Industrial Age Chemicals and Parkinson's Disease

Air date: Week of September 6, 1996

CURWOOD: One of the most touching moments of this summer's Olympic Games came when Mohammed Ali's trembling hand lit the Olympic torch. Many may have thought that the great boxing champion was shaking because he'd taken too many blows to his head. But like US Attorney General Janet Reno and hundreds of thousands of other Americans, Mohammed Ali suffers from Parkinson's Disease. It's a progressive brain disorder that causes violent tremors and the loss of the ability to control one's limbs. Medicine can't say for certain what causes Parkinson's, but as Living on Earth's Daniel Grossman discovered, there is a growing consensus that at least some of the blame lies with industrial age chemicals.

(Footfalls, water from a shower)

BELLIVEAU: As you can see I have one of these special showers.

GROSSMAN: Fred Belliveau is a sick man. But thinking back he has much to be thankful for. As an editor and author of medical books, he was well paid and respected, and he raised a family. But sitting in a darkened room overlooking Boston's Charles River, he says fate played tricks on him.

BELLIVEAU: I had a perfect kind of life, a good job, a nice family, and a house in the country, very nice house. So everything was kind of going my way. And then bam, right in the middle of everything, comes the shocking news.

GROSSMAN: He had Parkinson's Disease, an incurable brain disorder his doctor said would slowly but surely deny him control over his own body. Many sufferers walk with a shuffling gait, lose the ability to make facial expressions, or move their limbs with the jerky motions of a wind-up toy. Today, 17 years after he was diagnosed, Mr. Belliveau keeps his symptoms in check with medication. But even so, during this interview, his hands were in constant motion. His balding head rolled from side to side. He says at other times the illness becomes nearly unbearable.

BELLIVEAU: I get just kinetic, which means I start shaking and -- more than tremor. I can't pick up a book, for example. It would just -- I would shake violently and the book would go flying out of my hand. Of course you can figure the ramifications of that if you wanted to have dinner. You can't pick up a dish and have it go flying and your food go flying. That has happened to me.

GROSSMAN: About half a million mostly elderly Americans suffer from Parkinson's, including about one of every 50 people over the age of 60. Around the globe, millions are afflicted in a process well understood by medical researchers.

STANDAERT: Parkinson's is a disease where a very specific population of neurons have been lost.

GROSSMAN: Dr. David Standaert is a neurologist at Massachusetts General Hospital.

STANDAERT: These are neurons which make dopamine. But only those in the particular part of the brain which is involved in the control of movement are affected. These are in an area called the substantia nigra pars compacta, pars compacta meaning tightly packed. And what's tightly packed there are a cluster of cells which make dopamine and send projections up into the part of the brain known as the neostriatum, which has a very critical role in the regulation of movement.

GROSSMAN: Dr. Standaert says once scientists realized how the illness works they came up with drugs to help the brain overcome the loss of dopamine, the most effective being L-dopa. But science has been less helpful explaining why the brain cells die in the first place. That's left Fred Belliveau and others like him groping for answers.

BELLIVEAU: It's -- it's tough going. It is tough going. As much as you want to be upbeat and you can't always do it, you simply can't -- and then I think all of us have a tendency to say why me?

GROSSMAN: Mr. Belliveau's doctors have told him what doesn't cause the disease. It's not a viral or bacterial infection and it doesn't generally run in families. So far they're less certain what does cause it. But Dr. William Langston, President of California's Parkinson Institute, says he thinks the culprit may be a synthetic chemical. A conjecture supported, he says, by the great works of literature.

LANGSTON: Now, with many neurological diseases such as seizures and stroke, you can find writings in the very early literature, Biblical writings, the Greeks, where clearly that disease existed centuries if not much longer ago than that. With Parkinson's the first clear-cut, unequivocal description of that disease is actually James Parkinson's description in 1817, and it raises the very interesting question, because that's around the time of the Industrial Revolution: could it be a true manmade disease? A disease that was the result of something we introduced into our environment?

GROSSMAN: The Industrial Revolution was fueled by coal, which releases innumerable toxic byproducts when burned. Dr. Langston says this and other staples of the machine age, like the neurotoxic metals lead and mercury, are all suspect. The toxic compound theory got a major boost in 1983 when Dr. Langston solved a bizarre medical mystery. It began when a handful of young heroin addicts with unusual symptoms appeared in California hospitals.

LANGSTON: And when they came into the emergency rooms here in northern California, they looked for all the world like they had developed instant Parkinson's Disease, yet they weren't old and this had come on rapidly.

GROSSMAN: A team of scientists led by Dr. Langston discovered the drug users had all injected a designer drug made by underground chemists intended to mimic the properties of heroin.

LANGSTON: And it turned out by accident instead of making a heroin-like compound, they made probably one of the most selective brain toxins ever, ever known.

GROSSMAN: The toxin was called MPTP, a particularly nasty member of the common pyridine class of industrial chemicals. Further research confirmed the compound not only brought on the symptoms of Parkinson's Disease but struck the same area of the brain. Today more than a decade later, these addicts still suffer from the symptoms of Parkinson's. Dr. Langston says it was a tragedy for the drug users but a boon for medicine.

LANGSTON: And the immediate question everyone asked was my gosh, if a simple chemical in this heroin can cause Parkinson's, could there be something in the environment that also causes Parkinson's?

GROSSMAN: Researchers began searching for a previously undetected source of exposure to the chemical or a close relative. They found 2 that were in common use: the pesticides rotenone and paraquat. But neither could be linked to Parkinson's. Still, pesticides in general remain a source of concern. Many are neurotoxic by design, and exposure to them is widespread. Parkinson's sufferer Fred Belliveau used to spray pesticides on a small orchard at his country home.

BELLIVEAU: I'm sure that it was not good to do this, but I was not knowledgeable enough to protect myself accordingly, and I frequently would wear shorts and no shirt. And I would get up there with my little tank and I would spray around on these trees. So I'd get this solution on me and I did that many, many years, and of course I don't know what effect that could possibly have had.

GROSSMAN: But he does wonder if it played a role in his illness. Researchers have tested scores of pesticides and other chemicals, so far to no avail. Dr. Langston of the Parkinson's Institute now believes he knows why the search has proved fruitless. He thinks the disease may be caused by 2 or more separate factors operating together; for instance, a toxic agent might only strike individuals with the genetic inability to protect themselves. To overcome all these complexities, researchers are turning to epidemiology, the branch of science that tries to determine the cause of a disease from who it strikes.

(Woman: "Okay. Sit in the chair here." Scraping sounds.)

GROSSMAN: Kathy Taylor, a researcher at Boston University, sits across a table from Stanley Wirthheimer, a tan, muscular man. He's one of nearly 300 volunteers involved in an epidemiology study at BU's Department of Neurology. Half of them suffer from Parkinson's Disease. At 61, he's been living with the illness for about a decade.

TAYLOR: So as I explained to you over the phone what this is about is, it's a study designed to look at what might be causing Parkinson's Disease.

WIRTHHEIMER: Yes.

GROSSMAN: For more than hour, Kathy Taylor carefully notes down the most minute details of the subject's medical history and that of his family. She also asks him to list everywhere he's ever lived and worked.

WIRTHHEIMER: I started working when I was 13, for my uncle, oh, 10, 15 hours a week. We made what are called solder rings.

GROSSMAN: Later this year a statistician will electronically shuffle the thousands of facts Ms. Taylor has collected from Stanley Wirthheimer and the other subjects.

WIRTHHEIMER: I made many millions of these.

TAYLOR: Mm hm.

WIRTHHEIMER: That's lead.

TAYLOR: And what -- lead, okay.

WIRTHHEIMER: Lead and tin.

GROSSMAN: Many other epidemiological studies have already drawn relationships between Parkinson's Disease and exposure to industrial or agricultural chemicals. For instance, research in the US and Canada has uncovered 2 intriguing correlations. People who live in agricultural regions where pesticides are used, or who drink water from shallow wells which are often polluted with chemical runoff, are more likely to be afflicted with the illness than city dwellers and customers of cleaner public water supplies. Studies abroad like one in China by Dr. Carolyn Tanner of the Parkinson's Institute also link the disease to exposure to synthetic chemicals.

TANNER: People who had worked in settings where they had exposure to chemicals, working in chemical plants or in industrial settings, had a higher risk of getting Parkinson's Disease than people who did not. And it was about, between a 2- and 3-fold increase.

GROSSMAN: Dr. Tanner says the evidence that some environmental toxin or toxins play a role in causing Parkinson's is nearly unassailable. It's a conclusion that doesn't surprise University of Missouri biologist Fred Vom Saal. He's recently been involved in some groundbreaking research studying the effects of chemicals on other parts of the body and the brain.

VOM SAAL: We already know that there are environmental chemicals that can damage brain development and lead to permanent changes in the functioning of the brain systems that in fact are involved in certain types of human diseases.

GROSSMAN: Dr. Vom Saal is referring to hormone disrupters. Synthetic chemicals like dioxin and PCBs that can upset the development and growth of humans and animals. Recent research including a study of the children of women who consumed contaminated fish from the Great Lakes show these chemicals can cause behavioral abnormalities like reduced intelligence and increased aggression. Dr. Vom Saal wonders if the same poisons might cause Parkinson's Disease as well.

VOM SAAL: The interesting thing we know about these chemicals is that they can interfere with thyroid hormone, which is a major regulator of brain development. And one of the consequences of this is you also have abnormal dopamine levels. Which is exactly what you see later on in life in Parkinson's Disease.

GROSSMAN: Disrupting the thyroid is only one of many ways these chemicals might be implicated in Parkinson's. Researchers at New York State's Department of Public Health recently discovered that rats fed certain PCBs exhibit dramatic dopamine reductions in the same part of the brain, the substantia nigra, as people with Parkinson's. And Dr. Richard Seegal, who directed the research, says recent other new findings make him wonder if the effect is multiplied if more than one chemical is involved. Scientists at Tulane University announced last spring that a mixture of pesticides subjected to cells in the laboratory are hundreds of times more toxic than any one acting alone. Dr. Segal says the research is a call to arms. If a similar, synergistic mechanism is at work in Parkinson's Disease, that may explain why researchers who have been testing compounds one at a time have been stymied for so long.

(Pills spilling)

BELLIVEAU: Lots of pills in this business.

GROSSMAN: Like most people, Fred Belliveau was exposed to many synthetic chemicals in his life. Experts estimate about 70,000 different synthetic compounds are sold in the US. Sitting in his Boston apartment holding a handful of tablets, he says he doubts he'll live to learn which if any chemicals caused his ailment.

BELLIVEAU: I've been asked in the past on various surveys, were you ever exposed to or around insecticides? Another question that was asked is, did your drinking water come from a dug well, and ours did. I mean there are so many exposures that one has in life, whether those 2 things or other things played a part I simply don't know. I don't know.

GROSSMAN: No matter what the answer, it's too late to make a difference for George Belliveau. So he focuses on how to cope with his condition, not what caused it. But if the research underway in search of a specific pollutant or pollutants is successful, if the quest for the cause of Parkinson's bears fruit, ways could be found to prevent others from being stricken with this crippling illness. For Living on Earth I'm Daniel Grossman.