Prenatal Phthalate Exposure Linked to Higher Risk of Atopic Dermatitis in Infants

Exposure to endocrine-disrupting chemicals during pregnancy and the earliest days of life may carry greater risks than previously recognized. A new study has found that exposure to these chemicals during this critical window is associated with a higher likelihood of atopic dermatitis in infants after birth.

A research team led by Professors Kang Mo Ahn, Ji Hyun Kim, and Minyoung Jung of the Department of Pediatrics at Samsung Medical Center, in collaboration with Professor Byung Eui Kim of National Jewish Health in the United States, analyzed the association between urinary phthalate metabolite concentrations in newborns and the development of atopic dermatitis. The findings were recently published in the Annals of Allergy, Asthma & Immunology (Impact Factor: 7.1).

Phthalates are chemical compounds used to make plastics more flexible and are widely found in toys, food packaging, and everyday household products. They are known endocrine disruptors capable of interfering with the body's hormonal systems.

These chemicals can enter the body through food, inhalation, or skin contact. During pregnancy, phthalates cross the placenta to reach the fetus, and they have also been detected in amniotic fluid, suggesting that exposure may continue throughout fetal skin development.

Once inside the body, phthalates are metabolized and excreted in urine, meaning that a newborn's urine can serve as a marker of environmental chemical exposure spanning from fetal development through the earliest days after birth.

The research team analyzed urine samples collected within 48 hours of birth from 61 newborns delivered at four hospitals in Korea between December 2020 and June 2022. The infants were followed for 12 months, during which 11 were diagnosed with atopic dermatitis.

The results showed that higher total concentrations of Di(2-Ethylhexyl) Phthalate (DEHP) metabolites were associated with roughly twice the risk of developing atopic dermatitis. Among infants in the high-exposure group—those above the study's threshold concentration of 12.18 μg/L—the risk was 8.31 times higher.

The research team attributed this association to phthalate-induced weakening of the skin barrier and heightened inflammatory responses.

In laboratory experiments, treating skin cells with phthalate concentrations comparable to everyday exposure levels increased the expression of inflammation-related cytokines, while levels of a key protein responsible for maintaining the skin barrier dropped by roughly one-third. Experiments using artificial skin models likewise showed increased water loss, indicating impaired skin barrier function.

"Exposure to endocrine-disrupting chemicals early in life may affect an infant's skin health," said Professor Minyoung Jung. "Because this is such a critical period for the development of the skin barrier and immune system, careful attention to environmental exposures during pregnancy and the newborn period is warranted."