Multiple Chemical Sensitivity

SUMMARY: Toxic injury and psychological conditions may be mistaken for one another. A minority of medical practitioners enthusiastically support occupational or environmental Causation of Multiple Chemical Sensitivity (MCS) but their views cannot withstand scientific challenge. There is strong empirical evidence that MCS is a somatoform disorder.

Diagnostic Confusion

Toxic injury and psychological conditions may be mistaken for one another.

Potentially compensable injury by toxic substances may masquerade as psychiatric conditions (1).

Chronic poisoning by carbon monoxide, lead or mercury can cause neurological and psychiatric symptoms, that may be misdiagnosed as originating in emotional disorders.

Occupational exposure to manganese, arsenic and other metals, and to solvents and organophosphates may similarly elude initial diagnosis.

More frequently, however, personal injury lawyers are faced by claims of chemical injury that are hard to prove.

Claimants may seek compensation from employers, landlords, neighbours or others who they believe are responsible for causing a variety of symptoms (2, 3) or chronic ill-health:

Practice Point

1. HEAD - Headaches, sore throat, sinus, eye irritation, nasal stuffiness, eye focus difficulties, nasal soreness
2. CHEST - Shortness of breath, cough, wheeze, chest tightness
3. DIGESTION - Nausea, abdominal pain, gas, vomiting, constipation, bloating, decreased appetite
4. BALANCE - Dizziness, intoxication
5. PSYCHOLOGICAL - Memory concentration loss, numbness, tremors, palpitation, body pain
6. SKIN - Hives

This ill-defined (4) condition goes under a number of names, of which the most popular are Multiple Chemical Sensitivity, Environmental Illness and 20th Century Disease.

However, because of the multiplicity of possible symptoms, the condition does not qualify as a Syndrome, let alone a Disease.

The most universally accepted criteria for Multiple Chemical Sensitivity are those of Cullen (5):

Practice Point

1. Environmental exposure
2. Multiple organ systems
3. Recur when re-exposed
4. Different types of chemicals
5. After low-level exposure
6. Far below toxic levels
7. Unexplained by testing

Medical Enthusiasts

Litigators offering services in the area of medical law need a systematic approach to such would-be claimants.

A minority of medical practitioners will enthusiastically support occupational or environmental Causation of MCS but their views cannot withstand scientific challenge.

Although most registered physicians who claim expertise in this area of medicine are conventional Allergists, plaintiff personal injury lawyers should be aware that a minority of medical practitioners embrace beliefs and adopt tests that do not stand up to scientific scrutiny (6, 7).

Few such practitioners of alternative medicine will be found among members of university medical faculties, and these academic clinicians are a ready source of defence expertise.

Theories of Causation

The conventional and majority view (8)is that MCS is not a valid diagnostic entity(8):

"In conclusion, no consistent pattern of immune deficiency or other dysfunction can be identified among patients with MCS, even when case definition is reasonably rigorous." (9)

There are no consistent physical findings or laboratory abnormalities (10, 11).

Neither neurological nor neuropsychological testing produces characteristic results (12, 13).

Because awareness of an odour is a very common trigger of symptoms, a theory of limbic kindling held that physiological over-reaction was triggered by abnormal stimulation of the limbic arousal centre by smell of the particular toxin. However, no such hypersensitivity was found in MCS sufferers (14).

Electro-Encephalo-Graphic (EEG) changes seen after exposure to the offending smell were proposed as evidence for such a physiological mechanism.

These changes in response to food odours proved (15) to be no different from those occurring after the smell was imagined.

There is strong empirical evidence that MCS is a somatoform disorder.

Research (16) that is widely quoted as showing that the psychological symptoms of MCS sufferers post-dated the onset of "toxic exposure" depended entirely on patient recall, without corroboration by the previous medical records.

By contrast, various studies (17, 18, 19) have found significantly higher somatisation scores in MCS sufferers.

As noted previously , one study(13) suggests that at least 25% would have fulfilled the criteria for somatisation disorder before the development of MCS.

In another group of MCS patients studied(19), 75% fulfilled criteria for personality disorder.

Electrophysiological studies (scalp muscle tension and EEG patterns) show significant abnormalities that are characteristic of psychiatric groups and distinct from those of healthy controls (20).

The apparent mental health of MCS sufferers is probably illusory (21) and the failure to report psychological symptoms is likely a psychological defence mechanism.

It appears that sufferers are strong nocebo-reactors, showing no difference in their reactions to real and inert substitutes for substances they judge as "toxic" (22).

There is further evidence(23) that some of the symptoms of the condition arise from hyperventilation (over-breathing) that may be a response to fears about the harmful effects of the supposed toxins.

If MCS is indeed a somatoform disorder, there are a number of benefits that might accrue to the sufferer(1):

Practice Point

Secondary Gain:
1. Perceived as unique and sensitive
2. Others must adjust to their needs
3. Legitimised unemployment
4. Compensation
5. Spa-like "treatments"
6. Special environment
7. Special status

Copyright 2003 Electronic Handbook of Legal Medicine