Herbicide used in FL as a cure-all is more like a kill-all

April 1, 2021 7:00 am

University of Florida scientists study blood samples taken from manatees. They are finding traces of the active ingredient in Roundup weed killer. Source: Nancy Denslow, U.F.

Can you imagine what life was like for Florida’s earliest occupants?

Think of the unrelenting heat that led them to name so many places after Hell. Think of the rugged terrain, full of sharp-edged sawgrass and thorny thickets blocking every effort to pass. Think of how hard it was to combat all the skeeters and no-see-ums without the benefit of bug spray. Think of how stinky those settlers must have been!

The land was largely pristine then, but no one was calling this place “paradise.”

Such hardships are a big reason why Florida was the least populated Southern state in 1940. Historians say two inventions sparked our surge in population to 22 million: air conditioning and insecticide.

Our ease with those artificial ingredients that make life livable here tends to blind us to the consequences of what we do to control nature. Take how we handle those thorny thickets now, for instance.

Got some little things growing in your yard other than socially acceptable St. Augustine sod? Want to get rid of them? Since 1974, the solution for that problem has been a weedkiller known as Roundup, manufactured by chemical giant Monsanto. The stuff is used, as I read on one alliteratively inclined website, in “agriculture and aquatics” as well as “from forestry to flower beds.”

You’ve probably seen the TV ads. I am particularly fond of the Western-themed one where a tubby guy in shorts stands in his driveway and sings about how he’s “a loving husband and a real good dad but weeds just make me rattlesnake-mad. Now Roundup has a new sharp-shootin’ wand and I’m sending those weeds to the Great Beyond!” All that’s missing is a cowpoke cracking a whip and shouting, “Rawhide!”

For decades, we Floridians have been squirting this stuff on dandelions and other pesky lawn intruders just the way we used to squirt DDT around to kill mosquitoes before figuring out that it would also kill all the ducks and other birds. (See Carson, Rachel, “Silent Spring.”)

Golf course maintenance crews rely on it. So do farmers trying to keep their citrus groves and other agricultural operations free of noxious and unwanted growth. Hey, nobody’s paying them to raise weeds, you know!

Water hyacinth. Credit: FWC

Roundup, which is also sold under the names Rodeo and AquaNeat, has proven itself a handy weapon for government agencies that have declared war on invasive plants. Water hyacinth, water lettuce, and hydrilla clogging your canals? Grab some Roundup and give it a spritz or two or 20,000. Clears it right out!

Local governments, the Florida Fish and Wildlife Commission, the South Florida Water Management District, even the U.S. Army Corps of Engineers have been spraying that stuff allllllllllll over the Florida landscape, according to Paul Gray, who has a Ph.D. and the title of Everglades science coordinator for Audubon Florida.

Just one of those agencies, the wildlife commission, spent $17 million in 2017-2018 spraying for invasive aquatic weeds, according to a 2019 story by

These government agencies have squirted so much of this stuff around that they’ve killed off not just the “bad” plants but plenty of good ones too, Gray said. Just like the Vietnam War maxim about destroying the village to save it, they’ve improved the lakes so much that they’ve slaughtered them.

“There’s a lot of spraying going on,” Gray told me this week. “In some places, they’ve killed off entire marshes.”

He said he’s seen the effects up close at Lake Istokpoga in Highlands County, where he lives.

“We’ve got dead open water where we should have emergent marshes,” he told me. “There should be frogs and grass shrimp and snails and dragonflies and aquatic snakes, and there’s just nothing.”

Gray blamed “overzealous” spraying by agencies that have no overarching plan about how to use the stuff in a more surgical way. The result defeats the whole purpose.

“If you kill the patient to get rid of the disease,” Gray said, “then the treatment isn’t working.”

Now available in manatees

The active ingredient in Roundup is glyphosate, which sounds like one of the 300 million pharmaceuticals you see advertised constantly on TV these days in between the Roundup ads (“Ask your doctor if Glyphosate is right for you!”)

I guess that’s appropriate, since Monsanto is now owned by Bayer, the pharmaceutical company that invented aspirin and also collaborated with the Nazis to test drugs on the prisoners at Auschwitz (Is it rude of me to bring that up? Gosh, I hope it doesn’t give Bayer execs a headache.)

Just like those TV pharmaceutical products, though, it comes with some nasty side-effects — and I’m not talking about restless legs, twitchy eyes, or the occasional bout of projectile vomiting.

Here’s what you never see on those ads for Roundup:

Glyphosate wasn’t invented by Bayer or Monsanto, nor was it originally intended as a weed-killer. The Stauffer Chemical Co. patented it in 1961 as a descaling agent to clean out calcium and other mineral deposits in pipes and boilers of residential and commercial hot water systems.

Now do you see why that may not be the best thing to squirt on our lakes and rivers and estuaries?

A Florida manatee. Credit: Florida Fish & Wildlife Conservation Commission

Yet we’ve been putting out so much of the stuff that it’s now turning up in unexpected places — inside manatees, for instance.

A study by University of Florida scientists published earlier this month found more than half of the manatees they sampled had glyphosate floating in their blood.

Concentrations of glyphosate in their plasma went up in the decade between 2009 and 2019, the scientists found. The levels found in the manatees have been sufficient to cause kidney and liver damage in laboratory animals.

The results surprised even the scientists doing the study.

“We really didn’t know that we would find it,” said Nancy Denslow, U.F.’s director of aquatic toxicology and one of the authors of the study. They thought the chemical would break down too fast to be detected in the blood, she explained.

“It is breaking down,” she told me. “But it’s also a constant input.”

Denslow said the scientists still have a lot of questions about their own findings — for instance, whether the manatees are ingesting the chemical from the water they drink or the seagrass they eat, and what it’s doing to them. They would also like to know how much is being squirted all over Florida.

“We don’t know how much is being used” in this state, she said, pointing out, “You can just go buy it at Home Depot.”

Maybe people should think twice about doing that, she added.

“A friend of mine sprayed his lawn with it and then brought in a urine sample,” she said. “Glyphosate was in his urine.”

Roundup, the usual suspect

Dr. Denslow’s friend is far from the only American peeing Roundup. In 2016, a study by the University of California, San Francisco, found glyphosate residue in 93 percent of the urine tested. (On second thought, don’t ask your doctor whether Glyphosate is right for you — it’s not.)

Bayer has repeatedly denied that Roundup causes human health problems. That claim has been much harder to maintain in the face of more than 13,000 lawsuits blaming exposure to glyphosate in Roundup for users developing cancer, Bloomberg News reported last year. So far, Bayer has lost three of those cases, resulting in combined damages of $191 million.

As a result, Bayer agreed to pay $39.5 million to settle allegations that its Roundup ads included misleading information about the health risks to both humans and animals.

Around the same time Bayer was forking over all that cash, Citrus County’s aquatic spraying officials were so determined to coat Tsala Apopka Lake with herbicide that when a local homeowner objected, they showed up with gun-toting deputies. The cops made sure nobody tried to interfere with the spraying, according to

Florida anglers have been protesting the rampant spraying and its environmental consequences. Turns out the loss of fishing is making them “rattlesnake-mad,” so they’ve been pushing state agencies to put down the Roundup spray wand and walk away. A petition they launched called “Stop the State-sanctioned Poisoning of Our Lakes and Rivers!” has attracted more than 178,000 signatures.

A spokesman for the South Florida Water Management District, Sean Cooley, said they’ve listened to the public outcry.

“Overall, the agency is committed to reducing its herbicide use and utilizes other methods to control harmful invasives like prescribed burns, biocontrols (bugs and fish that remove harmful invasives without ecological damage), and mechanical removal,” he told me in an email.

In 2019, the FWC called a halt to its herbicide spraying for several months, but a year ago the agency started it up again, Gray said. During the shutdown, according to FWC spokeswoman Carli Segelson, the agency held a series of public workshops on its spraying practices, speeded up its efforts to write specific management plans for each lake the state maintains, explored using mechanical means to harvest invasive plants, and worked on improving the timing of their spraying.

“Glyphosate is not the herbicide most commonly used in our aquatic plant management program,” she said in an email.

Caloosahatchee River. Credit: Wikipedia.

I talked to John Cassani, a fisheries biologist who heads the Calusa Waterkeeper organization, which advocates for protecting the Caloosahatchee River, Lake Okeechobee, Estero Bay, and Charlotte Harbor from pollutants like glyphosate. Instead of blaming the state agencies for using so much of Bayer’s product, he pointed the finger at the U.S. Environmental Protection Agency.

The EPA initially labeled Roundup a cancer-causing chemical in 1985, but then, during the Reagan administration, flip-flopped. In spite of all the lawsuits, the EPA still labels it as safe to use and does not regulate purchases.

“The EPA label is the law,” he said. “That’s what controls usage. Until that changes, I don’t see usage going down.”

I wonder sometimes what would happen if one of those stinky early settlers traveled through time to visit our modern Florida. As the settler looked around at what we’ve done to the place, he or she would surely notice there are far fewer fish, frogs, and manatees now.

But hey, don’t our lawns and golf courses look pretty? And you can drive your motorboat through the canal without worrying about the motor getting hung up in the hydrilla. Surely that’s worth a few sick sea cows.

I think that’s when the settler would crack a whip over our heads and shout something a lot nastier than “Rawhide!”

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Craig Pittman
Craig Pittman

Craig Pittman is a native Floridian. In 30 years at the Tampa Bay Times, he won numerous state and national awards for his environmental reporting. He is the author of six books. In 2020 the Florida Heritage Book Festival named him a Florida Literary Legend. Craig is co-host of the "Welcome to Florida" podcast. He lives in St. Petersburg with his wife and children.