Chemical Sensitivity

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One such fact, Miller explains, is this: Over the past century, the United States has undergone a chemical revolution. “Fossil fuels, coal, oil, natural gas, their combustion products, and then their synthetic chemical derivatives are mostly new since World War II,” she says. “Plasticizers, forever chemicals, you name it: These are all foreign chemicals.” They’re everywhere you look, in homes and offices, parks and schools. They’re also, Miller believes, making people very sick.

In 1997, Miller proposed a career-defining theory of how people succumb to this condition. It came with a technical-sounding name, toxicant-induced loss of tolerance, and a convenient acronym, TILT. You can lose tolerance after one severe exposure, Miller says, or after a series of smaller exposures over time. In either case, a switch is flipped: Suddenly, people are triggered by even tiny amounts of everyday substances—cigarette smoke, antibiotics, gas from their stoves—that never bothered them before. These people become, in a word, TILT-ed. It’s not unlike developing an allergy, when the body labels a substance as dangerous and then reacts accordingly.

In 1999, Miller and her colleagues designed the Quick Environmental Exposure and Sensitivity Inventory, or QEESI (pronounced “queasy”), a survey to help doctors and researchers identify chemically intolerant patients. I’ve seen the QEESI cited in papers from 18 countries, but to date, most physicians still don’t know much about it. “It’s very frustrating to try to get these ideas across,” Miller says. The major problem is that, assuming TILT accurately describes the process of becoming chemically intolerant, we don’t know what biological changes occur inside the sensitized body, why so many symptoms crop up, or why one exposed person gets sick while others seem to walk away unscathed. But Miller thinks she’s closer than ever to an answer.