Multiple Chemical Sensitivity or MCS
Multiple Chemical Sensitivity is the name given to a syndrome in which a sufferer experiences multiple symptoms upon exposure to minute amounts of everyday chemicals. There is currently no officially recognized definition for Multiple Chemical Sensitivity. This is due to the fact that very little is known about it, especially the mechanisms involved with the onset of symptoms. Leading theories suggest a possible role for a hypersensitive central nervous system, immune dysfunction and impaired detoxification by liver enzymes. Some medical professionals, and even organizations, continue to insist that the syndrome is psychological in origin, even in the face of a growing amount of evidence from studies that show clear abnormalities in people with MCS on exposure to normally safe levels of chemicals. Through 1999 there were a total of 618 scientific articles, editorials, books, book chapters and reports relating to MCS. Of these, 308 supported an organic/physiological basis for symptoms whereas only 137 supported a psychological interpretatio (Source: www.mcsrr.org).
Although there is no definition universally accepted by the established medical institutions, Multiple Chemical Sensitivity experts (Heuser et al) have come to a consensus on the criteria for diagnosis, and thus far these criteria remain unrefuted in the published literature. These criteria are as follows:
It's reasonable to expect that these criteria will be officially adopted in a form very close to the above in the relatively near future.
To complicate matters, however, a number of influential medical institutions, such as the American Academy of Allergy Asthma and Immunology (AAAAI), have renamed the illness as 'Idiopathic Environmental Intolerance' (IEI). They cite the reason for this to be the fact that no immune system involvement has been proven thus far and since "sensitivity" in medical jargon technically refers to an immune reaction, they deem MCS to be inaccurate. For the general population "sensitivity" and "intolerance" generally mean the same thing and MCS is so well known now that most people are sticking with this name for now.
Many MCS sufferers can trace the start of their illness to an acute exposure to highly toxic chemicals (Gulf War veterans for example). For other sufferers the illness develops over a long period of time most likely involving chronic low level exposure to chemical substances. Although MCS can occur on its own, a large number of sufferers also suffer from CFS, Fibromyalgia and other related disorders. This obviously points to the possibility that all these illnesses are part of the same underlying process and likely have common causes.
MCS is a chronic condition with the patient usually experiencing some level of unwellness all the time. However, patients have an acute reaction when exposed to minute amounts of the chemicals to which they are sensitive. Often the level of a chemical that triggers a reaction may be so low that the sufferer can't even smell it.
Common symptoms of MCS upon exposure:
Most sufferers have a distinct reaction upon every exposure. It is common to first experience dizziness, disorientation, rapid heartbeat and mood changes followed by flu-like illness and muscle/joint aches. In severe cases, the flu-like illness and aching can persist for days.
Reactions in MCS are triggered by a vast array of everyday chemicals from perfume to diesel exhaust. The common ingredients in most of these chemical products are hydrocarbon based volatile organic chemicals (VOC's). Phenols (containing benzene) are commonly implicated. With everyday cosmetic and household chemical products, it is generally the addition of perfume that makes them bad news for MCS sufferers. Typically a sufferer will notice a sensitivity to one or two things to start with, perfume and cigarette smoke for example, and then will rapidly become sensitized to more and more chemical sources over a relatively short period of time. The reasons for this common occurrence are unknown but it is clearly something that needs to be investigated.
Common chemical triggers in MCS:
In addition to these VOC's that cause a reaction when inhaled, some sufferers also complain of symptoms when they ingest certain things. These include:
Although the amount of medical research into MCS is still a lot lower than would be desirable, a relatively high number of studies have discovered consistent abnormalities in MCS patients and also been able to show convincing evidence of possible mechanisms in animal and other laboratory models.
Cerebral Blood Flow
Porphyrias usually occur in acute episode triggered by medications, menstrual periods, malnutrition or other illness, at other times the sufferer may show no symptoms and normal porphyrin levels. Due to the similarity of symptoms between these illnesses and MCS, a number of researchers decided to test MCS patients for increased porphyrin content in urine and stool samples. One study found that 60-90% of MCS patients tested showed porphyrin abnormalities. Other findings come from a doctor who had a number of patients describing pink/purple urine. When tested a significant number had higher than normal levels in urine and stool samples. The abnormalities however have been less marked than in the traditional porphyrin illnesses. More research is definitely needed in this area to further substantiate abnormalities.
Other Areas of Research
A few studies have been conducted with
MCS sufferers regarding immune function but the findings have not been
consistent. A couple of studies have found increased T-cell activation
and autoantibodies, that is antibodies that react with the bodies own
tissues. How these findings would cause the myriad symptoms of MCS is
far from clear but immune dysfunction remains a popular theory for the
mechanism of the illness.
What do we know about common chemicals and health?
The simplest answer to this is...not much.
Since World War 2 the production of synthetic organic chemicals has skyrocketed. In 1945, total production of these chemicals was under 10 million tons compared to 110 million tons today(1).
A total of 4 million chemical compounds were described in the scientific literature between 1965 and 1989. Of the 60,000 chemicals in wide use in most western countries in 1989 only around 2% (1200) had been comprehensively examined by scientists. There is no research data at all available on about 50,000 commonly used chemical substances(2).
A UK academic recently recommended a program to rapidly test and catalogue 30,000 chemicals within the next 5 years. Chemicals found to cause health problems would then be subjected to more intensive longer term testing. This would certainly be a step in the right direction.
Sources: 1. Nicholas A. Ashford and Claudia S. Miller, Chemical Exposures: Low Levels and High Stakes (New York: Van Nostrand Reinhold, 1998)
2. Linda Lee Davidoff, "Multiple Chemical Sensitivities (MCS)," The Amicus Journal, Winter 1989.