Multiple Chemical Sensitivity is a discerned abnormal reactivity to common contaminants and chemicals in the environment that negatively affect quality of life, also known as “Environmental Illness”.
Synonyms: Environmental Illness. Idiopathic Environmental Illness, 20th Century Disease, Universal Allergy, Total Allergy Syndrome, Allergic Toxaemia.
Randolph hypothesised that the body was like “a barrel filling up with chemicals” until a critical point is reachedafter which it reacts to any further chemical exposure. With a plethora of household chemicals and agents captured in the aetiology, the label Multiple Chemical Sensitivity (MCS) was coined by Cullen in the 1980’s.
About 16% of individuals report some form of “unusual sensitivity” to common everyday chemicals—prompting the National Institute of Environmental Health (NIEH) in the USA to develop a consensus statement in 1992. NIEH called it Idiopathic Environmental Intolerance (IEI) with 6 diagnostic criteria.
Symptoms of MCS/IEI are diverse and include: recurrent headaches; sinus and nasal congestion; itchy eyes and throat; with abdominal symptoms. Other symptoms include insomnia; irritability; ,etc. These symptoms are attributed to a chronic prolongedand low dose environmental chemical exposure overlapped with other proposed environment-linked conditions like Sick-building syndrome (SBS), food intolerance syndrome (FIS) and Gulf War Illness (GWI). It’s postulated that certain chemicals like formaldehyde in furnishings and other materials are triggers.
Idiopathic Environmental Intolerance (IEI) diagnostic criteria include the following but not limited to:
Immunological mechanisms (mainly non-IgE) have been proposed but none have been satisfactorily proven. Aetiological theories also failed to provide any confidential link between ill-health and day-to-day low-level chemical exposure.
A genetic predisposition with heightened sensitivity and abnormal olfactory receptors has also been proposed but never confirmed to clinical studies. In studies where the chemical odour was masked or suppressed by menthol, there was no difference between the study and control group symptomatology.
Many physicians believe that symptoms of IEI are psycho-physiological in nature and affected persons are prone to panic responses which enhance their symptom.Lenzoff, Binckley and Kutcher’s studies reflected different body responses to chemical sensitivities.
In addition, IEI prone individuals appear to have a heightened olfactory awareness and odour aversion to otherwise harmless volatile organic compounds found in many household products, aerosols and even from trees. But findings by Das-Munshi, Rubin and Wessely proved this otherwise.
Psychological conditioning has been proposed as the underlying abnormality in IEI, but is complicated by a high incidence of pre-morbid psychological trauma (including childhood physical and sexual abuse).This may cause long-term effects on mood and affect cognitive processing, hypervigilence and entrenched beliefs of victimisation.
Finally, analysis after many years of investigation gives no convincing evidence for the existence of multiple chemical sensitivities in the medical literature—the underlying cause not triggered by everyday chemicals but a masked stress disorder with heightened olfactory awareness and associated behavioural conditioning.