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In more news that has steak lovers feeling deflated, a study published in this week's issue of the Archives of Internal Medicine finds that people who indulge in high amounts of red meat and processed meats, including steak, bacon, sausage and cold cuts, have an increased risk of death from cancer and heart disease. The findings add power to the growing push — by health officials, environmentalists and even some chefs — to cool America's love affair with meat.

The analysis of more than half a million Americans between the ages of 50 and 71 found that men in the highest quintile of red-meat consumption — those who ate about 5 oz. of red meat a day, roughly the equivalent of a small steak, according to lead author Rashmi Sinha — had a 31% higher risk of death over a 10-year period than men in the lowest-consumption quintile, who ate less than 1 oz. of red meat per day, or approximately three slices of corned beef. Men in the top fifth also had a 22% higher risk of dying of cancer and a 27% higher risk of dying of heart disease. In women, the figures were starker: women in the highest quintile of consumption had a 36% increase in death over a 10-year period compared with women who ate little red meat; eating lots of meat was associated with a 20% higher risk of dying of cancer and a 50% higher risk of dying of heart disease. (Read "A History of Beef, Times Two.")

The data for one of the largest analyses of meat consumption and mortality to date were first gathered for the National Institutes of Health and AARP Diet and Health Study in 1995. Researchers then tracked deaths for 10 years, until 2005, using the Social Security Administration Death Master File and the National Death Index, controlling for factors such as age, race, education, body-mass index and alcohol intake. (See pictures of a perfect steak instead of eating one.)

"Basically, the consumption of red and processed meat was associated with modest increases in mortality," says Sinha, a senior investigator at the National Cancer Institute's Division of Cancer Epidemiology and Genetics, who is careful to emphasize that the institute is a research organization and does not make health recommendations. She suggests, however, that the fat content of and heavy iron concentration in red and processed meats, along with high-temperature cooking methods that can lead to the development of carcinogens, may increase the risk for disease and death. In contrast, the study found that higher white-meat consumption was associated with a lower risk of death. (Read "Meat: Making Global Warming Worse.")

Dr. Barry Popkin, a nutrition epidemiologist and economist who directs the interdisciplinary obesity program at the University of North Carolina, would use a term other than Sinha's "modest." "You're talking about a lot of deaths that would be prevented by cutting your processed meat or cutting your red meat," he says. He suggests framing the issue in real terms. A McDonald's Big Mac contains 7.5 oz. of red meat, Popkin points out. So if your diet consists of a Big Mac every other day — roughly equivalent to the highest quintile of meat consumption in the study; in other words, the typical American diet — you could cut back to one Big Mac a week and see dramatic health benefits.

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The impact would be dramatic for the planet as well, Popkin writes in an editorial that accompanies the study. Popkin, whose recently published book The World Is Fat examines the global trends driving the obesity epidemic, joins a growing cohort of researchers, environmentalists and foodies clamoring for an overhaul of the American diet. Currently, the average American consumes more than 200 lb. of meat a year, a habit that comes at considerable environmental cost, Popkin says. He cites a recent United Nations Food and Agriculture Organization finding that livestock account for 18% of global greenhouse-gas emissions — more than transportation — and underscores the fact that the livestock industry uses up to five times the water necessary to cultivate crops. (See the top 10 food trends of 2008.)

What's more, the developing world seems to be falling in step, Popkin says. In India, meat and dairy intake more than doubled between 2000 and 2005. In 2006, the average diet of 67% of the Chinese population comprised at least 10% meat and dairy products, up from about 39% of the population in 1989. "We truly did this to the globe — changed the way the world eats," says Popkin.

But our diet can be changed back, says Mark Bittman, a cookbook author, New York Times contributor and deity in the world of foodies. He started by cutting back on meat and dairy and says he now consumes roughly one-third the animal products he used to, adhering to what's become known as the Vegan Before Six (or VB6) diet: vegan foods for the first two meals of the day, then anything you want for dinner.

In his new book Food Matters: A Guide to Conscious Eating, Bittman makes the case for limiting meat, eggs and dairy; increasing fruits and vegetables in our diet; and making small steps to eat healthier, rather than obsessing over terms like sustainable and organic. He advocates an incremental approach to tapering the whopping 600 lb. of animal products the average American eats each year. "I'm not looking to encourage people to do something that they're going to do for two weeks and then say, 'To hell with that!' and go back to eating their regular diet," Bittman says. That would be like trying to jump immediately to an all-bicycle transportation model. "Let's move toward eating less meat," he says, "and then in five years we can re-evaluate."

See nine kid foods to avoid.

See pictures of what makes you eat more food.

Every surgery poses risk, as doctors will inform you, but in most cases it's a necessary one. The benefits of going under the knife frequently outweigh the risks of infection or complications, or the dangers associated with anesthesia.

But balancing the benefits and risks is more difficult when the patients are babies, the most fragile population. Now a new study from the Mayo Clinic, published March 24 in the journal Anesthesiology, finds a link between exposure to anesthesia during surgery in infancy and learning disabilities later in life — the first such study to do so in humans — making the decision to operate even more fraught for both parents and doctors. (See TIME's A-Z Health Guide.)

Studying a group of more than 5,000 children born between 1976 and 1982 in Olmstead County, Minn., researchers tracked the number of operations each youngster received before age 4, as well as his or her scores on reading, writing and math tests, administered once a year from elementary school through high school. Infants who had just one exposure to anesthesia showed no greater risk of learning problems by the time they reached 19 years, but those who had had two or more exposures had a 60% increased chance of developing a learning disability compared with babies who did not have any operations. Three or more exposures to anesthesia by age 3 doubled children's risk of having difficulty in thinking, speaking, spelling or performing math calculations by the end of high school. (See 9 kid foods to avoid.)

The results reignite a long-standing controversy over the impact of anesthesia on still-developing minds and bodies. The hazards have been documented in earlier studies of animals: For example, rat studies have repeatedly shown that animals exposed to anesthesia drugs in the first seven days of life — when nerve cells are forming and connecting to the larger neural network — develop problems performing maze exercises, which require memory and reasoning skills. In the 1960s, based on similar concerns over possible injury to babies' immature nervous systems, doctors advocated only light anesthesia or none at all for infants undergoing surgery. Some experts believed that babies did not have sufficiently developed neural connections to even feel any pain. "There was a whole series of papers showing that [giving anesthesia] was a bad thing to do," says Dr. Robert Wilder, an author of the Mayo Clinic study. "One thing that is very clear is that kids who have surgery without the appropriate anesthetic have higher degrees of morbidity and, in some cases, even mortality associated with surgery compared to kids who have gotten the appropriate anesthetic." (Read a TIME cover story on children.)

But that anesthesia may also put babies at greater risk for cognitive problems later in life, according to Wilder's latest findings. The author is quick to point out, however, that the data is preliminary and does not necessarily suggest a direct or definitive causal link between anesthesia and learning disabilities, only an association. "We clearly have not demonstrated that anesthetics are the cause of learning disability," says Wilder. "We don't want this to alarm the public to the point they aren't giving children appropriate medical care." It could be dangerous to deny children surgery to spare them the anesthesia, Wilder says, since in most cases of pediatric surgery, the procedure is a necessary and potentially life-saving one that cannot be avoided or postponed.

Wilder and his colleagues are cautious about their results also because the data do not make clear whether it was the anesthesia that contributed to the children's learning deficits, or whether it was an underlying condition that may have required surgery and precipitated the learning problems. Of the more than 5,000 babies studied, 593 needed at least one surgery and just over 100 infants needed more than two before age 3. There may be something unusual about this population of children that could have made them vulnerable to learning problems and required they undergo surgery and anesthesia. "The data we have is very preliminary," says Dr. Randall Flick, Wilder's co-author at the Mayo Clinic. "It really doesn't prompt me or any of my colleagues to say we should change the way we practice."

Not yet perhaps. But it does highlight the need for future research; while the study does not establish a direct link between anesthesia and learning disabilities, it doesn't rule one out. The babies who underwent surgery in the Mayo study were treated for a wide range of conditions, few of which were brain-related. By far, the most common procedure performed on the infants involved the insertion of tubes in the ears to remove fluid to prevent hearing loss and potential delays in speech and language skills; 26% of the babies undergoing surgery fell into this category. One-quarter of the infants needed general surgery, while 13% required some type of orthopedic procedure. Only 1% of the infants who had surgery needed a neurological procedure. That may suggest that some aspect of the operation or anesthesia — and not the condition that required surgical treatment — could have influenced the babies' cognitive development. (See TIME's pictures of the week.)

What's more, the Mayo researchers found hints of a dose-dependent effect: The longer infants stayed under anesthesia, the greater their chance of developing problems reading, writing and doing math later.

Still, experts are not willing to say that babies should never be given anesthesia. "We don't want to delay surgery or withhold surgery for the kids who need it," says Dr. Sulpicio Soriano, an anesthesiologist at Harvard Medical School and Children's Hospital in Boston. "But we need more research and clinical investigation to find new drugs and new combinations of drugs that can attenuate or mitigate the cognitive effects."

Already, the Food and Drug Administration is supporting further study into the connection between anesthesia and cognition to find such alternatives. In the meantime, says Flick, "it's just not time yet to make any recommendations about changing practices."

See TIME's A-Z Health Guide.

Read a TIME story on anesthesia.

Twenty years since the Exxon Valdez tanker ran aground on the night of Mar. 24, 1989 — spilling nearly 11 million gallons of crude oil, which would coat 1,300 miles of coastline — Alaska's Prince William Sound is still feeling the effects. Despite the extensive, years-long clean-up effort, oil can still be found in spots on the Alaskan coast, especially under the surface. (See pictures of the Exxon Valdez disaster.)

Thousands of sea otters, seals and eagles and a quarter of a million seabirds died as a result of the spill, one of the worst ecological disasters in history, and the populations of those species have yet to fully recover. The lucrative herring and salmon fisheries are still damaged — by one estimate, the spill cost local fishermen nearly $300 million. "On the surface, Prince William Sound looks like it has regained its majesty," says Keith Colburn, an Alaskan fisherman and one of the stars of the reality TV series The Deadliest Catch. "But below the surface it's completely different." (Listen to Colburn talk about the Exxon Valdez anniversary on this week's Greencast.)

Alaskans like Colburn are worried that on the eve of the 20th anniversary of the Valdez accident, the spill and its toll are in danger of being forgotten — even as new offshore oil and gas exploration is being considered in Alaska. In 2007, former President George W. Bush ended a long-standing executive ban on offshore oil drilling in Bristol Bay in the southeastern waters of the Bering Sea, potentially opening up what's been called America's "fish basket" to the fossil fuels industry. Although the Obama Administration has slowed the process, it hasn't stopped it — and Alaska's Republican Gov. Sarah Palin would be happy to "drill, baby, drill," especially as the declining price of oil diminishes state revenues. (Read "Drilling for Oil Way, Way Offshore.")

The oil industry claims that safety standards have improved, and that the chances of another accident are small. But to environmentalists, the Valdez is still a looming reminder that oil will always threaten the vulnerable marine environment — and that a single mistake can have ramifications that last for decades. "If it's lost, it's lost forever," says Margaret Williams, the Alaska director for the World Wildlife Fund (WWF), which is calling for Bristol Bay and other parts of the Arctic to be made "no-go zones" for oil and gas development. "There are lessons to be learned from the Exxon Valdez, but they're not being learned well." (See pictures of the fragile earth.")

One of those lessons is that the Arctic ecosystems are unusually vulnerable to oil spills, according to long-term research funded by some of the $1 billion settlement from Exxon. Scientists found that, thanks in part to the cold environment, oil lingered in the area for years, some of it still biologically active and toxic. Because many Arctic species have long lifespans and slow reproductive cycles, wildlife recovery has been slow. Pacific herring — a keystone of both the commercial fishing industry and the marine food web in Prince William Sound — were spawning at the time of the spill, and were hit particularly hard. "The herring stocks still haven't recovered," says Colburn.

Another catastrophic spill or accident notwithstanding, even the work of setting up offshore oil drilling could impact the marine environment. The oil industry uses seismic blasts as part of initial exploration, and environmentalists fear that sound waves could harm nearby fish. But if there were an accident on the scale of the Valdez in Bristol Bay, where more than 40% of all wild seafood consumed in America is caught, the result would be not just an environmental disaster, but also an economic one. The Bristol fisheries bring in over $2 billion to the Alaskan economy annually — losing the bay even for a short time because of a spill would be "devastating," says Colburn. "We don't know the impacts on juveniles. We don't know the impacts on soft-shelled crab. To me, [oil exploration] is just such a near-sighted policy."

The new Secretary of the Interior Ken Salazar has indicated that he will review oil and gas leases for Arctic waters, and for now, the sudden drop in the price of oil has blunted some of the impetus to drill. Although Salazar is in no rush to go fishing for petroleum, as soon as the world economy recovers, so will demand for oil and the pressure to drill offshore in Alaska. And that pressure will surely only grow as climate change causes the Arctic ice to recede. But that is precisely the lesson that must be remembered from the Exxon Valdez: that some parts of the world are too precious to be risked for a few million barrels of oil. "This place was a Shangri-la of the Arctic, a very special place," says Williams. "And today it's lost."

Read "The Stain Will Remain On Alaska".

See pictures of South Korea's oil spill.

It's been two years since the U.N. Intergovernmental Panel on Climate Change laid out the definitive case that human beings were causing global warming, and two decades since NASA scientist James Hansen first told Congress of the threat of rising CO2 emissions. So, why has it taken this long for the Environmental Protection Agency (EPA) to announce that greenhouse gases endanger human health? Change can be slow in Washington.

On March 20 the EPA sent what is called an "endangerment finding" to the White House, a proposal that means the agency found that there is a scientific case that man-made global warming poses a threat to human welfare. (Reporters found out about the EPA decision the following Monday, after it was posted on a government website.) The finding is a response to an April 2007 Supreme Court decision ordering the EPA to figure out how CO2 from cars should be regulated under the Clean Air Act.

Scientific staff in the George W. Bush–era EPA found that CO2 is a pollutant, but then administrator Stephen Johnson rejected the recommendation and delayed the process of regulating it, part of the Bush Administration's general obstructionism on climate change. When Lisa Jackson took over the EPA under the new President, however, she told Congress that one of her first acts would be to reevaluate her predecessor's decision, and she didn't drag her feet. "It's an exercise in leadership that takes the first step in regulating CO2 emissions from automobiles," says John Walke, the clean air director for the Natural Resources Defense Council.

By concluding that greenhouse gases pose a threat to human welfare, the EPA's finding could lay the groundwork for nationwide regulation of CO2 emissions — just as the EPA is require to regulate pollutants like smog-causing sulfur dioxide. But regulating CO2 will be immensely more complicated — the U.S. emitted over 6 billion metric tons of CO2 in 2007 from countless sources — and business groups have raised the specter of a meddlesome EPA using greenhouse gases as an excuse to regulate projects large and small.

While the EPA has so far been silent about how it might actually regulate CO2 — and the endangerment finding is only an early step in a process that could take a year or longer — environmentalists say it's difficult to imagine that the agency would attempt to control every possible source of greenhouse gas emissions. "People running the EPA have common sense," says Frank O'Donnell, head of the environmental group Clean Air Watch. "They're going to focus the efforts on the biggest sources" like the auto industry and the utility sector.

Of course, if the Obama Administration achieves its stated goal of passing carbon cap and trade legislation, EPA regulations might be superseded — and even deep greens generally prefer Congressional action to federal fiat. But with cap and trade looking like it may become a victim of the White House's need to prioritize amidst a sea of crises, the EPA's actions could provide a much-needed nudge to Congress. "This is a strong message," says O'Donnell. "Congress either has to face the reality that something has to be done, or the Obama Administration will just do it itself." What's one more item on the world's longest Presidential to-do list?

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Dr. Peter J. Bentley, a research scientist at University College London, can answer questions on almost any scientific topic. His book Why Sh*t Happens: The Science of a Really Bad Day explores 39 typical mishaps — breaking a bone, losing your balance, getting crapped on by a bird — and explains exactly what happens and why. Bentley talked to TIME about the science behind a bad day.

TIME: You write about why we get dizzy — the liquid in our inner ears sloshes around. Is that similar to when people get motion sickness?
Bentley: Yes, it is. We're all hardwired to correlate a jolt in our balance with a jolt in our vision systems; that helps us maneuver through the world. If one happens without the other, it's a bit weird and we don't like it so much. Basically, if you're in a vehicle, your vision is stationary. You aren't seeing the bumps in the road, but you are feeling them, and that's when you start getting uncomfortable.

It reminds me of an experiment you can perform on yourself. When we move around, our eyes are hardwired to balance things out, a bit like an antishake mechanism in a camera. As we wobble about, our eyes wobble to smooth out the picture. They can move up and down and left and right, but our eyes balance in a rotational way as well. If you look in a mirror and tilt your head all the way to one side so that one ear is pointing to the ceiling, and then tilt your head all the way to the other side, look at what your eyes are doing in the mirror. Your eyes are actually rotating around in their sockets, on an axis from your nose to the back of your head. It looks really weird and a bit freaky.

You also talk about honeybees, and you mention the dance that bees do to tell other bees where food is. I've always wondered, How did we figure something like that out? Did a bunch of scientists sit around one day and suddenly go, "Oh, so that's what they're doing!"?
Basically, we ran a bunch of experiments on bees and it was clear that they had some way of telling each other what was going on. They were definitely communicating something, but it wasn't clear what. So a number of trials were conducted where certain factors were controlled. One of the factors [that was] changed was the direction of the sun. And the bees' behavior changed. When they went back in the hive, they started wiggling about differently. The next step is to correlate the exact position of the sun with the direction in which they do their dance. It's detective work, basically. (Read about honeybees in California's almond orchards.)

You also write about bird poop.
That I did.

One of the things you mention is that white bird poop means a bird is stressed. But when I see it around, it's almost always white. Are birds always stressed?
I meant when it's almost completely white. Um, I don't know how much detail you want, but the dark bits in the middle? If you don't see any of that and it's all white, then the bird is a bit more stressed.

You talk about blood and muscles. One of the things you mention is varicose veins. What exactly are they?
Well, your blood runs all over your body, so it obviously has to go against the direction of gravity sometimes. The only way you can do that is to have valves. They keep the blood from falling back down in between your heart pulses. Varicose veins are when valves don't work. Blood can't work its way up anymore, so it starts to pool and the vein starts to swell and it gets painful and horrible. At the moment with our technology, we can't replace the valve, so the cure is often to strip them out and rely on the remaining healthy veins.

You claim that if you scratch the top part of a CD, where the label is, it's actually worse than if you scratch the bottom.
Yes, it's surprising, isn't it? The laser looks through the clear bit, so we assume that's the delicate side. But actually, because of the way they're made — you start off with this lump of clear plastic and then you stick the foil on it, and then you stick a label on top of that — it's much thinner on the label side than it is on the other side. If you scratch the clear side, you can kind of polish it out. But if you scratch the label side, you're screwed. This is why jewel cases are designed to hold CDs in the air and stop [both sides] from touching.

So you pretty much know everything about everything?
Obviously, I can't answer everything, but the point of the book is to encourage people to be curious. Little kids have it right — running around and asking "Why?" all the time is the right thing to do. I think we should all keep doing that. And that's why being a scientist is the best job in the world. There's a lot of misinformation out there, like the CD thing, and it's nice to be able to explain the truth to people. With a little effort, you can learn something that lets you see the world in a completely different light.

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