Tiny red flecks — rayon fibers — will soon identify the only BPA-free thermal-printed store receipts in North America. Credit: Appleton

Appleton Paper, a company in Wisconsin, makes the kind of paper used for sales receipts. Starting in the first two weeks of November, the company’s receipt paper comes with something new — tiny flakes of red fibers on the back. Next time you come across a receipt, flip it over and see whether you can see red.

If you do, rest easy — because Appleton’s receipts do not contain bisphenol A (BPA), a chemical that has been in the news. Recent studies show BPA could be hazardous to your health. BPA is called a hormone disruptor, which means it enters the body and acts like a hormone, a chemical that can control body processes. When BPA acts like hormones, the body’s real hormones may have trouble doing their job.

Studies have turned up a link between BPA and heart disease, and exposure to the chemical might make a person more likely to develop diseases such as diabetes. In roundworms, which are often used in the laboratory as a model for humans, BPA interferes with reproduction. That could mean bad news for human reproduction, too.

In three separate studies last year, conducted all over the world, researchers discovered BPA in cash register and ATM receipts. Worse yet, further studies showed that the BPA rubs off easily onto a person’s hand. A recent report from the French government says this BPA is quickly absorbed into the skin and then the bloodstream.

“I won’t touch receipts now,” Frederick vom Saal told Science News. He is a scientist at the University of Missouri in Columbia who investigated receipts as part of a study by the nonprofit Environmental Working Group. He is now working on a study that looks not only at how BPA travels from receipt to skin, but also at how much of that BPA later turns up in a person’s urine or blood.

A recent study of pregnant American women found that cashiers, who work with receipts all day, have higher levels of BPA in their blood and urine. Since BPA passes so easily into the body, it may also pass easily into the fetus, which means a mother’s BPA exposure could be hazardous to her children.

Receipts are not the only source of BPA — far from it. BPA is used in the production of plastic. Plastic is everywhere, which means BPA is all around us. The BPA travels from the plastic into the body when the plastic is heated — in a dishwasher or microwave, for example — or when it is scratched.

In addition to water bottles and other containers, plastic shows up in places you wouldn’t expect: bike helmets, telephones, computers. As a quick example, consider a typical automobile: plastic is used in the seats, dashboard, parts of the body and some engine parts.

BPA is in receipts and in plastic, and a recent study turned up BPA in yet another alarming source: food. In a recent study, scientists in Texas tested 31 types of canned foods or foods packaged in plastic. They discovered measurable amounts of BPA in 60 percent of the food products.

The Environmental Protection Agency recommends people consume no more than 50 micrograms of BPA per kilogram (2.2 pounds) of body weight. The food-based BPA measured by the Texas scientists is far below that guideline.

Scientists are still trying to determine both the real risks of BPA, and how much of the chemical is too much. To be on the safe side, check your receipts — and your plastic.

POWER WORDS (from the Yahoo! Kids Dictionary and the National Institutes of Health)

plasticizer Any of various substances added to plastics or other materials to make or keep them soft or pliable.

plastic Any of various organic compounds produced by polymerization, and capable of being molded, extruded, cast into various shapes and films, or drawn into filaments used as textile fibers.

BPA A chemical produced in large quantities for use primarily in the production of plastics.

hormone A substance produced by one tissue that travels through the bloodstream to another tissue to effect physiological activity, such as growth or metabolism.

Here, two juvenile elkhorn corals only 26 days old have survived a sojourn in the open water but have successfully settled onto a surface to begin their life’s work of building a colony. Future endeavors may not be as successful. Credit: Rebecca Albright/RSMAS, Univ. of Miami

The oceans are changing. You can’t tell by standing on a beach and watching waves roll in, but experiments show that ocean water is becoming more acidic. This process is called “acidification,” and it may mean bad news for animals like the elkhorn coral, which is found throughout the Caribbean Sea.

Elkhorn coral used to be easy to find in shallow water, but now it’s an endangered species. In the last 30 years, many populations of elkhorn coral have collapsed, thanks to disease outbreaks, hurricanes and elevated temperatures. Scientists are working on ways to save the coral, but they have a long way to go. A new study suggests that coral may face yet another threat: In more acidic waters, elkhorn coral are less successful at reproducing sexually.

A substance may be an acid or a base. Acids taste tart and may be corrosive, like vinegar or even battery acid. Bases tend to be slippery. Water is neutral, which means it’s right between acids and bases. Right now, the oceans are slightly more basic than water. But oceans are beginning to move more to the acidic side.

As acidification worsens, these elkhorn coral may produce fewer offspring. This change could mean fewer or smaller coral reefs — which could be a problem for the many animals and plants that live on those reefs.

Acidification happens because oceans absorb a gas called carbon dioxide from the atmosphere, and carbon dioxide makes the water more acidic. Carbon dioxide, or CO₂, in the atmosphere comes from many sources, and human activities have added a significant amount. When we burn oil or gas to generate power (such as electricity or to fuel cars), we add CO₂ to the air.

Carbon dioxide is also a greenhouse gas, which means it traps heat in the air — which leads to warmer temperatures on Earth’s surface. This is called global warming, and CO₂ is one of many gases that drive global warming.

And since the beginning of the industrial revolution more than 200 years ago, the amount of CO₂ in the atmosphere has been increasing quickly. This change in the air has affected the oceans, forcing them to absorb even more carbon dioxide.

Scientists estimate that oceans have become about 30 percent more acidic in the last 200 years. Previous studies have shown that marine animals like corals, oysters and sea urchins have a hard time building their shells and skeletons in more acidic water.

The new study was led by Rebecca Albright, a graduate student at the University of Miami. She wanted to know how elkhorn coral would reproduce in acidic water. To find out, she and her team added bubbles of carbon dioxide to ocean water in a tank to make it more acidic — like it will be in the future. The scientists placed elkhorn coral in the water.

Coral usually grows in reefs, and coral reefs often look like giant, colorful rocks in shallow parts of the ocean. They provide a home to many kinds of plants and animals. But coral is neither a rock nor a plant — it’s an unusual animal. Like other animals, elkhorn coral reproduces sexually, which means a sperm cell and egg cell come together to create a new organism.

Albright and her team observed that for coral living in water with extra carbon dioxide, sperm and egg combined less often than they do in ordinary seawater. Then she observed another obstacle to coral reproduction: Even if a sperm and egg managed to join, they had a hard time getting settled on the reef to grow.

As oceans become more acidic, the elkhorn coral may face increasing problems producing offspring. And it’s just one species.

It’s possible that elkhorn coral could evolve and adapt to the changing climate. “One of the limits with this kind of study is that it doesn’t tell you whether there is any potential for evolutionary changes to deal with the new stress,” Steve Gaines told Science News. He is an ecologist at the University of California, Santa Barbara, and did not work on Albright’s study.

However, Gaines points out, the climate is changing unusually fast. The bottom line remains the same: More carbon dioxide means more acidification, which probably means bad news for the elkhorn coral.

POWER WORDS (adapted from the Yahoo! Kids Dictionary)

acid Any of a class of substances whose aqueous solutions are characterized by a sour taste, the ability to turn blue litmus red, and the ability to react with bases and certain metals to form salts.

evolution The process by which species adapt and change over time.

carbon dioxide A colorless, odorless, incombustible gas formed during respiration, combustion and organic decomposition and used in food refrigeration, carbonated beverages, inert atmospheres, fire extinguishers and aerosols.

coral Any of numerous, chiefly colonial marine polyps of the class Anthozoa.

Elkhorn coral used to be easy to find in shallow water, but now it’s an endangered species. In the last 30 years, many populations of elkhorn coral have collapsed, thanks to disease outbreaks, hurricanes and elevated temperatures. Scientists are working on ways to save the coral, but they have a long way to go. A new study suggests that coral may face yet another threat: In more acidic waters, elkhorn coral are less successful at reproducing sexually.

A substance may be an acid or a base. Acids taste tart and may be corrosive, like vinegar or even battery acid. Bases tend to be slippery. Water is neutral, which means it’s right between acids and bases. Right now, the oceans are slightly more basic than water. But oceans are beginning to move more to the acidic side.

As acidification worsens, these elkhorn coral may produce fewer offspring. This change could mean fewer or smaller coral reefs — which could be a problem for the many animals and plants that live on those reefs.

Acidification happens because oceans absorb a gas called carbon dioxide from the atmosphere, and carbon dioxide makes the water more acidic. Carbon dioxide, or CO₂, in the atmosphere comes from many sources, and human activities have added a significant amount. When we burn oil or gas to generate power (such as electricity or to fuel cars), we add CO₂ to the air.

Carbon dioxide is also a greenhouse gas, which means it traps heat in the air — which leads to warmer temperatures on Earth’s surface. This is called global warming, and CO₂ is one of many gases that drive global warming.

And since the beginning of the industrial revolution more than 200 years ago, the amount of CO₂ in the atmosphere has been increasing quickly. This change in the air has affected the oceans, forcing them to absorb even more carbon dioxide.

Scientists estimate that oceans have become about 30 percent more acidic in the last 200 years. Previous studies have shown that marine animals like corals, oysters and sea urchins have a hard time building their shells and skeletons in more acidic water.

The new study was led by Rebecca Albright, a graduate student at the University of Miami. She wanted to know how elkhorn coral would reproduce in acidic water. To find out, she and her team added bubbles of carbon dioxide to ocean water in a tank to make it more acidic — like it will be in the future. The scientists placed elkhorn coral in the water.

Coral usually grows in reefs, and coral reefs often look like giant, colorful rocks in shallow parts of the ocean. They provide a home to many kinds of plants and animals. But coral is neither a rock nor a plant — it’s an unusual animal. Like other animals, elkhorn coral reproduces sexually, which means a sperm cell and egg cell come together to create a new organism.

Albright and her team observed that for coral living in water with extra carbon dioxide, sperm and egg combined less often than they do in ordinary seawater. Then she observed another obstacle to coral reproduction: Even if a sperm and egg managed to join, they had a hard time getting settled on the reef to grow.

As oceans become more acidic, the elkhorn coral may face increasing problems producing offspring. And it’s just one species.

It’s possible that elkhorn coral could evolve and adapt to the changing climate. “One of the limits with this kind of study is that it doesn’t tell you whether there is any potential for evolutionary changes to deal with the new stress,” Steve Gaines told Science News. He is an ecologist at the University of California, Santa Barbara, and did not work on Albright’s study.

However, Gaines points out, the climate is changing unusually fast. The bottom line remains the same: More carbon dioxide means more acidification, which probably means bad news for the elkhorn coral.

POWER WORDS (adapted from the Yahoo! Kids Dictionary)

acid Any of a class of substances whose aqueous solutions are characterized by a sour taste, the ability to turn blue litmus red, and the ability to react with bases and certain metals to form salts.

evolution The process by which species adapt and change over time.

carbon dioxide A colorless, odorless, incombustible gas formed during respiration, combustion and organic decomposition and used in food refrigeration, carbonated beverages, inert atmospheres, fire extinguishers and aerosols.

coral Any of numerous, chiefly colonial marine polyps of the class Anthozoa.

When coffee grounds are loose inside the balloon, they can meld to the shape of the object (a shock absorber here). Then, when the vacuum is switched on, the grounds act like a solid and keep a tight hold on the object.View the video. Credit: John Amend/Cornell Univ.

Sometimes, scientists use coffee to come up with new ideas — though not necessarily by drinking the caffeinated beverage. In the case of one new invention, scientists used coffee grounds to build a new tool that can help robots lift, hold and move objects.

We human beings use our hands to hold things, so it’s not surprising that many human-looking robots have human-looking hands with fingers and thumbs. These robots might be programmed to use their hands as humans do: to lift and hold objects.

But the new tool, called the “universal gripper,” suggests robots don’t need fingers to move things around. It’s a simple device made of a small balloon filled with coffee grounds and attached to a vacuum. This strange but smart design means the robot gripper can pick up all kinds of objects, including fragile things.

“One of the tricky things about picking up delicate objects is that you have to know how much pressure to apply: too little and you drop the object; too much and you break it,” Peko Hosoi told Science News. “This new gripper works by exactly conforming to the shape of the object.”

Hosoi is a mechanical engineer at the Massachusetts Institute of Technology, or MIT. She did not work on the new gripper, but she says it’s a good idea.

Coffee grounds, like grains of sand, are very small. When they’re all together in a container, they sit very close together. When you dump ground coffee, or pour sand, you probably notice that these materials flow like a liquid. That’s because in a liquid, the molecules are free to move past each other — just as the grounds or grains can.

It can even pick up a glass and pour water. Credit: John Amend/Cornell Univ.

If you were to fill a balloon with water, you’d notice that the filled balloon changes shape easily. A balloon filled with ground coffee may not be wet, but because the grounds are loose, the balloon can change shape to fit on a surface. And because the grounds are so small, they flow past each other the way molecules in liquid do. The scientists say other materials with small particles — like sand or couscous — could also be used.

When the balloon bag sits on top of an object, such as a marker, it changes shape and fits around the object. Then the vacuum starts and sucks the air out of the coffee-filled balloon. With the air gone, the grounds move closer together and can no longer flow freely. They act more like a single solid object, and stiffen around the object. And because they had at first acted like a liquid, now that they’re acting like a solid, the grounds are stuck together in the shape of the marker. At this point, the robotic tool has a strong grip on the object and can lift and hold it.

In a video produced by the scientists, the robotic tool is shown lifting all kinds of objects, including a jack, an egg and a shock absorber. The video also shows that the tool allows a robot to write with a pen or pour water from one glass into another.

“Our goal was to pick up objects where you don’t know what you’re dealing with ahead of time,” Eric Brown told Science News. Brown is a scientist at the University of Chicago who worked on the new tool.

The new tool is small, but the scientists are thinking big. They say that a giant gripper three feet across would be strong enough to lift and move something weighing 2,000 pounds — like a small car.

Of course, to get enough grounds to fill such a big balloon, the scientists would need a lot of coffee.

POWER WORDS (adapted from Yahoo! Kids Dictionary)

pressure Force applied the same over a surface

engineering The application of scientific and mathematical principles to practical ends such as the design, manufacture and operation of efficient and economical structures, machines, processes and systems.

liquid The state of matter in which a substance exhibits a characteristic readiness to flow, little or no tendency to disperse, and relatively high incompressibility (can’t be packed down solid).

solid A substance having a definite shape and volume; one that is neither liquid nor gaseous.

For the last ten years, a large group of scientists have also spent a lot of time counting. They’ve been working on an exploration of creatures that live underwater. The project is called the Census of Marine Life, and the research was designed to answer three main questions.

What did live in the oceans? What does live in the oceans? What will live in the oceans?

During the project, the number of scientists involved grew to 2,700, and they came from 80 different countries. These scientists studied historical documents closely and, all together, went on 540 expeditions. They published thousands of scientific papers, spent $650 million and collected millions of specimens from various aquatic environments.

More than 6,000 of those specimens may be new species. A species is a particular kind of living creature. (Human beings, for example, are all members of the same species, Homo sapiens.) Already, researchers doing the Census of Marine Life have described 1,200 new species, and they’re hard at work studying thousands more. Many of those new species are invertebrates, or creatures that don’t have backbones.

These creatures look like they belong on another planet. There are fish with tongues, crabs with hairy pincers and a transparent sea cucumber that appears to have intestines. (See the slideshow featuring some of these oddities.)

When the Census of Marine Life is added to work done before it, scientists have, the Census researchers report, identified more than 190,000 different species that live underwater.

In addition to counting, scientists used new technology to look at where animals live. Census researchers placed electronic tags on some animals and discovered a place dubbed the “White Shark Café” — a spot in the Pacific Ocean popular among predators. The Café is roughly halfway between Hawaii and Mexico. (See the map.)

Scientists launched the study ten years ago because they were worried that humans don’t know enough about the kinds of creatures that dwell underwater. These researchers were right — as work from the last ten years demonstrates, the oceans host a wild variety of living organisms that look like nothing else we’ve seen on Earth.

The Census is only the beginning, a preview of the strange things scientists will probably turn up in Earth’s wettest environments.

POWER WORDS (from the Yahoo! Kids Dictionary)

census An official, usually periodic enumeration of a population, often including the collection of related demographic information

invertebrate Lacking a backbone or spinal column; not vertebrate

marine Of or relating to the sea

expedition A journey undertaken by a group of people with a definite objective

biodiversity The number and variety of organisms found within a specified geographic region

Dogs (such as this Labrador retriever) and other hairy mammals shake at just the right frequencies to remove water most efficiently from their bodies — and directly on to any unfortunate humans nearby. Credit: Andrew Dickerson et al./Georgia Institute of Technology

Mice do it. Chihuahuas do it. So do tigers, rats and pandas. These animals really know how to shake.

Researchers at the Georgia Institute of Technology in Atlanta recently recorded video of 40 different animals, representing 15 different species. The scientists wanted to see how wet, hairy mammals shake off water after they get drenched. What the videos revealed is that animals’ shaking behavior could be described by physics — the science of matter, energy and motion. (Watch a video.)

The scientists say the animals oscillate at just the right frequencies to lose water droplets as efficiently as possible. Oscillate means to move back and forth, and frequency is the number of cycles — movements back and forth — per second.

“I think it’s pretty amazing they can do that,” David Hu told Science News. Hu is an engineer, but he’s also a mathematician and does research in biology. At his laboratory at the Georgia Institute of Technology, Hu studies the physics of fluids, which means he wants to know how fluids move and react to forces. He is particularly interested in how animals interact with water.

This study was led by Andrew Dickerson, a graduate student in Hu’s lab. His team calls this get-dry shake “nature’s analogy to the spin cycle of a washing machine.” Both the washing machine and shaking animals can get rid of water quickly — but animals are much more efficient than washing machines. For animals, this process helps them control heat in their bodies.

“If a dog couldn’t dry itself, we calculated that it would have to use 25 percent of its daily calories to heat its body to get rid of the water,” Hu told Science News. “Every time they got wet they would get hypothermia and die.”

The bigger the animal, the slower it shakes, according to Dickerson and his team. A mouse moves its body back and forth 27 times per second, but a grizzly bear shakes only four times per second.

Animals’ skin also helps them get rid of water. When the scientists placed a fluorescent straw on the back of a dog and watched the dog wiggle, they observed that the skin can move halfway down the dog’s side in either direction. Loose skin lets the dog lose more water than if the skin were tighter.

The scientists are continuing to look at how animals interact with water in the natural world. In particular, the scientists want to know how water droplets interact with hair — which means investigating animals that have adapted to life in the water, like beavers and otters.

POWER WORDS

frequency The number of times a specified periodic phenomenon occurs within a specified time interval.

engineering The application of scientific and mathematical principles to practical ends such as the design, manufacture and operation of efficient and economical structures, machines, processes and systems.

biology The science of life and of living organisms, including their structure, function, growth, origin, evolution and distribution.

oscillate To swing back and forth with a steady, uninterrupted rhythm.

This is a view of part of the surface in the northern hemisphere of Venus as captured by the Magellan spacecraft. The red areas are hotter than the other areas and could also be pretty new lava that is still cooling. Credit: Nataliya Bondarenko et al/GRL

Scientists know of more than 1,000 volcanoes on the surface of Venus, Earth’s “sister” planet. A big question has been: Are they still active?

The scientists behind a new study say yes.

Their evidence for recent volcanic activity on Venus comes from a lava flow in the planet’s northern hemisphere. The flow is hotter than the rocks around it, which means the lava might still be cooling off.

Spacecraft orbiting Venus collect data about the planet’s surface, helping scientists “see” this peak: Idunn Mons in the planet’s southern hemisphere. Information gathered by the Venus Express suggests that the peak could have lava flows on one side. Fly around the volcano in this video. Credit: European Space Agency, Jet Propulsion Laboratory

“The flow we studied seems to be very young — it is still warm inside,” Nataliya Bondarenko told Science News. Bondarenko, who is at the University of California, Santa Cruz, worked on the new study. She is a planetary scientist, which means she studies planets and planetary systems, such as the solar system.

Venus is a difficult planet to study from Earth because it is surrounded by thick clouds. Telescopes on Earth can’t see through these clouds, so the best information about Venus comes from spacecraft orbiting it.

Bondarenko and her colleagues studied the lava flow using data from NASA’s Magellan mission. That spacecraft spent four years in orbit around Venus and used radar to make a map of 98 percent of the planet’s surface. On October 11, 1994, the mission ended, and the spacecraft plunged through Venus’ heavy cloud cover and crashed onto the planet below.

The Hubble Space Telescope captured this image of Venus on Jan. 24, 1995. The planet is completely surrounded by thick clouds. Credit: Photojournal/Jet Propulsion Laboratory

While in orbit, the Magellan craft sent microwaves, which can go through Venus’ clouds, to the surface. Microwaves are invisible and, despite their name, can be as long as three feet. These waves are a kind of energy, like light. And like light, they bounce off surfaces. The way the waves bounced off Venus’ surface and back to the craft supplied information that the scientists used to estimate the temperature of various parts of the planet’s surface. Bondarenko’s team found that the lava flow was hotter than its surroundings — which may mean the lava flow is in the process of cooling.

The scientists say the lava flow can’t be very old because if it were, it would have cooled off enough that Magellan wouldn’t have noticed the difference in microwaves. Bondarenko told Science News the flow can’t be more than 100 years old. For a volcano, that’s still active. She adds that the flow appears in a 1978 view of the surface that a craft called the Pioneer Venus Orbiter captured.

Bondarenko and her team are not the first scientists to claim evidence of activity on Venus. In April, a different team of scientists described several lava flows in Venus’ southern hemisphere. According to the scientists, those flows probably formed in the last 250,000 years ― which is recent for geology.

In 2006, the European Space Agency and the Planetary Society sponsored a contest for the best art depicting what Venus might be like. The grand prize winner was this illustration by Tatianna Cwick, then 17 and living in Cape Girardeau, Mo. Credit: Planetary Society (http://planetary.org)

Suzanne Smrekar, a planetary geologist, studied the lava flows in southern Venus. She works at the Jet Propulsion Laboratory in Pasadena, Calif. She and her team used data from the Venus Express, a European Space Agency spacecraft currently observing Venus.

Smrekar hasn’t studied northern Venus, so she’s not sure about the evidence of such recent volcanic activity. But she has her doubts. That sort of study, she told Science News, “sort of falls into the ‘extraordinary claims require extraordinary proof’ category.”

This means that in her mind, the question of whether or not Venus is still active is not yet settled. Stay tuned — Bondarenko and her fellow researchers are looking for new data on potentially even more new flows.

POWER WORDS

lava Molten rock that reaches a planet’s surface through a volcano or fissure.

Venusian Of, relating to, or characteristic of the planet Venus. Also, a hypothetical inhabitant of the planet Venus.

orbit The path of a celestial body, such as a moon, or an artificial satellite as it revolves around another body, such as Earth. In this case, the path followed by the Magellan spacecraft as it moved around Venus.

microwave A high-frequency electromagnetic wave, one millimeter to one meter in wavelength, intermediate between infrared and short-wave radio wavelengths.