Chemical Intolerance

Abstract

Chemical intolerance (CI) is a term used to describe a condition in which the sufferer experiences a complex array of recurrent unspecific symptoms attributed to low-level chemical exposure that most people regard as unproblematic. Severe CI constitutes the distinguishing feature of multiple chemical sensitivity (MCS). The symptoms reported by CI subjects are manifold, involving symptoms from multiple organs systems. In severe cases of CI, the condition can cause considerable life-style limitations with severe social, occupational and economic consequences. As no diagnostic tools for CI are available, the presence of the condition can only be established in accordance to criteria definitions. Numerous modes of action have been suggested to explain CI, with the most commonly discussed theories involving the immune system, central nervous system, olfactory and respiratory systems as well as altered metabolic capacity, behavioral conditioning and emotional regulation. However, in spite of more than 50 years of research, there is still a great deal of uncertainties regarding the event(s) and underlying mechanism( s) behind symptom elicitation. As a result, patients are often misdiagnosed or offered health care solutions with limited or no effect, and they experience being met with mistrust and doubt by health care professionals, the social care system and by friends and relatives. Evidence-based treatment options are currently unavailable, however, a person-centered care model based on a multidisciplinary treatment approach and individualized care plans have shown promising results. With this in mind, further research studies and health care solutions should be based on a multifactorial and interdisciplinary approach.

Gene expression profiling in persons with multiple chemical sensitivity before and after a controlled n-butanol exposure session

“…Symptoms from the central nervous system (CNS), for example, headache, dizziness or fatigue, are considered mandatory in most definitions of MCS,10 often in combination with one or several non-specific symptoms from other organ systems including the mucosa/respiratory tract, musculoskeletal system and the gastrointestinal tract 3 10 15. How to define and isolate cases with MCS is an ongoing challenge both clinically and in terms of research and variable case definitions have been proposed and applied across the scientific literature,8 most prominently being the 1999 US Consensus Criteria,9 later extended with clarifications suggested by Lacour and colleagues in 2005 9 10. However, considering the complexity of MCS it may not even be possible to compose a single definition that is sensitive and specific enough to cover both diagnostics and various research and epidemiological purposes 8 16 17…”

“…How to define and isolate cases with MCS is an ongoing challenge both clinically and in terms of research and variable case definitions have been proposed and applied across the scientific literature,8 most prominently being the 1999 US Consensus Criteria,9 later extended with clarifications suggested by Lacour and colleagues in 2005 9 10. However, considering the complexity of MCS it may not even be possible to compose a single definition that is sensitive and specific enough to cover both diagnostics and various research and epidemiological purposes 8 16 17…”

“…Multiple causative modes of action have been suggested to explain the disease mechanisms behind MCS, encompassing both physiological and psychological processes 11 18–22. However, although some clinical evidence in support of several suggested pathophysiological models is available, no conclusions can be drawn based on current knowledge 8 23. Consequently, participants with MCS are offered insufficient healthcare solutions and experience being met with doubt or limited understanding of their condition by healthcare professionals, the social welfare system and the society in general 8 24–26.…”

Unmet medical care needs in persons with multiple chemical sensitivity: A grounded theory of contested illness

“…Fifteen participants identified as straight, two as gay, and two identified as bisexual. Participants were primarily unemployed (14), with two participants working part-time from home, one working part-time outside the home, one working full-time outside the home, and one working fulltime from home. Eight were single, four were living with a partner, three were divorced or separated, three were married, and one was widowed.…”

“…Dantoft and others (2015) have recently reviewed the hypotheses and research regarding causes, including neurogenic inflammation, neural sensitization, immune dysfunction, olfactory cuing, genetics, and even psychogenic theories. [14] For example, to cite just one theory, upper airway inflammation has been found in some studies of persons with MCS, but not in others. [15,16] A full discussion of etiology is beyond the scope of this paper and is complicated by many factors.…”