2010 marked the completion of a bizarre telescope composed mainly of ancient ice. One billion tons of ice.

Buried a mile deep in the ice at the South Pole, IceCube is the world’s strangest telescope. Composed of water, it’s looking for the neutrino, nature’s most unusual particle. Eighty years after the neutrino was “invented” to balance a physics equation, it remains ultra-difficult to detect, measure and understand.

IceCube is focused mainly on particles that come all the way through the Earth. In other words, this telescope looks down.

Scientists say neutrinos can pass unscathed through a long bar of lead. How long? Say, one light year long — about 10 trillion kilometers. Because neutrinos can slip through everything in their path, including stars, galaxies and vast clouds of dust, they are unrivaled tattle-tales of ancient explosions in the deep universe.

The bad news is that the same property makes neutrinos extremely difficult to see.

But if you can somehow observe the neutrino’s insanely rare interaction with matter, you could learn something about the universe, and the gargantuan energy released by exploding stars.

Roots of a frozen telescope

That is the promise and the premise of IceCube, a $271-million project intended to solve a problem posed in 1930, when physicist Wolfgang Pauli proposed a new and rather odd particle. Tiny, energetic, with no electric charge and not necessarily any mass, it would be virtually undetectable.

Pauli himself admitted “I have done a terrible thing. I have postulated a particle that cannot be detected.”¹

The “now-you-don’t-see-it-and-you-never-will” neutrino was tailor-made for controversy; scientists detest what they can’t detect. Pauli’s idea was mocked² as “simply wrong” or “crazy.”

Today, scientists are sure nature is full of these shadowy characters: Rough calculations say a hundred trillion neutrinos whistle through your body every second.

Why make a big deal about neutrinos, which are, after all, less offensive than campaign ads? Because that ability to pass through all manner of interstellar crud allows neutrinos to carry messages from the far reaches of the universe.

Moreover, some neutrinos carry more punch than the wildest gamma ray. And just as you can’t pull a hot coal from a cold fire, you shouldn’t get “hot” neutrinos from “cool” sources like ordinary stars. These neutrinos, in other words, may deliver signals of some hip, blazingly hot stuff — neutron stars, active galactic centers, and exploding stars.

Finally, according to some scenarios, lower-energy neutrinos may comprise a small proportion of the mass — the stuff — of the universe, but they played a key role in the evolution of the universe.

In astronomy, as in love and antiques, “hard-to-get” translates into “most-wanted.” “The hope is that the particle that is almost nothing will tell us almost everything about the universe,” says Francis Halzen, a theoretical physicist at University of Wisconsin-Madison. Halzen directs IceCube, and did the same at IceCube’s predecessor, AMANDA, the Antarctic Muon and Neutrino Detector Array.

Search strategy for an elusive character

Neutrinos may be shy, but once in a great while, they actually hit an atom and produce a subatomic particle called a muon, which is easier to see.

Because the odds of a neutrino hitting anything are so dismal, physicists require bigger targets. It’s the same principle that lottery players use to “beat” the tiny odds of winning by buying hundreds of tickets.

Previous neutrino targets have included tubs of oil or dry-cleaning fluid and 5,000 tons of steel plates salvaged from battleships. To block spurious signals due to cosmic rays rather than neutrinos, these detectors have been sunk in the ocean or placed inside deep mines.

IceCube relies on a two-step detection sequence: First, the tiny percentage of neutrinos that interact with atomic nuclei in the ice produce muons. Second, these muons create Cherenkov light when they interact with matter.

When the detectors see Cherenkov light, they digitize the data and send it through electric cables to the surface for analysis. The detectors are housed inside 5,160 crush-proof glass spheres placed in holes drilled through the ice, and located 1450 to 2450 meters deep.

Another 324 detectors at the surface detect muons made by cosmic rays arriving from the Southern sky.

The Antarctic ice also has little radiation, and the detectors are so deep that air bubbles have been squeezed out, ensuring great optical clarity. Yet while the detectors are shielded from damage, they are under crushing pressure, and if they go bad, they will be busted forever.

IceCube will only look at muons that trigger at least eight detectors, says Halzen, and is most interested in muons moving upward — coming from the Northern Hemisphere. Downward signals can be confusing, as most of them are due to cosmic rays or lower-energy neutrinos, which Earth blocks.

Data from IceCube should suggest where the neutrinos originated and what sort of cosmic engine started them on their journey.

This desire to concentrate on neutrinos rather than cosmic rays explains why this frozen telescope, oddly but logically, looks downward.

What can these neutrinos tell us?

Neutrinos, “invented” to balance a physics equation, have grown to fascinate astrophysicists, galactic voyeurs seeking signals from astonishingly energetic structures and events in the deep universe. The direction and energy of neutrinos from each source should offer clues about the origin:

Image: NASA/JPL-Caltech/STScI/CXC/SAO

Located 10,000 light-years away in the constellation Cassiopeia, Cassiopeia A is the remnant of a massive star that died in a violent supernova 325 years ago. The dead star (turquoise dot in center) became a neutron star surrounded by a shell of junk blasted away in the explosion. Image is a composite from three orbital telescopes: Infrared data from the Spitzer Space Telescope is red; Visible light from the Hubble Space Telescope is yellow; Chandra X-ray Observatory data is green and blue.

Although supernova neutrinos have low energy and are hard to detect, a nearby supernova could light up IceCube enough to overwhelm the system. To prep for a supernova, Reina Maruyama, an assistant professor of physics at University of Wisconsin-Madison, is working to ensure that IceCube can handle this once-in-a-lifetime chance to get good data on a stellar explosion.

If something like the 1987 supernova exploded nearby in our galaxy, Maruyama says, “there would be so many neutrinos, the whole ice would glow. We expect that a few supernovas will occur each century in the galaxy, if one goes off, IceCube has to be ready. We stand to learn a whole lot about how they explode, and about the particle nature of neutrinos.”

Dark matters

Even weirder than neutrinos, IceCube may explore dark matter, a type of, well, something, that comprises 23 percent of the overall universe. A measly 4 percent of matter, including the galaxies, stars and planets, is visible. The balance is an even stranger quantity called dark energy.

The first inkling that some matter is invisible came in the 1930s, when a physicist noticed that galaxies rotate too fast: their visible mass would create too little gravity, and thus they should spin themselves into oblivion.

The explanation for that increased gravity is now called dark matter, and the race is on to detect it.

Since dark matter affects gravity, Maruyama says it must gather in the sun and the galaxies. When dark matter particles collide, they are expected to release a type of neutrino called muon neutrinos. But IceCube found no muon neutrinos coming from the sun and the Milky Way, using a technique that was 1,000 times more sensitive than previous ones.

Does absence make the heart grow fonder?

It depends on your perspective whether that’s good or bad, says Halzen. “There was a big celebration when we published, because we placed limits on that particular type of dark matter, but I looked at it another way: We had gone 1,000 times deeper, and it was very disappointing not to see dark matter.”

However, an experiment in Italy may have seen dark matter interacting with a hunk of sodium iodide, based on an annual variation in the signal. If Earth indeed orbits through a cloud of dark matter, the detector would register alternating downstream and upstream motions that could account for that annual cycle.

The cycle could, however, be due to something unrelated to dark matter.

To answer that riddle, Maruyama wants to place a similar detector deep in the Antarctic ice, and has already piggybacked two prototypes onto IceCube strings. The prototypes are working well enough to justify a larger, more expensive detector, Maruyama says.

If and when the experiment is replicated in Antarctic Ice, Maruyama says, “A positive result would be interesting, and a negative result would be interesting. If we can see a signal with the same timing, that confirms the [Italian] results. If we don’t see a signal, the source must be something aside from dark matter.”

Lurking behind the IceCube project is the tantalizing prospect of learning more about the bizarre particle it detects — the neutrino. We already know that neutrinos have a tiny amount of mass, and that they range in energy through at least 30 orders of magnitude — an unimaginable range of energies. There have been recent — and controversial — reports that neutrinos can travel faster than light — breaking a basic law of physics.

Why so weird?

That’s another indication that neutrinos exist at the edge of the standard model that attempts to explain everything by gravity, electromagnetism, and two nuclear forces, Halzen says. “We are measuring the properties of neutrinos any way we can, and extrapolating to see what the standard model predicts, and looking for variations. The simple way to describe the experiment is that we collect muons and neutrinos, and everything you don’t understand is a discovery, either it’s physics beyond the standard model, or it’s new astrophysics.”

Halzen anticipates spotting an extremely high-energy particle called the GZK neutrino. “These are predicted by theory, and if one hits the detector, we won’t have to do any analysis, we will be able to look at the event display and know that we have made the discovery.” GZK neutrinos are, according to theory, made by cosmic rays that strike photons in the microwave background, Halzen says, and thus could finally reveal the origin of the cosmic rays, one century after their discovery.

Neutrinos are slippery characters; shy, coming in incomprehensible numbers, being emitted by sources we cannot pinpoint. Maruyama notes that neutrinos seemingly change to a different “flavor” without any apparent cause, and says this “oscillation” from one state to another is the strangest part of the neutrino story. “Oscillation could have implications on how the universe evolved to have matter, and not anti-matter,” she says. “These tiny particles could have such an influence on the universe.”

So what?

Why should non-scientists worry about neutrinos? Halzen, who has answered this question many times, says “I have a personal answer. The reason we know our place in the universe is not because of French philosophers, it’s because of physicists. With dark matter and dark energy, we know most of the universe is not made of the same material we are made of. … Is that important to know? I think so.”

IceCube is not intended to produce technology or solve today’s problems, Halzen acknowledges. “This is total curiosity-driven science, and you are allowed not to care. But if you don’t do fundamental research, we’re going to be a developing country, that is clear.”

Particle physics proves that theoretical pursuits can have results that are unpredictable, yet practical and profitable, Halzen says. “My previous job was at CERN [the European particle-physics lab], where people discovered the Web in 1989, to enable collaboration among remote scientists. I think we have paid for all theoretical physics with that one discovery.”

Robots are great at what they do — if the job is dull and predictable. Throw in the unexpected, and robots can do the unpredictable.

The task of programming a robot’s brain for the real world can be gnarly, says Josh Bongard, an assistant professor in the University of Vermont College of Engineering and Mathematical Sciences. “It turns out that building a robot, and programming it to do something interesting is a very non-intuitive process, and it’s a difficult one for humans to do well.”

The real world, he says, “is quite messy.”

Robots, in the jargon, need “adaptive behavior” to accommodate changing circumstances, says Bongard. When programming a free-roaming robot, “We are not likely to factor in a lighting change or people moving in and out of the field of view.”

It’s not clear how animals or people make adaptations, Bongard says, “and so it’s difficult to program a robot to do them.”

Robots: Are they alive?

Bongard, like a number of roboticists, is turning to biology for answers. But he does not want to emulate living structures. Instead, he wants to use evolution to craft robot control.

The process is akin to the “artificial selection” that helped lay the foundation for the science of evolution. Darwin, after all, wrote about how animal breeders had changed their livestock by repeatedly breeding the best animals and eating the rest.

In January, 2011, Bongard reported that he had taught four-legged, digital robots to stand and run toward a light source, by grading their control software on its ability to meet those goals.

Adaptive behavior was necessary, he says, because the light source could appear anywhere, or even take evasive action, “so the robot can’t just move its legs blindly every time.”

The robots had five seconds to do or die, and their first movements were grotesque because the control software initially moved their body parts at random. After every attempt, the control programs were graded by their ability to walk, stay upright and approach the light.

It’s brutal. More than 100 million failed programs went to the virtual graveyard in the name of science, Bongard says. The programs that showed some promise were retained, randomly varied and re-tested.

The same process is found in nature, where successful genes that face random mutation are re-tested by tomorrow’s environment.

Like the average biological mutation, the mutated robot software usually failed. But over a year of supercomputer time — equivalent to 1,000 years on a desktop computer — the winning programs evolved the ability to walk toward the light.

Weird winners

Considering the amount of trial and error, that was a satisfying but not necessarily surprising result. But here’s something to chew on. Bongard found that robots “born” with four legs had a handicap. During repeated simulations, the robots that started as snakes and developed legs during the five-second experiment were much quicker to learn the task.

You might guess — we would have — that the quick learning would have occurred in robots with full-time four-leg drive, given their longer experience with legged locomotion, but Bongard says the leg-free starters benefited by chunking the challenge: a) learn to approach the light, and b) learn to walk.

These robots “could evolve the ability to go from point A to point B while they still look like a snake, they don’t have to worry about balance, because they are already on the ground,” Bongard says. “Once evolution has figured out how to move toward the light, the ability to move on four legs could evolve.”

Meanwhile, the four-legged counterparts may still be flipping, flopping and floundering (Note to self: sell soul as political hit-man if science-writing gig crash-burns?) “The robots that had to stand upright would fall over, and it took evolution a long time to master balance,” Bongard says.

The approach — take the winners and vary them for a retest — resembles directed chemical evolution, which aims to create a better antibiotic by modifying and retesting molecules that show some ability to kill bacteria. “It’s basically the same idea,” says Bongard, “but instead of a candidate drug, we have virtual robots, and instead of selecting for … resistance to disease, they are selected for the ability to get to the light.”

Robots resemble rodents?

As a final exam for the digital robots, Bongard tested their balance with a blast of air. Although the leg-less robots “had evolved into legged robots that looked exactly like the other species, they were better able to run around under simulated windy conditions,” Bongard reports.

Bongard is first to acknowledge that he is “stealing from biology to help us build better robots,” but says, “the more interesting question is what this tells us about biological evolution. This recent work suggests that robots that change their bodies gain an adaptive advantage … and you see the same radical changes in body plan in nature: in insects, reptiles and in humans as they develop from infant to adult.”

Interested in waterfront property in Southern California? A new study of a continental schism running east of Los Angeles offers a clear “buy” signal for the long-term investor: The North American continent is splitting apart along a rift, and if you got the patience, we have the real-estate-appreciation potential!

In just a few million years, as the North American continent sunders in a weak zone called the Salton Trough, the Gulf of California will stretch further north.

On our unstable Earth, not even the continents are rock solid. Instead, they shift around like blocks of sea ice that join, fissure and separate once again — over millions of years.

Geologists know the process is occurring in the Southern California desert, and we’ve just read a sophisticated analysis that finds an ominous thinning of the strong crustal layer in the Salton Trough.

Ominous, that is, unless you are planning a waterfront resort here, with a grand opening in, say, 2,002,011.

The study helps to fill a gap in our understanding of the earth, says first author Vedran Lekic, a National Science Foundation post-doctoral fellow at Brown University. “The main question is, how do continents come to break apart? This process is really fundamental to shaping how the Earth looks; if not for rifting, once Pangaea formed, it would never have broken apart and we would have only one continent.”

Pangaea is a giant agglomeration of continents that broke up about 150 million years ago, creating our current collection of continents.

Scoping out the Earth

The lithosphere, Earth’s crust and the rigid rock beneath it, essentially floats on the asthenosphere, the soft and hot outer layer of the mantle that is located tens of kilometers belowground.

As a continental rift grows, one would expect to find a thinned lithosphere at the Salton Trough. But Lekic says the actual thinning was more dramatic than expected — as much as a 50 percent reduction compared to adjacent areas.

By studying earthquake waves passing through Earth, Lekic and colleagues measured the thickness of the lithosphere by locating its lower border. They knew that one type of wave converts to a faster wave type as it passes up from the asthenosphere into the lithosphere, so the conversion could be used to mark the base of the lithosphere.

It turned out that the lithosphere measured about 40 kilometers thick beneath the Salton Trough, compared to 60 to 80 kilometers on nearby areas. That thinning translates into a weakening that will eventually allow open water into the Trough, and myriad real-estate opportunities along the new shoreline.

Previous efforts to estimate the lithosphere’s depth have relied mainly on surface data, says Lekic, and that limited our knowledge of how the continental splitsville takes place. From relying on “surface observations of faults, topography, heat flow, and some studies of the crustal structure, we have not been able to image the detailed topography of the base of the tectonic plate, as it looks during rifting.”

Rift terrific

Although the study relied on the interest in Southern California seismology that is a response to extreme seismic activity, the finding says little about earthquake probabilities.

But earthquakes are not the only tectonic game in town, says Eugene Humphreys, a professor of geophysics at the University of Oregon. “While most people know southern California is being sheared by the San Andreas and related faults, most people are not aware that the region also is being pulled apart as the Pacific plate also moves slowly away from North America. These researchers have imaged the deep structure of the plate where it is being torn apart by this process, and contrary to what many have thought, the tears go through the entire plate right where the surface expression of this rifting is seen. It’s exciting work.”

The study provides insight into deep structure and processes of fluid migration up into the plate, says Humphreys. “These lower-plate interfaces were not expected to exist at all, and the scientific community is excited but struggling to determine what could create relatively sharp interfaces.”

Although Earth warms with depth, that is unlikely to explain the weakness, Humphreys says, “so the search for other causes is on. By associating the position and shape of these interfaces with a specific deformation history, this study provides important information on the origin of these interfaces.”

Lekic, who worked with co-author Karen Fischer of Brown, on the study, says that “Even at great depth, we see the same stretching and deformation that we see near the surface. At the bottom of the lithosphere, there is this persistent weakness, in a zone that runs more or less vertically, and that’s surprising.”

But as scientists wrestle with the geological goulash that is Southern California, we suggest you send a down payment to Rift ‘n Grift Realty on the ocean-front lot of your dreams – and wait a few million years!

— David J. Tenenbaum

How did galaxies form? It’s a cardinal mystery of the early universe. Microwave radiation created 380,000 years after the Big Bang shows a smooth array of molecules, spread out like a fog. The contrast to the situation one billion years later is complete: by then, matter was concentrated in stars and galaxies, separated by empty space.

Nowadays, most galaxies hide at least one super-dense black hole, whose gravitation prevents even light from escaping. Until now, nobody knew about black holes in the earliest galaxies.

Yesterday, Ezequiel Treister of the University of Hawaii and colleagues reported that most or all of the earliest galaxies also had black holes.

A problem of roots

The data illuminates the ultimate roots question – how our universe formed its present structure, and in particular, what happened during the billion years after the Big Bang banged about 13.7 billion years ago.

For 380,000 years, “During the embryonic universe, the fluctuations in density were about one-one thousandths of a percent, but over a billion years, structures developed,” Alexey Vikhlinin, author of a commentary in Nature, told The Why Files. “These galaxies are essentially the same type of objects in the present universe,” says Vikhlinin, an expert in X-ray astronomy at the Harvard-Smithsonian Center for Astrophysics.

How did we go from the primordial fog to a universe with ultra-dense galaxies, neutron stars and black holes separated by a vast nothingness where each cubic centimeter has about one lonely atom?

The vast epoch of ignorance, Vikhlinin says, “is called the dark age because little has been observed, and one of the major questions in astrophysics is how this transformation took place.” The new observations show that roughly the same proportion of matter (excluding the enigmatic dark matter and dark energy) was concentrated in galaxies and black holes then as now.

“These results show that pretty much every galaxy must have contained a substantial black hole, similar to today,” says Vikhlinin, “but this is the first observation that the relationship between galaxies and black holes that exists today, existed 1 billion years after the Big Bang.”

An extraordinary step

In the study, Treister and colleagues correlated long exposures from

Hubble Space Telescope, which can see extraordinarily distant (and ancient) galaxies, and

Chandra X-ray observatory, which picked up X-rays from distant, unidentifiable sources.

By pinpointing the source of Chandra’s X-rays on Hubble’s galactic snapshots, the scientists located ancient black holes inside some of the first galaxies.

The study benefited from three features, says Vikhlinin. “The necessary Chandra and Hubble data were taken only recently, and the observations were immediately made available to every interested scientist,” along with some money for their interpretation.

Treister also looked at the highest energy range that Chandra can detect, Vikhlinin adds. Because Chandra’s mirrors are more sensitive to lower-energy X-rays, “most people work in this region.”

The newly detected black holes produced a surprising result – that the basic structure of the universe has not changed terribly much in the 12.7 billion years since that ancient light embarked toward a planet that did not yet exist.

The “so-what?” part

Although the study shines some light on the presence of black holes and galaxies during the dark age, it does not provide a complete answer, says Vikhlinin. “It definitely seems as if galaxies and black holes have evolved in parallel. The growth of one controls the growth of the other, and vice versa, but the nature of the process and why they evolve in parallel is not entirely clear.”

Logically, a black hole would require a galaxy to provide the cold gas that it inhales. (This gas heats up as it enters the hole, creating the black hole’s X-ray signature; it also supplies material for the stars in the galaxy.)

But why a galaxy would need a black hole is less clear, Vikhlinin says. “We don’t know if galaxies can form in regions that initially don’t have the right conditions for the growth of a black hole. Maybe whenever a galaxy starts to grow actively, it makes a black hole in the center.”

Although the new evidence for an unchanging relationship between galaxies and black holes narrows the possible explanations, the formation of the first galaxies and black holes “remains one of the biggest unsolved problems in astrophysics,” Vikhlinin says.

– David J. Tenenbaum

Fish in the Gulf of Mexico: How safe?

The fire and deadly explosion of the Deepwater Horizon drilling rig on April 20, 2010 spewed a gusher of crude oil — about 4.4 million barrels — into the Gulf of Mexico.

The blowout flooded all levels of the Gulf with oil. And that oil, combined with millions of gallons of an oil-degrading chemical, raised questions about the health of Gulf seafood, both shellfish and finfish.

Fishing is major in the Gulf of Mexico, which in 2008 produced 15 percent of total weight of U.S. commercial fishing, and which has more sport fishers than any other American region.

Within two weeks, as a precaution to prevent the sale of contaminated fish, the government began closing parts of the Gulf to commercial fishing.

A report published today in Environmental Health Perspectives reviews the aftermath: How big was the threat? Did the closures harm the fishing industry by giving, in effect, official endorsement to the idea that the fish were contaminated? Were there any gaps in protection?

Not very filthy

The report came to an optimistic conclusion: government-sponsored studies of Gulf fish since the blowout found no significant contamination with heavy, persistent compounds called polycyclic aromatic hydrocarbons. “I don’t know that we have any evidence that the fish were contaminated, ever,” says study first author Julia Gohlke, an assistant professor of environmental health science at the University of Alabama-Birmingham.

PAHs can cause cancer and are often used as a measure of hydrocarbon contamination. According to the new study, “Federal seafood testing results released to date” show PAH levels at roughly 1 percent of the “level of concern” that the Food and Drug Administration established for assessing food safety after the Deepwater blowout.

Other results, she says, have focused on total hydrocarbons derived from oil, rather than PAHs. “My analysis looked at what the government has done,” she says. “There are independent reports of contamination that I tried to include, but they did not measure PAHs, only total petroleum hydrocarbons.”

Large oil spills are so ominous that people can overreact, says Gohlke. “People see an oil spill and fisheries closures and assume everything must be contaminated, and nobody wants to eat anything. There is a misunderstanding of what is considered contamination. There is now a large dataset, at this point, to show there hasn’t been significant hydrocarbon contamination to date.”

Gohlke and colleagues looked at data on the BP blowout, and previous oil spills from around the world, to compare toxicity levels and evaluate the procedures used to close and open fisheries. The project was funded by a grant from the Walton Family Foundation to the Environmental Defense Fund.

Looking at samples taken during and after the blowout, no results suggested that eating fish – whether with shells or fins – would contain elevated levels of PAHs, says Gohlke, who cautions that monitoring should continue for years because buried oil may re-enter the water and contaminate fish.

After the BP spill, fishing was banned in as much as 37 percent of the Exclusive Economic Zone in the Gulf of Mexico, which extends 200 nautical miles from the coast. These bans were precautionary, since they were made in advance of contamination tests, says Gohlke.

Although “safe, not sorry” can be justified, closures can also have unintended consequences, or even backfire, she says. “Part of me thinks the precautionary approach is appropriate, but I don’t know how it has contributed to consumer confidence. Without sufficient risk communication, precautionary closures may create an expectation that the fish is contaminated. The last survey I saw, from February, suggested people were still considering Gulf seafood to be contaminated.”

“I think they make some pretty good recommendations to continue monitoring for PAHs,” says Ron Kendall, director of the Institute of Environmental and Human Health at Texas Tech University. “There is a lot of debate about underwater oil mats that are still floating, and how much oil may still be on the seafloor or in coastal marshes. With hurricane season approaching, we don’t know what kind of remobilizing of suspended oil and the mats will take place.”

To date, Kendall says, the data show that seafood has safe levels of PAHs, but “You’ve got to understand that all this oil is not gone. This story is still unfolding.”

When plywood came into industrial use a century ago, the criss-crossing layers of wood were glued with a soybean derivative. Then, in the 1930s (long before tofu sprouted in the American diet), strong, synthetic glues, derived from natural gas or oil, started to shoulder aside the soy stuff.

Cheap and water-resistant, these urea formaldehyde glues helped plywood, particle board and similar composite wood products dominate the furniture and building industries.

Formaldehyde was also used in clothing, paint, paper, wall covering and roll insulation.

Many of these products released formaldehyde (CHOH) but inside the average house, the bulk of the exposure came from plywood and its plural planar progeny.

In 1991, the U.S. Environmental Protection Agency branded formaldehyde a probable human carcinogen. The compound quickly dissolves in mucus membranes in the nose, throat and lungs, causing irritation and triggering asthma attacks.

Inside the home, formaldehyde can be released from composite wood in furniture, cabinets, sub-floors and wall panels. The notorious FEMA trailers that sparked so many health complaints after Hurricane Katrina were chock-a-block with cheap, formaldehyde-glued structures.

Photo: FEMA

After Hurricane Katrina, “FEMA trailer” residents blamed health problems on formaldehyde released from composite wood products in the trailers. A new soybean-based glue could eliminate these problems after it is adopted more widely by manufacturers of particle board.

Legumes to the rescue!

Although manufacturers have taken steps to reduce formaldehyde releases, a more comprehensive solution could reside in the plant that was originally used to glue plywood — the soybean.

Charles Frihart, a chemist at the U.S. Department of Agriculture Forest Products Laboratory, described the evolution of a soy super glue to the American Chemical Society meeting in Boston yesterday. “Biological materials were used as adhesives until petroleum became very cheap after World War II,” he told us, “and the synthetics displaced agricultural, natural material.”

The soy-story is developing into a key advance for “green chemistry,” the quest to reduce toxic burdens from the factory to the disposal site. Until a few years ago, soy glue was less water-resistant than synthetics, Frihart says. Then, Kaiching Li of Oregon State University discovered how to increase water resistance by “cross-linking” the strands in soy-based adhesive.

More links = more power!

Long ago, cross-linking became the key to converting soft, sticky natural rubber into a useful product. “Rubber was never very useful because it would soften in the heat, until they developed a way to crosslink it,” says Frihart. Charles Goodyear invented vulcanizing, a process for cross-linking rubber, in about 1840, laying the groundwork for the bicycle and then the automobile.

Invention is usually a group activity these days, and Frihart points to cooperation between scientists at the Forest Products Lab and Columbia Forest Products, Inc., which is already making products with soy-based glues.

A key driver for the new glue came from California, which deemed formaldehyde-based glues an indoor health hazard. Before it banned the use of formaldehyde in indoor products, however, California needed to know that an alternative technology was available. Once the cross-linked soy glue was proven to work, the state enacted a low-formaldehyde standard that, in effect, went national. “California is the largest market and people are not going make a separate product for California,” Frihart says.

The cross-linking invention is already reducing indoor formaldehyde at the top of the furniture market, where plywood is used instead of particle board, Frihart says. “More than 50 percent of interior plywood used for cabinets and furniture is now being made with the improved soy-based adhesive.”

Researchers at Forest Products Laboratory in Madison, Wis. test the strength of soy glues: Two rams compress and heat the joint, then clamps at each end of the wooden strips pull until the joint breaks.

Practical for particle board?

Particle board remains the basis for most cheaper furniture, and while some particle board already uses formaldehyde-free glue, “We want to make it better, with higher strength, especially in wet conditions,” Frihart says.

Charles Goodyear did not have to integrate vulcanization into a rubber industry – which barely existed — but today, a new adhesive “has to fit into the way the product is being made commercially,” Frihart says, “and we continue to work on modifying the adhesive to fit better individual plants.”

Frihart says the soy story echoes a larger, but behind-the-scenes evolution in materials. “Because we better understand materials, and how to manipulate them, we keep figuring out ways to make them work better, even if they are not labeled new-and-improved.”

– David J. Tenenbaum