Breathing very dirty air may boost obesity risk

Beijing smog

Serious air pollution, like this smog over China’s capital city, may increase the risk of obesity.

Air pollution is bad for our lungs. It may not be great for our waistlines either, a new study in rats finds.

China’s capital city of Beijing has some of the worst air pollution in the world. On really bad days, its air can host more than 10 times as many tiny pollutant particles as the World Health Organization says is safe for human health. In a new study, rats breathed in this air. And those rodents gained more weight, and were unhealthier overall, than were rats breathing much cleaner air. The results suggest that exposure to air pollution can raise the risk of becoming extremely overweight.

And, adds Loren Wold, “It is highly likely that this is happening in humans.”

Wold works at Ohio State University in Columbus. There, he studies how air pollution affects the heart. He was not involved in the new study. But he says it agrees with many other studies that have suggested air pollution can affect metabolism, which is how the body breaks down food and uses it for fuel.

Polluted air contains particles of ash, dust and other chemicals. Sometimes these particles are so numerous that they create a thick, dense smog can cuts visibility.

Earlier experiments among 18-year olds in Southern California had linked heavier traffic with higher body mass index (a measure of overweight and obesity). Areas with heavy traffic also tend to have more of those pollutant particles. Another study found that when pregnant mice were exposed to exhaust from diesel engines, their pups grew up to be heavier. The pups also developed more inflammation in their brains.

In the new study, researchers tested how Beijing’s polluted air affects the health of pregnant rats.

Jim Zhang is an environmental scientist at Duke University in Durham, N.C. He and his co-workers put rats in two indoor chambers in Beijing. They piped polluted air from the city directly into one chamber. Air piped into the other chamber went through a filter. That filter removed almost all of the big pollution particles from the air and about two-thirds of the smaller ones. This made the air more like what people breathe in typical U.S. cities and suburbs, Zhang says.

All rats ate the same type and amount of food. But after 19 days, the pregnant rats breathing the heavily polluted air weighed more than the rats breathing the filtered air. They also had higher amounts of cholesterol — a waxy, fatlike substance — in their blood than did the rats breathing filtered air.

Those breathing the dirtier air had higher levels of inflammation. This is a sign of the body responding to tissue damage. These rats also had higher insulin resistance. This means their bodies weren’t responding as well to insulin, a hormone that helps with using sugar for energy. Insulin resistance can lead to diabetes, a dangerous health condition.

Taken together, the scientists say, these symptoms indicate the rats were developing metabolic syndrome. It’s a condition that puts the animals at risk of heart disease and diabetes.

During the experiment, the pregnant rats gave birth. Their pups stayed in the chambers with their mothers. And young rats that breathed in the polluted air were heavier than pups born to moms living in the cleaner air. Like their moms, the pups breathing very polluted air had more inflammation and insulin resistance.

The longer these pups breathed the dirty air, Zhang says, the more unhealthy they became. This suggests that breathing polluted air for a long time can lead to sickness, Zhang says.

It’s not yet clear exactly how air pollution affects rat metabolism. But it seems, Zhang says, to impair how the animals process fat and sugar. Pollution also increases signs of inflammation in the lungs, blood and fat. Zhang says this is probably what led to weight gain in the animals.

Wold says it might be possible to create medicines that reverse the negative health effects of air pollution. But these medicines will take time to develop.

Until then, Zhang and Wold say that paying attention to air pollution levels can help people manage their health risks. On days when pollution levels are high, they recommend that people stay indoors, if possible — or at least avoid tough outdoor exercise


Sharks become science helpers

Sensors stuck to sharks have begun gathering climate data throughout the Pacific
Fitted with special sensors, hammerhead sharks (like the one seen here) can collect valuable data as they take deep nightly dives and long trips through the Pacific. Those data will help the computer programs used to predict weather and climate.

CHICAGO — Those gray triangles that peek above ocean waves can terrify beachgoers. They flag a cruising shark. But those same fins could mark science at work for climate researchers. Some scientists have begun strapping sensors to the sharks’ otherwise ominous fins. Now when those fish travel the seas, they can collect a rich trove of data from the far reaches of the Pacific.

Maintaining devices that monitor conditions in the ocean is expensive, notes Kim Holland. He’s a marine scientist of the University of Hawaii at Manoa. Using sharks instead could provide a new and less costly source of data for those scientists who use computers to try to understand and anticipate weather and climate conditions.

“Sending sharks to do the heavy lifting makes a lot of sense,” Holland says.

Other animals have proven useful as climate-data collectors. These include elephant seals. But to date, sharks represent an untapped resource.

Holland and his team recently discovered that sharks take nightly dives to depths of as much as 800 meters (2,600 feet). Some of the fish also embark on unexplained 1,000-kilometer (620-mile) cruises to the center of the Pacific. These long and deep jaunts provide unmatched access to parts of the subsea world that scientists never visit, Holland says. He presented his latest findings February 14, here, at the annual meeting of the American Association for the Advancement of Science.

Off the coast of Hawaii, Holland and his team have begun fitting the fins of tiger and hammerhead sharks with sensors, calledtags. Each device, which doesn’t hurt the fish, is about the size and shape of an ice cream cone. Holland began tagging sharks to get information on their behavior. Soon, however, he realized the data that these ferocious fishes were bringing back could help scientists in other fields as well.

His team’s tagged sharks are now collecting ocean temperature data. These can help map how those temps vary with depth.

Future shark tags will record oxygen levels in the water. Some will measure other chemical properties, including electrical conductivity, a gauge of the water’s saltiness.  Every time a shark surfaces, its sensors can beam data it has collected to a satellite system above the ocean.

Sharks: A relatively inexpensive alternative

Tagging sharks? “It’s a great idea,” said James Overland at the Chicago meeting. An oceanographer, he works for the National Oceanic and Atmospheric Administration in Seattle, Wash. The bonus ocean data that sharks glean will certainly be useful, he says. Using tags also is relatively cheap. By comparison, the cost each day to operate some of the research ships used for ocean monitoring is $10,000 to $20,000 each.

U.S. scientists had set up an array of buoys across the Pacific to collect data and to monitor El Niños and La Niñas. (These common, years-long climate events get their start in the Pacific.) But recently, money problems have put the usefulness of this Tropical Atmosphere Ocean array in jeopardy. Right now, roughly half of the buoys are in need of repair and are no longer collecting data.

Overland also notes that curious, chomping sharks can destroy robotic vehicles that monitor the ocean, such as gliders. But putting those sharks to work by ferrying tags around the ocean makes sense.

Jennifer Francis agrees. An oceanographer at Rutgers University in New Brunswick, N.J., she has not been part of the shark-monitoring team. In addition to providing inexpensive ocean data, she says, tagging also can track variations in shark behavior, where the fish hang out and where they dine.

“All of this gives us clues as to how the ocean is changing,” said Zdenka Willis. She is director of the U.S. Integrated Ocean Observing System in Silver Spring, Md. It’s a government project involving many U.S. agencies. And this system is building a broad network for collecting data from tagged animals. 

“It is hard to pinpoint a single data stream as being most important,” Willis said. But given that the Pacific is large and sampled nowhere nearly enough, she argues that data from tagged animals are certainly poised to become more important.

Power Words

array  A broad and organized group of objects. Sometimes they are instruments placed in a systematic fashion to collect information in a coordinated way. Other times, an array can refer to things that are laid out or displayed in a way that can make a broad range of related things, such as colors, visible at once.

behavior  The way a person or animal acts towards others, or conducts itself.

climate  The weather conditions prevailing in an area in general or over a long period.

data  Facts and statistics collected together for analysis but not necessarily organized in a way that give them meaning.

El Niño  Extended periods when the surface water around the equator in the eastern and central Pacific warms.  Scientists declare the arrival of an El Niño when that water warms by at least 0.4 degree Celsius (0.72 degree Fahrenheit) above average for five or more months in a row. El Niños can bring heavy rainfall and flooding to the West Coast of South America. Meanwhile, Australia and Southeast Asia may face a drought and high risk of wildfires. In North America, scientists have linked the arrival of El Niños to unusual weather events — including ice storms, droughts and mudslides.

glider  A vehicle (such as a plane in air or uninhabited submarine) that takes advantage of currents to travel long distances using little or no fuel. It also tends to move smoothly, creating few disruptions in the fluid or airstream through which it moves.

habitat  The area or natural environment in which an animal or plant normally lives, such as a desert, coral reef or freshwater lake. A habitat can be home to thousands of different species.

La Niña  Extended periods when the surface water around the equator in the eastern Pacific cools for long stretches of time. Scientists will announce the arrival of a La Niña (lah NEEN yah) when the average temperature there drops by at least 0.4° C (0.72° degree F). Impacts on global weather during a La Niña tend to be the reverse of those triggered by an El Niño: Now, Central and South America may face severe droughts while Australia floods.

oceanography  The branch of science that deals with the physical and biological properties and phenomena of the oceans. People who work in this field are known as oceanographers.

electrical conductivity  The ability of some substance (such as water or metals) to transport an electrical charge or current.

sensor  A device that picks up information on physical or chemical conditions — such as temperature, barometric pressure, salinity, humidity, pH, light intensity or radiation — and stores or broadcasts that information. Scientists and engineers often rely on sensors to inform them of conditions that may change over time or that exist far from where a researcher can measure them directly.

shark  A type of predatory fish that has survived in one form or other for hundreds of millions of years. Cartilage, not bone, gives its body structure.

tagging  (in biology) Attaching some rugged band or package of instruments onto an animal. Sometimes the tag is used to give each individual a unique identification number. Once attached to the leg, ear or other part of the body of a critter, it can effectively become the animal’s “name.” In some instances, a tag can collect information from the environment around the animal as well. This helps scientists understand both the environment and the animal’s role within it.

courtesy by: https://student.societyforscience.org/article/sharks-become-science-helpers