By Deborah Zabarenko, Environment Correspondent

WASHINGTON, July 17 (Reuters) - The U.S. Environmental Protection Agency, under fire for apparently discounting the impact of climate change, on Thursday said global warming poses real risk to human health and the American way of life.

Risks include more heat-related deaths, more heart and lung diseases due to increased ozone and health problems related to hurricanes, extreme precipitation and wildfires, the agency said in a new report.

"Climate change poses real risk to human health and the human systems that support our way of life in the United States," the agency's Joel Scheraga said in a telephone briefing.

The report does not specify how many people in the United States could die due to climate change, because that number can be changed by taking action, Scheraga said.

"We are not saying in this report that more people will die in the future due to climate change," he said. "What we are saying is that there's an increased risk of deaths due to heat waves in the future as the climate changes.

"We have an opportunity to anticipate these increased risks ... and to due to prepare for the future in order to mitigate these risks."

Limited to climate change impacts in the United States, the report found a likely increase in food and water-borne germs as the world warms and habitat ranges expand for some disease-causing organisms.

Also, the inequities now found in the U.S. health care system are likely to be exacerbated by global warming: "Many of the expected health effects are likely to fall disproportionately on the poor, the elderly, the disabled and the uninsured."

Global warming is expected to affect water supplies across the country, with reduced water flow in rivers, lower groundwater levels and more salt creeping into coastal rivers and groundwater, the report said.

People who live along the coasts will face the consequences of rising sea levels and severe weather events while city dwellers can expect higher energy demand to cool buildings -- though the demand for heat will probably decline.

The report covers much of the same substance as an EPA document released on Monday that found global warming endangers human health. This document was part of the agency's response to a 2007 Supreme Court ruling that found the EPA had the power to regulate climate-warming greenhouse gas emissions if it was found that they hurt human health.

However, the agency has indicated no action is likely before the Bush administration leaves office next January.

Stephen Johnson, head of the environmental agency, has been called to testify on July 30 before the Senate Judiciary Committee hearing on alleged White House interference with the agency. Researchers have repeatedly complained of White House censorship of environmental science. (For more Reuters information on the environment, see http://blogs.reuters.com/environment/) (Editing by Eric Walsh)

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