The state has reaffirmed that the cross-border sewage crisis does not warrant an emergency declaration. And it has agreed with San Diego County that there is no evidence of increased pollution-related diseases.

But that hasn’t stopped local and state public health departments from enlisting the help of the national public health agency, the Centers for Disease Control and Prevention (CDC), to investigate reported symptoms such as abdominal pain, diarrhea, nausea and asthma, from people who live and work near where sewage and toxic chemicals spill over the U.S.-Mexico border.

Last week, the county sent a formal request to the CDC’s National Center for Environmental Health (NCEH) for epidemiologic assistance, also known as Epi-Aid.

Dr. Seema Shah, medical director of the county’s epidemiology and immunization services branch, specifically enlisted the help of the NCEH’s Emerging Environmental Hazards and Health Effects division. It’s one of NCEH’s five branches and provides expertise in epidemiology and medical toxicology to investigate outbreaks.

“NCEH’s expertise in investigation and responding to environmental public health events, including air quality impacts, is requested to review the actions taken by the county and assist in planning next steps to meet the needs of San Diego County residents,” she said.

To be considered a formal request, the county needed the state’s blessing, which it received last week, according to an email from state epidemiologist Erica Pan to Aaron Bernstein, director of the NCEH, confirming coordination among county and state public health authorities.

Dr. Wilma Wooten, the county’s former public health director, issued the first formal step in May at the direction of county Board of Supervisors Chair Nora Vargas when she asked the state public health department to “make an official request to the Centers for Disease Control and Prevention (CDC) to deploy a liaison to San Diego County to further investigate these concerns.”

The county’s request now clears the way for the following, per CDC guidelines: an initial discussion of the type of assistance needed and a determination by the federal agency if it can support the Epi-Aid.

An Epi-Aid is a study of “an urgent public health problem, such as infectious or noninfectious disease outbreaks, unexplained illnesses, or natural or manmade disasters,” according to the CDC’s website.

The county requested Epi-Aids last year for a Legionella outbreak and in 2022 for an outbreak of Burkholderia multivorans, an emerging cause of meningitis.

Investigations generally last about one to three weeks on-site and focus on helping health departments make “rapid, practical decisions” to address public health problems.

Paula Stigler Granados is a San Diego State University environmental health professor and member of a task force researching how sewage and chemical exposure impacts South County residents. She said that because Epi-Aids tend to be “rapid (and) short-term,” the investigation —  if approved — “should serve as a first step to getting federal involvement on the ground level to observe what’s happening locally.”

A short-term investigation might miss “active outbreaks” potentially happening outside of the probe’s window. Some San Diego researchers and elected officials made a similar argument when a county investigation in February showed “no conclusive evidence” of increased illness at a South Bay health clinic. They questioned whether the two-week analysis was sufficient to deduce that people who do not come into contact with polluted water cannot get sick.

“(T)here would need to be discussions with local experts on how to proceed with observations and monitoring over a longer time period and then hopefully setting up communication and expert networks to support over time,” said Granados.

Additionally, she said the Epi-Aid should not only focus on working with local health authorities but also with officials such as Imperial Beach Mayor Paloma Aguirre, who has been urging the state and federal governments to declare the sewage crisis an emergency and for the CDC to intervene.

In a June 27 letter to Gov. Gavin Newsom, Aguirre said the state agreeing with the county’s conclusion of finding no evidence of increased infectious diseases “does not fully address the broader spectrum of public health concerns, including long-term exposure to pollutants and the cumulative effects on community health.”

She also said that cross-border pollution has surpassed the capacity of local agencies and even the state to manage and control, so it was vital for the state to ask for the CDC’s help.

“The residents of south San Diego are reporting illnesses and rashes that need to be investigated, not ignored,” Aguirre wrote.

The county’s Epi-Aid request comes after numerous informal petitions by elected officials who also asked for an epidemiological study. State Sen. Steve Padilla has even introduced a joint resolution urging the CDC to conduct an investigation. It has yet to be considered by legislators.

“We need the highest levels of government to investigate the health concerns residents face, so we can get them the treatment options that they need,” he said in a statement.

On Tuesday, the county said it had yet to hear an update from the NCEH.