Children and young adults with high blood levels of dichlorodiphenyldichloroethylene (DDE) — a chemical used in pesticides — may be twice as likely to develop celiac disease as their peers who haven’t had much exposure to this pollutant, according to a study published in May 2020 in Environmental Research.
For the study, researchers tested for toxic chemicals in blood samples from 30 children and young adults ranging in age from 3 to 21 years old who had recently been diagnosed with celiac disease. They also ran blood tests for 60 young people who didn’t have celiac disease but were similar in age, gender, and race to the participants with this diagnosis.
In addition to DDE, researchers also looked for polybrominated diphenyl ethers (PBDEs) — fire-retardant chemicals used in products like curtains, baby clothes, and couches — and perfluoroalkyls (PFAs) — nonstick chemicals used in Teflon and other cookware.
Among female participants, high blood levels of PFAs were associated with a five to nine times greater chance of developing celiac disease, the study found. Males, meanwhile, had a doubled risk of celiac disease when they had high blood levels of PBDEs.
“We already knew synthetic chemicals can disrupt basic immune functions,” says Leonardo Trasande, MD, the co-lead investigator of the study and chief of environmental pediatrics at NYU Langone in New York City.
“Autoimmune conditions like celiac disease arise from immune disruption, but because it is relatively rare, few studies have examined exposure in humans as a risk,” Dr. Trasande says.
Up to about 1 in 141 Americans have celiac disease, according to the National Institutes of Health (NIH). The digestive disorder damages the small intestine, and is triggered by foods containing gluten. It can’t be cured, but people can manage symptoms by avoiding foods with gluten, such as wheat, barley, and rye.
While the exact cause is unknown, it does run in families, and genetics and environmental factors are thought to play a role. The condition is more common in Caucasians, and is diagnosed more often in women than men, according to the NIH.
The current study is the first to make a connection between exposure to chemicals in the environment and celiac disease, says Luz Claudio, PhD, a professor of environmental medicine and public health at the Icahn School of Medicine at Mount Sinai in New York City.
“There was previous evidence to suggest that these chemicals can disrupt the immune system, either directly or by way of affecting hormones that help modulate it, and could produce autoimmune reactions such as those seen in diseases like celiac,” says Dr. Claudio, who wasn’t involved in the study. “Thus, it was conceivable that exposure to these types of chemicals could play a role in risk of celiac disease.”
All the chemicals in the study — known as persistent organic pollutants (POPs) — can disrupt the immune system and contribute to a variety of diseases in childhood that result from immune system dysregulation, according to the World Health Organization.
Some previous studies, mostly in animals, have linked PBDEs, PFAs, and DDE to thyroid disorders and type 1 diabetes as well as immune system abnormalities. None of these studies were controlled experiments designed to prove that the pollutants directly caused specific health problems, and none focused on celiac disease.
“Even though previous studies have not looked at this health end point specifically, it is plausible that POPs like PBDEs and PFAS are linked to celiac disease because these chemicals are known to be endocrine disruptors or immunotoxins,” says Xindi Hu, a doctor of science and a data scientist at Mathematica in Oakland, California, who wasn’t involved in the study.
While the current study is small, and larger studies are needed to confirm the results, it offers fresh evidence that parents should do what they can to limit kids’ exposure to these pollutants, Trasande says.
DDE is a chemical by-product of DDT, a pesticide widely used in agriculture and to kill mosquitos that carry malaria. It was banned in the United States in the 1970s but is still used in some other countries. People can be exposed to DDE by eating contaminated foods, and through exposure to polluted air, soil, and drinking water, according to the Centers for Disease Control and Prevention (CDC).
PFAs are found in a wide variety of consumer products, according to the CDC. These include:
- Microwave popcorn bags, pizza boxes, candy wrappers, and fast food containers
- Nonstick cookware
- Water resistant clothes
- Household cleaners
- Cosmetics and personal care products
- Paints, varnishes, and sealants
PBDEs are chemical blends added to a range of products to make them fire resistant, including clothing, upholstered furniture, carpets, drapes, and older computers and electronics, according to the CDC. Some chemicals are no longer used, but people may still have things containing PDBEs in their homes. People can be exposed to PDBEs through contaminated water, soil, food, and air — and inhale PDBEs in household dust.
“Because consumer products are common exposure sources for PFAS and PBDEs, consumers should read the labels and pay attention to ingredients when they make purchases,” Dr. Hu says.