Lifestyle and Environment · Environmental Exposures
RRM Academy Synopsis
NICU infants using more DEHP plastic devices had higher urinary MEHP
A cross-sectional study of 54 newborns in two Boston-area intensive care units found that infants with the most device exposure had urinary MEHP levels 5.1 times those of infants with the least. DEHP softens plastic tubing. MEHP is its breakdown product in urine.
Key Findings
- Researchers observed 54 infants in two Boston-area level III NICUs in March and April 2003 and grouped them by devices in use: 13 low exposure, 24 medium, 17 high.
- Urinary MEHP rose step by step from the low exposure group to the medium group to the high group.
- After adjustment for institution and sex, the high group's urinary MEHP was 5.1 times the low group's (95% CI, 1.2–21.9; p = 0.03).
- With the same adjustment, the medium group's level was twice the low group's (95% CI, 0.5–7.4; p = 0.3). The test across all three groups gave p = 0.09.
- Hospitals differed: 12 of the 17 high-exposure infants were at institution B, where unadjusted urinary MEHP was higher (p = 0.002).
Interpretation
The paper reports a cross-sectional study. It gives one snapshot of device use and urine levels, which shows association. An investigator watched each infant's care and collected spot urine samples. The two hospitals differed in device use and urinary levels, so the adjusted result accounts for hospital. The authors note that their sample was small and that larger studies with follow-up are needed to learn the health risks, if any. The authors suggest the findings may generalize to infants in other level III units.
RRM Context
Restorative reproductive medicine asks what contributes to reproductive and developmental problems. The authors cite animal studies in which MEHP was toxic to development, reproduction, and the liver. Newborns under 3 months old have an immature system for clearing chemicals in urine. The authors call it glucuronidation and say it may slow MEHP clearance.
Abstract
Objective
Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer used in medical products made with polyvinyl chloride (PVC) plastic and may be toxic to humans. DEHP is lipophilic and binds noncovalently to PVC, allowing it to leach from these products. Medical devices containing DEHP are used extensively in neonatal intensive care units (NICUs). Among neonates in NICUs, we studied exposure to DEHP-containing medical devices in relation to urinary levels of mono(2-ethylhexyl) phthalate (MEHP), a metabolite of DEHP.
Design
We used a cross-sectional design for this study.
Participants
We studied 54 neonates admitted to either of two level III hospital NICUs for at least 3 days between 1 March and 30 April 2003.
Measurements
A priori, we classified the infants' exposures to DEHP based on medical products used: The low-DEHP exposure group included infants receiving primarily bottle and/or gavage feedings; the medium exposure group included infants receiving enteral feedings, intravenous hyperalimentation, and/or nasal continuous positive airway pressure; and the high exposure group included infants receiving umbilical vessel catheterization, endotracheal intubation, intravenous hyperalimentation, and indwelling gavage tube. We measured MEHP in the infants' urine using automated solid-phase extraction/isotope dilution/high-performance liquid chromatography/tandem mass spectrometry.
Results
Urinary MEHP levels increased monotonically with DEHP exposure. For the low-, medium-, and high-DEHP exposure groups, median (interquartile range) MEHP levels were 4 (18), 28 (58), and 86 ng/mL (150), respectively (p = 0.004). After adjustment for institution and sex, urinary MEHP levels among infants in the high exposure group were 5.1 times those among infants in the low exposure group (p = 0.03).
Conclusion
Intensive use of DEHP-containing medical devices in NICU infants results in higher exposure to DEHP as reflected by elevated urinary levels of MEHP.
