Dana Perino, a White House spokeswoman, answered reporters questions today and made the case that the cuts were made because scientists in other government agencies thought some of the testimony was not well grounded in the latest science, as described in reports by the Intergovernmental Panel on Climate change   earlier this year. Dr. Gerberding said in an interview that she was able to say everything she wanted to say.

The science on the potential health effects from rising temperatures and changing weather patterns in a greenhouse-warmed world remains laden with questions. The clearest risks lie overseas, particularly in poor countries with weak public health agencies, according to a draft government report on climate impacts on human health and welfare, done at the request of President Bush.

The Bush administration has repeatedly been questioned about incidents in which political appointees adjusted government reports, statements, news releases and other material on climate change in ways that toned down a sense of urgency. The White House almost always says this is done to reflect the science most accurately, or to stress points that fit policy goals.

Last year, for example, the mission statement for NASA was altered to delete the phrase to understand and protect our home planet.