This is Science in the News, in VOA Special English. I’m Sarah Long.
And, I’m Bob Doughty. This week ... a study examines health risks from salmon raised in farms. Workers count India's big cats very carefully. And scientists discover the bones of an ancient lion in Egypt.
Coming up -- lions and tigers and ... fish!
The magazine Science published the findings. A group of scientists from the United States and Canada tested salmon for chemicals linked to cancer. They studied seven-hundred-fifty salmon bought in North America, South America and Europe. They used guidelines established by the United States Environmental Protection Agency.
The study took two years. It found higher levels of P-C-B’s, dioxin and other chemicals in farm-raised salmon. The levels were an average of ten times higher than in salmon caught in the open sea.
The study found that salmon from European markets generally had the highest levels of pollutants. The study included the cities of Edinburgh, Frankfurt, London, Oslo and Paris. The researchers found the lowest levels in salmon bought in the American cities of New Orleans and Denver.
The researchers say people can safely eat four to eight servings of wild salmon a month. A serving is about two-hundred-thirty grams. But they say eating more than one serving of farmed salmon a month in most cases creates what they call an "unacceptable cancer risk."
The United States Food and Drug Administration, however, disagrees with this advice. Agency officials say they find no health concern. Their advice to people is not to change their eating of farmed or wild salmon.
Federal and industry officials say the level of dangerous chemicals in salmon has decreased by ninety-percent since the nineteen-seventies. They say any threat is small compared to the good that eating salmon can do.
Salmon is high in omega-three fatty acids. These can help prevent heart disease. Salmon is also among fish that are lower in levels of mercury pollution. Mercury is especially bad for the nervous systems of young children and the babies of pregnant women and nursing mothers.
The study tested uncooked salmon with the skin left on. Health officials say most pollutants are in the skin and the fat just below. They say removing the skin and cooking away fat removes many of the pollutants.
The study says the chemicals apparently entered the farm-raised salmon through the fish products they were fed. Salmon in the wild eat small fish and sea organisms that contain fewer P-C-B's and other chemicals.
The salmon industry notes that meat and milk products can also contain P-C-B's. But it says salmon farmers are reducing the levels in their food by using, for example, soybean oil in place of fish oil.
P-C-B's were used to make products like plastics and paint. The United States banned this group of chemicals in the nineteen-seventies. But they remain in the environment.
Another chemical, dioxin, is released when plastics and some other materials are burned. Dioxin has been linked to reproductive and developmental problems in addition to cancer.
Raising salmon in floating cages has become a major industry. In the United States, ninety percent of the fresh salmon that people buy is farm-raised. More than half comes from Chile. The study says chemical levels in farmed salmon from Chile are lower than in most other areas. But it says the levels are still higher than in wild salmon.
People do not always know if the salmon they eat was farmed or wild or where it came from. The study calls for stores and eating places to provide more information.
In December, the Food and Drug Administration advised people not to eat shark, swordfish, king mackerel or tilefish. These contain high levels of mercury.
The agency says people can generally eat other fish and shellfish two to three times a week. But it says fish caught in local waterways may not be as safe. The F-D-A also says people should not eat the same kind of fish or shellfish more than once a week.
In the United States, tuna is one of the most popular kinds of fish. The Food and Drug Administration says tuna is safe for pregnant women. But it says tuna steaks and canned albacore tuna generally contain higher levels of mercury than canned light tuna.
|(Photo - P. Chapuis/MAFB, Copyright Hypogees)|
Lions are described in the art and writings of ancient Egypt. But the researchers say no physical evidence had been found until now.
They reported that they found the lion south of Cairo in the burial place of Maia. She served as a caretaker for King Tutankhamen. The boy king died more than three-thousand years ago.
The scientists say the discovery confirms that Egyptians considered lions a sacred animal. They reported that the lion had been placed on a rock in a large room in the burial place.
Alain Zivie led the team. He says it was immediately apparent that the animal was a lion. He says the skeleton of the male lion was in almost perfect condition.
The report appears in the magazine Nature. The researchers say the lion apparently lived to an old age and had been cared for by humans.
Mister Zivie says the animal could have represented a god. But some other scientists question this theory. They point out that the researchers did not find evidence of the cloth used to wrap important people and animals after death. One scientist suggests that the lion might have been important as a family pet.
The Sunderbans forest is one of twenty-seven protected areas for India's tigers. Pradeep Vyas is the field director. He led the teams that did the count. The workers searched the ground and collected hundreds of footprints. Each tiger has a paw print that can be used for identification, just like a human fingerprint. The workers used plaster material to make copies.
Mister Vyas says gathering prints is dangerous. The collector could come across the owner of the prints at any time.
Mister Vyas says collectors gathered twenty percent more prints this year than in the last count two years ago. He says this is a good sign. But more prints do not necessarily mean more tigers. Myster Vyas, however, say he feels sure that the number of young tigers has increased. He says this is a sign of a healthy environment.
Estimates place the Sunderbans tiger population at about two-hundred-seventy on the Indian side and four-hundred in Bangladesh.
The Indian government started Project Tiger in nineteen-seventy-three in an effort to save the cats. But since the nineteen-seventies, the number of Indian tigers has dropped from about five thousand to an estimated three-thousand-five-hundred. One problem is illegal hunting. Tiger parts are highly valued in East Asia for use in traditional medicines.
Another problem is development. Dipankar Ghosh works for the Wildlife Trust of India. He says people and tigers compete for food and space. Tigers kill an estimated fifty villagers a year in the Sunderbans forest. Forest officials are trying to improve economic conditions for villagers. And they urge people not to kill tigers that enter villages. The tigers are part of the environmental system that the villagers depend on.
SCIENCE IN THE NEWS was written by Caty Weaver and Cynthia Kirk, who was also our producer. This is Bob Doughty.
And this is Sarah Long. Join us again next week for more news about science in Special English on the Voice of America.