By Ellen Huet
 
SAN FRANCISCO -- Calling a proposed oil pipeline across the nation's midsection a threat to public health in California, more than 1,000 nurses streamed across the Golden Gate Bridge on Thursday to urge that President Obama block its construction. 

It might not have seemed like an obvious target for nurses who had gathered for a convention in San Francisco, but the protesters - clad in red scrubs - said the connection between health problems and the proposed Keystone XL pipeline was real.
 

The proposed 1,700-mile-long pipeline, which would carry oil from the tar sands oil fields in Canada to refineries in Texas, is a public health risk to all, even those a thousand miles away in San Francisco, said members of the group National Nurses United.
 

"Back at the bedside, nurses see patients every single day admitted to hospital beds and emergency rooms as a result of air pollution, water pollution and the degradation of our environment," said Deborah Burger of Sebastopol, who has worked as a nurse for 41 years and is co-president of the nurses union. "We knew we really had to speak up on this issue. The Keystone pipeline will have deadly consequences to our communities."

Not everyone got the point right away.

"I don't know what the Keystone pipeline is - well, I do, but I don't know why it would be protested here," said John Kane, 47, as he and his family tried to figure out how to ride their rented bikes across the bridge when their main bike path was blocked by the protest. "We'll see if we can weasel our way around."

The nurses were joined by smaller environmental groups and activists, some who came to promote their own causes - flyers were handed out in support of Bradley Manning and saving Sutro Forest - as well as unaffiliated locals who wanted to voice opposition to the pipeline.

"I feel like if everyone who felt against this came out and showed it, we'd get a much better response," said Hilary Avalon, 47, who runs a bed and breakfast in Sebastopol and took time off to come to the march after she heard about it on the radio. "We should be wall-to-wall. But I guess it's also a Thursday."

Before the bridge march, protesters rallied at a field just south of the bridge as speakers led chants and an Irish band played songs whose lyrics painted pictures of nurses unions fighting big corporations.
 
Michael Macor, The Chronicle
 
Gail Graham of Stinson Beach joined hundreds of protesters for a pre-march rally as they prepared to cross the Golden Gate Bridge.

Even Kat Taylor, wife of billionaire climate activist Tom Steyer, kept a musical momentum going with a Keystone-themed homage to Marvin Gaye - "I Heard It Through the Pipeline."
"Waiting for Obama to deny the pipeline's faulty promi-i-ise," she sang to cheers.

Steyer, who hosted Obama in a ritzy fundraiser at his Pacific Heights home in April, also launched a 10-week online campaign Thursday to push the president to reject the pipeline.

The nurses from around the country were already gathered in San Francisco for an annual conference that will last until Friday, said Doreen McIntyre, 54, a nurse from Minneapolis. The annual NNU conferences usually center on a cause and a protest.

"I feel good to be a part of a movement that speaks its mind," she said.

Ellen Huet is a San Francisco Chronicle staff writer