Hospitals rush newborns into a neonatal intensive care unit when those babies are struggling to survive. Although NICUs offer tender and vigilant care, many of the devices they rely on can expose their tiny patients to a relatively large dose of a hormone-mimicking pollutant, bisphenol A.
Newborns in intensive care excrete BPA, on average, at levels of around 17.8 micrograms per liter — well above the 0.45 µg/l typical of healthy infants, researchers report in the March Pediatrics. One of the most reliable indicators of BPA exposure was the level of care that a baby received, reflected by the number of devices used to deliver that care, notes nurse and exposure-science researcher Susan Duty of Simmons College in Boston. Breathing tubes, intravenous drug delivery lines and enclosed incubators are plastic, and several types of plastic can contain BPA.
Although researchers have not figured out what doses of BPA cause toxicity in people, several studies have linked elevated prenatal exposures to later behavioral problems (SN Online: 7/16/12) and moodiness (SN: 11/7/09, p. 12) in young children. Animal studies have also linked BPA exposure during development to feminization in males and risks of later hypertension and diabetes.
Duty’s team studied 55 infants, each of whom spent at least three days in a NICU in the Boston area, and most of whom had been born prematurely or were for other reasons very small. The researchers measured BPA in the breast milk and formula that these tiny babies consumed. Both nutritional sources had small, comparable amounts of BPA.
Regular urine samples then revealed how much BPA the babies had encountered.
The urine of newborns who had received treatment with four or more NICU devices contained 36.6 µg/l BPA on average. That level was almost three times as much as babies treated with three or fewer devices. “I was surprised,” Duty says, “especially because this particular [NICU] had taken considerable care to purchase products that were BPA-free whenever possible.”
Roughly one-fifth of the babies had been treated with at least four medical devices. Contrary to her expectations, Duty found that respiratory devices, not IV tubing, proved to have the strongest link with elevated BPA levels.
Another surprise was that prematurity accounted for 30 percent of the variability in urinary BPA, says Laura Vandenberg, a developmental biologist at Tufts University in Medford, Mass., who was not involved in the study.
One possible explanation for prematurity’s link to BPA levels emerged at the American Association for the Advancement of Science annual meeting in Boston. On February 17, researchers with the Food and Drug Administration’s National Center for Toxicological Research in Jefferson, Ark. reported rodent and monkey experiments showing that very young animals broke down BPA very slowly (SN: 3/9/13, p. 9).
If the animal data hold true for humans, Vandenberg says, immature babies may get a more potent punch from BPA simply because their bodies are relatively inefficient at breaking down the compound.