KETTLEMAN CITY, Calif. (AP) — Grieving parents testified Thursday before California legislators about a rash of infant deaths and birth defects in an impoverished farm town next to the biggest hazardous waste landfill in the West.

"How many more children will have to be born with these conditions for them to listen to us?" asked Magdalena Romero, whose daughter, America, died a few months after she was born with a cleft palate and other health problems. "Our children are dying, and we don't know why. For such a small town, it's just too big of a coincidence."

Residents in this small, rural town have blamed the toxic waste dump for at least 11 birth defects since 2007, but state waste management officials have said there is no evidence linking the central California landfill to the deformities.

Members of the state Latino Legislative Caucus organized the hearing to get the latest from state and federal regulators who are probing what may have caused the grouping of cleft palates and heart problems. Environmental officials on Thursday also started taking samples of the air, water and soil and going door-to-door to talk with families to assess community exposure.

The hearing comes nearly five months after Gov. Arnold Schwarzenegger ordered the California Department of Public Health and the state Environmental Protection Agency to conduct a full investigation, including interviews with residents and reviews of medical records.

The Kettleman Hills Facility is a major employer in the largely Spanish-speaking community of 1,500 people along Interstate 5, the busy artery linking Northern and Southern California. The town is crisscrossed by high-tension power lines; pesticides and chemical fertilizers are routinely sprayed on nearby fields and some local drinking water sources are contaminated.

Company officials won approval to expand the 1,600-acre facility this year from the Kings County Board of Supervisors despite opposition from hundreds of residents, who accused officials of ignoring complaints from those without political clout.

The expansion permit is on hold while state health and state and federal environmental investigations continue.

"We're not here to judge anyone, we're not here to crucify," said Assemblyman Tony Mendoza, D-Norwalk, the caucus' co-chair. "We're here to get to the bottom of this, we're here to get to the truth and I think the families are here for the same reason."

Last month, the U.S. Environmental Protection Agency warned the company to use an independent laboratory to analyze the site's chemical content. It said Waste Management's in-house tests of zinc and cadmium levels were unreliable.

In April, the federal agency cited the facility for violating the law by improperly disposing of PCBs, or polychlorinated biphenyls, which are chemicals banned long ago that are linked to cancer and other health effects.

The company said it has since cleaned up a storage building and the adjacent soil area.

In February, state health officials said they had discovered no common cause for the birth abnormalities and facial defects among children in Kettleman City.

Public health officials have finished interviewing six mothers whose children were born with birth defects and continue to analyze broader survey results, said Kevin Reilly, chief deputy director of the health department.