William J. Meggs, MD; PHD


Neurogenic Inflammation

Hypothesis for Induction and Propagation of Chemical Sensitivity

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Stages of “MCS”


Dr. Meggs provides an excellent description of the observed stages of chemically induced illness described as the "Hypothetical Chemical Stress Syndrome".

STAGE ZERO -- TOLERANCE: is what it appears to be, the ability of a person to tolerate their chemical environment.

STAGE ONE -- SENSITIZATION: or the irritant phase, "occurs when an individual is chemically stressed either by an acute high-dose chemical exposure, or by a chronic insidious exposure. Individuals in Stage 1 have symptoms on exposure to chemicals, but no physical findings on physical examination." Symptoms may include joint pain, muscle pain, headache, fatigue, flushing, pruritis, nausea, et al.

STAGE TWO -- INFLAMMATION: is when the chemical exposure has led to tissue inflammation, such as arthritis, vasculitis, some types of dermatitis, colitis, myositis, non-allergic asthma, multiple sclerosis and rhinitis. "It is at this stage that both findings in physical examination appear and a medical diagnosis can be given... The progression from Stage 1 to Stage 2 again follows increasing chemical exposures, and if tissue damage has not occurred, the inflammation can be reversed by removal of the chemical stimuli." When a person is in stage 2, the symptoms can be controlled through various medications if a person is not sensitive to those medications.

However, one needs to exercise caution because the medications are not a cure for chemical exposure, but rather can mask the root cause of the symptoms, allowing further subtle cell damage to occur if the chemicals are not avoided: "That is, progression between Stages 1 and 2 is a two-way process, with regression from Stage 2 to Stage 1 being possible if chemicals are avoided. The inflammation of Stage 2 can be reduced by medications such as corticosteroids and the non-steroidal anti-inflammatory agents, but these agents are not a curative. If the chemical stimuli are not removed, there is immediate relapse of inflammation with discontinuation of anti-inflammatory medications. Further, these medications do not prevent the progression from Stage 2 to Stage 3."

STAGE THREE -- TISSUE AND ORGAN DETERIORATION: is when chronic inflammation caused by chemical exposure has finally led to tissue damage such as nerve damage, kidney damage, liver damage, lung damage, autoimmune damage, etc. This stage is irreversible: "Unfortunately, once tissue is damaged there is little hope in current medical practice for reversal, and organ function is lost." This doesn't mean it's time to throw in the towel. It is a point where patients need to carefully reevaluate their situation and further examine their environment for possible contributing factors. They then need to adjust by making the necessary lifestyle changes to try to prevent sill worse damage from occurring. It is important to note here that individuals can pass throughout these apparent stages without ever having developed MCS, or even without making a mental connection to chronic chemical exposure in their environment.

MCS becomes debilitating for most of the individuals who eventually progress to stages two and three. Although MCS is very controversial both the U.S. Dept. of Housing and Urban Development and the Social Security Administration have recognized MSC as a disability. Many state agencies will help individuals with MCS by providing assistance with homemakers, counselors and many other very important services.