Review of Multiple Chemical Sensitivity: Identifying
Is MCS related to other syndromes or disorders?
Download 454.32 Kb.
|
- Navigate this page:
- 3Mechanisms of Multiple chemical sensitivity
2.7Is MCS related to other syndromes or disorders?The multiple subjective non-specific symptoms and timecourses associated with MCS have been reported to be noticeably similar to other multi-organ or multi-symptom conditions that have ICD classifications such as chronic fatigue syndrome (CFS), fibromyalgia (FM) and post-traumatic stress disorder (PTSD) (Aaron et al., 2001; Bornschein et al., 2001; Pall, 2002; Lacour et al., 2005). Buchwald and Garrity (1994) compared 30 adults with CFS, 30 with FM, and 30 with MCS to evaluate the similarities between these three conditions. Approximately 80% of individuals in both the FM and MCS groups met the Centres for Disease Control and Prevention's (CDC) major criteria for CFS (Holmes et al. 1988), and both groups also frequently reported the symptoms of CFS that are classified as minor criteria for this disorder. Jason et al. (2000) found that out of 90 individuals diagnosed with MCS, 13 (14.4%) met the criteria for CFS and 8 (8.9%) met the criteria for FM. In another study, a similar proportion (15.2%) of cases defined as MCS among British military personnel met the criteria for CFS (Reid et al. 2001). One study investigating the medical conditions of navy personnel deployed in the Gulf War reported a higher prevalence of CFS, PTSD, MCS, irritable bowel syndrome and a number of other conditions compared to other navy personnel (Gray et al. 2002). Similarly, a subsequent systematic literature review revealed greater reporting of multi-symptom conditions, including CFS and MCS, in Gulf War veterans compared to non-Gulf veterans (Thomas et al., 2006). The significant overlap in symptoms between these syndromes has suggested shared aetiological mechanisms (Pall 2001, 2002). However, different multi-symptom conditions are regarded to be triggered by distinct, different short-term stressors, most commonly infection for CFS, physical trauma for FM, severe psychological stress in PTSD and exposure to some environmental agents in MCS (Pall 2002; 2003). In addition to CFS, FM and PTSD, several other multi-symptom syndromes have been associated with MCS (see Table 3). Table 3. Syndromes that may be associated with MCS (from Staudenmayer et al., 2003b)
The sick building syndrome (SBS) is a poorly understood condition temporally related to working in particular buildings. Similar to MCS, persons with SBS experience diverse symptoms that include eye, nose and throat irritation, headaches, cough, difficult breathing, fatigue, dizziness and difficulty in concentrating. SBS is thought to result predominantly from poor building ventilation causing a build-up of biological contaminants or vapours from sources that include building materials, furnishings and office equipment (Burge, 2004). Occasionally, some people with SBS report that they later develop MCS (Hodgson, 2000). Contaminants in the indoor environment are similarly implicated in Aerotoxic syndrome (Winder, 2002). Self-reported health complaints attributed to dental amalgam have been compared to MCS (Malt et al., 1997) and the evidence linking amalgam dental restorations to a wide variety of diseases has been reviewed (Dodes, 2001). Exposures to electromagnetic radiation has been associated with a dermatological syndrome consisting of symptoms of dermal irritation but more recently also to a general syndrome of non-specific sensory, nervous, respiratory and gastrointestinal system complaints similar to MCS (Levallois, 2002). The symptomatology of MCS is indistinguishable from that of other multi-system disorders which have established ICD classifications. These disorders are sometimes deemed as conditions caused by, or that predispose to, or that exist as comorbid conditions with MCS (Staudenmayer et al., 2003b; Lacour et al., 2005). Some are of the view that a diagnosis of these other multi-symptom disorders should exclude a diagnosis of MCS (Lacour et al., 2005). 3Mechanisms of Multiple chemical sensitivityThe literature on MCS highlights differences in views regarding the underlying mechanisms through which MCS occurs. Indeed, the heterogeneity of symptoms has given ground for doubt as to whether MCS is a single disease entity with a specific aetiology and pathogenesis (Altenkirch, 2000; Lacour et al., 2005). The underlying biological basis for MCS and its range of variable symptoms remains unresolved. Indeed, a review by Winder (2002) identified dozens of possible causative mechanisms. Generally, the debate on mechanisms of MCS has aligned traditionally to views as to whether MCS symptoms are due to psychosomatic responses to perceived chemical toxicity or to a physiological/pathological interaction between chemical agents and organ systems. While some believe MCS is purely a psychological disorder, others consider it to be an overt, albeit poorly understood, physiological response to chemical exposure. Given the increasingly recognised complex interplay between behavioural traits and physiological functions, it is also possible that both physiological and psychological factors play a part in the pathogenesis of MCS (Bock and Birbaumer, 1997; österberg et al., 2006; Das-Munshi et al., 2007; Haustener et al., 2007; Bauer et al., 2008; Goudsmit and Howes, 2008). It is important to note that the use of the broad terms psychological, psychogenic or psychosomatic in this report acknowledges an incomplete understanding of the neurochemical processes involved in behavioural susceptibilities and responses. The exacerbation of a variety of different disease states by psychological influences is well documented in the literature and on this basis the possibility that psychological processes influence the development and/or course of MCS is considered (Sorg, 1999). A useful framework when considering the biological basis for an adverse health outcome is the concept of a mode of action - mechanism of action continuum. This facilitates understanding of the different evidential needs in establishing a cause for an observed effect. This concept is used in chemical risk assessment and assists in determining the level of evidence needed in making a regulatory decision in relation to adverse effects observed in animal models or symptoms observed in humans. Mode of action is defined as a series of key biological events leading to an observed toxicological effect (for example, metabolism to a toxic entity, cell death, regenerative repair and tumours). While a hypothesized mode of action is supported by experimental observations and related mechanistic data, it contrasts with mechanism of action, which generally involves understanding the molecular basis for an effect. In the toxicological sciences, the concept of mode of action is becoming increasingly important in interpreting toxicological data for risk assessment and in recommending additional relevant research. Directory: data -> assets -> word doc word doc -> Northern territory of australia word doc -> Number: caveat in the [Will/Will and Codicil/Estate of] word doc -> List of accessible executive records word doc -> National Industrial Chemicals Notification and Assessment Scheme word doc -> This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from the Commonwealth word doc -> Commonwealth of Australia 2002 word doc -> Commonwealth of Australia 2000 word doc -> Priority Existing Chemical word doc -> Rail safety news issue 6 – October 2011 word doc -> Board Endorsed October 2009 amended 13-09-11 with extra units Download 454.32 Kb. Share with your friends:
|