Some flea control products may have environmental impacts, trace amounts of pesticides found in San Francisco Bay

SAN FRANCISCO (KGO) -- Some popular flea control products may be responsible for trace amounts of pesticides getting into the San Francisco Bay. According to a new study, the amounts are very small, but experts say the bay ecosystem could be at risk.

Americans spend more than a billion dollars a year to keep fleas and ticks off their pets. A lot of pet owners use topical spot-on treatments that need only a few drops on the back of the animal's neck to kill fleas and ticks for a month. But some of those products contain a pesticide called fipronil, and that's turning up where it's not supposed to be, in sediment at the bottom of the San Francisco Bay.

Rebecca Sutton is with the San Francisco Estuary Institute, part of a regional program that monitors bay water quality. Sutton and other scientists are concerned fipronil could be harmful to tiny creatures at the bay bottom. According to Sutton, "that's the base of our food web. So if those critters experience impacts, it could go up and harm our fish and our wildlife."

Sutton's team believes some fipronil is getting into the bay through outdoor pesticide use, and now their research indicates it may also be coming from inside our homes. They used sales data of fipronil products to help identify a possible source.

Jennifer Teerlink with the California Department of Pesticide Regulation says the concentration of fipronil used in flea treatments is "high enough...compared to a lot of other products that make their way down the drain" to be worthy of more research.

Spot-on flea control products use the natural oil on your pet's skin to spread the pesticide around its body. Photos from a U.C. Riverside study indicate how fipronil spreads after it is applied.

According to Sutton: "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."

Sutton's team tested wastewater, flowing in and out of eight sewage treatment plants around the bay area and found fipronil at all of them. She says " the treatment, even at our most advanced facilities was not removing significant levels of these pesticides."

Researchers say that means the pesticide is flowing into the bay.

The amount of fipronil found in the wastewater is tiny, roughly equivalent to a medicine tablet in an Olympic-size swimming pool. But even at that level, it is above the Environmental Protection Agency guidelines for freshwater creeks and streams. There are no guidelines for salt water.

Another new study focused on washing dogs treated with fipronil. Researchers with the California Department of Pesticide Regulation washed 34 dogs, up to 28 days after they got flea treatments. Then they tested the water to see how much pesticide ran off.

Teerlink says all the water samples contained fibronil and the study concluded: "Pesticides wash off animals during just routine bathing at concentrations that are high enough to be significant for overall wastewater loading."

The researchers say more study is required on fipronil, and on other flea and tick pesticides that may be getting into the bay. They will be doing more tests this summer.

One way to potentially reduce pesticides on your pet's fur is to use oral flea treatments that are now available for dogs and cats, but you have to go to a veterinarian to get them. Experts say frequent vacuuming and washing of pet bedding can often eliminate the need for any flea pesticide.

Click here for more information on San Francisco Estuary Institute research.

Not all topical flea treatments contain fipronil, but many popular products do. One of the leading manufacturers is Frontline. Its parent company sent this statement: Fipronil is an active ingredient used around the world in a variety of formulations for many different uses, including pesticides to protect crops and lawns, as well as pet products. There are more than 130 registered fipronil products in the State of California. Fipronil is used very differently for topical pet products than for agricultural pesticides, including different formulations and methods of administration.

When evaluated for treating and controlling fleas and ticks on dogs and cats for example, topical products containing fipronil undergo a rigorous assessment of safety, efficacy and quality; and regulatory bodies worldwide review and approve its use.

The cited studies do not identify a direct causal link to pets as a contamination source. And, as the studies suggest, more research is required to better understand this situation.

We remain committed to address issues that threaten the ability of animals to live healthier, happier lives, including the sustainability of the environments in which they live.

Photo courtesy: Melinda Bigelow Dyk, Yu Liu, Zhenshan Chen, Helen Vega & Robert I. Krieger (2012)
Fate and Distribution of Fipronil on Companion Animals and in their Indoor Residences
Following Spot-on Flea Treatments
Journal of Environmental Science and Health, Part B:
Pesticides, Food Contaminants, and Agricultural Wastes, 47:10, 913-924.
reprinted by permission of Taylor & Francis, LLC (http://www.tandfonline.com)
Click here to read the article.

Written and produced by Jennifer Olney