Exposure to initiating and triggering agents can take place via the respiratory system, the digestive system, skin contact, contact with infectious agents, injection of products and medical interventions. Exposure can happen as early as mother to child transmission during pregnancy and breastfeeding.
The body reacts differently depending on the type of exposure and whether it is a chemical, physical or biological contaminant.
Table 1 Agents likely to bring about the onset of environmental sensitivities.
Type of agent |
Examples of agents |
Examples of sources or products |
Volatile Organic Compounds (VOCs) |
Formaldehyde |
Urea-formaldehyde foam insulation* Wood glues** (e.g. plywood and pressed wood/ chipboard) Paint |
Solvents |
Varnishes Paint thinners and strippers, glues Air fresheners |
|
Perfumes |
Perfumes, personal care products, Household cleaning products Fabric softeners |
|
Off-gassing mixtures |
Equipment (e.g. computers) Furniture |
|
Products containing petrochemicals |
Carpets Ink from books and periodicals Fuels, petroleum |
|
Combustion products |
Tobacco smoke Vehicle exhaust Barbecue or wood smoke |
Cigarettes, Buses, trucks, cars Barbecues, wood stoves, fireplaces |
Microbial products |
Moulds Mycotoxins Bacteria Metabolites produced by moulds or bacteria |
Mould or bacteria in structures Mould or bacteria
in ventilation and air conditioning systems |
Pesticides |
Insecticides |
Products to kill insects |
Natural inhalants |
Pollen |
Tree pollen (Spring) |
Foods |
Allergenic proteins Preservatives Individual/specific flavouring agents |
Peanuts, milk, gluten |
Electromagnetic radiation |
Lighting |
Lamps |
Radio waves and microwaves |
Wiring problems |
|
Very low-frequency electromagnetic fields |
Television |
|
Telluric currents |
Power supply systems that let the current pass through the ground, pipes or structures |
|
Other factors |
Temperature |
Workplace or home infrastructure |
* Now prohibited in Canada. ** Prohibited in new products in many countries. |
Source: Sears, 2007. |