Dust collected from the homes of children with persistent allergic symptoms had higher levels of common chemical additives

Dust collected from the homes of children with persistent allergic symptoms had higher levels of certain phthalates, a class of common chemical additives, in it than dust found in homes of children without symptoms, according to a study published in the October 2004 issue of the peer-reviewed journal Environmental Health Perspectives (EHP).

(In honor of Children’s Health Month, the October issue of EHP is focused specifically on children’s environmental health.) The study of 198 symptomatic children and 202 control children found associations between certain phthalate compounds and asthma, rhinitis, and eczema. The study shows that phthalates, within the range of what is normally found in indoor environments, are associated with allergic symptoms in children.

Phthalates are widely used in plastic products such as food containers and wraps to add flexibility. They are also used in skin softeners and moisturizers, nail polishes, insect repellants, shower curtains, hairsprays, building products including polyvinyl chloride (PVC) flooring, and more. Because phthalates leach out of these products, they've become a ubiquitous environmental contaminant.

The increase in the incidence of allergy and asthmas in the developed world over the last 30 years suggests that changes in environmental exposure, rather than genetic changes, are the cause. The worldwide production of compounds from phthalates has risen from very low levels at the end of World War II to approximately 3.5 million metric tons per year.

This study, of children 1 to 6 years of age in the county of Varmland, Sweden, also found that PVC flooring in the child’s bedroom was positively associated with symptoms. Different phthalate compounds in dust samples were associated with different symptoms. The researchers suggest that their study design was stringent, and the actual impact may be larger.

“To be included as a ‘case,’ a child was required to have at least two symptoms…meaning it was more difficult to find associations between single symptoms and exposures,” the study authors write. “The associations between selected building factors and single symptoms is meaningful and possibly underestimates true associations.”

The researchers report that the associations held up, even when potential confounding factors were considered.

“Phthalates are all around us in a host of plastic products,” said Dr. Jim Burkhart, science editor for EHP. “This study suggests that they may be having a direct influence on the health of a great number of children. We need to continue research in this area to balance the benefits of plastics with the need to battle asthma and allergies in children.”

The lead author of the study was Carl-Gustaf Bornehag of the Swedish National Testing and Research Institute. Other authors were Jan Sundell, Charles J. Weschler, Torben Sigsgaard, Bjorn Lundgren, Mikael Hasselgren, and Linda Hagerhed-Engman. The article is available free of charge at http://ehp.niehs.nih.gov/docs/2004/7187/abstract.html.