Dog owners across San Francisco are gathering in opposition to the latest threat to face their furry companions — the San Francisco Recreation and Parks Department. It seems the city department regularly uses an herbicide labeled as carcinogenic by the state of California to control invasive species throughout the San Francisco park system. The effect that this herbicide has on dogs, and, well, people (especially children), is of growing concern to those who spend their time in city parks.

The herbicide in question, glyphosate, is commercially sold as Monsanto's Roundup and was labeled as "probably carcinogenic" by the World Health Organization in March of this year.

In response to the city's use of the carcinogenic herbicide, one concerned park user has launched a Change.org petition with the goal of convincing "lawmakers to ban dangerous pesticide use at schools and public parks." The petition tells the story of how one parent discovered glyphosate was to be sprayed at the park near her child's San Francisco nursery school.

I was recently walking through my neighborhood public park in San Francisco (where my little boy goes to nursery school), and found signs posted all around the playground, soccer field and nursery school announcing that glyphosate will be sprayed next week. These signs were in wooded areas with mulch and dirt on the ground, no weeds anywhere in site. It appears to be a preventive campaign simply to stop anything from growing in these areas, perhaps just a routine "general maintenance" initiative.

A few of my local neighbors have mentioned to me that their dogs who once played freely in this particular park came down with unusual mouth and nose cancers, and now they believe this San Francisco government practice of spraying Roundup in this park is the reason for this.

At of press time, the petition has 563 signatures.

Design and technology blog Inhabitat yesterday detailed one pet owner's tragic story — drawing a connection between the oral tumor that killed the dog and the application of glyphosate in the neighborhood dog park.

San Francisco resident Victoria Hamman’s beloved pup Barack died a few weeks ago from a horrific case of oral cancer. The dog was very fond of eating the grass in his local dog park, which is maintained by San Francisco Rec and Park. When she realized that the San Francisco parks department was routinely spraying the grass and surrounding areas with an herbicide called glyphosate... she wondered if there was a connection between her dog’s cancer and this herbicide.

The post included the following flyer:

Inhabitat goes on to share the case of a second dog owner, and mentions that Monday was a scheduled application day for the cancer-causing herbicide.

San Francisco resident Carolyn Plakias, whose dog also came down with cancer said: “she got cancer when she was two years old and her vet said it was really unusual to see a mast cell tumor in such a young dog and also in her breed (border collie mix). I’ve met several dog owners in Glen Canyon Park who said their pups have had weird cancers of the nose and mouth.”

And what does the city have to say about all of this? Inhabitat Editor In Chief Jill Fehrenbacher reached out for comment to both the Mayor's Office and the San Francisco Parks Department but received no response.

We'll update you if we receive one.