Increasingly, scientists are identifying a two-phase process leading to environmental sensitivities.
Phase 1: Onset of the illness
The onset of the illness takes place either after chronic low-level exposure to contaminants or after one high-level exposure to a chemical substance, electromagnetic radiation, or a biological agent. The factors involved are called initiating agents (Table 1).
The most common initiating agents of the illness are:
- Pesticides ?
- Volatile organic compounds (VOCs: solvents, perfumes, formaldehyde and other petrochemical products, exhaust gases from vehicles) ?
- Moulds ?
- Electromagnetic radiation and/or fields
These agents can emanate from the structure of a building, some types of furniture and equipment, neighbourhood surroundings, cleaning products, etc. There are also environmental factors which can worsen the symptoms of environmental sensitivities such as lighting, humidity, heat, cold and noise.
The initiating agents cause a loss of tolerance in affected people, thereby triggering the environmental sensitivities cycle.
Phase 2: Manifestation of the illness
Once environmental sensitivities are triggered, people who are affected often react to several other triggering agents (Table 1), even at very low doses or concentrations. A series of metabolic reactions then brings about many symptoms (figure 1), resulting in a chronic condition.