Due to recent comments on MCS/ IEI I am posting the following report by the Australian Dept. of Health and Ageing. Please note that while it is open to the possibility that MCS is a definite disease entity with possible multifactorial etiology, at this time:
1. The underlying mode(s) of action of MCS, i.e. the biological mechanisms by which the chemical sensitivity occurs, remain uncertain.
2. Although non-specific neurological symptoms are common, overall there is no characteristic symptom profile that identifies MCS.
3. Presently, a diagnosis of MCS is based commonly on self-reported symptoms and chemical exposure histories. The symptom profile of MCS is indistinguishable from other multi-symptom disorders. No laboratory tests currently exist for diagnosing MCS.
4. There are no standardised treatments for MCS.
To read the Full Report, go to:
Multiple Chemical Sensitivity (MCS) is the most common term used to describe a condition presenting as a complex array of symptoms linked to low level chemical exposures. The underlying mode(s) of action of MCS, i.e. the biological mechanisms by which the chemical sensitivity occurs, remain uncertain.
A common theme reported by individuals is experiences of heightened responsiveness to chemicals at extremely low exposure levels. The agents linked with MCS symptoms in susceptible individuals are numerous and chemically diverse. They include individual chemicals and chemical products encompassing air pollutants, workplace and domestic chemicals, agricultural chemicals, therapeutics and foods.
Similarly, the symptoms experienced by individuals from exposures are diverse and involve multiple organ systems. Although non-specific neurological symptoms are common, overall there is no characteristic symptom profile that identifies MCS. Nevertheless, reported symptoms can, in some cases, be debilitating.
Numerous modes of action have been postulated for MCS. These include immunological changes, respiratory/neurogenic inflammation, limbic sensitisation, elevated NMDA receptor activity, altered metabolism as well as behavioural conditioning and psychological disorders. Alternative names for MCS in part reflect views on particular modes of action.
Several attempts have been made to establish diagnostic criteria for this disorder. A set of ‘Consensus Criteria’ developed in 1999 describes MCS as a chronic condition involving multiple organ systems with reproducible symptoms following low-level exposure to multiple unrelated chemicals. These criteria have been used to a limited extent for research and survey purposes. Worldwide, a small number of available studies indicate the prevalence of medically diagnosed MCS at 0.2% – 4%. In Australia, only limited surveys of the prevalence of chemical sensitivities and MCS in the community have been conducted. South Australian state health surveys reported a prevalence of medically diagnosed MCS of 0.9%.
At this time, worldwide, MCS is not an internationally classified disorder, with only Germany and Austria (via adoption of German diseases documentation) listing MCS in their national disease classifications.
Presently, a diagnosis of MCS is based commonly on self-reported symptoms and chemical exposure histories. The symptom profile of MCS is indistinguishable from other multi-symptom disorders. No laboratory tests currently exist for diagnosing MCS. Different case definitions and the lack of a characteristic symptom profile and objective laboratory biomarkers for MCS have impeded recognition of the disorder as a distinct clinical entity.
There are no standardised treatments for MCS. Current treatments advocated for MCS include dietary changes, nutritional supplements, detoxification and desensitisation techniques, holistic or body therapies, as well as prescription medicines and behavioural therapies. The most common management regime for MCS is avoidance of agents that trigger symptoms.
A Review of Multiple Chemical Sensitivity
Research into biological mechanisms underpinning MCS
There is considerable debate as to what biological mechanisms (modes of action) are responsible for the state of chemical sensitivity in MCS. The literature describes numerous potential causative modes of action, both physiological and psychological in nature, many of which are amenable to further testing. MCS may have a multifactorial origin.
An understanding of mode of action and how chemicals interact with organ systems would be assisted by more detailed identification of the chemical species and the exposure scenarios responsible for symptoms in MCS.
Finding 1: Targeted research into mode (s) of action
While there are a number of proposed mechanism(s) that warrant further research consideration, based on biological plausibility, testability and known research gaps, the following modes of action for MCS are highlighted for further scientific research and investigation as priorities:
Respiratory disorder/neurogenic inflammation;
Limbic kindling/neural sensitisation and psychological factors;
Elevated nitric oxide, peroxynitrite and NMDA receptor activity;
Altered xenobiotic metabolism.
Clinical research needs
An Australian clinical review has highlighted differences with criteria used for the diagnosis of MCS and methods to treat MCS.
Overall, a number of primary clinical research needs are evident:
Standardising diagnostic criteria that are acceptable to, and utilised by, clinical and scientific groups;
Determining the prevalence of MCS in the community, for both self-reported cases and those that are medically diagnosed;
Exploring initiating/triggering agents/events and modes of action in MCS through the use of well designed and conducted blinded challenge tests and longitudinal studies of illness course;
Determining and documenting effective treatment/management protocols for MCS based on long-term therapeutic alliances and individual self-management.
Finding 2. Longitudinal study
To get a better understanding of the clinical picture of MCS in Australia there is a need to look more closely at the natural history of people with MCS. A longitudinal clinical and sociological study should assist in identifying key elements of MCS such as how MCS is initiated and/or triggered and how sensitivities vary over time.
Such a study should examine eliciting agents/events, diagnostic experiences, clinical course and impacts of treatment/management strategies. To undertake such a longitudinal study it would be necessary to identify people with MCS who would be prepared to be involved. Findings in Appendix 1 provide some practical suggestions to address this issue.
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A Review of Multiple Chemical Sensitivity
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Finding 3: Education/training
A survey of clinical approaches to MCS of Australian medical practitioners identified a lack of coverage of MCS within the current Australian medical curriculum given the relatively small amount of time devoted to minor specialties. Other than hospital protocols containing practical measures to assist inpatients with chemical sensitivities, there are also currently no clinical guidelines available to inform medical practitioners as to how to provide appropriate care for MCS individuals.
The development of a clinical education program should be investigated. Such a program should be based on evidence currently available, utilise any findings from clinical research in Australia (such as a longitudinal investigation) and consider the practical guidance on approaches to MCS clinical management agreed by participants in the recent clinical review of MCS.