This is SCIENCE IN THE NEWS in VOA Special English. I'm Bob Doughty.
And I'm Pat Bodnar. This week: Action on health concerns over a chemical used to make Teflon and other products ...
What happens when scientists go fishing for the world's smallest fish ...
And a genetic study of modern cats follows their steps back in time.
We begin with new developments in a story we first reported in two thousand four. It involves concern about possible health risks from a chemical used to make Teflon and other non-stick products.
The chemical is known as PFOA, perfluorooctanoic acid. Over the years, PFOA has become widespread in the environment. Many people have small amounts of it in their blood. It has also been found in wildlife, even in polar bears in the Arctic.
On January twenty-fifth, the United States Environmental Protection Agency sent letters to eight manufacturing companies. The E.P.A. invited them to reduce their releases of the chemical into the environment. Another goal is to reduce the presence of PFOA in products.
The aim is to reduce both levels by ninety-five percent by two thousand ten. Companies are supposed to work toward cutting the levels completely by two thousand fifteen.
The eight companies are all in the United States. They are expected to honor the request.
DuPont, the maker of Teflon, has agreed to join the program. But in a statement the company says, "Products made with or using DuPont materials are safe."
Non-stick surfaces keep food from sticking to pots and pans. They help clothing stay clean and dry. They have industrial and even medical uses.
Research on PFOA continues, but the concerns are that it could be linked to birth disorders and other conditions. Last week, an independent scientific committee advised the E.P.A. to consider the chemical a "likely" cause of cancer. DuPont disagreed.
The plan by the Environmental Protection Agency calls for yearly public reports about the progress made toward reaching the goals. Methods for measuring PFOA reductions must also be developed.
In December, the agency announced a sixteen and one-half million dollar settlement with DuPont involving PFOA. Officials found that DuPont violated federal law on reporting chemical risk information.
Perfluorooctanoic acid is a processing aid used by different companies to make high-performance plastics. Some of these are sold under the Teflon name. DuPont says studies done under normal cooking conditions have not found any release of PFOA from Teflon products. The company says, in its words: "Cookware coated with Teflon has been safely used for more than forty years."
DuPont says it has also agreed to cut the amount of PFOA that is present in its soil, stain and grease repellant products. The chemical is not used in those products, but is created when they are manufactured.
You are listening to SCIENCE IN THE NEWS in VOA Special English, from Washington.
Most people who hope to catch a record-size fish hope to catch a really big one. Scientists compete to see who can claim the world's smallest fish.
A report published last month tells of a newly discovered kind of fish in Southeast Asia. It lives in blackwater wetlands. Scientists said it appeared to be the smallest fish known, as well as the smallest vertebrate. Vertebrates are animals with a backbone.
Experts discovered it on the Indonesian island of Sumatra. And they needed a microscope to measure it.
The smallest fully grown female they measured was just seven-point-nine millimeters. The longest was ten-point-three millimeters. Scientists say the new fish is a member of the carp family. It has a body so thin, light can pass through it.
Maurice Kottelat from the Raffles Museum of Biodiversity Research, National University of Singapore, led the study team. The Royal Society in London published the findings.
In the competition to find small fish, a few tenths of a millimeter or even a single tenth of a millimeter can make a big difference. And some scientists argue that smallest can also mean lightest.
The new report did not include any weights. But one interesting discovery about the new fish is an area of hardened skin on the underside of the male. The scientists say no other fish is known to have this. They believe it is used to hold the female during mating.
The fish is also unusual in that its brain is not completely covered by protective bone, like most vertebrates.
The scientists say development and agriculture threaten the Indonesian wetlands that are home to the fish. Several populations of fish are reported to have disappeared already. So the researchers hope to learn as much as possible before this little fish could be lost.
Examples were first collected in nineteen ninety-six. But scientists only recently recognized the fish as a new species. They call it Paedocypris progenetica, a long scientific name.
Now this fish story has gotten longer since the report appeared late last month. On January twenty-seventh the University of Washington in Seattle put out a news release. It said the scientists with the seven-point-nine millimeter fish "have failed to make note of work published last fall."
In that work, a University of Washington professor, Ted Pietsch, described some fully grown male anglerfish. He reported that the shortest one measured six-point-two millimeters. It was collected in the Philippines. It was attached to the back of a forty-six-millimeter long female anglerfish. "That is how they mate," the news release explained.
Professor Pietsch tells us that he is friends with the scientists in Singapore, and they told him that they just missed his report. The Ichthyological Society of Japan published it. Ichthyology is the study of fishes.
Anglerfish live deep in oceans around the world. But those fish on Sumatra live in freshwater. So perhaps they might be called the world's smallest freshwater fish ... at least for now.
When you find a fish, you might also find a cat hoping for a tasty meal.
Thirty-seven kinds of cats are alive today. They include big cats like lions and tigers. They also include the small cats that share their homes with people.
A study of modern cats shows they developed from animals that lived in Asia almost eleven million years ago. The newly published research shows how new kinds of cats developed as they spread around the world.
Warren Johnson and Stephen O’Brien led an international team that did the study. The two scientists work for the National Cancer Institute at its Laboratory of Genomic Diversity in Frederick, Maryland. Science magazine published the results.
The researchers suggest that cats became world explorers because of the rise and fall of sea levels. Land bridges appeared as water levels fell. The researchers say ancient cats used the Bering land bridge to travel from East Asia to North America. They are also said to have crossed the Panamanian land bridge that connected North and South America.
There are few remains of old cat bones. And it is difficult to identify differences between these fossils. So it has been hard for scientists to understand the cat family. But the new study of cat genetics might even help researchers who study human diseases.
The researchers examined genetic material from the sex chromosomes of all thirty-seven kinds of cats. They also studied material from energy-producing mitochondria in cells.
Evidence of genetic changes over time helped the scientists produce a history of the cat family. Dating of the fossils assisted in the placement of cats into this genetic family tree.
The researchers placed every kind of cat into one of eight lines of ancestry. They say cats moved between continents at least ten times.
Low ocean levels let the first modern cats spread from Asia into Africa. The spread into North America produced other kinds of cats. The researchers say the most recent of the ancestry lines started about six million years ago in Asia and Africa. They believe it produced the cats of today.
And today cats can be found on all continents except Antarctica.
SCIENCE IN THE NEWS was written by Caty Weaver, Brianna Blake and Jerilyn Watson. Cynthia Kirk was our producer. I'm Bob Doughty.
And I'm Pat Bodnar. Internet users can read and listen to our programs at voaspecialenglish.com. Join us again next week for more news about science in Special English on the Voice of America.