Tijuana River pollution isn't just in the ocean — it's in the air too
Add Axios as your preferred source to
see more of our stories on Google.
Photo illustration: Lindsey Bailey/Axios; Photo: Patrick T. Fallo/Getty Images
Researchers have provided some of the strongest evidence yet that pollutants from the Tijuana River aren't just flowing into the Pacific Ocean — they're in the air, too.
Why it matters: The study does not draw any conclusions on the effects to the environment or human health, but found harmful pollutants carried by the river are being aerosolized by sea spray.
Between the lines: In the fall, one of the researchers — Kim Prather, an atmospheric scientist at Scripps Institution of Oceanography — was involved in a dispute with county officials about air quality in the Tijuana River Valley.
- She was among researchers who held a press conference warning they had recorded harmful levels of gasses in the air.
- A day later, former County Supervisor Nora Vargas held her own press conference assuring residents that county testing showed no public health concerns.
The latest: The new study, from UCSD and the Scripps researchers published Wednesday in Science Advances, is one of the most comprehensive demonstrations that chemicals from Tijuana River wastewater are being transferred from water to the air.
- Researchers found that illicit drugs, substances formed when bodies metabolize drugs, and chemicals from tires and personal care products carried by the river are being turned into tiny particles flung into the air when waves break.
- The pollutants they tracked are higher in the Tijuana River than in the ocean, and higher in the water and air in Imperial Beach than they are in La Jolla, reinforcing that the concentrations they found were tied to the wastewater crisis.
How it works: The team tracked a chemical produced when a body metabolizes cocaine, because they knew it was carried in wastewater, to determine the source of the pollutants.
- They found levels of the chemical in the ocean spiked when Tijuana River flows did, and its levels in the air did the same alongside increased sea spray aerosol emissions.
What they're saying: Researchers measured one pollutant — octinoxate, a UV filter in sunscreen — that correlated with Tijuana River flow surges in amounts near the coast that were comparable to the levels found standing directly above a vat at a wastewater treatment plant.
- "It's been shown that octinoxate can degrade DNA when exposed to light," said Jonathan Slade, a UCSD professor of chemistry and biochemistry, in a statement. "And if it's in these tiny aerosols we're breathing in, it can get deep into our lungs and pass into our bloodstream. That's very concerning, especially considering the high levels at which we found it in the air."
Fine print: Although most pollutants were found in relatively small doses in the air, the researchers stressed that residents living close to the border are inhaling those small amounts over years or even decades.
The bottom line: "Truthfully, we don't yet know the acute health effects," Slade said.
- "But the numbers we report can be incorporated into models to help us better understand what we're breathing in and how much we're exposed to."