The World Health Organization warned on Wednesday that a global flu pandemic was imminent, raising its threat level as the swine flu virus spread and killed the first person outside of Mexico, a toddler in Texas.

“Influenza pandemics must be taken seriously precisely because of their capacity to spread rapidly to every country in the world,” WHO Director General Margaret Chan told a news conference in Geneva.

“The biggest question is this: how severe will the pandemic be, especially now at the start,” Chan said, but added the world “is better prepared for an influenza pandemic than at any time in history.”

Fears of a global swine flu pandemic grew with new infections in the United States and Canada on Sunday, and millions of Mexicans hid indoors to avoid a virus that has already killed up to 81 people.

While the only deaths have been in Mexico, the flu is spreading with 20 cases in the United States and six in Canada, and possible cases as far afield as Europe and New Zealand.

investigation by Rebecca Renner of Salon has revealed that the Center for Disease Control(CDC) had withheld evidence of dangerously high levels. An influential CDC report released in 2004 (and since cited by officials in Seattle to calm nervous parents) downplayed the role that chloramination played in the D.C. lead crisis, saying that it “might have contributed a small increase in blood lead levels.” However, according to Renner, “the results of thousands of blood tests that measured lead contamination in children were missing from the report, potentially skewing the findings and undermining public health.

Antidepressant medications appear to help only very severely depressed people and work no better than placebos in many patients, British researchers said.

The researchers found that compared with placebo, these new-generation antidepressant medications did not yield clinically significant improvements in depression in patients who initially had moderate or even very severe depression. The study found that significant benefits occurred only in the most severely depressed patients.

Ex-EPA chief Christie Whitman was bombarded by boos and a host of accusations Monday at a hearing into her assurances that it had been safe to breathe the air around the fallen World Trade Center.

The confrontation between the former head of the Environmental Protection Agency and her critics grew heated at times. Some members of the audience shouted in anger, only to be gaveled down by Rep. Jerrold Nadler, D-N.Y., who chaired the hearing.

For three hours Whitman faced charges from Nadler and others that the Environmental Protection Agency’s public statements after the Sept. 11, 2001, attacks gave people a false sense of safety.