In the Silicon Valley town of Mountain View, Google sits right on top of one Superfund site. The cleanup of the area, which was polluted by previous occupants, is currently incomplete and will continue for many decades.48 In the meantime, residents, who own some of the most expensive real estate in the country, risk being exposed to TCE.
When one resident, Jane Horton, bought her house near Google’s current location, she had no idea what was in the ground.49 After learning that she lived across the street from a Superfund site, she had her indoor air tested and found that it was contaminated, as she wrote in a 2014 piece in The Guardian. She also discovered that a toxic plume of TCE ran right under her home.50 Even after 75% of the TCE was removed from the groundwater at the Superfund site, the chemical’s levels in Horton’s indoor air were still above the EPA’s safety threshold. Consequently, her home had to be “cut, butchered, vented and fanned with tubes and vents.”51
In 2002, a local newspaper, the Mountain View Voice, reported that six residents who lived on or around Walker Drive, a short street in Horton’s neighborhood, had been diagnosed with Parkinson’s disease.52 In addition, four others who lived nearby had brain tumors. (The EPA classifies TCE as a carcinogen.)53
Today, Horton lives in her same home, with her air-remediation system running twelve hours a day (Figure 3). It funnels TCE-contaminated air from under her house to above her house. She has her air tested through the EPA once or twice a year and says that her indoor “air is probably the cleanest in Mountain View.”
While she has little concern about her own air, Horton worries about the community. She says, “Who is benefiting from this contamination? Why can’t we just clean this up? …[It is] so frustrating that people’s lives are put at risk.”
Tainting up to 30% of US drinking water supplies, TCE is now the most common organic (i.e., carbon-containing) contaminant in groundwater in the United States.54 As of July 3, 2018, the EPA had 1,346 sites on its National Priorities List eligible for remediation and financing under the federal Superfund program.55 Of these, almost half are contaminated with TCE.56 The map in Figure 4 and the website www.endingPD.org show the locations of TCE-contaminated Superfund sites throughout the United States.
A LOCAL STORY
Superfund sites are only the beginning. Thousands of additional locations across the country are contaminated with the chemical. “Superfund sites are [only] a fraction” of the areas contaminated with TCE, according to Lenny Siegel, the former mayor of Mountain View and the executive director of the Center for Public Environmental Oversight.
The TCE leaching through the ground in Victor, New York, which is just fifteen minutes from the home of one of our authors, Ray Dorsey, is one example.57 In 1990, the New York State Department of Health began sampling small community water supplies across the state, including in Victor, which has a population of 14,000. The water supply for many of the residents came from a local spring that was found to be contaminated with TCE at levels more than twice what is considered safe.
The contamination may have begun ten years earlier and was traced to a local sand and gravel pit. Inspectors found a mile-long TCE plume emanating from the pit that has contaminated a handful of local private wells, increased TCE levels in the soil, and, in six nearby homes, raised the TCE levels in the air above safe levels.58
Jamie Myers (not her real name) is a fifty-one-year-old nurse who lives in Victor. Her house was supplied by the contaminated spring, and for ten years, four times a week, she used to jog up the steep incline to the TCE-laced gravel pit. In 2014, she noticed that she could no longer make it up the hill. She was later diagnosed with Parkinson’s.
Myers became aware of the history of TCE contamination in 2008, and she always suspected that her Parkinson’s might be due to environmental factors. She has no family history of the disease, eats a salad for lunch, and has been a lifelong runner. Today, she says, “I am frustrated because [the contamination] has become personal to me.”
Now that her home has an air-remediation system that moves TCE from under her house to a vent above, she is less worried about her three kids. Her water, like everyone else’s in Victor, now comes from a municipal source instead of a well. She says, “If I were worried about my kids, we’d get out right away.”
According to local reports, a 2009 cancer study in the area was “inconclusive” but did show an “unusual number of brain tumors.” The pattern is similar to what was found in Jane Horton’s Mountain View neighborhood.59 The cancer study did not asses the risk of Parkinson’s.
TCE contamination is not just a US problem. Global consumption of the chemical is projected to increase 2% annually. In China, where Parkinson’s rates are increasing most rapidly, use of the solvent is projected to increase 4% per year.60
Parts of Europe have banned TCE altogether.61 In late 2016 and early 2017, the EPA proposed banning its use for spot-cleaning in dry cleaning facilities and for commercial degreasing, such as cleaning motors. The agency had several health concerns, including the fact that TCE is “carcinogenic to humans by all routes of exposure” and that chronic exposure is harmful to the brain and nervous system.62
Industry groups sought to delay or prevent regulatory action.63 The National Cleaners Association, a dry cleaning trade group, has argued that alternatives to TCE are not as effective.64 The Association of Global Automakers said that the EPA did not follow sound economic principles in its analysis.65 Then, in late 2017, the EPA announced that it would postpone its proposed ban indefinitely.66
Those who have been and are being exposed to TCE are tired of waiting. Senator Tom Udall, whose uncle, Congressman Morris Udall, had Parkinson’s, is pressuring the EPA to ban TCE. In August 2018, he held a press conference with families. They shared stories of loved ones passing away from diseases that have been linked to the solvent and emphasized the need for swift action. EPA administrator Andrew Wheeler said, “Absolutely, we need to be moving forward to do something on TCE and these other chemicals.”67 As of July 2019, the EPA had yet to act.
HOPE FOR ENDING PARKINSON’S
Toward the end of his lecture on causation, Sir Austin Bradford Hill said, “In occupational medicine our object is usually to take action.”68 These actions can improve health.
The Netherlands is one of the few countries in the world where rates of Parkinson’s disease are actually waning.69 A 2016 study found that from 1990 to 2011, the number of new cases of the disease “decreased sharply.”70
The reason is not known for sure, but just as the skyrocketing rates of Parkinson’s tracked with industrialization, the disease’s auspicious fall follows the country’s efforts to clean up. The Netherlands, along with other European countries, was among the first to ban paraquat.71 Use of other pesticides linked to Parkinson’s decreased or stopped altogether. As a result, levels of DDT, dieldrin, and their metabolites in the fat, blood, and breast milk of Dutch citizens also went down. For example, from 1968 to 1986, fat levels of dieldrin decreased by about 75% and levels of DDT by 90%.72 The Netherlands also banned TCE, and in 1981 the TCE levels in the air were among the lowest in all of Europe.73 Air pollution in general—also linked to Parkinson’s—has also decreased substantially.74 From 1990 to 2012, emissions of multiple air pollutants decreased by 50% or more.75
Many degenerative and man-made diseases reflect the environment that our parents and grandparents created. Just as environmental contamination can worsen health and create disease, cleaning up the contamination can have the reverse effect. Enlightened by science, we now can rectify any prior shortcomings for ourselves and our descendants. But we, as Hill suggests, must act.