According to the U.S. Centers for Disease Control and Prevention, allergies to foods such as milk, wheat, peanuts, soy and shellfish shot up 18 percent in the United States between 1997 and 2007.
Other studies have shown that environmental pollution is on the rise. Researchers at the Albert Einstein College of Medicine in New York suggest there is a link between the two trends.
They analyzed health data from the 2005-2006 U.S. National Health and Nutrition Examination Survey, in which more than 10,000 Americans took part. The researchers identified more than 2,500 individuals with measurable levels of dichlorophenols — chemicals found in pesticides and chlorinated water — in their urine. The study team, led by allergist and immunologist Elina Jerschow, narrowed their sample down to 2,200. Out of this group, Jerschow says, 411 of the subjects had some sort of food allergy.
“People who had high levels of dichlorophenols were about 80 percent more likely to have allergic sensitization to foods than people who had low levels of dichlorophenols in the urine," she said.
The team found that more than a thousand of the participants had an environmental allergy that was not linked to the chemicals.
There’s evidence that people with protected immune systems, which have not been challenged by foreign substances, are ultimately more likely to develop allergies. Jerschow thinks that may help explain her study's findings.
“If you think about people who have a lot of allergies, they may be particularly prone to keep the environment specifically clean," she said. "And so they may use more bactericidal agents and more insecticides and pesticides and that’s how they can have more levels of dichlorophenols.”
People are exposed to dichlorophenols not only through tap water, but handling fruits and vegetables, according to Jerschow, who says pesticide residues on farm produce may be a greater source of exposure to the chemicals than tap water.
Allergic reactions from food range from a mild rash to anaphylaxis, a systemic reaction that can lead to death within a few minutes.
An article by Elina Jerschow and colleagues on food allergies and dichlorophenols is published in the Annals of Allergy, Asthma and Immunology.