Doctors used to make house calls.
Today, a group of UT Health San Antonio researchers is pioneering the use of “environmental house calls” (EHCs) to help patients who suffer from chemical intolerance, which is often due to contaminated air in homes—air that may seem fine, but carries hidden molecules that can spur symptoms in susceptible people.
The new study on EHCs, led by Dr. Claudia Miller, allergist/immunologist, professor emeritus, and leader of the TILT Research Program at UT Health San Antonio, was recently published in the journal Primary Health Care Research & Development.
Past research has shown that indoor air pollutants are at concentrations up to 10 times greater than outdoor levels, with fragranced products like cleaning supplies and air fresheners often causing symptoms.
For the new study, researchers conducted five structured EHCs per home in 37 homes of patients in a university family medicine clinic who had high chemical intolerance scores—a total of 185 visits—to test whether EHCs can help people address their symptoms by making changes to their indoor air exposures.
Researchers collected samples of the homes’ indoor air, which were then analyzed for minute quantities of contaminants, at the nanogram per liter (ng/L) of air, levels that often would not be consciously detectable. The culprits causing symptoms included combustion byproducts from gas stoves and tobacco smoking, volatile and semi-volatile organic compounds (VOCs) present in disinfectants, pesticides, and fragrances, as well as chemicals off-gassing from new furnishings and construction materials.
Subsequently, the team met with the patients and their families to show them how to reduce exposures to chemicals in their indoor air.
“We show, by presenting three case studies, that home interventions can teach patients how to minimize indoor air exposures and thereby reduce their symptoms of chemical intolerance,” said Dr. Miller, corresponding author of the study.
A closer look at one of the environmental house calls in the new study
The study’s first case involved a 68-year-old woman, a house cleaner for 16 years.
She experienced worsening symptoms such as headaches, abdominal pain, fatigue, and cognitive problems after exposure to scented cleaners at work.
She also developed sensitivities to smoke and combustion products, leading to depression and irritability, ultimately forcing her to leave her job. In house calls, her home was found to contain multiple scented cleaning products, candles, and mothballs.
As part of the research team’s intervention, they created an action plan to reduce VOCs and eliminate mothballs. Follow-up visits included further air sampling and re-evaluating her symptoms, as well as a teaching session developed to provide families with information on reducing indoor air exposures.
The figures show the reduction in those levels following the EHC intervention.
GC/MS air VOC sampling results, pre and post-EHC intervention. Significant VOC reductions were achieved for personal care and alcohol products, fragrances (terpenes), paints and coatings, and mothballs and moth crystals.
Indoor air sampling pre- and post-EHC intervention showed a significant decrease in VOCs from mothballs, moth crystals, coatings, fragrances and odorants.
Her chemical intolerance symptoms were assessed using the internationally validated, 50-question diagnostic instrument called the QEESI—the Quick Environmental Exposure and Sensitivity Inventory. The analysis generated a QEESI Symptom Star, as seen below.
The QEESI Symptom Star showed significant pre- and post-EHC intervention improvements in head-related, cognitive, affective, neuromuscular, musculoskeletal, skin, gastrointestinal, and airways/mucous membrane symptoms.
Surveys have shown that chemical intolerance may affect 20-30% of the U.S. population, with many patients and their doctors not understanding why they feel sick or what they can do about it.
Where does chemical intolerance come from? What do we know about it today?
Chemical intolerance is now understood to stem from a condition known as Toxicant-Induced Loss of Tolerance, or TILT.
Dr. Miller, leader of the TILT Research Program at UT Health San Antonio, has been researching TILT since the mid-1990s, when she pioneered this emerging field.
TILT is a two-stage disease process characterized by an initial exposure event, which can be acute, repeated, or chronic. Examples of acute exposures include mold, implants, pesticides, military hazards, fires/combustion products, solvents, oil spills/fracking, and indoor air VOCs.
Dr. Miller has served as an expert medical consultant on Gulf War Syndrome, Breast Implant Illness, the World Trade Center’s 9/11 Registry, the EPA’s own “Sick Building,” exposures to pesticides, mold, and complex chemical combustion products such as the East Palestine, Ohio, train derailment and fire.
Once a toxic exposure has altered and sensitized an individual’s mast cells, the second stage of TILT called triggering begins. After that, exposure to molecular quantities of structurally unrelated substances can trigger multisystem symptoms. These triggers include formerly well-tolerated fragrances, traffic exhaust, caffeine, alcoholic beverages, foods, and medications. In some people TILT results in lifelong, debilitating symptoms, made worse by the fact that most medical and public health professionals do not yet recognize the condition.
Individuals suffering from TILT characteristically report a host of medically unexplained symptoms, including brain fog, chronic fatigue, gastrointestinal distress, headaches, respiratory problems, mood disorders, cognitive difficulties, and many more conditions too often dismissed as psychological in origin.
After many years of research, in 2021 Miller and colleagues identified mast cells as the biological mechanism behind TILT. Mast cells are the body’s first line of defense against foreign substances. They originate in the bone marrow but eventually migrate to the interface between all of our tissues and the external chemical environment. When they encounter a foreign invader, they can release hundreds or even thousands of inflammatory mediators in sub-second time, the best-known of which is histamine.
Our evolutionarily ancient mast cells first appeared more than 500 million years ago in early vertebrates. In contrast, exposures to fossil fuels (coal, natural gas, oil), and their combustion products began less than 300 years ago during the Industrial Revolution (1760-1840). Likewise, our exposures to synthetic derivatives of fossil fuels including endocrine disruptors, persistent organic pollutants, fragrances, many food additives, etc., began and have increased exponentially since WWII (1939-1945).
Learn more about TILT in this tutorial.
“Eliminating fragrances indoors is essential in schools, workplaces, homes, multifamily housing, etc. for optimal function. Not because these low levels are toxic but because so many people’s mast cells appear to have been altered epigenetically so that formerly tolerated substances (chemicals, foods, and drugs) sensitize mast cells—in the olfactory-limbic (nose to brain) pathway, digestive tract, skin, and elsewhere—and can be triggered by everyday cleaning, laundry, personal care, and other fragrance-containing products.”
What can you do to improve the air in your home?
Most of us spend most of our time indoors.
That is why there is rising demand for services like environmental house calls (EHCs) and eco-friendly real estate and building healthier homes.
Use the TILT Research Program’s guide, “7 Steps to Create a Clean Air Oasis,” to select the right cleaning materials and improve the air quality in your home.
“Choose a room where you spend the most time (often the bedroom) or transform your entire home,” Miller said.
How do you know if you have TILT and chemical intolerance?
Answer these three questions from the TILT Program on Chemical Intolerance:
- Do you feel sick when you are exposed to tobacco smoke, certain fragrances, nail polish/remover, engine exhaust, gasoline, air fresheners, pesticides, paint/thinner, fresh tar/asphalt, cleaning supplies, new carpet or furnishings? By sick, we mean: headache, difficulty thinking, difficulty breathing, weakness, dizziness, upset stomach, etc.
- Are you unable to tolerate or do you have adverse or allergic reactions to any drugs or medications (such as antibiotics, anesthetics, pain relievers, X-ray contrast dye, vaccines or birth control pills), or to an implant, prosthesis, contraceptive chemical or device, or other medical/surgical/dental material or procedure?
- Are you unable to tolerate or do you have adverse reactions to any foods such as dairy products, wheat, corn, eggs, caffeine, alcoholic beverages, or food additives (e.g., MSG, food dye)?
If you answer YES to any question, take the TILT Self Assessment and share the results with your doctor!