Maricela Mares-Alatorre was well aware of the industrial and agricultural pollutants that surrounded her as she grew up in this tiny farm town just three miles from the largest toxic waste dump in the West.

Her parents had founded People for Clean Air and Water two decades ago to successfully fight a proposed incinerator at the dump. It was an early but defining struggle for the environmental justice movement.

Years later, with infant deaths and birth defects mounting in this Spanish speaking community, Mares-Alatorre worried that those same poisons would damage her unborn baby.

Now she and other activists will take the battle to the Kings County Board of Supervisors Tuesday, urging a rejection of the proposed expansion of Chemical Waste Management Inc.'s 1,600 acre facility. In addition to recent infant deaths and birth defects, they point to the high asthma and cancer rates in this largely Latino town of 1,500 people.

Of 20 children known born here between September 2007 to November 2008, five had a cleft in their palate or lips, according to a health survey by community activists. "That just raises a red flag," said Mares-Alatorre.

Owners of the waste facility have offered to fund a health study, but they say there's no evidence linking the dump to the maladies. Other potential culprits are pesticides sprayed on nearby fields, discolored drinking water and exhaust from Interstate 5, the West Coast's major north-south highway, that borders the town.

Mares-Alatorre, 37, had a healthy baby girl but one of her relatives wasn't as fortunate.

"A month before my child was born I was told he was going to have problems _ he was going to be born with cleft palate, some deformity in his nose and part of his brain missing," said Maura Andrade-Alatorre, 25.

Andrade-Alatorre's son was born with severe birth defects. He survived but three infants born with similar problems have since died. Clefts of the lip or palate routinely occur in fewer than 1-in-800 births in California, according to state health statistics.

Activists say the birth defects bolster their argument that the facility should not be allowed to grow pending an investigation. The Board of Supervisors recently directed the county health department to ask the state to oversee that study, but any results will not be known prior to Tuesday's board vote on the expansion.

Chemical Waste's proposed growth has been slowly moving through a permitting process that involves local, state and federal regulators. Activists say they are prepared to sue if the supervisors approve the project.