Environmental sensitivities are adverse responses to agents in the environment (in air, dust, food, water, and consumer products) at exposure levels commonly tolerated by many people . The responses may be to chemicals (multiple chemical sensitivities, sensitivity or intolerance(s)), to electromagnetic radiation (electrohypersensitivity), or to other environmental factors that collectively may be called environmental illness, sensitivity or intolerance, or sensitivity-related illness.
Three stages in the development of sensitivity-related illness have been identified: 1) exposure to a harmful agent or agents; 2) stimulation of the body’s defence mechanisms and initiation of a state of sensitivity; and, 3) triggering of diverse symptoms on subsequent exposure to the same agents .
Symptoms can be triggered in multiple body systems by low-dose exposures to a number of common chemicals, either individually or in combination . The most prominent symptoms are having a stronger sense of smell than most people, feeling dazed, dull or groggy, and having difficulty concentrating . Other symptoms may include muscle aches, fatigue, wheezing, digestive problems, and skin rashes. People affected by environmental sensitivities have reported that the most effective way to manage these adverse responses is the avoidance of chemicals, foods, inhalants and other agents such as electromagnetic radiation that trigger symptoms . Clinicians working with chemically sensitive people have concurred on this point [6-7].
The underlying mechanisms of environmental sensitivities are not yet fully understood . However, it is now recognized that there has been an increase in exposure to many environmental factors since the Second World War, and that environmental factors, interacting with genetic susceptibilities found in those with environmental sensitivities, may lead to toxicant-induced loss of tolerance in the population .
The Canadian Community Health Survey (CCHS) (2005) by Statistics Canada revealed that other chronic conditions co-occurred with environmental sensitivities, including myalgic encephalomyelitis/chronic fatigue syndrome and fibromyalgia . The 2005 CCHS also found that 1.2 million Canadians aged 12 or older, or 5% of the population, reported being diagnosed with at least one of these three conditions. About 14% of the affected population had 2 of the 3 conditions. In the 2005 National Survey of the Work and Health of Nurses, 3.6% of Canadian nurses reported experiencing multiple chemical sensitivities, 1.9% fibromyalgia and 1.4% chronic fatigue syndrome .