Biologist Sees Environmental Link To Cancer
Her first memory was of riding her tricycle on the patio and looking down into the river valley to watch tugboats pushing barges as big as football fields.
Sounds idyllic, doesn’t it?
Steingraber developed bladder cancer in her twenties and now believes it had a lot to do with the environment in which she grew up.
She had an aunt who died of the same kind of bladder cancer, she told a full house at the Aquinas College Wege Student Center ballroom where she recently discussed “The Myth of Living Safely in a Toxic World.”
Her mother was in treatment for breast cancer at the same time she was in treatment for bladder cancer. Two of her uncles have colon cancer. She recently lost another uncle to prostate cancer. An aunt and uncle recently died of leukemia, and a third relative was just diagnosed with the disease.
“There is a lot of cancer that runs in my family, but this is the punch line for my story: I’m adopted.”
As a biologist, that got Steingraber thinking about what else family members have in common besides their genetics. They share living quarters, work places, drinking water, the same food and the same air, she said.
“My life as a cancer survivor and my identity as an adopted person drove my scientific interest.”
She recalled spending a lot of time in the Harvard medical library looking at the evidence for the link between cancer and the environment. She went back to her hometown and spent a year as an “environmental detective,” backed by right-to-know laws, Freedom of Information Act queries and national and state cancer registry data.
“Going back to my high school, it turns out there was a pesticide factory right next door that formulates pesticides that are banned in this country but shipped abroad.
“The law that prohibits use of those chemicals in this country does not prohibit their manufacture. I didn’t know in all the years I lived there that those chemicals were being formulated right next to the school.”
She tested the drinking water wells in town, which she found were contaminated with a chlorinated solvent often used by drycleaners to remove dirt and oils from textiles. People employed in the dry-cleaning industry, Steingraber noted, have higher rates of bladder cancer than the general population.
Though there are not a lot of drycleaners in her hometown, there are a number of machine shops that use the solvent to degrease metal parts, she said.
“When you’re all done, you have this greasy, oily solvent. A lot of times it would just get dumped out back of the shop. Like a falling curtain of chemicals, the solvent found it’s way through the soil and into the drinking water well.”
She also investigated a landfill 1.5 miles from her house. What she learned was that the everyday garbage that went into the landfill included hazardous waste imported from as far away as New Jersey and Pennsylvania. The businesses were paying to have their waste dumped in the landfill.
What did the results of her study suggest?
“Essentially I found that there is no one study that constitutes what we in the science community would call absolute proof. But what I did uncover were many well-designed, carefully constructed studies that all together tell a consistent story. When you start assembling the data together from many different studies a kind of startling picture emerges, and I became convinced that we ignore it at our peril.”
One line of evidence comes from cancer registry data. Registries measure the incidence of cancer in the population and each state keeps its own registry.
When the registries from all over the country are pooled together, Steingraber said, they show that non-tobacco related cancers are rising in incidence among all age groups, all ethnicities and both sexes.
“When I was born in 1959, one out of every four Americans could expect to get cancer sometime in their lifetime. Now it’s four in every 10.
“One out of every three women get cancer and one out of every two men get cancer. The reason we believe men have a higher incidence of cancer is the additional workplace exposures men receive in trades that historically have been closed to women. As those trades are open and more women enter those workplaces, we expect to see that gender gap close.”
Cancers for which there are no effective screening tools are accelerating at the quickest rate of all, including childhood cancers, she added. Statistics show that cancer among children, in fact, is rising more rapidly than cancer among adults.
“That’s an important statistic to keep in mind because kids — especially 2-, 3- and 4-year-old kids — don’t smoke, drink or hold stressful jobs, so all the usual reasons we use to explain cancer among adults doesn’t really count for the preschool set. The fact is that we have more 4-year-old girls with more brain tumors than ever before and more 2-year-olds with leukemia than ever before.”
Another line of evidence comes from computer mapping, which clearly shows that cancer is not a random tragedy, she said. Such maps use color-coding to identify the “hot spots” where different kinds of cancers are more predominant geographically.
There tend to be higher rates of breast, bladder and colon cancer, for instance, in parts of the United States that historically have been home to heavy industry. Non-Hodgkins lymphoma, on the other hand, is higher in the Midwest and Great Plains, where there is greater use of herbicides in agriculture.
There also are some “provocative links” between pesticides and certain kinds of physical malformations at birth, she noted, adding that children born to families that are employed in farming are at higher risk for birth defects than children living in rural areas whose families are not actively engaged in farming.
“Causation is not the same as correlation, yet we can’t ignore correlations because they are often clues for further inquiries. They are like little red flags.”
Overall, cancer rates are higher in U.S. counties that have contaminated ground water.
Steingraber said there is cancer registry data that has looked at all 500 counties across the United States that have their sole source of ground water contaminated by toxics.
People living in those counties have higher rates of certain kinds of cancers over and over again when compared to counties with similar socioeconomic and demographics but without contaminated water, she said.
A third line of evidence linking cancer and the environment comes from people’s own bodies.
“We know with certainty that a whole kaleidoscope of chemicals linked to cancer exists in all of us. (In) the most recent biological studies measuring everything from blood to urine, to fat tissue to breast milk, what has turned out is an average of about 200 different toxic chemicals inside the body of every human adult. What we don’t know with certainty is what the cumulative effect of all these multiple exposures is.”
More recently, Steingraber has been working in the area of gerontology and looking at how early exposure to certain toxic chemicals may predispose an individual to develop dementing diseases like Parkinson’s and Alzheimer’s later in life.