3s, so the latter are blocked from doing their jobs. The modern U.S. diet has an omega-6 to omega-3 ratio of more than 10 to 1. Research shows we evolved with a ratio closer to 1 to 1, and would be a lot healthier if we could achieve that again ...
A Norwegian researcher looking at diets fed to farmed fish and lab animals found that the simple switch in concentrations of these two key fatty acids to favor omega-6s provoked obesity and inflammation. Restoring the ratio to a more natural balance reversed both obesity and inflammation ...
Oddly, studies of omega-3 sources have focused almost exclusively on fish, and were this the end of the story, humanity would be in a terrible jam. Red meat from beef and pork, as well as poultry meat, has been generally ignored, simply because grain-fed animals face exactly the same problem as farmed fish: They're fed corn and soy, which are so high in the wrong kind of fats.
Almost all the beef, pork and poultry raised in the United States comes from animals fed such a diet, which is cheap in more ways than one, and fattens them up quickly. Their meat, milk and eggs are significantly different from products that come from animals raised on their original, pastured diets ...
As is the case with wild fish, products provided by pasture-raised animals deliver the DHA we require. While grass-fed beef, eggs and dairy products are not as rich in DHA, pound for pound, as wild, cold-water fish, they still have it in abundance.
Besides DHA, there are four other discrete omega-3s, and each has a role to play. Compared with feedlot products, milk and meat from pasture-raised animals also have 300 to 500 percent more conjugated linoleic acid, or CLA -- another omega-3 fatty acid (distinct from omega-6 linoleic acid). This CLA offers benefits for brain health different from those of DHA ...
Taken together, all of this evidence drives a "steak" in the heart of fat-phobic advice and warnings about high cholesterol. The widespread and unanimous evidence correlates reduced omega-3 fats with reduced brain function, especially the long-term, corrosive effects that lead to dementia and Alzheimer's disease.
Research even shows a connection between the widely prescribed statin drugs that lower blood cholesterol, such as Lipitor, and reduced brain function. This is not a side effect of the drugs, but a primary effect -- statins reduce cholesterol. Now, consider that while your brain is about 2 percent of your body's weight, it holds about 25 percent of your body's cholesterol, and is composed of approximately 60 percent fat. In short, your brain must have cholesterol ...
The following, simple rules will point us in the right direction:
Avoid processed foods. They're loaded with soy- and corn-based ingredients, and are too high in sugars, as well as preservatives and other dubious additives.
Embrace variability. Don't take all of your eggs out of one basket. Seek rich sources of omega-3s, especially DHA, and the rest of the essential fatty acids will come with the package ...
Choose wisely and eat well. The best sources of healthful fats and the whole array of micronutrients are wild, cold-water fish; wild game; and meat, dairy and eggs from grass-fed animals. Complement those with the abundant micronutrients and fats in fresh, unprocessed foods, nuts, fruits and vegetables -- and see what you think. Or, more accurately, see how you think, and how you move and feel ...
Richard Manning is the author of Against the Grain: How Agriculture Has Hijacked Civilization, and, with Dr. John Ratey, of Go Wild.
[80,000 chemicals in global commerce]
November 28, 2015
New York Times
by Nicholas Kristof
In recent weeks, two major medical organizations have issued independent warnings about toxic chemicals in products all around us. Unregulated substances, they say, are sometimes linked to BREAST and PROSTATE cancer, genital deformities, obesity, diabetes and infertility.
"Widespread exposure to toxic environmental chemicals threatens healthy human reproduction," the International Federation of Gynecology and Obstetrics warned in a landmark statement [in October 2015].
The warnings are a reminder that the chemical industry has inherited the mantle of Big Tobacco, minimizing science and resisting regulation in ways that cause devastating harm to unsuspecting citizens.
In the 1950s, researchers were finding that cigarettes caused cancer, but the political system lagged in responding. Now the same thing is happening with toxic chemicals.
The gynecology federation's focus is on endocrine disrupters, chemicals that imitate sex hormones and often confuse the body. Endocrine disrupters are found in pesticides, plastics, shampoos and cosmetics, cash register receipts, food can linings, flame retardants and countless other products.
"Exposure to toxic chemicals during pregnancy and lactation is ubiquitous," the organization cautioned, adding that virtually every pregnant woman in America has at least 43 different chemical contaminants in her body. It cited a National Cancer Institute report finding that "to a disturbing extent babies are born 'pre-polluted.'"
This warning now represents the medical mainstream. It was drafted by experts from the American College of Obstetricians and Gynecologists, the American Society for Reproductive Medicine, the World Health Organization, Britain's Royal College of Obstetricians and Gynecologists, and similar groups.
Such medical professionals are on the front lines. They are the ones confronting rising cases of hypospadias, a birth defect in which boys are born with a urethra opening on the side of the penis rather than at the tip. They are the ones treating women with breast cancer. Both are conditions linked to early exposure to endocrine disrupters.
The other major organization that recently issued a warning is the Endocrine Society, the international association of doctors and scientists who deal with the hormone system.
"Emerging evidence ties endocrine-disrupting chemical exposure to two of the biggest public health threats facing society -- diabetes and obesity," the Endocrine Society said in announcing its 150-page "scientific statement."
It added that "mounting evidence" also ties endocrine disrupters to infertility, prostate cancer, undescended testicles, testicular cancer, breast cancer, uterine cancer, ovarian cancer and neurological issues. Sometimes these problems apparently arise in adults because of exposures decades earlier in fetal stages.
"The threat is particularly great when unborn children are exposed," the Endocrine Society warned.
Tracey J. Woodruff of the University of California, San Francisco notes, "One myth about chemicals is that the U.S. government makes sure they're safe before they go on the marketplace." In fact, most are assumed to be safe unless proved otherwise.
Of the 80,000 or more chemicals in global commerce today, only a tiny share have been rigorously screened for safety. Even when a substance is retired because of health concerns, the replacement chemical may be just as bad.
"It's frustrating to see the same story over and over," Professor Woodruff said. "Animal studies, in vitro tests or early human studies show that chemical A causes adverse effects. The chemical industry says, 'Those are bad studies, show me the human evidence.' The human evidence takes years and requires that people get sick. We should not have to use the public as guinea pigs."
Europe is moving toward testing chemicals before they go on the market, but the United States is a laggard because of the power of the chemical lobby. Chemical safety legislation now before the Senate would require the Environmental Protection Agency to start a safety assessment of only 25 chemicals in the first five years -- and House legislation isn't much better.
"There are almost endless parallels with the tobacco industry," says Andrea Gore, a professor of pharmacology at the University of Texas at Austin and editor of the journal Endocrinology ...
The chemical lobby spent the equivalent of $121,000 per member of Congress [in 2014], so expect chemical companies to enjoy strong quarterly profits, more boys to be born with hypospadias and more women to die of breast cancer.
Big Chem, Big Harm?
August 25, 2012
by Nicholas Kristof
New York Times
New research is demonstrating that some common chemicals all around us may be even more harmful than previously thought. It seems that they may damage us in ways that are transmitted generation after generation, imperiling not only us but also our descendants.
Yet following the script of Big Tobacco a generation ago, Big Chem has, so far, blocked any serious regulation of these endocrine disruptors, so called because they play havoc with hormones in the body's endocrine system ...
Maybe it seems surprising to read a newspaper column about chemical safety because this isn't an issue in the presidential campaign or even firmly on the national agenda. It's not the kind of thing that we in the news media cover much.
Yet the evidence is growing that these are significant threats of a kind that Washington continually fails to protect Americans from. The challenge is that they involve complex science and considerable uncertainty, and the chemical companies -- like the tobacco companies before them -- create financial incentives to encourage politicians to sit on the fence. So nothing happens.
Yet although industry has, so far, been able to block broad national curbs on bisphenol-A [BPA], new findings on transgenerational effects may finally put a dent in Big Chem's lobbying efforts.
One good sign: In late July, a Senate committee, for the first, time passed the Safe Chemicals Act, landmark legislation sponsored by Senator Frank Lautenberg, a New Jersey Democrat, that would begin to regulate the safety of chemicals.
Evidence of transgenerational effects of endocrine disruptors has been growing for a half-dozen years, but it mostly involved higher doses than humans would typically encounter ...
Now Endocrinology, a peer-reviewed journal, has published a study measuring the impact of low doses of bisphenol-A [BPA]. The study is devastating for the chemical industry.
Pregnant mice were exposed to bisphenol-A at dosages analogous to those humans typically receive. The offspring were less sociable than control mice (using metrics often used to assess an aspect of autism in humans), and various effects were also evident for the next three generations of mice.
The bisphenol-A seemed to interfere with the way the animals processed hormones like oxytocin and vasopressin, which affect trust and warm feelings. And while mice are not humans, research on mouse behavior is a standard way to evaluate new drugs or to measure the impact of chemicals.
"It's scary," said Jennifer T. Wolstenholme, a postdoctoral fellow at the University of Virginia and the lead author of the report. She said that the researchers found behaviors in bisphenol-A-exposed mice and their descendants that may parallel autism spectrum disorder or attention deficit disorder in humans.
Emilie Rissman, a co-author who is professor of biochemistry and molecular genetics at University of Virginia Medical School, noted that bisphenol-A doesn't cause mutations in DNA. Rather, the impact is "epigenetic" -- one of the hot concepts in biology these days -- meaning that changes are transmitted not in DNA but by affecting the way genes are turned on and off.
In effect, this is a bit like evolution through transmission of acquired characteristics -- the theory of Jean-Baptiste Lamarck, the 19th-century scientist whom high school science classes make fun of as a foil to Charles Darwin. In epigenetics, Lamarck lives.
"These results at low doses add profoundly to concerns about endocrine disruptors," said John Peterson Myers, chief scientist at Environmental Health Sciences. "It's going to be harder than just eliminating exposure to one generation."
The National Institutes of Health is concerned enough that it expects to make transgenerational impacts of endocrine disruptors a priority for research funding, according to a spokeswoman, Robin Mackar.
Would you like chemicals with your popcorn?
By NICHOLAS KRISTOF
June 6, 2015
What do a pizza box, a polar bear and you have in common?
All carry a kind of industrial toxicant called poly-perfluoroalkyl substances, or PFASs, that do two things: They make life convenient, and they also appear to increase the risk of cancer.
The scientists I interviewed say that they try to avoid these chemicals in their daily lives, but they're pretty much unavoidable and now are found in animals all over the planet (including polar bears in Greenland and probably you and me).
PFASs are used to make nonstick frying pans, waterproof clothing, stain-resistant fabrics, fast-food wrappers, microwave popcorn bags, firefighting foam and thousands of other products. Many are unlabeled, so even chemists sometimes feel helpless.
This should be a moment when government steps up to protect citizens. But from tobacco to lead paint to chemicals, industry has used donations, obfuscation and lobbying to defer regulation until the human casualties are too vast to be hidden.
PFASs are "a poster child" for what's wrong with chemical regulation in the United States, says John Peterson Myers, chief scientist of Environmental Health Sciences, a research and publishing group in Virginia. PFASs are just about indestructible, so, for eons to come, they will poison our blood, our household dust, our water and the breast milk our babies drink.
Warnings of health risks from PFASs go back half a century and are growing more ominous. In May  more than 200 scientists released a Madrid Statement warning of PFASs' severe health risks. It was published in Environmental Health Perspectives, a peer-reviewed journal backed by the National Institutes of Health.
The scientists cited research linking PFASs to testicular and kidney cancer, hypothyroidism, ulcerative colitis and other problems.
Arlene Blum is a chemist whose warnings about carcinogens have proved prophetic. In recent years, she has waged an increasingly successful campaign against modern flame-retardant chemicals because of evidence that they also cause cancer, but she told me that PFASs "are even a bigger problem than flame retardants."
The chemical industry acknowledges that older, "long-chain" PFASs are a problem but says that it is replacing them with "short-chain" versions that should be fine. It's true that there is less evidence against the short-chains, but that's perhaps because they have been studied less.
Americans expect that chemicals used in consumer products have been tested for safety. Not so. The vast majority of the 80,000 chemicals available for sale in the United States have never been tested for effects on our health. Any testing is being done on all of us. We're the guinea pigs.
Congress may finally pass new legislation regulating toxic chemicals, but it's so weak a bill that the chemical industry has embraced it. The Senate version is better than nothing, but, astonishingly, it provides for assessing high-priority chemicals at a rate of about only five a year, and it's not clear that the House will go that far.
Yes, of countless toxicants suspected of increasing the risk of cancer, obesity, epigenetic damage and reproductive problems, the United States would commit to testing five each year. And that would actually be progress.
For safety reasons, Europe and Canada already restrict hundreds of chemicals routinely used in the United States. Perhaps the danger of tainted brands and lost sales abroad -- not the risk to Americans -- will motivate U.S. companies to adopt overseas limits.
Scientists are already taking precautions and weighing trade-offs in their personal lives. R. Thomas Zoeller, a biology professor at the University of Massachusetts, Amherst, says he now avoids buying nonstick pans. Rainer Lohmann, an oceanographer at the University of Rhode Island, told me that he is replacing carpets in his house with wood floors in part to reduce PFASs ...
The chemical lobby is following the same script as the tobacco and lead lobbies a generation ago, throwing around campaign donations and lobbying muscle to delay regulation. The chemical industry spent $190 million lobbying in the last three years. If only it would devote such sums to developing safer products, rather than to defending its right to produce suspected carcinogens.