Here are some of the latest health and medical news developments, compiled by editors of HealthDay:

Government-Issued Trailers for Hurricane Victims Pose Health Risks: CDC

Many of the trailers used to house Gulf Coast victims of hurricanes Katrina and Rita contain toxic levels of formaldehyde fumes, U.S. health officials said Thursday.

Officials from the Centers for Disease Control and Prevention said people living in the government-issued trailers should be moved out as soon as possible because tests showed that fumes from 519 trailers and mobile homes in Louisiana and Mississippi averaged about five times higher than levels found in most modern homes. In some trailers, the levels were nearly 40 times higher, prompting concerns that the residents could come down with breathing problems, the Associated Press reported.

The CDC urged the Federal Emergency Management Agency, which supplied the trailers, to move people from the trailers as quickly as possible, with priority given to families with children, elderly people, or anyone with asthma or other chronic respiratory problems.

"We do not want people exposed to this for very much longer," said Mike McGeehin, director of a CDC division that focuses on environmental hazards.

FEMA provided about 120,000 travel trailers to victims of the 2005 hurricanes Katrina and Rita. In 2006, some occupants began reporting headaches and nosebleeds. The complaints were linked to formaldehyde, a colorless gas with a pungent smell used in the production of plywood and resins, the AP said.

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China Factory in Heparin Case Never Inspected by FDA

The U.S. Food and Drug Administration has never inspected a Chinese factory where the active ingredient in the blood thinner heparin is made, although agency officials stressed it is not yet known whether this plant played a role in recent problems with the now-suspended drug.

While no FDA inspection of the facility has been conducted to date, preparations are being made to perform an inspection as soon as possible, an FDA spokesman said in a statement, the Wall Street Journal reported Thursday.

FDA spokeswoman Heidi Robello told the Associated Press that the agency was also making plans to inspect a finishing plant in New Jersey as soon as possible.

Hundreds of people have suffered severe allergic reactions and at least four people have died recently after being given heparin, and Baxter International has suspended the sale of the drug while it investigates the source of the problem. Baxter is responsible for half of the U.S. supply of heparin. The medication is used in kidney dialysis and heart surgery to ward off the risk of clotting. The active ingredient in the medication is made from pig intestines, but Robello said she did not know whether the pigs used to make the active ingredient came from China.

Baxter Spokeswoman Erin Gardiner told the AP that the company bought the active ingredient from another concern, which she would not identify other than to say it had plants in the United States and China.

Gardiner did tell the Los Angeles Times that the supplier had been manufacturing heparin for more than 30 years, and had supplied Baxter for more than two decades. The plant in China had only been in operation for several years.

The General Accounting Office has said that the FDA appears to inspect only 7 percent of drug-making plants outside the United States, so this latest news is likely to lead to more criticism of the agencys inability to police the nations drug supply, the WSJ reported.

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Month on Fast-Food Diet Damages Liver: Report

Otherwise healthy people who were asked to eat mainly fast food for four weeks and cut down on their physical activity quickly developed signs of liver damage and pre-diabetic insulin resistance, Swedish researchers report.

In the study, 18 slim, healthy men and women were asked to reduce their daily physical activity to 5,000 steps per day and to consume at least two fast-food meals per day, preferably from well known chain restaurants.

The goal: to double daily caloric intake and boost body weight by 10 to 15 percent and then observe the effects on the liver.

A second group of healthy adults were asked to continue on their normal diet.

As reported in the journal Gut, researchers at the University of Linkoping found that the participants' levels of a particular liver enzyme called alanine aminotransferase (ALT) spiked within a week of being on the fast-food diet and more than quadrupled during the four-week study period.

In fact, ALT levels reached concentrations that indicated liver damage in 11 of the 18 participants, the researchers said. One participant also developed signs of a condition called "fatty liver," where unhealthy levels of fat collect in the organ.

The participants on the fast-food regimen also showed a sharp rise in the fat content of their liver cells, which is commonly associated with insulin resistance. Cellular resistance to insulin boosts risks for diabetes and cardiovascular disease, the researchers noted.

None of these unhealthy effects were noted in participants who ate normal diets, the researchers added.

Overall, people on the fast-food/low exercise regimen gained an average of more than 14 pounds within 4 weeks, and one person gained more than 26 pounds in just two weeks, the researchers said.

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Avastin Shown Effective in Treating Breast Cancer, Maker Says

The Genentech drug Avastin (bevacizumab), approved in the United States to treat colorectal and lung cancers, has proven effective in recent clinical tests as a treatment for breast cancer, The New York Times reported, citing a company statement.

The drug lengthened the time before the cancer grew worse, the company said. The newer trials followed initial testing that did not include all "procedures in place that the FDA would have liked," the newspaper said.

The U.S. Food and Drug Administration is scheduled to decide by Feb. 23 whether to sanction Avastin for breast cancer, although that decision may be delayed to give the agency more time to evaluate the newer clinical data, the Times reported.

In December, an FDA advisory panel of experts voted to recommend against approving the drug for breast cancer, saying the drug's ability to slow the disease didn't outweigh Avastin's potential toxic side effects, "especially since women getting Avastin did not live significantly longer," the newspaper said.

The full FDA isn't bound by the decisions of its expert panels but usually follows them.

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Patches Containing Potent Painkiller Recalled

Patches containing the powerful prescription opiod painkiller fentanyl have been recalled because a flaw could cause patients or caregivers to overdose on the drug, the Associated Press reported.

Sold in the United States under the brand name Duragesic by PriCara and generically by Sandoz Inc., the recall includes all 25-microgram-per-hour patches with expiration dates on or before December 2009. The patches were also sold in Canada under the Duragesic brand by Janssen-Ortho Inc. and generically by Ranbaxy Laboratories Ltd., the AP said.

A total of about 32 million patches will be recalled. PriCara estimates that two patches per million -- or a total of 64 -- have the defect, the Wall Street Journal said.

The AP said some of the patches might have a cut in the lining that contains fentanyl in gel form. If the gel leaks into the drug's packaging, it could cause a patient or caregiver to come in contact with the drug, possibly leading to difficulty breathing and even a fatal overdose. The drug is often prescribed for people dealing with chronic pain, such as cancer patients.