Hurricane Katrina’s smelly mold linked to Parkinson’s disease

After Hurricane Katrina devastated New Orleans, toxic molds infested residents’ houses. A decade on, we talk with a fungal geneticist about the mold's connection with Parkinson's disease.

Joan W. Bennett  sampled the fungi growing in her home and linked their natural chemical odors with symptoms of Parkinson's disease in a genetic model. Bennett shares her research – and the sight and smell of her house that lead to her discovery – in vivid detail.

RG: In Silver linings: a personal memoir about Hurricane Katrina and fungal volatiles, you wrote Hurricane Katrina transformed your life. How so?

JB: I’m a specialist in toxic mold and before the hurricane hit I’d spent my life studying how agricultural molds contaminate food supplies. That meant my concerns about the flood waters were unlike most people: Some worried about heavy metal poisoning, others cholera, but I was very aware that there’d be fungus everywhere when the flood waters receded.

I’m still surprised it didn’t receive more attention from the scientific community. The city was rife with mold; everything organic decayed. A few people did some very superficial spore counts and they were off the scale, but at the time almost no one studied it because the focus was elsewhere. So I did my own study. And that ties into what’s probably the most direct way my life changed – geographically. During the post-Katrina evacuation I accepted the offer to work as a professor at Rutgers University, New Jersey – first on a sabbatical and then full time. It’s here at Rutgers that I studied the mold that grew in the aftermath of Katrina.

RG: You reported significant findings from this research – can you describe them here?

JB: We used genetic models on mold’s volatile organic compounds (VOC) to cause symptoms of Parkinson's disease in fruit flies. VOCs are natural odor chemicals fungi release into the surrounding air. Using fruit flies, we found a VOC popularly known as mushroom alcohol affected two genes involved in handling and transporting dopamine. Parkinson’s is associated with dopamine deficiency, so by showing the compounds can potentially cause defects in some of these genes, we could show they may also cause Parkinson’s symptoms. It’s obviously a long leap from fruit flies to human beings. However, certain pesticides are correlated with higher rates of Parkinson’s disease. Our compounds were giving results very similar to what pesticides do in fruit flies.

Some students in my lab have also shown molecules from one genus of fungi can make tomatoes grow better, faster, and bigger.

RG: What caused you to study fungal VOCs? Was this your initial intention?

JB: Initially I had some fantasy that I was going to discover a new mold from Hurricane Katrina. I even had a name for it: Aspergillus Katriniantus! But we soon realized that wasn’t the case and changed focus. It was the smell of the fungi in my house that tipped me off on the idea –the fumes left a big impression on me. It’s hard to describe: it was a very overpowering unpleasant odor. Sometimes when a smell gets concentrated it doesn’t really smell like the thing it’s thought to be, so in that sense it didn’t smell like moldy basement or damp cave – it was more like a skunk.

It made me so uncomfortable that I was feeling sick with headaches and nausea, and my reaction was just to leave. But I had a mask and gloves on because I was determined to sample my house after the hurricane hit. I was partly taking my role as a scientist to calm myself - to deal with the fact I’d lost a lifetime of my possessions, my memories. When I left my house my suitcase was half-filled with clothes and half-filled with mold samples in petri dishes.

RG: So you’ve got a suitcase half full of petri dishes and you’re in the lab. How did you test the fungi?

JB: I’m a geneticist and so I believe in genetic models. We figured out ways to expose some famous genetic models (with a bit of fiddling) to growing the molds.  We used C. elegans, D. melanogaster and Arabidopsis thaliana.  To my knowledge no one else has ever done this. We saw the VOCs were showing differential toxicity effects to different molds, so we started analyzing and quantifying them to find out what kinds of volatiles were being made, and testing the most common ones.

RG: You’ve described the smell of your house after the hurricane hit, what about the sight?

JB: Fungi was growing everywhere and made all the surfaces fuzzy. When mold runs out of the early flush of nutrients they sporulate. Patches of green and light blue were all over the walls and carpet, just like on rotten fruit. My whole couch turned into a giant petri dish. Since mold has different colors I guess on some abstract level you could say it was attractive, but not when it’s happening to your house.

I found looking at my collection of books the worst of all. There was just no hope of saving them. They were water saturated. Mold was growing on the binding and on the top of the paper. They all had to be thrown away.


RG: Could these fungi and their VOCs still be prevalent in New Orleans’ houses?

JB: Louisiana is a wet humid place. All around the world people live in these sub-tropical environments and they’re exposed to a lot of mold metabolism. In toxicology there’s a saying: the dose makes the poison. Almost all compounds can become toxic at some dose, but I don’t think low concentrations of these mold VOCs are necessarily detrimental. When the flood hit the molds got out of control, and it’s these extremely high concentrations of the VOCs that are potentially problematic.

In saying that, I think nowadays we’re much more likely to be exposed to these compounds and their unusual effects. In the old days buildings were drafty and in sub-tropical environments windows and doors were kept open to attract a breeze, so there was a lot of air dilution. Our modern building practices have air tight windows and air conditioning. It’s a lot more comfortable but allows a new indoor environment to be made: the compounds can build into higher concentrations.

RG: Does this tie into building-related illnesses?

JB: Yes - in recent years a lot of people in the United States have claimed certain buildings make them ill. One popular theory links it to the mold (and their mycotoxins) and other microbes growing indoors. I don’t believe it’s possible to breathe in enough fungal spores to be exposed to the amount of toxins that would cause these symptoms. But I did know of work that connected this illness with fungal VOCs, and smelling my house after the hurricane was my ‘conversion experience.’

More biologists ought to be looking at gas phase compounds because I’m quite certain we’ll find a lot of unexpected effects that we’ve been ignoring.  A lot is going on there, I guarantee it.

(l. to r.) Joan W. Bennett (Associate V.P., WISEM) and Natalie Batmanian (Associate Director, WISEM)
Joan W. Bennett

RG: Has there been an increase in Parkinson’s disease cases since the Hurricane?

JB: I have thought about analyzing whether there’s an increase in Parkinson’s disease cases in New Orleans but it’s near impossible. It’s is a more affluent city than it was before, and so you’re not comparing the same kind of population. It would be very, very difficult to do a good epidemiology.

RG: How are you developing your work into the fungal VOCs now?

JB: I’m not. Unfortunately I haven’t been able to get funding to take the Parkinson’s disease research to the next step. I’ve applied several times but the reviewers’ answer is the same: I’m not a neurobiologist. And it’s true. While I’m disappointed, we have got funding from the Department of Agriculture to develop the effects of VOCs on plants. I consider the Parkinson’s work more important, but as a scientist you do what you can.

RG: You’ve done a lot of work for women in science. What has this involved and how has the situation improved during your career?

JB: My work in this area and the hurricane are intertwined because my Rutgers University job offer was to both become a professor and start an office for women in science. I’ve been working here at Rutgers and nationally to try and make things better for women. We’ve developed mentoring programs and run a leadership course at Rutgers. We offer women the tools and knowledge they need to enhance their likelihood of career success – like negotiation skills and lecturing styles. It’s definitely a lot better to be a women in science now than when I entered the field. It’s not where I’d thought it would be, but I’m optimistic a greater positive change is still to come.

Featured photograph courtesy of michaël stone; photo of wall destroyed by mold courtesy of melanie innis; photo of Joan W. Bennett courtesy of SciWomen2006