Goldman along with his colleagues identified six specific solvents previously suspected to be related to the development of Parkinson's, two of which were TCE and PERC.
Researchers then reached out to 99 all-male pairs of twins, each composed of one twin with Parkinson's and one without. The test subjects were all male as they were part of the National Academy of Sciences/National Research Council World War II Veteran Twins Registry that was founded in the 1960s using military records.
The medical team then interviewed the twins using detailed job-specific questionnaires to gauge the likelihood of each person being exposed to the predetermined solvents.
"We designed these extremely detailed interviews so that we didn't have to rely on the memory or the knowledge of the respondent," Goldman explains.