BOSTON — Sewage-treatment plants in Southern California are failing to remove hormones and hormone-altering chemicals from water that gets flushed into coastal ocean waters, according to the results of a study released Saturday.
The preliminary findings were part of the most ambitious study to date on the effect of emerging chemical contaminants in coastal oceans. It confirms the findings of smaller pilot studies from 2005 that discovered male fish in the ocean were developing female characteristics, and broadened the scope of the earlier studies by looking at an array of man-made contaminants in widespread tests of seawater, seafloor sediment and hundreds of fish caught off Los Angeles, Orange and San Diego counties.
The results, outlined by a Southern California toxicologist at a conference in Boston, reveal that a veritable drugstore of pharmaceuticals and beauty products, flame retardants and plastic additives are ending up in the ocean and appear to be working their way up the marine food chain.
Flame retardants used in upholstery and plastic additives are showing up in fish tissues at levels as high or higher than lingering residue of the banned pesticide DDT and another stubborn industrial pollutant, polychlorinated biphenyls, or PCBs.
The study also showed that male flatfish contain unusually high levels of the female hormone estrogen, possibly in reaction to one or more of these hormone-altering chemicals.
As many as 90% of these male fish were found to have produced egg yolk proteins, and one had actually produced eggs, indicating that the feminizing of fish seen in freshwater streams and lakes can happen in the open ocean as well. This evidence, scientists said, suggests that diluting pollution with a vast amount of seawater may not be an effective way to dispose of these new and little-understood contaminants.
"Dilution is not the solution for some of these newer compounds," said Steven Bay, a toxicologist with the Southern California Coastal Water Research Project in Costa Mesa. He expects the study to raise policy debates over upgrading sewage-treatment plants.
Although some of these contaminants may be in urban runoff, the main source appears to be the 1 billion gallons of partially treated sewage that flows into the ocean every day from the region's four major sewage outfalls.
