Home » About Toxicant‐Induced Loss of Tolerance (TILT) » Comparing TILT to Multiple Chemical Sensitivity (MCS) or IEI

The two-step TILT process parsimoniously describes the collective experiences of chemically intolerant individuals who report becoming ill after an identifiable exposure event. In Stage I of TILT, individuals develop multisystem symptoms and intolerances for everyday substances that never bothered them previously and do not bother most people. In Stage II, tiny amounts of structurally unrelated chemicals, foods, and drugs trigger a broad range of symptoms that wax and wane with exposures.

Multiple Chemical Sensitivity (MCS)

Worldwide, this problem has had different names— Multiple Chemical Sensitivity (MCS), Idiopathic Environmental Intolerance (IEI), Environmental Illness (EI), and others. Some of these have been viewed as psychosomatic, specifically Multiple Chemical Sensitivity (MCS). This may be because neuropsychological symptoms can predominate, and because women are disproportionately affected (for a variety of reasons). This has resulted in an unfortunate bias against women that is perpetuated by the name MCS. Gulf War veterans and even physicians with this condition often refuse to label themselves as having Multiple Chemical Sensitivity (MCS).

Likewise, the term “Idiopathic Environmental Intolerance” (IEI), coined during a 1993 Berlin workshop, has been used in media, courtrooms, and scientific papers to mean “self-originated,” rather than “being of unknown etiology”— the usual definition of “idiopathic” in medicine. Thus, like Multiple Chemical Sensitivity (MCS), IEI fails to invoke the many chemical initiators and triggers reported worldwide, in every industrialized nation where the condition has been studied.

In contrast, “Toxicant-Induced Loss of Tolerance” calls for exploration of potential TILT initiators. Of course, psychological symptoms are not necessarily psychogenic. They accompany infectious diseases such as encephalitis and immunological illnesses like lupus. Since WWII, we have been dealing with unprecedented chemical exposures, especially indoors, where most people spend 90% of their time.

No matter what you call it, this constellation of symptoms and intolerances can be explained by TILT. This is why TILT is the most comprehensive term for this illness.