Episode #65: TILT & MCS Uncovered: The Science Behind Chemical Intolerance with Dr. Shahir Masri

What if even small exposures to common chemicals, like perfumes and cleaning products, could make you sick for hours, days, or even weeks? Dr. Shahir Masri explains how this reality affects those suffering from Toxicant-Induced Loss of Tolerance (TILT) and Multiple Chemical Sensitivity (MCS)—where a single exposure can trigger a lifetime of sensitivities. 

Dr. Masri discusses diagnosis, potential treatments, and offers practical advice on how to avoid triggers. He also explores the differences between TILT and MCS, the role of “masking,” and why some people develop the condition while others don’t. Get an in-depth look at the two stages of TILT and learn what needs to happen for it to gain broader recognition in the medical community. Tune in to understand why “the dose plus the host makes the poison,” and how these often overlooked and misunderstood conditions are challenging traditional medical beliefs.

Episode Highlights:

• What are Toxicant-Induced Loss of Tolerance (TILT) and Multiple Chemical Sensitivity (MCS)? (2:01)
• Why does Dr. Masri believe that TILT is a better term than MCS? (4:35)
• What are the two stages of TILT? (10:26)
• What role does “masking” play in TILT and MCS?  (17:03)
• How are TILT and MCS diagnosed?  (19:54)
• What’s Dr. Masri’s take on Paracelsus’ statement, “The dose makes the poison”? (24:48)
• Why do some people develop TILT and others don’t? (27:09)
• How are TILT and MCS treated? How would an Environmental Medical Unit (EMU) work, and what are some tips to reduce symptoms? (30:58)
• What needs to happen for TILT and MCS to be more widely acknowledged by the medical community? (38:16)

Links Mentioned in Interview:

TILT Research Program for Chemical Intolerance: https://tiltresearch.org/

Chemical Intolerance Self-Assessment (QEESI):  https://tiltresearch.org/self-assessment/

Quick Environmental Exposure and Sensitivity Inventory (QEESI): https://tiltresearch.org/wp-content/uploads/sites/231/2024/06/qeesi.pdf

Brief Environmental Exposure and Sensitivity Inventory (BREESI): https://aseq-ehaq.ca/wp-content/uploads/2021/08/BREESI.pdf

TILT and MCS Assessment Tools: https://hsph.harvard.edu/research/hoffman-program/resources/chemicals-in-your-life/assessment-tools/

Research by Masri, S., et al. https://www.researchgate.net/publication/351924396_Toxicant-induced_loss_of_tolerance_for_chemicals_foods_and_drugs_assessing_patterns_of_exposure_behind_a_global_phenomenon

Flame Retardants, Formaldehyde & Your Indoor Air Interview with Lara Adler: https://changetheairfoundation.org/flame-retardants-formaldehyde-your-indoor-air/

The Truth About VOCs, Greenwashing, and Healthy Homes: Part 1 Interview with Andy Pace: https://changetheairfoundation.org/the-truth-about-vocs-greenwashing-and-healthy-homes-part-1/

Get in Touch with Our Guest:

Website:  https://www.shahirmasri.com Instagram: @dr.shahirmasri and @environmentalhealthresource

Disclaimer: Your Indoor Air Podcast, a Change the Air Foundation production, is for ge