Agencies, such as the CDC and WHO, have declared antibiotic resistance a “global threat” due to the lack of effective treatments and poor disease outcomes.
Non-targeted chemical analysis can discover toxic chemicals present in water entering the US from Tijuana, including industrial and domestic compounds banned in CA. A recent study found that coastal water pollutants in the Tijuana River discharge were detected in coastal aerosols.
The Tijuana River and its estuary form a shared watershed between Mexico and the United States. Water flows from Tijuana into the U.S. and eventually reaches the Pacific Ocean near San Ysidro and Imperial Beach, California. Unfortunately, this watershed faces serious challenges. Large amounts of untreated sewage and runoff from homes, businesses, and factories enter the river and estuary. This happens because of aging infrastructure and rapid, unplanned development in Tijuana.
As a result, the river is heavily polluted, creating ongoing risks for nearby communities—affecting health, local economies, and quality of life. For example, contaminated water flowing into the ocean caused beach closures in Imperial Beach for 300 days in 2020 and 247 days in 2021. Heavy rainstorms, including Hurricane Hilary in 2023, made the situation worse by overwhelming drainage systems on both sides of the border.
Currently, decisions to close beaches are based only on basic water tests for certain bacteria. However, we don’t yet know how harmful microbes and chemicals from the river might move into the air—and what that means for people living nearby.
In a recent SDSU HealthLINK Center-funded project, we studied water in the Tijuana River and Estuary over two years. Using advanced testing methods, we found:
Microbes carrying antibiotic-resistant genes (ARGs)—these are especially concerning for children.
Microbial species that aren't usually monitored but could cause illness, such as A. cryaerophilus, along with other known pathogens.
High levels of toxic chemicals linked to untreated sewage and industrial waste near the border.
Study how pollutants from the river move into the air in areas like San Ysidro and Imperial Beach.
Examine homes and children's microbiomes near the river for signs of contamination.
Develop strategies to reduce health risks for families.
Creating lasting impact for border communities and beyond
Find out what harmful microbes and chemicals from the Tijuana River may be getting into the air we breathe. This will help reduce uncertainty and give families in San Ysidro and nearby areas clear answers about possible health risks.
Current water tests don't catch everything. Potential to develop better tools to detect complex pollutants—both microbes and chemicals—that are often missed by routine testing.
By looking at indoor samples from homes and studying children's microbiomes, determine whether pollution from the river is making its way inside and how it might affect families.
Provide clear, science-based recommendations to help households and local leaders take steps to protect health.
Develop methods and data that can be used in other regions facing similar challenges, helping other communities everywhere be better prepared for cross-border pollution issues.
Professor, School of Public Health
