May 18, 2017

A report from ABC7's Dan Ashley on May 17, 2017 highlighted key findings from a recent RMP study on the pesticide fipronil. The study identified spot-on flea control products as likely to be an important source of this contaminant to the Bay, and one that has received very little study previously.

Fipronil is used for flea, ant, and termite control in California. Outdoor pesticide use can contaminate local creeks and urban runoff that enters San Francisco Bay. The RMP study was the first to suggest indoor uses like flea control may also be significant. The research team tested wastewater flowing in and out of eight sewage treatment plants around the Bay Area and detected fipronil at all of them. Even the most advanced facilities did not remove significant levels of fipronil and related compounds. This means the contaminants are also discharged to the Bay via treated wastewater.

SFEI's Dr. Rebecca Sutton, a study coauthor, said: "These chemicals get on our hands when we pet our pets, get on our clothing and the pet bedding, so when we wash our hands or wash our clothes, this all goes down the drain." Also reported was a new study by the California Department of Pesticide Regulation that measured significant levels of the pesticide in fipronil-treated dogs that were washed up to 28 days after receiving treatments. 

Fipronil is considered an emerging contaminant of moderate concern for San Francisco Bay because levels in Bay sediment are in the range of toxicity thresholds for freshwater aquatic life; limited data are available for estuarine or marine species. Safer flea control alternatives include oral medications or frequent vacuuming.


Dan Ashley
Associated Staff: 
Other Contributors: 
Jennifer Teerlink
Kelly Moran
Programs and Focus Areas: 
Clean Water Program
Bay Regional Monitoring Program
Contaminants of Emerging Concern