Multiple Chemical Sensitivity (MCS) was found in three studies in the USA, totaling over 5000 subjects, to occur with a prevalence of between 3.9 and 6.3% of the population (although about 16% report reacting on exposure to any single chemical). As with all allergies, the problem has been growing rapidly in the past two decades. It is typically triggered by a single exposure to a high, toxic level of a single chemical, following which the subject experiences symptoms on re-exposure to very low levels of that chemical alone. “Recruitment” follows almost inevitably, in which reactions are experienced to an increasing number of chemicals. There is almost invariably a psychological component to the symptoms, but psychological causation has never been successfully demonstrated. Indeed rapid improvement on transferring to a chemical-free environment is invariable and diagnostic, which indicates physical causation.
Prevention and remediation in the office or school context require attention to minimising the commonest exposures, such as:
- Fumes from electronic equipment (mainly flame-retardants from circuit boards etc)
- Photocopying toner
- Adhesives in carpets and building materials
- Chemical fumes circulated through ventilation systems
- Fumes from felt-tip pens, paints and varnishes
Electromagnetic Hypersensitivity (EHS) typically occurs in subjects with pre-existing MCS, or else after a heavy exposure to EMFs (electromagnetic fields). The prevalence is certainly no greater than MCS, although again more report single or occasional such reactions. Current evidence points to the involvement of trans-membrane receptors on cells – particularly calcium channels, which would explain the non-linear nature of the problem; reducing exposure intensity does not always reduce symptom severity. Recruitment occurs as in MCS; the range of frequencies and exposures that trigger symptoms in an individual will increase if they are not appropriately managed.
There are two common patterns of response; some subjects are worst on exposure to the radio frequencies generated by mobile phones, phone masts and wi-fi (300KHz to 300MHz), with the Tetra system used by emergency services being a particular problem, while some react most to the 50Hz mains frequency produced by domestic and other ring mains.
Prevention and remediation are key elements in helping subjects with EHS. This can be difficult, particularly if there are phone masts on top of the building itself or nearby. Relocation may be the only solution.