Why you should care
Because how something smells might profoundly affect your health: A recent study links mold compounds to Parkinson’s disease.
Joan Bennett, an expert in mold toxins, didn’t believe that mold in homes could make people sick. She had even testified in support of insurance companies fighting “sick building syndrome” (SBS) claims. Symptoms of the syndrome could range from skin irritation to nausea — symptoms which disappeared upon exiting the building. Some people claimed that inhaling moldy air caused their SBS, but Bennett argued that it was impossible to breathe in enough mold toxins to cause any of these effects.
But then Hurricane Katrina flooded her New Orleans home in 2005, forcing her to evacuate. She returned five weeks later and was horrified. A swarm of fuzzy green patches had engulfed everything from her prized physics books to the Turkish rugs she had bought on her honeymoon. And it smelled awful . Even wearing a mask and gloves, she still felt dizzy and nauseated. Her head throbbed. But like any good scientist, she seized the opportunity by snapping photos and swabbing samples of the mold onto petri dishes.
We started out looking at sick building syndrome. But we ended up with Parkinson’s.
“I literally had a conversion experience,” Bennett said. Her gut told her the odor permeating her home was to blame. Maybe moldy homes could make people sick — only it wasn’t because of the fungal toxins she’d studied throughout her career, but the so-called microbial volatile organic compounds (MVOCs) that give mold its rank, musty smell.
It would take eight more years to prove her intuition right: Last November, she and a postdoctoral researcher in her lab, Arati Inamdar, led a study published in the Proceedings of the National Academy of Sciences suggesting that a compound emitted by mold — known as mushroom alcohol — might contribute to Parkinson’s disease .
“I believe some people are being made sick by things in their environment,” Bennett said. “It’s a new era for humans. We used to spend most of our time outside. Now we spend 90 percent of our time indoors.”
Earlier studies linked MVOCs to asthma, allergies and other health problems — but not neurological conditions. Hurricane Katrina had caused massive power outages, and destroyed the frozen samples in Bennett’s lab at Tulane University where she’d studied the genetics of fungal toxins. So she had to start from scratch, opening a lab at Rutgers University to test her mold odor hypothesis, zeroing in on on the mushroom alcohol MVOC isolated from the mold in her home.
As the flies inhaled the mushroom alcohol, they displayed tremors, clumsiness, a slow gait…
Bennett, Inamdar and other scientists from Rutgers and Emory University ran experiments on fruit flies, simple animals frequently used in molecular biology research. The team enclosed them in vials containing cotton soaked in mushroom alcohol, wafting the aroma at a level comparable to a moldy building.
They noticed something strange. As the flies inhaled the mushroom alcohol, they displayed tremors, clumsiness, a slow gait — much like people with Parkinson’s disease. When they examined the flies’ brains under a microscope, they found that flies exposed to mushroom alcohol had significantly fewer dopamine-producing nerve cells than unexposed controls — confirming that the compound had caused the fly equivalent of Parkinson’s disease.
Although the causes of Parkinson’s aren’t entirely clear, the way it manifests in the body is well understood; nerve cells that produce the neurotransmitter dopamine, located in a region of the brain known as the substantia nigra, die off as symptoms worsen. In humans, the substantia nigra is connected to parts of the brain that control movement, and dopamine helps control these circuits. As the dopamine-making cells die, movements become slow, uncoordinated and difficult.
Bennet’s findings raise the possibility that aromatherapy might actually hold some kernel of truth. “Maybe these traditional medicines like lavender and basil do soothe the brain,” she said.
A drug known as L-dopa — the raw material that the body uses to create dopamine — can restore the neurotransmitter and motor function in humans. So Bennett gave L-dopa to the tremor-ridden flies. Sure enough, their movements returned to normal.
As many as 10 million people worldwide have Parkinson’s disease. Around 15 percent of Parkinson’s patients have a parent, sibling or child with the disease, suggesting inheritability, but environmental factors might also play a role. A study published in the journal Neurology last year found that exposure to weed killer, solvents and pesticides increases Parkinson’s risk by as much as 80 percent. And a 2012 Annals of Neurology study reported that living in rural areas and farming can also boost Parkinson’s risk, presumably due to increased pesticide exposure — but rural environments also have lots of mold and mushroom growth, Bennett’s team noted in the study.
“We started out looking at sick building syndrome,” she said. “But we ended up with Parkinson’s. It was something we weren’t looking for.”
Oh, the Irony
Today, Bennett is applying for NIH funding to test whether her findings apply to mammals more closely related to humans, like mice. But there’s one problem. Even though she’s looking at Parkinson’s, her project’s focus on household mold might give the impression that it’s examining sick building syndrome. This could lower her funding chances, since the NIH still doubts that SBS exists; ironically, Bennett herself contributed to this doubt.
The WHO coined the term “sick building syndrome” in 1986, when it released a report estimating that up to 30 percent of new office buildings in Western countries had poor indoor air quality. A wide range of causes was proposed, yet researchers failed time and again to identify a cause. The variety of symptoms and lack of a clear cause made diagnosis extremely difficult, leading many scientists to conclude that SBS was “all in patients’ heads,” Bennett said. Since then, research on SBS has fallen by the wayside.
Bennett notes that SBS is still poorly defined. But her research has made her more open to the possibility that inhaling moldy air really can harm health. She recently met a 31-year-old woman who lived in a house overgrown with mold due to water damage after it was hosed down to put out a fire. Afterward, she menstruated nonstop for six months and eventually needed a hysterectomy. Others living in water-damaged homes have complained of a persistent sore throat and concentration problems.
“We’re going to keep at it,” Bennett says of her petition for NIH funding.
“If common environmental fungi or molds are further validated as producing toxins that contribute to Parkinson’s disease, this will have obvious public health implications,” said Joseph Heitman, a chair in Duke University’s department of molecular genetics and microbiology.
Bennett noted that the small, trace amounts of mold that people occasionally smell probably wouldn’t trigger neurological damage. It’s only when people are continually exposed to mold in humid, enclosed rooms, or after flooding or water damage.
She knows the mystery of smell’s health effects probably won’t be fully unraveled for a long time, especially now that her work has raised more questions than answers. “But I’m excited about the results,” Bennett said. “I hope other people will pick it up.”
Today, Bennett’s lab is using genetic models to better understand the mechanism behind mushroom alcohol’s effects. Inamdar says that the results are sure to intrigue others, too. “We’ve given the epidemiologists some new avenues to explore .”