Phthalate Exposures in the Neonatal Intensive Care Unit

Neonatal di-(2-ethylhexyl)phthalate exposure induces permanent alterations in secretory CRH neuron characteristics in the hypothalamus paraventricular region of adult male rats

Corticotrophin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN) play a critical role in the modulation of the hypothalamic-pituitary-adrenal (HPA) axis. Early-life exposure to di-(2-ethylhexyl) phthalate (DEHP) has been associated with an increased risk of developing psychiatric disorders in adulthood. The present work was designed to explore the impact of neonatal exposure to DEHP on adult PVN CRH neuronal activity. DEHP or vehicle was given to male rat pups from PND16 to PND22. Then, anxiety-like behaviors, serum corticosterone and testosterone, immunohistochemistry, western blotting, fluorescence in situ hybridization and acute ex vivo slice electrophysiological recordings were used to evaluate the influence of DEHP on adult PVN secretory CRH neurons. Neonatal DEHP-exposed rats exhibited enhanced anxiety-like behaviors in adults, with an increase in CORT. Secretory CRH neurons showed higher spontaneous firing activity but could be inhibited by GABAAR blockers. CRH neurons displayed fewer firing spikes, prolonged first-spike latency, depolarizing shifts in GABA reversal potential and strengthened GABAergic inputs, as indicated by increases in the frequency and amplitude of sIPSCs. Enhancement of GABAergic transmission was accompanied by upregulated expression of GAD67 and downregulated expression of GABABR1, KCC2 and GAT1. These findings suggest that neonatal exposure to DEHP permanently altered the characteristics of secretory CRH neurons in the PVN, which may contribute to the development of psychiatric disorders later in life.

Health system decarbonization on obstetric and newborn units

The healthcare industry makes up 4.6 % of greenhouse gas (GHS) emissions worldwide. Although it is not known what proportion of GHGs come from obstetric and newborn units, newborns and pregnant individuals are likely to face some of the largest consequences from climate change. We review the literature in the areas of decarbonization on labor and delivery (L&D) and neonatal units and describe innovations from the fields of surgery and anesthesia. Best practices for L&D include refining disposable equipment packs, decreasing the use of single-use medical devices, adequately triaging waste, and decreasing the use of potent anesthetic gases such as nitrous oxide and desflurane. In neonatal settings, similarly triaging waste and decreasing the use of plastics containing endocrine disrupting chemicals can lower the carbon and environmental footprint and improve neonatal health. Additionally, avoiding unnecessary cesarean deliveries and increasing breastfeeding practices are also likely to improve the carbon footprint of L&D and neonatal units.

Exposure of preterm neonates receiving total parenteral nutrition to phthalates and its impact on neurodevelopment at the age of 2 months

This prospective study assessed the exposure to phthalates of preterm neonates who received total parenteral nutrition (TPN) during their stay in the neonatal intensive care unit (NICU) and the risk of neurodevelopment delays at the age of 2 months. Our study recruited 33 preterm neonates who required TPN upon NICU admission. Urine samples for analyzing phthalate metabolites were obtained at admission and then daily until the last day of receiving TPN. Phthalates in the daily TPN received by the preterm neonates were analyzed. The neurodevelopment of the neonates was assessed using the Ages and Stages Questionnaire Edition 3 (ASQ-3). Diethyl phthalate and butyl benzyl phthalate were found in all TPN samples, while 27% and 83% contained dibutyl phthalate and di-(2-ethylhexyl) phthalate (DEHP), respectively. Yet, the daily dose of each phthalate that our preterm neonates received from TPN was much lower than the recommended tolerable limit. Urinary levels of monobenzyl phthalate and four metabolites of DEHP [i.e., mono-(2-ethylhexyl) phthalate (MEHP), mono-(2-ethyl-5-hydroxyhexyl) phthalate, mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP)] and the sum of four DEHP metabolites (∑₄DEHP) increased significantly in preterm neonates before discharge. However, these levels were not correlated with their phthalate parent compounds in TPN, suggesting other sources of exposure in the NICU. At 2 months, we found that urinary levels of mono-iso-butyl phthalate (MiBP), MECPP, MEHP, and ∑₄DEHP were inversely related to fine motor skills. After adjusting for head circumference, the inverse relationships remained significant, suggesting direct effects from phthalates. Given the extreme vulnerability of our population, it is critical to minimize exposure to phthalates during their NICU stay.

The cumulative risk assessment of phthalates exposure in preterm neonates

Phthalates are widely used plasticizers in various consumer products and medical devices, with some reporting as having estrogenic and anti-androgenic endocrine-disrupting effects. Premature neonates may be exposed to high levels of specific phthalates during hospitalization in the neonatal intensive care unit (NICU) because of reliance on multiple medical procedures that pose a possible health risk. The present study utilized seven urinary phthalate metabolites of dibutyl phthalate isomers [(di-n-butyl phthalate (DnBP) and diisobutyl phthalate (DiBP)], butylbenzyl phthalate (BBzP), and di(2-ethylhexyl) phthalate (DEHP) that had been previously measured in 33 preterm neonates sampled at hospital admission (N = 23) and daily during their NICU stay (N = 260). We aimed to perform: (1) cumulative risk assessment (CRA) using the volume and creatinine-adjusted models; (2) examine the temporal variability of CRA from repeated measures and (3) estimate the risk of cumulative exposure to phthalates based on their anti-androgenic and/or estrogenic properties. We multiplied the relative activity of individual phthalates exhibiting estrogenic or anti-androgenic effects by daily intake. For each preterm neonate, CRA was assessed based on the hazard index (HI) metric [the sum of hazard quotients] based on three reference doses for anti-androgenicity: the tolerable daily intake (TDI) from the European Food Safety Authority, the reference dose (RfD-AA) published in 2010 and newly revised published in 2020 (NRfD-AA). The metabolites of BBzP and DEHP were 2-23 fold higher in preterm neonates during their NICU stay. Median HIs increased in the order of HI_NRfDAA > HI_RfDAA > HI_TDI. In the creatinine-based model, 87% (92%), 87% (96%), and 100% (100%) of preterm neonates at admission (during NICU stay) showed HI_TDI, HI_RfD-AA, and HI_NRfD-AA exceeding 1, respectively with DEHP the most prevalent. The temporal reproducibility of HI (based on three reference doses) during preterm neonate stay in the NICU was high, with intra-class correlation coefficients ranging between 0.77 and 0.97, suggesting persistent exposure to phthalates. The four phthalates that preterm neonates were exposed to in the NICU exhibited estrogenic binding and anti-androgenic effects with median values (creatinine-based) of 98.7 and 56.9 μg/kg body weight/day, respectively. This was especially true for DEHP. The results indicate that preterm neonates in this NICU setting are probably at high risk of cumulative phthalate exposure with anti-androgenic properties that may have long-term adverse reproductive and developmental effects.

Phthalates cause a low-renin phenotype commonly found in premature infants with idiopathic neonatal hypertension

Since the 1970s, when the initial reports of neonatal hypertension related to renal artery thromboembolism were published, other secondary causes of neonatal hypertension have been reported. Those infants with no identifiable cause of hypertension were labeled with a variety of terms. Herein, we describe such infants as having idiopathic neonatal hypertension (INH). Most, but not all, of these hypertensive infants were noted to have bronchopulmonary dysplasia (BPD). More recently, reports described common clinical characteristics seen in INH patients, whether or not they had BPD. This phenotype includes low plasma renin activity, presentation near 40 weeks postmenstrual age, and a favorable response to treatment with spironolactone. A small prospective study in INH patents showed evidence of mineralocorticoid receptor activation due to inhibition of 11β-HSD2, the enzyme that converts cortisol to the less potent mineralocorticoid-cortisone. Meanwhile, phthalate metabolites have been shown to inhibit 11β-HSD2 in human microsomes. Premature infants can come in contact with exceptionally large phthalate exposures, especially those infants with BPD. This work describes a common low-renin phenotype, commonly seen in patients categorized as having INH. Further, we review the evidence that hypertension in INH patients with the low-renin phenotype may be mediated by phthalate-associated inhibition of 11β-HSD2. Lastly, we review the implications of these findings regarding identification, treatment, and prevention of the low-renin hypertension phenotype seen in premature infants categorized as having INH.

Risk Assessment of Phthalates and Their Metabolites in Hospitalized Patients: A Focus on Di- and Mono-(2-ethylhexyl) Phthalates Exposure from Intravenous Plastic Bags

Phthalate esters (PAEs) are plasticizers associated with multiple toxicities; however, no strict regulations have been implemented to restrict their use in medical applications in Lebanon. Our study aimed at assessing the potential risks correlated with phthalate exposure from IV bags manufactured in Lebanon. GC–MS analysis showed that di-(2-ethylhexyl) phthalate (DEHP) is the predominant phthalate found in almost all samples tested with values ranging from 32.8 to 39.7% w/w of plastic. DEHP concentrations in the IV solutions reached up to 148 µg/L, as measured by SPME-GC–MS/MS, thus resulting in hazard quotients greater than 1, specifically in neonates. The toxicity of DEHP is mainly attributed to its metabolites, most importantly mono-(2-ethylhexyl) phthalate (MEHP). The IV bag solution with the highest content in DEHP was therefore used to extrapolate the amounts of urinary MEHP. The highest concentrations were found in neonates having the lowest body weight, which is concerning, knowing the adverse effects of MEHP in infants. Our study suggests that the use of IV bags manufactured in Lebanon could pose a significant risk in hospitalized patients, especially infants in neonatal care. Therefore, Lebanon, as well as other countries, should start imposing laws that restrict the use of phthalates in medical IV bags and substitute them with less toxic plasticizers.