A new study from the University of California has found that chemicals in sewage-contaminated coastal water are not just a problem for the oceans – they’re becoming airborne.
Focusing on the Tijuana River, which flows from Mexico into the U.S. and dumps millions of gallons of untreated wastewater into the Pacific Ocean every day, the team found that a wide range of pollutants, including drug residues, tyre chemicals and sunscreen ingredients, are entering the atmosphere through coastal aerosols – tiny particles that form when ocean spray picks up contaminants from polluted water.
The most polluted air samples were collected north of the U.S.-Mexico border, where ocean conditions and wind carry the particles inland.
Among the pollutants identified were benzoylecgonine, a byproduct of cocaine use; methamphetamine, and octinoxate, a UV blocker in sunscreen known to break down into harmful compounds.
Assistant Professor of Chemistry and Biochemistry Jonathan Slade said: ‘In some cases, the octinoxate levels were comparable to measurements made directly above wastewater treatment plant vats, meaning that in some ambient conditions at the coast, the concentrations of pollutants that people are inhaling can be comparable to a worker at a wastewater treatment plant.
‘It’s been shown that octinoxate can degrade DNA when exposed to light. 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.’
The researchers point out that this represents a significant and under-recognised air quality threat. Long-term exposure, even to small amounts, could affect communities living near polluted coastlines. Indeed, residents in the affected areas have long reported respiratory issues and other symptoms, while nearby beaches have faced frequent closures due to contamination.
The study also points to a much wider global issue, with 80% of the world’s wastewater going untreated, similar airborne risks may be present in coastal communities worldwide.
Atmospheric chemist Kimberly Prather said: ‘The air pollution angle is a game-changer. People don’t expect to inhale wastewater, but that’s exactly what’s happening.’
The full research can be read here
Photo: Adam Cooper / UC San Diego
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