Environmental Sensitivities: Prevalence of Major Symptoms in a Referral Center: The Nova Scotia Environmental Sensitivities Research Center Study

Environmental Health Perspectives, Feb, 2001 by Michel R. Joffres, Tim Williams, Brenda Sabo, Roy A. Fox

Although the phenomenon of environmental sensitivities (ES) has no clear etiology nor well-accepted pathophysiology, affected individuals experience symptoms that cause varying levels of dysfunction. Through a dedicated, government-funded research and treatment center, a detailed questionnaire covering 217 symptoms in 13 systems was mailed in 1997-1998 to 812 individuals referred to the center by physicians. A total of 385 (47%) questionnaires were returned, and data were analyzed on 351 individuals. Participants tended to be women (80%), middle-aged individuals (37% age 40-49 years), and those in higher educational groups (28% completed university), but there was wide variation in demographic variables. General symptoms such as difficulty concentrating, fatigue, forgetfulness, and irritability dominated the overall prevalence of symptoms since the start of their illness. Those related to irritation such as sneezing, itchy or burning eyes, and hoarseness or loss of voice were more common after exposure to environmental irritants. Ranking of symptoms using severity scores was consistent between men and women. Overall scores were higher in women, in participants who were separated or divorced, and in low-income groups. The type and consistency of symptoms experienced after exposure to triggering substances may not fit a purely psychogenic theory. Key words: multiple chemical sensitivities, survey, symptoms. Environ Health Perspect 109:161-165 (2001). [Online 24 January 2001] http://ehpnet1.niehs.nih.gov/docs/2001/109p161-165joffres/abstract.html

Environmental sensitivities (ES) are still considered by many to be an enigmatic health concern. Within the medical community, disparate views on the origins and pathophysiology abound (1-15). Nevertheless, individuals continue to experience symptoms that produce varying degrees of disability. The most frequently cited term to describe this clustering of medically unexplained symptoms has been multiple chemical sensitivities (MCS), originally coined by Cullen in his initial paper on workplace health risks (16). Several theories have been advanced to explain the diverse symptoms occurring after exposure to low-level irritants, foods, or electromagnetic radiation (1,3,4,5-15).

In the 1995 Nova Scotia Health Survey, 3% of the population reported being environmentally sensitive (17). A more recent study conducted by Kreutzer et al. (18) stated that 16% of Californians reported being "allergic or unusually sensitive to everyday chemicals." There were no specific questions on symptoms other than a list of products or situations "bothering" or making individuals "sick." In a telephone survey conducted in North Carolina, Meggs et al. found that 33% of those surveyed reported sensitivity to chemicals (19), and 4% of the total population reported daily or almost daily frequency of their symptoms. The most common symptoms among individuals with chemical sensitivity were nausea (47%), headache (33%), and eye irritation (16%). There was no detailed evaluation of symptoms in this phone interview survey. Kipen et al. (20) found a prevalence of sensitivity to chemicals of 13% among Gulf Registry Veterans (20). Common within all these reports was the need to explore further and more accurately describe this phenomenon.

To answer this need, we used a symptom-based questionnaire to explore the frequency, severity, and type of symptoms experienced by a Canadian patient population referred to a specialty center for environmental sensitivities.

Methods

The Nova Scotia Environmental Health Center is a government-funded facility dedicated to research in the context of management of individuals referred to the center by their family physician or another physician. Confirmation of the diagnosis is based on symptomatology consistent with ES (16,21). Alternative reasons for their symptoms, such as cancer or other major illness including major depression or a psychiatric diagnosis, are routinely ruled out before their referral and after consultation with the center physicians.

A self-administered questionnaire was mailed between October 1997 and February 1998 to 812 patients of the center who had been referred for management of ES. A total of 385 (47%) questionnaires were returned. Thirty-four participants were not included in the study because ES were ruled out by the treating physician, leaving 351 people for analyses.

In the questionnaire, a general health section covered patients' health status since the beginning of their illness (ES). The next section focused on limitations in their daily activities due to their illness, and a section on health problems documented major conditions diagnosed by a physician.

The section on symptoms covered symptoms that the patients may have experienced since the start of their illness, frequency and intensity of these symptoms, and whether or not these symptoms occurred or got worse after identified exposure. Symptoms were subdivided into 13 categories addressing different organ systems: eye, ear, nose, mouth, throat, lung, heart and circulation, blood and gland, muscle and joint, nervous system, stomach and bowel, bladder and genital, and skin. At the bottom of each system an "other" category allowed additional symptoms to be listed. A section for women looked at reproductive systems. A lifestyle section covered smoking, alcohol intake, physical activities, and hobbies.