In a study published online in the Journal of Exposure Science and Environmental Epidemiology, Mount Sinai researchers identify noninvasive respiratory support as a source of phthalate exposure in the neonatal intensive care unit (NICU).

The study builds on earlier work by the same researchers that showed differences in behavior of hospitalized premature infants who had been exposed to higher levels of specific mixtures of phthalates. Phthalates are chemicals that make plastic medical equipment more flexible and durable.

The research team used these earlier findings to look for the source of these specific mixtures of phthalates, and found that noninvasive respiratory support equipment—nasal prongs delivering oxygen and air pressure—are a previously unrecognized source of significant phthalate exposure in the NICU.

“The finding that noninvasive respiratory support circuits may convey exposure to potentially neuroactive phthalates provides a possible avenue to improve neurobehavioral outcomes among NICU graduates,” says Annemarie Stroustrup, MD, MPH, Chief of Newborn Medicine, Mount Sinai Health System, and Associate Professor of Pediatrics; Environmental Medicine and Public Health; and Obstetrics, Gynecology, and Reproductive Science at the Icahn School of Medicine at Mount Sinai.

“Our study suggests exposure to common and clinically impactful phthalates still exists, despite efforts by hospital NICUs and medical equipment manufacturers to limit exposure by changing the materials used in feeding supplies. The big takeaway is that there is still more that can be done to protect developmentally vulnerable newborns in the hospital environment,” says Dr. Stroustrup.

In the United States, more than 300,000 infants are admitted to NICUs every year. The majority of these patients, an estimated 200,000 inpatients, require noninvasive respiratory support during their hospitalization, sometimes for weeks or even months.

Phthalates are a family of industrial chemicals that are bonded to plastic materials to enhance flexibility and durability. Because they are not chemically integral to the plastic scaffold, phthalates leach from the solid plastic matrix, particularly in hot and humid conditions, such as are found in the neonatal incubator. With a chemical structure that is similar to naturally occurring steroid hormones, phthalates belong to a class of synthetic chemicals referred to as “endocrine disruptors.” As noted above, in a previous study published in PLOS ONE, also led by Dr. Stroustrup, researchers documented an association between NICU-based phthalate exposure and neurobehavioral performance in infancy. The current study is an extension of this inquiry.

In this study, premature newborns with birth weight less than 1,500 grams were recruited via their parents to participate in a prospective environmental health cohort during their NICU hospitalization. Exposure to specific NICU equipment was recorded daily during the NICU hospitalization. Researchers analyzed 149 urine specimens from 71 infants for the presence of phthalate metabolites.

In initial analyses, exposure to medical equipment was directly related to phthalate levels, with biomarkers for the most commonly studied phthalate, di(2- ethylhexyl)phthalate, abbreviated as DEHP, 95% to 132% higher for infants exposed to specific medical equipment types compared to those without that equipment exposure.

This association was mirrored for clinically relevant phthalate mixtures, whether composed of DEHP metabolites or not. In models accounting for concurrent equipment use, exposure to respiratory support was associated with DEHP biomarkers that were 50% to 136% higher in exposed infants compared to unexposed infants.

“If validated in larger studies, this research could pave the way for improvements in medical equipment manufacturing to focus on reductions in hospital-based exposure to clinically important phthalates for vulnerable populations,” says Dr. Stoustrup.

—Newswise