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We have identified TILT in up to 20 percent of the patients in our clinics. Pregnant women, children, the elderly, those with chronic disease and/or chemical intolerance are among the most susceptible populations.

Few doctors, nurses, or respiratory therapists have received training on recognizing the impact of environmental exposures on health. Consequently, patients are not being questioned about their air quality at home or work.

Through presentations and peer-reviewed publications, we will share what we learn during this study to teach health care professionals who encounter TILTed patients. Our ultimate goal is that people with TILT have access to information and healthcare specific to their needs.

Environmental House Calls

One of the key components of the Hoffman TILT project was our certified indoor air quality team that conducted home assessments for local study participants. The house calls included indoor air quality assessments to measure levels of volatile organic compounds (VOCs), mold, allergens, particulates as well as temperature and humidity.

Participants in the study received a series of home visits, including an initial assessment, a visit to share results and help them develop an action plan. The final visit determined whether indoor air quality had improved, and symptom triggers had been reduced. Those who followed our recommendations to improve indoor air quality experienced improvements in symptoms related to their chemical intolerance.

The top graph shows the pre and post study symptom scores of the EHC participants. The bottom graph are those who did receive the EHC. The participant group shows a large reduction in symptoms while the other group did not. The study is now closed and results of the program were published in the journal of Primary Health Care and Research Development, 2021. It is available here: Does improving indoor air quality lessen symptoms associated with chemical intolerance?

Biological Testing

We have used biological testing to investigate genetic and other TILT-susceptibility markers. We are currently investigating if those with chemical intolerance have vitamin B12 deficiencies. We are using a special assay method that reliably measures B12 in a small sample of urine. This study is no longer open and we are currently writing up our results for publication.

Chemical Intolerance Repository

Those wishing to participate in future studies can join as part of a list of willing participants. Those who consent to join will be asked to complete a series of surveys including the QEESI (our chemical intolerance assessment) and a medical history checklist. You will periodically be contacted to ask if you would like to participate in our latest studies as they arise. To join the repository list, please contact Dr. Ray Palmer at For more details see the information sheet here (PDF)

Recent Publications

1. Palmer, Raymond F., David Kattari, Rodolfo Rincon, and Claudia S. Miller. 2024. “Assessing Chemical Intolerance in Parents Predicts the Risk of Autism and ADHD in Their Children” Journal of Xenobiotics 14, no. 1: 350-367.

2. Johnson-Esparza Y, Wood R, Cruz I, & Palmer, R. (In press). Diabetes quality of life, chemical intolerance, and generational status in a Latino sample: an RRNeT study. Journal of Diabetes & Metabolic Disorders.

This study highlights generational differences in the impact of diabetes and chemical intolerance on quality of life. Latino immigrants were less likely to have scores indicative of chemical intolerance as compared to U.S.-born Latinos. This is the first studies to understand the impact of chemical intolerance on chemical intolerance in the context of a chronic condition such as type 2 diabetes.

3. Palmer RF, Almeida M, Rincon R, Perales RB. (2023) A genome-wide SNP investigation of chemical intolerance. Environmental Advances, We identified several novel gene markers associated with chemical Intolerance. These genes are associated with many comorbidities of Chemical Intolerance.

4. Miller CS, Palmer RF, Kattari D, et al., (2023) What initiates chemical intolerance? Findings from a large population‑based survey of U.S. adults. Chemical Intolerance. Environmental Sciences Europe 35:65,  This large population study identified mold, pesticides, remodeling/new construction, medical/surgical procedures, fires/combustion products as well as protracted antibiotic use as primary initiators of chemical intolerance.

5. Palmer RF, Dempsey TT, Afrin LB. (2023) Chemical Intolerance and Mast Cell Activation: A Suspicious Synchronicity.  Journal of Xenobiotics. 13, 704–718. A replication and confirmation of the first Mast Cell paper by Miller et al., (2021) indicating the potential role of Mast Cells affecting Chemical Intolerance.

6. Perales RB, Palmer RF, Rincon R, Viramontes JN, Walker T, Jaén CR, Miller CS. (2022) Does improving indoor air quality lessen symptoms associated with chemical intolerance? Primary Health Care Research & Development 23(e3): 1–12. This study describes the results of our Environmental House Calls demonstrating improved symptoms among those with chemical intolerance who improved the indoor air quality as a result of our recommendations.

7. Palmer, RF, Rincon R, Perales, RB, Walker T, Jaén C, Miller CS. (2022)The Brief Environmental Exposure and Sensitivity Inventory (BREESI): an International Validation study. Environmental Sciences Europe  34:32, The study shows the effectiveness of this 3-item survey as a screener for Chemical Intolerance in 5 countries.

8. Palmer RF, Walker T, Perales RB, Rincon R, Jaén CR, Miller CS. (2021) Disease comorbidities associated with chemical intolerance. Environ Dis 2021;6:134-41. This paper reveals a list of chronic diseases reported by those with and without chemical intolerance. Those with chemical intolerance experience more chronic illnesses compared to those without chemical intolerance

9. Palmer, R.F.; Walker, T.; Kattari, D.; Rincon, R.; Perales, R.B.; Jaén, C.R.; Grimes, C.; Sundblad, D.R.; Miller, C.S. (2021) Validation of a Brief Screening Instrument for Chemical Intolerance in a Large U.S. National SampleInt. J. Environ. Res. Public Health, 18, 8714. Our second demonstration that a brief 3-item survey is an excellent screener for chemical intolerance. This was tested in a US population sample of over 10,000 participants. Again, the BREESI correctly classified chemical intolerance 90% of the time. This is an excellent tool for screening chemical intolerance in epidemiological or other survey research.

10. Miller, C.S., Palmer, R.F., Dempsey, T.T. Ashford, N. (2021)Mast cell activation may explain many cases of chemical intoleranceEnviron Sci Eur 33, 129 This paper provides for the first time a plausible biological mechanism for chemical intolerance. Overactive mast cells may be responsible for the various symptoms experienced by those with CI. Some dietary and medical interventions are discussed.

11. Masri S, Miller CS, Palmer RF, Ashford, N (2021)Toxicant-induced loss of tolerance for chemicals, foods, and drugs: assessing patterns of exposure behind a global phenomenonEnviron Sci Eur 33, 65 This study is a review of the chemical intolerance phenomena in terms of the exposures that can initiate the disease.

12. Palmer RF, Jae´n CR, Perales RB, Rincon R, Forster JN, Miller CS (2020) Three questions for identifying chemically intolerant individuals in clinical and epidemiological populations: The Brief Environmental Exposure and Sensitivity Inventory (BREESI)PLoS ONE 15(9): e0238296. Our first demonstration that a brief 3-item survey is an excellent screener for chemical intolerance. Used in our clinical study of 200 individuals, the BREESI correctly classified those with chemical intolerance when validated with our 50-item survey (QEESI). This is an excellent tool for screening chemical intolerance in a busy health care clinic.