Activists blocked construction crews set to install artificial turf fields in Golden Gate Park on Thursday, in a showdown marking the latest escalation in a battle by critics who say the turf carries health risks.
Votes are still being counted from Tuesday's dueling ballot measures on artificial turf — Proposition I, which would let the city install the turf, and Proposition H, which would bar it from replacing the natural grass fields. The votes are still being counted, but so far election results show the ban failing.
In Golden Gate Park, crews were forced to halt their work removing trees Thursday when activist Kathleen McCowin stood, then sat, in front of heavy equipment around the Beach Chalet soccer fields.
"They're taking out trees that took 30 years to grow," she said.
Artificial turf has attracted opposition nationwide for worries about its possible health risks, and although San Francisco voters appeared set to OK the new turf, voters in one New Jersey town decided Tuesday by a wide margin to reject it.
NBC News reported last month that anecdotal reports of cancer among soccer players have raised concerns about whether the "crumb rubber" — made of ground-up car tires — in artificial turf could have potential long-term impacts on players' health.
Many experts and turf backers say that evidence shows it's safe, and federal agencies have said their "limited" studies found no increased health risks. But some doctors, scientists and activists say more research is needed.
In San Francisco, McCowin and other artificial turf opponents like the Coalition to Protect Golden Gate Park say park authorities should not dig in until all the votes from Tuesday have been counted.
"People are very upset," said the coalition's Mike Murphy. "The fact that they have gone ahead with the construction without waiting for the certification of the vote — a lot of people feel it's disrespectful to the democratic process."
Park authorities say they have all the proper permits to begin work, however. Before they began removing trees Thursday, they had already installed a fence around the fields Wednesday, a day after voters weighed in on the plans at the polls.
“We are grateful to the voters of San Francisco for voting to let our kids play," the city's parks department said in a statement. "We will now proceed with a much-needed renovation that will allow thousands of kids to play sports in our city."
McCowin and others plan to be back out on Friday to stop crews from working on the fields.
—Sam Schulz contributed to this report.