MELBOURNE, Fla. — As a kid growing up in Montgomery, Alabama, in the 1960s, Melanie Oliver used to love riding her banana-seat bike behind the mosquito truck.
Mosquito-control districts regularly sent the trucks, nicknamed foggers, through neighborhoods and public places beginning in the late 1940s, spraying the pesticide DDT to ward off mosquitos and the threat of disease. A swarm of kids often followed behind, playing in the chemical-smelling fog. It offered cool relief on hot, humid evenings.
Starting in her 20s, Melanie again found herself immersed in pesticides, this time for her professional job at Disney World in Orlando. As a gardener at Epcot, her duties consisted of ensuring every plant was picture-perfect, every day. That meant clocking in at 4 a.m., kneeling in the dirt beds in the pavilions surrounding Epcot’s landmark silver dome and inspecting every flower petal and plant leaf for signs of wilting or browning. If she saw any blemished bloom, her job was to rip the plant out and replace it.
That was easy enough, with thousands of plants to choose from in eight separate greenhouses.
Entering the sprawling, 40-by-50-foot greenhouses during the 1980s and ‘90s, she never thought twice about grabbing a plant soaked in water and pesticides. The damp, wet feeling on her skin was just part of the job.
She spent hours in those greenhouses. Back in the park, she also found herself frequently in the path of pest-control workers who whizzed by fogging the grounds for mosquitoes before guests arrived.
“They didn't stop spraying when they came near you,” she said.
And while Oliver spent years worrying about the health of the flowers, she never worried about her own occupational health and safety.
That was, until she was diagnosed with early-onset Parkinson’s disease at 34 years old. The average age of onset is 70.
As one of more than 1 million North Americans now living with the disease, Melanie is part of what some neurologists describe as a pandemic of Parkinson’s, the world’s fastest-growing neurological disorder.
“Pan means all, and demos means people,” said Melanie’s neurologist Dr. Michael Okun, director of the University of Florida’s Normal Fixel Institute for Neurological Diseases. “You have something that's across all continents, that's growing in a large space and the growth is explosive.”
Okun and other neurologists and researchers increasingly attribute that explosive growth to chemical exposure. Over a lifetime, that could mean exposure to pesticides as a child; working in farming or landscaping; breathing air pollution; living near a Superfund site; handling toxic chemicals in the military; or other known risks.
“Now, all of a sudden, these degenerative diseases are going up, and now Parkinson's is growing faster than Alzheimer's disease,” Okun said. “What changed? What is it that we may have put into our environment?”
‘The shaking palsy’
At the turn of the 19th century, London roared with the Industrial Revolution. Factories popped up on every block and the city’s population surged. Everyone wanted to live in London.
But while the city was thriving on industrialization, it was also growing dirtier. Thick clouds of coal smoke poured from chimneys and factories, polluting the air. It became so densely saturated, Londoners later coined the term “smog” to describe it.
Through the fog, a local doctor named James Parkinson noticed a pattern of older men and women slowly shuffling along the cobbled streets with stooped posture and tremors. Some he saw from a distance. Some he questioned in depth.
He concluded it was an undiscovered disease caused by something in the brain. He called it “the shaking palsy.”
It is now recognized as Parkinson’s disease.
Researchers today know the disease can originate in the nose or the gut — like something breathed in or ingested. They credit Parkinson as one of the first doctors to notice the links between the environment and the disease named for him, even if he didn’t know it at the time.
In fact, neurologists and researchers conclude that most cases of Parkinson’s disease are caused by external factors. Only about 15% of cases are linked to genetics, according to a study conducted in 2021.
The other 85%, they believe, likely involve environmental exposures like London’s dirty air in the 1800s.
According to Brian Copeland, an associate professor of clinical neurology at Louisiana State University, in the era of modern pollution control, chemical exposures are still too frequent.
“They’re everywhere in our environment,” he said.
Tracking a lifetime of exposure
Disney World recruited Melanie fresh out of high school. After a few training classes at the local community college, she spent her first three years working for the resort as a monorail operator, driving guests to and from its hotels in her white go-go boots, neon vest and hard hat — what her husband, Tom, calls her ‘60s sci-fi jumpsuit.
She was eventually promoted to work as a gardener in Disney’s Polynesian Village Resort, tending to the lobby’s lush rainforest then filled with native-Hawaiian plants. But of her almost three decades at Disney, she spent most of her time uprooting and removing the imperfect plants in the pavilions around Epcot.
Some time into her career, she started noticing signs posted outside the greenhouses warning employees not to enter at certain times. Her supervisors said doing so could be dangerous.
But most everyone—including her—disregarded it and went in anyway to grab the plants they needed for their jobs. None of them used protection. No gloves, no goggles, nothing.
“What’s the worst that could happen?” Melanie thought to herself.
“We went in there anyway because we didn't think we were gonna get Parkinson’s,” she said.
Melanie doesn’t remember what prompted the signs. But in 1988, the Florida Department of Environmental Regulation–precursor to today’s Department of Environmental Protection–fined Disney World $150,000 for hazardous waste violations that included mishandled pesticides.
News articles from that year describe several steel, rusty drums of unlabeled hazardous waste and pesticides lying on their sides, abandoned or leaking in multiple pavilions around Epcot.
“This site is completely out of control,” said a DER inspector quoted by the Orlando Sentinel.
The agency ordered Disney to begin clearly labeling its thousands of gallons of paint, chemicals and pesticides, according to a consent order, and to establish a training program so employees would know how to handle hazardous waste.
All the horticulture products Disney’s crews use meet state regulatory requirements and are subject to safety evaluations and oversight.
Melanie was diagnosed with Parkinson’s two years after the fine, representing a growing number of people worldwide who developed the disease before turning 50. She said no one in her family had ever been diagnosed with the disease.
“It should catch the attention of people, this idea that young people are getting Parkinson disease,” Okun said. “If they don't have a gene and they're young and they're getting Parkinson's, why?”
Melanie’s story also raises a question neurologists and researchers have tried to answer for decades.
How much exposure is too much?
DDT trucks, Disney foggers and handling pesticides could all have been contributing factors for Melanie. One exposure could have had more of an effect than another.
“We don't completely understand that,” Okun said. “We don't understand why some people get the same exposure and don't get the disease, and other people get the exposure and get the disease.”
What experts do know, though, is that certain occupations carry more risk than others.
That includes farmers and agricultural workers who were exposed to pesticides while spraying their crops along with military veterans who never imagined that serving their country came with the risk of Parkinson’s disease.
On the front lines of risk
Kevin McNease spent some of his best years as a young rescue swimmer flying around the world in his grey Navy helicopter.
He was constantly on the lookout for any drowning victims or sinking pilots and would hoist them up into the air if he found one. He did that for 18 of his 20 years in the Navy, racking up over 4,000 hours of flight time.
In 1990, he was on a more notable mission in the Persian Gulf about a month after the U.S. expelled Iraqi forces from Kuwait following Saddam Hussein’s invasion. That mission is known as Operation Desert Storm.
As their last retreating act, Hussein’s soldiers blew up some 700 Kuwaiti oil wells, painting the sky black with smoke and igniting unchecked fires that burned for 10 months.
That same smoke drifted across the gulf where Kevin was stationed for three months. The sky was just one, constant, black cloud, he said. He breathed it in constantly.
“I was sick as a dog every day of the month for three months,” he said. “I got out of that and never gave it a second thought.”
That was until about four years ago when he saw his Garmin fitness watch telling him his running pace was getting slower. His VO4 numbers, the amount of oxygen his body could hold, were getting smaller.
Kevin had always been a hard-core triathlete. As a rescue swimmer, he had to be.
In his 40s and 50s, he completed in three Ironman races, so to him, his body slowing down was just a sign to train harder.
“I thought, well, maybe I'm just getting old,” he said. “I must be lazy.”
He was wrong.
Kevin, now 67, was diagnosed with Parkinson’s about two and a half years ago and attributes his diagnosis with his polluted three-month post in the Persian Gulf.
Other unsuspecting veterans have lasting impacts from various environmental exposures during service, too, including chemicals like TCE, PCE and Agent Orange. All were used during wartime or on army bases.
In one of the heaviest contaminations of TCE and PCE documented, thousands of soldiers and their families were exposed to the solvents at North Carolina’s Camp Lejeune from 1953 to 1987. Historically used in dry cleaning or to degrease metal parts, the chemicals leaked into the base’s wells, poisoning the drinking water.
While Agent Orange was banned in 1971, the EPA didn’t issue a rule to ban the use of all TCE and most use of PCE until Dec. 2024. It still hasn’t gone into effect.
“TCE unfortunately is a very volatile chemical and so it ends up in the air and then you're just breathing it in and it's used in so many different applications,” said Dr. Sneha Mantri, a neurologist and movement-disorder specialist at Duke University who serves as Chief Medical Officer at the Parkinson’s Foundation.
Agent Orange showed the world that chemical exposure could be a precipitating factor to Parkinson’s Disease in veterans, Mantri said. Now, researchers have an obligation to veterans and others to understand other chemical compounds that increase risk and make sure they are protected.
Living with what’s left
Melanie first noticed a symptom of Parkinson’s disease when she was 32 and reading the newspaper. Her fingers trembled when she went to turn the page. She ignored it.
The second sign came during Jazzercise. An instructor told her to push her arms out as part of an exercise. She raised her right arm just fine, but her left wouldn’t budge. Only then did she realize that her symptoms might be something bigger.
After visiting multiple doctors for two years, including one who misdiagnosed her with an autoimmune disease, she finally had an answer: Parkinson’s.
By that point she was just relieved to know what was wrong. She didn’t know much about the disease. No one in her family had ever had it, so she gave little thought as to how it would affect her life going forward.
She continued to work at Disney for 10 years after her diagnosis, during which she was promoted to the lead manager where she oversaw a team of other gardeners. For her 25-year mark, park executives honored her with a banquet and gave her a bronze Tinkerbell statue. It now sits in a dark, wooden case in the foyer of her home alongside two others recognizing her work at Disney.
In 2001, she left to take care of her mother who had been diagnosed with cancer. While that was her deciding factor to retire, she was already seeing more frequent Parkinson’s symptoms—especially when she was driving her Disney-issued semi truck and struggled to push the gas pedal down with her foot as she drove plants around the park.
So, she told her supervisor of her Parkinson’s diagnosis, filed for disability benefits and "retired" from Disney World at just 45 years old.
Now 69, she lives in Melbourne with her husband Tom. The two never had children; one of her Parkinson’s drugs posed fetal risk.
She rarely goes out—partly because the Florida Department of Highway Safety and Motor Vehicles took away her license a few years ago.
Instead, she spends her days inside playing solitaire and assembling puzzles. She used to be an avid reader, but Parkinson’s has negatively affected her eyesight, too. When it comes time for her doctor’s visits, Tom drives her the two and a half hours to the University of Florida in Gainesville. She’s been seeing Dr. Okun for over 20 years now.
Okun is a modern James Parkinson, feeling for his patients and observing what else they have in common—chemical exposure now not only in the air, but in water, soil and food.
“Diseases have causes, and so the question is, what are the core causes that can set off Parkinson? Where does it start?” Okun said.
“When we find the root causes, that’s how we can prevent diseases and also develop treatments.”
This story is part of Poisoned Pathways, an investigation into chemical exposure and Parkinson’s disease supported by the Pulitzer Center and reported by the WUFT Environment & Ag Desk at the UF College of Journalism and Communications.
