Multiple chemical sensitivity
The word chemical in the name is used loosely and includes natural substances (e.g., the aromas produced by pine trees or other fragrant plants).
[10][obsolete source] The panel accepted the existence of "a disease of unclear pathogenesis", rejected the claim that MCS was caused by chemical exposure, and proposed these three diagnostic requirements for a group of conditions that includes MCS, which they called idiopathic environmental intolerances (IEI): In Japan, MCS is called chemical hypersensitivity or chemical intolerance (化学物質過敏症; kagaku bushitsu kabinsho), and the 1999 Japanese definition requires one or more of four major symptoms – headaches; malaise and fatigue; muscle pain; joint pain – combined with laboratory findings and/or some minor symptoms, such as mental effects or skin conditions.
[9] Another definition requires a known precipitating event (e.g., an injury or an illness) followed by the appearance of multi-organ symptoms that predictably wax and wane in response to a variety of exposures that do not bother other people.
[12] Symptoms mainly arise from the autonomic nervous system (such as nausea or dizziness) or have psychiatric or psychological aspects (such as difficulty concentrating).
[16] "Most recently," it said, "some peer-reviewed clinical research has emerged from centres in Italy, Denmark and Japan suggesting that there are fundamental neurobiologic, metabolic, and genetic susceptibility factors that underlie ES/MCS.
"[16] The US Occupational Safety and Health Administration (OSHA) says that MCS is highly controversial and that there is insufficient scientific evidence to explain the relationship between any of the suggested causes of MCS – it lists "allergy, dysfunction of the immune system, neurobiological sensitization, and various psychological theories" as the suggested causes – and its symptoms.
[14] It has been hypothesized that there is a heritable genetic trait which pre-disposes people to be hypersensitive to low-level chemical exposure and so develop MCS.
[14] Gaétan Carrier and colleagues write that the genetic hypothesis appears implausible when the evidence around it is judged by the Bradford Hill criteria.
A 2018 systematic review concluded that the evidence suggests that abnormalities in sensory processing pathways combined with peculiar personality traits best explains this condition.
[19] These other conditions may or may not have any relationship to MCS symptoms, but they should be diagnosed and treated appropriately, whenever the patient history, physical examination, or routine medical tests indicates their presence.
[15]: 17 [12] The goal of treatment is to improve quality of life, with fewer distressing symptoms and the ability to maintain employment and social relationships, rather than to produce a permanent cure.
[19] Some literature recommends a multidisciplinary treatment approach that takes into account the uncommon personality traits often seen in affected individuals and physiological abnormalities in sensory pathways and the limbic system.
[19] Avoiding triggers, such as by removing smelly cleaning products from the home, can reduce symptoms and increase the person's sense of being able to reclaim a reasonably normal life.
[19] However, for other people with MCS, their efforts to avoid suspected triggers will backfire, and instead produce harmful emotional side effects that interfere with the overall goal of reducing distress and disability.
[4] Treatments that have not been scientifically validated, such as "elimination or rotary diversified diets", hormone supplement and chemical detoxification through exercise have been used by people with MCS.
[23][24] Symptoms attributed to Gulf War syndrome are similar to those reported for MCS, including headache, fatigue, muscle stiffness, joint pain, inability to concentrate, sleep problems, and gastrointestinal issues.
[4] MCS is also similar to sick building syndrome, with both showing non-specific symptoms such as headaches, respiratory irritation and fatigue.
As a consequence of his insistence upon his own, non-standard definition of allergy and his unusual theories about how the immune system and toxins affect people, the ideas he promoted were widely rejected, and clinical ecology emerged as a non-recognized medical specialty.
[26] In 1994, the AMA, American Lung Association, US EPA and the US Consumer Product Safety Commission published a booklet on indoor air pollution that discusses MCS, among other issues.
The booklet further states that a pathogenesis of MCS has not been definitively proven, and that symptoms that have been self-diagnosed by a patient as related to MCS could actually be related to allergies or have a psychological basis, and recommends that physicians should counsel patients seeking relief from their symptoms that they may benefit from consultation with specialists in these fields.
[9] Memoirs about multiple chemical sensitivity tend to follow a predictable pattern, with a description of various toxins and their effects alongside requests for others to help the writers by changing their behavior (e.g., by not wearing perfume).
[32] Being able to get paid for medical services and collect statistics about unspecified, idiosyncratic reactions does not mean that MCS is recognized as a specific disease or that any particular cause has been defined by the German government.
