Tag Archive for: DEHP

Illustration showing phthalate exposure during cardiopulmonary bypass

Pediatric heart patients exposed to plastic chemicals during cardiopulmonary bypass

Children undergoing cardiac surgery using cardiopulmonary bypass are exposed to high levels of plastic chemical additives called phthalates, including DEHP, according to the largest single center study to date to measure this exposure. The findings were authored by a multi-disciplinary group from Children’s National Hospital and appear in the journal Transfusion.

What is it?

Di(2-ethylhexyl) phthalate (DEHP) is one of the most commonly used plasticizers in polyvinyl chloride (PVC) plastics, making up 40% to 80% of the finished weight of medical-grade tubing and blood storage bags. The study’s primary goal was to quantify three aspects of pediatric cardiac surgery: the phthalate exposure with and without cardiopulmonary bypass (the heart and lung machine), the time it takes for phthalates to clear after surgery and any correlations between higher phthalate exposures and postoperative complications.

The authors suggested that, like infants in the NICU exposed to various medical equipment, children on cardiopulmonary bypass are likely exposed to significant DEHP levels from blood products, bypass circuit components, and endotracheal tubes, potentially impacting postoperative outcomes.

Why does it matter?

Despite daily phthalate exposure in the general population, studies link high phthalate levels to developmental delays in language and motor skills. Phthalates accumulate in the hearts of infants undergoing umbilical catheterizations or blood transfusions. This is worrisome as even low-dose environmental exposure correlates with higher risks of overall and cardiovascular-related mortality.

Knowing these risks exist, it is important to understand these exposures, what causes them and implement measures to mitigate them, safeguarding medically fragile children. Regulatory actions in NICUs have reduced DEHP-containing plastics, yet no such efforts have been made for children on cardiopulmonary bypass.

The study also found some associations between postoperative complications and higher levels of phthalates, especially in younger children. They write, “it is plausible that a combination for risk factors (young age, longer CPB duration, increased phthalate exposure) collectively contribute to these complications.” More research is needed to understand the association and the impact of phthalates on how children recover from surgery.

Children’s National leads the way

The study involved 110 pediatric patients undergoing 122 cardiac surgeries at Children’s National, marking the largest single-center investigation into phthalate exposures in cardiac surgery. Led by a multidisciplinary team, including divisions of Transfusion Medicine and Cardiac Surgery, along with researchers from the Sheikh Zayed Institute for Pediatric Surgical Innovation, the study’s findings are some of the first to quantify that pediatric cardiac surgery patients are exposed to greater levels of these phthalate chemicals from plastic medical products, with increasing exposure the longer they require cardiopulmonary bypass. This is especially true when the bypass uses a prime based on red blood cells.

What’s next

The teams are exploring strategies to minimize chemical exposures, such as:

  • Using freshly donated blood products (made possible at Children’s National by the unique on-site Blood Donor Center).
  • Storing blood in DEHP-free storage bags prior to use when possible.
  • Increasing use of cell-saver equipment, which washes red blood cell products and removes extracellular contaminants.
  • At Children’s National, cardiac surgeons prioritize the use of recently collected, washed red blood cells in cardiopulmonary bypass cases, especially for younger and/or smaller patients.

“These exposures will affect patients undergoing pediatric cardiac surgery at any institution,” says first author Devon Guerrelli, M.S. “But we hope understanding what’s causing the exposures will help operating rooms around the United States take immediate small steps, like using washed red blood cells, to begin mitigating these exposures as soon as possible.”

Senior author Nikki Posnack, Ph.D., adds that the implications of phthalates on health are tremendous. “Studies have shown that heightened phthalate exposure increases your risk of all-cause and cardiovascular mortality,” she said. “Now is the time to support research efforts to understand how plastic chemicals damage the heart and to investigate strategies to reduce their overall impact.”

Read the study:
Prevalence and clinical implications of heightened plastic chemical exposure in pediatric patients undergoing cardiopulmonary bypass

pile of plastic bottles

The linkage between chemicals used in plastics and cardiovascular disease

pile of plastic bottles

For people across the globe, plastics are synonymous with modern life and it’s impossible to avoid exposure to them, including clinical environments where a variety of frequently used materials, such as tubing and blood storage bags, are made from plastics.

For people across the globe, plastics are synonymous with modern life and it’s impossible to avoid exposure to them, including clinical environments where a variety of frequently used materials, such as tubing and blood storage bags, are made from plastics. Led by Nikki Posnack, Ph.D, principal investigator at The Sheikh Zayed Institute for Pediatric Surgical Innovation at Children’s National Hospital, a team of Children’s National researchers has been studying the potential effects of chemicals found in plastics, such as BPA and DEHP, as possible contributors to cardiovascular disease.

Along with conducting proprietary studies of the potential effects, Posnack and her team recently reviewed available scientific studies to further identify and illuminate the potential links between exposure to the synthetic additives contained in plastics and cardiovascular mortality. The article was published this month in Nature Reviews Cardiology.

In the article Posnack cites a 10-year longitudinal study with the finding that high exposure to BPA was associated with a 46-49% higher hazard ratio for cardiovascular and all-cause mortality, compared with low exposure to BPA.

“Plastics may be indispensable materials, but their ubiquity does raise concerns about the effects of our continuous exposure to plasticizer additives like di(2-ethylhexyl) phthalate (DEHP) and synthetic chemicals used to create polymers like BPA,” said Posnack. “Although disease causation can be difficult to pinpoint in population and epidemiological studies, experimental work has clearly demonstrated a direct link to plastic chemicals and cardiac dysfunction. It is clear that future collaborative endeavors are necessary to bridge the gap between experimental, epidemiological and clinical investigations to resolve the impact of plastics on cardiovascular health.”

Nikki Gillum Posnack

Nikki Posnack, Ph.D, principal investigator at The Sheikh Zayed Institute for Pediatric Surgical Innovation at Children’s National Hospital.

Posnack added that, given the omnipresence of plastics and their related chemicals, biomonitoring studies have reported detectable levels of DEHP and BPA in 75-90% of the population. Occupational or clinical environments can also result in elevated exposures to these dangerous chemicals. Previous epidemiological studies have reported links between elevated urinary levels of phthalate or bisphenol, common additives in plastic, and an increased risk of coronary and peripheral artery disease, chronic inflammation, myocardial infarction, angina, suppressed heart rate variability and hypertension.

Additionally, available research has shown that incomplete polymerization or degradation of BPA-based plastic products can result in unsafe human exposure to BPA. Despite these links, the article points out, both BPA and DEHP are still manufactured in high volumes and are used to produce a wide variety of consumer and commercial products.

Further exploring implications for pediatrics, a June 2020 article published by Posnack in Birth Defects Research looks at the potential effects of plastic chemicals on the cardiovascular health of fetal, infant and pediatric groups. The article highlighted experimental work that suggests plasticizer chemicals such as bisphenols and phthalates may exert negative influence on pediatric cardiovascular health. The article systematically called out areas of concern supported by research findings. Also addressing current gaps in knowledge, Posnack outlined future research endeavors that would be needed to resolve the relationship between chemical exposures and the impact on pediatric cardiovascular physiology.

In related work, Posnack and her team are expanding their work on plastics used in blood bags to also investigate the role of blood storage duration on health outcomes. A recently published first study demonstrates that “older” blood products (stored 35 or more days) directly impact cardiac electrophysiology, using experimental models. Published October 22, 2020 in the Journal of the American Heart Association, the study concludes that the cardiac effects are likely caused by biochemical alterations in the supernatant from red blood cell units that occur over time, including but not limited to, hyperkalemia (elevated potassium levels).

Plastic leaching illustration

Plasticizer interaction with the heart

Calling an ambulance during an emergency, emailing a journal article before a 5 p.m. deadline and maintaining conditions during the fifth week of a 6-week lab study, without altering the light or temperature, requires electricity and translates into time, money and lives saved. During critical moments, we appreciate the tiny particles and ions in electric currents that power our phones, computers or laboratory equipment. We seldom think about the speed of these connections or potential disruptors when conditions are stable. The same applies to the electric currents, or electrophysiology, of our heart.

Arrhythmias affect millions of Americans but can be controlled with routine screenings and preventive care. In an intensive care setting, helping a patient maintain a steady heart rate, especially if they are at risk for cardiac complications, may support a faster recovery, shorter hospital stay, reduced health care costs and improved health outcomes, such as avoiding complications from heart failure or stroke.

A preclinical study, entitled “Plasticizer Interaction With the Heart,” appears in the July issue of Circulation: Arrhythmia and Electrophysiology and examines the role plastic exposure, akin to exposure in a medical setting, has on heart rhythm disruptions and arrhythmias.

changes in heart rhythm due to plastics

New preclinical research finds acute exposure to MEHP, a common plasticizer used in medical equipment, increases risk for alternans and arrhythmias, disruptions in heart rhythm. The images above show changes in heart rhythm, measured by slowed epicardial conduction velocity, enhanced action potential prolongation and impaired sinus node activity.

The research team, led by researchers at Children’s National Health System, discovered increased risks for irregular heart rhythms after exposing intact, in vitro heart models to 30 minutes of mono-2-ethylhexyl phthalate (MEHP), a metabolite from Di-2-ethylhexyl phthalate (DEHP). DEHP is a chemical commonly used to make plastics pliable in FDA-approved medical devices. This phthalate accounts for 40% of the weight of blood storage bags and up to 80% of the weight of tubes used in an intensive care setting, such as for assisted feeding or breathing, and for catheters used in diagnostics or to conduct minimally invasive cardiac procedures.

The team chose to study the heart’s reaction to 60 µM of MEHP, a level comparable to stored blood levels of MEHP observed in pediatric patients and in neonatal exchange transfusion procedures. They found 30-minute exposure to MEHP slowed atrioventricular conduction and increased the atrioventricular node effective refractory period. MEHP prolonged action potential duration time, enhanced action potential triangulation, increased the ventricular effective refractory period and slowed epicardial conduction velocity, which may be due to the inhibition of Nav 1.5, or sodium current.

“We chose to study the impact of MEHP exposure on cardiac electrophysiology at concentrations that are observed in an intensive care setting, since plastic medical products are known to leach these chemicals into a patient’s bloodstream,” says Nikki Gillum Posnack, Ph.D., a principal investigator with the Sheikh Zayed Institute for Pediatric Surgical Innovation at Children’s National and an assistant professor of pediatrics at the George Washington University School of Medicine and Health Sciences. “In critical conditions, a patient may have a blood transfusion, require extracorporeal membrane oxygenation, undergo cardiopulmonary bypass or require dialysis or intravenous fluid administration. All of these scenarios can lead to plastic chemical exposure. Our research team wants to investigate how these plastic chemicals can impact cardiac health.”

In this review, Dr. Posnack’s team mentions one reason for the observed changes in the preclinical heart models may be due to the structure of phthalates, which resemble hormones and can interfere with a variety of biological processes. Due to their low molecular weight, these chemicals can interact directly with ion channels, nuclear receptors and other cellular targets.

Existing epidemiological research shows associations between exposure to phthalates and adverse health outcomes, including metabolic disturbances, reproductive disorders, inflammatory conditions, neurological disorders and cardiovascular disease. This is the first study to examine the link between cardiac electrophysiology in intact hearts and exposure to MEHP, comparable to levels observed in an ICU.

Dr. Posnack’s team previously found DEHP reduced cellular electrical coupling in cardiomyocyte cell models, which slowed conduction velocity and produced an arrhythmogenic phenotype. A microarray analysis found heart cells treated with DEHP led to mRNA changes in genes responsible for contracting and calcium handling. Another preclinical study showed DEHP altered nervous system regulation of the cardiovascular system. Future studies to expand on this research may include the use of larger preclinical models or human assessments. For the latter, stem cell-derived cardiomyocytes can be used to compare the safety profile of plastic chemicals with potential alternatives.

An accompanying editorial, entitled “Shocking Aspects of Nonconductive Plastics,” authored by cardiology researchers at the University of Wisconsin-Madison, puts this novel research into perspective. Like Dr. Posnack, the team notes that while the clinical impact plasticizers have on heart health still needs to be determined, the work contributes to compelling data among multiple researchers and shows DEHP and MEHP are not inert substances.

“Toxic plasticizers in children’s toys and baby products hit public headlines 20 years ago, but exposure to these compounds is up to 25x higher in patients undergoing complex medical procedures,” write the University of Wisconsin-Madison researchers. “We readily (and unknowingly) administer these compounds, and at times in high quantity, to some of our most vulnerable patients. This work highlights the need for further investigation into short and long-term plasticizer exposure on cardiac electrophysiology.”

The Agency for Toxic Substances and Disease Registry (ATSDR), part of the Centers for Disease Control and Prevention (CDC), released a public health statement about DEHP in 2002, noting more research in humans is needed to issue formal warnings against this phthalate.

ATSDR states there is no conclusive evidence about the adverse health effects of children exposed to DEHP in a medical setting, such as procedures that require the use of flexible tubing to administer intravenous fluids or medication. However, the CDC statement includes limits of DEHP exposure, based on preclinical models, used to guide upper DEHP limits in consumer products, including food packaging, drinking water, and air quality in the workplace.

“It’s important to note that this was a preliminary study performed on an ex vivo model that is largely resilient to arrhythmias”, says Rafael Jaimes III, Ph.D., the first author of the study and a senior scientist at Children’s National. “Due to the nature of the design, it was somewhat alarming that we found such significant effects. I predict that electrophysiological disturbances will be more pronounced in models that more closely resemble humans. These types of models should absolutely be studied.”

“And, importantly, our results may incentivize the development and use of new products that are manufactured without phthalates,” Dr. Posnack adds.

These questions are powering Dr. Posnack and her team through a decade-long, multi-institution research investigation to understand how plastic chemicals and medical device biomaterials can impact cardiac health.

Additional study authors for this paper include Damon McCullough, B.S., Bryan Siegel, M.D., Luther Swift, Ph.D., Daniel McInerney, B.S., and James Hiebert, B.S., with the Sheikh Zayed Institute for Pediatric Surgical Innovation and Children’s National Heart Institute, part of Children’s National Health System in Washington, D.C.; Erick A. Perez-Alday, Ph.D., and Larisa G Tereshchenko, M.D., Ph.D., with the Knight Cardiovascular Institute at Oregon Health and Science University in Portland, Ore.; Javier Saiz, Ph.D., and Beatriz Trenor, Ph.D., with Ci2B-Universitat Politecnica de Valencia in Spain and Jiansong Sheng, Ph.D., from CiPA Lab, LLC, in Rockville, Md.

The study was supported by the National Institutes of Health (R00ES023477 and R01HL139472), Children’s Research Institute and Children’s National Heart Institute. NVIDIA corporation provided graphics processing, with partial support by the Direccion General de Politica Cientifica de la Generalitat Valenciana (PROMETEU2016/088).

NPosnack-Heart-image

NIH funding to improve devices and safeguard cardiovascular health

Nearly 15 million blood transfusions are performed each year in the U.S., and pediatric patients alone receive roughly 425,000 transfused units. Endocrine-disrupting chemicals, such as bisphenol A and di-2-ethylhexyl-phthalate (DEHP), can leach from some plastic devices used in such transfusions. However, it remains unclear how many complications following a transfusion can be attributed to the interplay between local and systemic reactions to these chemical contaminants.

NPosnack-Heart-image

Top: Live, excised heart that is being perfused with a crystalloid buffer via the aorta. The heart is stained with a voltage-sensitive fluorescent dye, which is excited by an LED light source. Bottom, right: Cardiac action potentials are optically mapped across the epicardial surface in real-time by monitoring changes in the fluorescence signal that are proportional to changes in transmembrane voltage. Bottom, left: An activation map (middle) depicts the speed of electrical conduction across the heart surface. Credit: Rafael Jaimes, Ph.D.; Luther Swift, Ph.D.; Manelle Ramadan, B.S.; Bryan Siegel, M.D.; James Hiebert, B.S., all of Children’s National Health System; and Daniel McInerney, student at The George Washington University.

The National Heart, Lung and Blood Institute within the National Institutes of Health has awarded a $3.4 million, five-year grant to Nikki Gillum Posnack, Ph.D., assistant professor at the Children’s National Heart Institute within the Sheikh Zayed Institute for Pediatric Surgical Innovation (SZI) at Children’s National Health System, to answer that question and to provide insights that could accelerate development of safer biomaterials.

According to the Food and Drug Administration, patients who are undergoing IV therapy, blood transfusion, cardiopulmonary bypass or extracorporeal membrane oxygenation or who receive nutrition through feeding support tubes have the potential to be exposed to DEHP.

Posnack led a recent study that found that an experimental model exposed to DEHP experienced altered autonomic regulation, heart rate variability and cardiovascular reactivity and reported the findings Nov. 6, 2017, in the American Journal of Physiology. The pre-clinical model study is the first to show such an association between phthalate chemicals used in everyday medical devices like IV tubing and cardiovascular health.

In the follow-on research, Posnack and colleagues will:

  • Use in vivo and whole heart models to define the extent to which biomaterial leaching and chemical exposure alters cardiovascular and autonomic function in experimental models
  • Determine whether biocompatibility and incidental chemical exposure are linked to cardiovascular and autonomic abnormalities experienced by pediatric patients post transfusion
  • Compare and contrast alternative biomaterials, chemicals and manufacturing techniques to identify safer transfusion device options.

“Ultimately, we hope to strengthen the evidence base used to inform decisions by the scientific, medical and regulatory communities about whether chemical additives that have endocrine-disrupting properties should be used to manufacture medical devices,” Posnack says. “Our findings also will highlight incentives that could accelerate development of alternative biomaterials, additives and fabrication techniques to improve safety for patients undergoing transfusion.”

Nikki Gillum Posnack

Experimental model study links phthalates and cardiovascular health

Nikki Gillum Posnack

“Because phthalate chemicals are known to migrate out of plastic products, our study highlights the importance of adopting safer materials, chemical additives and/or surface coatings for use in medical devices to reduce the risk of inadvertent exposure,” explains study senior author Nikki Gillum Posnack, Ph.D.

An experimental model exposed to di-2-ethylhexyl-phthalate (DEHP), a chemical that can leach from plastic-based medical devices, experienced altered autonomic regulation, heart rate variability and cardiovascular reactivity, according to a study published online Nov. 6, 2017 by the American Journal of Physiology. The pre-clinical model study is the first to show such an association between phthalate chemicals used in everyday medical devices like IV tubing and cardiovascular health.

“Plastics have revolutionized medical devices, transformed how we treat blood-based diseases and helped to make innovative cardiology procedures possible,” says Nikki Gillum Posnack, Ph.D., study senior author and assistant professor at the Children’s National Heart Institute within the Sheikh Zayed Institute for Pediatric Surgical Innovation (SZI) at Children’s National Health System. “Because phthalate chemicals are known to migrate out of plastic products, our study highlights the importance of adopting safer materials, chemical additives and/or surface coatings for use in medical devices to reduce the risk of inadvertent exposure.”

According to the Food and Drug Administration, patients who are undergoing IV therapy, blood transfusion, cardiopulmonary bypass or extracorporeal membrane oxygenation or who receive nutrition through feeding support tubes have the potential to be exposed to DEHP.

Patients undergoing extensive interventions to save their lives may be exposed to multiple plastic-based devices that supply oxygen and nutrition or that pump newly oxygenated blood to oxygen-starved organs.

“These interventions keep very fragile kids alive. What’s most important is getting patients the care they need when they need it,” Posnack says. “In the biomaterials field, our ultimate goal is to reduce inadvertent risks to patients that can result from contact with plastic products by identifying replacement materials or safer coatings to lower overall risk.”

In order to assess the safety of phthalate chemicals used in such medical devices, the Children’s-led research team implanted adult experimental models with radiofrequency transmitters that monitored their heart rate variability, blood pressure and autonomic regulation. Then, they exposed the experimental models to DEHP, a softener used in making the plastic polymer, polyvinyl chloride, flexible.

DEHP-treated pre-clinical models had decreased heart rate variability with lower-than-normal variation in the intervals between heart beats. The experimental models also showed an exaggerated mean arterial pressure response to ganglionic blockade. And in response to a stressor, the experimental models in the treatment group displayed enhanced cardiovascular reactivity as well as prolonged blood pressure recovery, according to the study team.

“The autonomic nervous system is a part of the nervous system that automatically regulates such essential functions as blood pressure and breathing rate without any conscious effort by the individual,” Posnack adds. “Because alterations in the autonomic balance provide an early warning sign of trouble – before symptoms of hypertension or atherosclerosis manifest – our findings underscore the importance of additional studies to explore the potential impact of phthalate chemicals on organ function.”

Billie Lou Short, M.D., chief of Children’s Division of Neonatology, called the paper an “important study” that builds on a foundation laid in the late 199os by Children’s researchers who were the first to show that plasticizers migrated from tubing in the extracorporeal membrane oxygenation (ECMO) circuit. Children’s researchers also led a study published in 2004 that evaluated the effect of plasticizers on the human reproductive system. A small number of adolescents who had undergone ECMO as newborns did not experience the complications that had been seen in in experimental models, Dr. Short says.

Posnack’s study co-authors include Rafael Jaimes III, Ph.D., SZI staff scientist; Meredith Sherman, SZI research technician; and Adam Swiercz, Narine Muselimyan and Paul J. Marvar, all of The George Washington University.