Chemical intolerance contributes to the illnesses of 1 in 5 patients but the condition seldom figures in their diagnosis, according to clinical research published July 9 in the journal Annals of Family Medicine.

(Note: I was a co-author of the paper, which is available from the Annals of Family Medicine website. The study struck a national nerve, and it has been reported widely in the news media, including highly-read Medscape.com, which ran an excellent account. You’ll need a free Medscape login and password to view it. Other accounts are published at Science Daily and Fox News.)

Here’s a summary sent to the media:

Chemical intolerance contributes to the illnesses of 1 in 5 patients but the condition seldom figures in their diagnosis, according to clinical research published July 9 in the journal Annals of Family Medicine.

Clinical tools are available to identify chemical intolerance but health care practitioners may not be using them, said lead author Dr. David Katerndahl, professor of family and community medicine at the University of Texas Health Science Center at San Antonio.

The study’s authors said physicians need to know how chemical intolerance affects certain people and understand that conventional therapies can be ineffective. Some patients would improve by avoiding certain chemicals, foods and even medical prescriptions, the authors said.

Patients with chemical intolerance go to the doctor more than others, are prone to having multi-system symptoms and are more apt to have to quit their job due to physical impairment, the authors said.

The study involved 400 patients who gave personal health information while waiting to be seen at primary care clinics in San Antonio. The researchers asked the patients to respond to 90 questions about their illnesses, mental health and ability to function.

In the end, the authors said, 20.3 percent of the patients questioned met the scientific criteria for chemical intolerance.

Researchers surveyed patients with chronic conditions such as allergies, asthma, diabetes and heart disease. They excluded patients who were at the clinics for acute conditions such as earaches, flu or bone fractures.

The origins of chemical intolerance have been the subject of much speculation, the authors acknowledge, but the condition is also understudied. People with chemical intolerance, or “CI,” are highly sensitive to common substances such as cleaning products, tobacco smoke, fragrances, pesticides, new carpet and auto exhaust.

“Apart from the debate over causality, the fact that so many patients meet the criteria for chemical intolerance holds particular relevance for primary care providers,” said Dr. Katerndahl.

Chemically intolerant individuals often have symptoms that affect multiple organ systems simultaneously, especially the nervous system. Symptoms commonly include fatigue, changes in mood, difficulty thinking and digestive problems.

Study co-authors are Dr. Claudia S. Miller, professor in environmental and occupational medicine, vice chair of family and community medicine, and director of the South Texas Environmental Education and Research (STEER) Program, among her roles; Dr. Raymond F. Palmer, associate professor of family and community medicine at the University of Texas Health Science Center at San Antonio; and Dr. Iris R. Bell, professor emeritus in the Department of Family and Community Medicine at the University of Arizona College of Medicine and research professor in the College of Nursing at the University of Arizona.

An added comment: Healthcare professionals as well as the public can assess chemical, food, drug and other intolerances using the QEESI, the Quick Environmental Exposure and Sensitivity Inventory, which I developed. It is available free for download.