For many months, San Fernando and Simi valleys residents and local leaders have been asking Gov. Jerry Brown to demand tougher cleanup standards at the contaminated Santa Susana Field Laboratory, where the rumbling of test rockets was once a daily reminder of a bygone Space Race era.

But nothing has happened so far, residents say. That’s why, as the November election looms, they are taking the issue to gubernatorial candidates, seeking a new push from a fresh generation of leaders to get moving on cleaning up a site where concerns still linger about the effects of radiation.

More than 30 parents and residents gathered outside the Los Angeles headquarters of Lt. Gov. Gavin Newsom on Wednesday calling on him to put pressure on the state’s Department of Toxic Substance Control to regulate the clean-up of the site.

In a letter addressed to Gov. Brown — but with his name crossed out — the residents asked Newsom, who is competing against John Cox for governor in the Nov. 6 election, to conduct “the safest and most comprehensive cleanup” of the 2,900-acre site, which sits in the hills above San Fernando and Simi valleys.

“We need to do the proper clean-up,” said West Hills resident Melissa Bumstead, adding that a similar request will be delivered to Cox. “Whoever becomes a governor, they need to take care of the issue.”

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Bumstead also delivered a petition she launched on Change.org, which has been signed by more than 360,000 people. Bumstead initiated the petition after her daughter Grace was diagnosed with leukemia when she was 4 years old. The girl, who relapsed last year, is cancer-free now. But according to the petition, the girl is one of 50 children within 20 miles of the site with cancer, a product, they suggest, of an era of nuclear research and rocket engine testing that left a tragic imprint in the area.

The lab was developed in the 1940s, and in 1959, it became the site of a partial meltdown accident that left the area polluted with radioactive and chemical contamination.

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In 2010, the U.S. Department of Energy and NASA inked an agreement, promising to clean up all detectable contamination in their operational areas by 2017. DTSC officials also asked Boeing, which owns most of the site, to conduct its own cleanup.

A year later, the clean-up has not yet started. That makes Bumstead and other parents concerned that their families continue to be exposed to dangerous radionuclides and carcinogenic chemicals.

“The timing is critical because DTSC is planning to be done with the cleanup documents soon,” Bumstead said. “If a new governor doesn’t jump in and does something quickly, we are left with things like plutonium and uranium at the site, only 5 miles away from my house.”

DTSC officials say their agency has followed the protocols outlined in clean-up agreements.

Newsom, who is known for a pro-environment stance, issued a statement Wednesday pledging to know more about the issue.

“Lt. Governor Newsom is committed to understanding more about the complexities around Santa Susana and the long-standing issues there, and charting a path – in partnership with the community – to clean up the site without further and unnecessary delays,” according to the statement.

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A 1997 UCLA study concluded Rocketdyne workers who were exposed to radiation in years of nuclear testing at the site have an increased risk of dying of cancer.

At the rally, a group of parents held signs that read “Newsom are you bold enough to get full cleanup?” and “Save our kids full cleanup” as passing commuters honked their support.

Woodland Hills resident Angela Smith joined the rally with her 16-year-old son Chico Ryder, who was diagnosed with rhabdomyosarcoma, a cancer of the soft tissue, about six years ago. As Smith was taking care of her son, she met other parents who lived in close proximity to the site and whose children had cancer.

“My son got cancer and I wouldn’t wish it to anybody,” she said. “We just need to get the place cleaned up, so people don’t get cancer. It’s kind of a no-brainier, isn’t’ it?”

Milissa Ospina, who lives is Simi Valley, wore a gas mask during the protest, holding a sing that read, “Newsom, pick kids not cancer.” Ospina believes her daughter’s cancer was triggered by the release of radiation from the site. She said she expected Newsom to make it his top priority to clean up the area near her home.

“It is one of the most important issues,” she said. “He needs to take care of it now, so we feel comfortable in our homes.”