Circulating concentrations of di(2-ethylhexyl) phthalate and its de-esterified phthalic acid products following plasticizer exposure in patients receiving hemodialysis

Organic Pollutant Exposure and CKD: A Chronic Renal Insufficiency Cohort Pilot Study

Rationale & Objective

This study aimed to assess the effect of exposure to organic pollutants in adults with chronic kidney disease (CKD).

Study Design

This was a cross-sectional and longitudinal analysis.

Setting and Participants

Forty adults enrolled in the Chronic Renal Insufficiency Cohort (CRIC).

Exposures

Exposure at baseline and longitudinally to various organic chemical pollutants.

Outcomes

The outcomes were as follows: death; composite of congestive heart failure, myocardial infarction, and stroke; event-free survival from kidney failure or ≥50% decline in estimated glomerular filtration rate (eGFR); and longitudinal trajectory of eGFR.

Analytical Approach

We used high-performance liquid chromatography with tandem mass spectrometry to measure urinary concentrations of bisphenols, phthalates, organophosphate pesticides, polycyclic aromatic hydrocarbons, melamine, and cyanuric acid at years 1, 3, and 5 after enrollment in the CRIC. Univariate and multivariable logistic regression were used to examine the association of individual compounds and classes of pollutants with the outcomes. The Cox proportional hazards model and Kaplan-Meier method were used to calculate hazard ratios and 95% CIs for each class of pollutants.

Results

Median baseline eGFR and urinary protein-to-creatinine ratio were 33 mL/min/1.73 m2 and 0.58 mg/g, respectively. Of 52 compounds assayed, 30 were detectable in ≥50% of participants. Urinary chemical concentrations were comparable in patients with CKD and healthy individuals from contemporaneous National Health and Nutrition Examination Survey cohorts. Phthalates were the only class with a trend toward higher exposure in patients with CKD. There was an inverse relationship between exposure and the eGFR slopes for bisphenol F, mono-(3-carboxypropyl) phthalate, mono-benzyl phthalate, mono-[2-(carboxymethyl)hexyl] phthalate, and melamine. There were no associations between organic pollutant exposure and cardiovascular outcomes.

Limitations

Small sample size, evaluation of single rather than combined exposures.

Conclusions

Simultaneous measurement of multiple organic pollutants in adults with CKD is feasible. Exposure levels are comparable with healthy individuals. Select contaminants, especially in the phthalate class, may be associated with more rapid deterioration in kidney function.

How does continuous venovenous hemofiltration theoretically expose (ex-vivo models) inpatients to diethylhexyladipate, a plasticizer of PVC medical devices?

Continuous venovenous hemofiltration (CVVH) is widely used in intensive care units to treat patients with acute kidney injury requiring renal replacement therapy. The medical devices (MD) used for CVVH include a hemofilter and tubings made of plasticized PVC. Due to its known reprotoxicity, diethylhexyl phthalate (DEHP) has been replaced by alternatives such as diethylhexyladipate (DEHA) in some of these tubings. The migration of DEHA from hemofiltration systems has not been assessed and thus the level of patient exposure to this DEHP-alternative remains unknown. In this study, 2 CVVH models were used to evaluate the potential migration of DEHA from PVC tubings, allowing the determination of (Rachoin and Weisberg, 2019) the highest rates of DEHA able to migrate into a simulant flowing in a marketed adult CVVH circuit by disregarding any metabolisation and (Krieter et al., 2013) the clinical-reflecting exposure of patients to this plasticizer and its metabolites by assessing their migration into blood. In the first model, we showed that patients undergoing a CVVH procedure may be exposed to high rates of DEHA. Moreover, DEHA is continuously hydrolyzed into its primary metabolite MEHA (monoethylhexyladipate), which may reach cytotoxic level in the patients' blood. When looking from a « safer » MD perspective, DEHA might not be the best alternative plasticizer for CVVH tubings. However, to reflect clinical conditions, this study should be completed by an in-vivo evaluation (biomonitoring) of the oxidized metabolites of DEHA in urines of inpatients undergoing CVVH.

The Fate of Leached Di(2-Ethylhexyl)Phthalate in Patients Undergoing Capd Treatment

Objectives

To evaluate the degree of exposure to and the fate of di(2-ethylhexyl)phthalate (DE HP) and its major derivatives mono(2-ethylhexyl)phthalate (ME HP), 2-ethylhexanol (2-EH), and phthalic acid (PA) in patients undergoing regular continuous ambulatory peritoneal dialysis (CAPD) during a 4-hour dwell period.

Design

Prospective, controlled.

Setting

Teaching hospital, Department of Nephrology.

Participants

Seven elderly patients on stable CAPD using Fresenius instruments and dialysate and 6 agematched healthy controls.

Interventions

During a routinely performed peritoneal equilibration test (PET), blood and dialysate samples were drawn before and 120 and 240 min after the dwell was started. In addition, blood samples were taken from a group of volunteers participating in a pharmacological study.

Measurements

Quantitative analysis of DE HP and its hydrolysis products was performed by selected ion-monitoring gas chromatography/mass spectrometry, operating the mass spectrometer in a combined positive and negative ion chemical ionization mode.

Results

Serum concentrations of DE HP and PA were significantly higher in patients (median: 0.079 I1g/mL, range: 0.032 -0.210 I1g/mL; and 0.167 I1g/mL, range: 0.097 0.231 I1g/mL, respectively) than in controls [0.0195 I1g/mL, range: 0.016 -0.025I1g/mL (p = 0.0027) and 0.0120 I1g/mL, range: 0.006 -0.034I1g/mL (p = 0.0026), respectively]. Concentration of ME HP in the fluid of CAPD bags prior to use was four times higher than that of the parent compound. During the first 4 hours of dwell time, the concentrations of ME HP and 2-EH in dialysate consistently decreased from 0.177 (range: 0.137 -0.239119/ mL) to 0.022 I1g/mL (range: 0.005 -0.058 I1g/mL) (p = 0.017), and from 0.087 (range: 0.075 -0.097I1g/mL) to 0.05 I1g/mL (range: 0.023 0.064I1g/mL) (p = 0.017), respectively, while the concentration of DE HP remained stable. Remarkably high concentrations of PA (0.129 I1g/mL; range: 0.038 -0.466 I1g/mL) were found in CAPD bags prior to use, and these concentrations tended to increase during dwell time, without statistical significance, however (0.135I1g/mL; range: 0.073 -0.659I1g/mL, p = 0.062).

Conclusions

Patients on CAPD are regularly exposed to considerable amounts of phthalic ester derivatives, mainly to MEHPand PA. ME HP seems to bewellabsorbed by the peritoneal membrane. The long-term effects of this exposure remain to be elucidated.

Influence of Plasticizer-Free CAPD Bags and Tubings on Serum, Urine, and Dialysate Levels of Phthalic Acid Esters in CAPD Patients

Objectives

To evaluate the impact of a plasticizer-free device on exposure to di-(2-ethylhexyl) phthalate (DEHP) and its major metabolites in patients on continuous ambulatory peritoneal dialysis (CAPD). DEHP is the most commonly used plasticizer in polyvinyl chloride (PVC) products; it is added to CAPD bags in order to improve the flexibility of the material. Since DEHP leaches out of the plastic matrix, patients on CAPD are exposed to considerable amounts of DEHP and its metabolites.

Design

A prospective cross-over study.

Setting

Department of nephrology in a teaching hospital.

Participants

Six patients (4 female, 2 male) stable on peritoneal dialysis (PD) for at least 6 months.

Interventions

Patients were switched from a plasticizer-containing PVC CAPD system (A.N.D.Y. Plus, Fresenius Medical Care, Bad Homburg, Germany) to a polyolefine-made plasticizer-free system (stay-safe, Fresenius).

Main Outcome Measures

Prior to and 42 days after the switch, 24-hour effluent dialysate and urine collections were performed and 10 mL blood was drawn. Concentrations of DEHP, mono-(2-ethylhexyl) phthalate (MEHP), phthalic acid (PA), and 2-ethylhexanol (2-EH) in urine, dialysate, and serum were determined using gas chromatography/mass spectrometry.

Results

Complete data were obtained from 5 patients. Serum levels of PA decreased significantly during the study period (0.137 ± 0.078 mg/L vs 0.124 ± 0.049 mg/L, p = 0.04), and the respective levels of DEHP decreased insignificantly (0.097 ± 0.076 mg/L vs 0.069 ± 0.046 mg/L, p = 0.07), whereas the concentrations of MEHP and 2-EH remained unchanged. Urine concentrations of PA were high (0.81 ± 0.69 mg/L) but did not change substantially (0.70 ± 0.50 mg/L). Effluent dialysate concentrations of MEHP and PA decreased significantly (0.0176 ± 0.004 mg/L vs 0.0040 ± 0.0007 mg/L, p = 0.043 and 0.158 ± 0.056 mg/L vs 0.111 ± 0.051 mg/L, p = 0.043, respectively).

Conclusions

Although PD patients seem to be exposed to other sources of phthalates in addition to dialysis, use of plasticizer-free devices may help to reduce potentially immunosuppressive exposure to phthalate esters.

Plasticizer Interaction With the Heart: Chemicals Used in Plastic Medical Devices Can Interfere With Cardiac Electrophysiology

BACKGROUND

Phthalates are used as plasticizers in the manufacturing of flexible, plastic medical products. Patients can be subjected to high phthalate exposure through contact with plastic medical devices. We aimed to investigate the cardiac safety and biocompatibility of mono-2-ethylhexyl phthalate (MEHP), a phthalate with documented exposure in intensive care patients.

METHODS

Optical mapping of transmembrane voltage and pacing studies were performed on isolated, Langendorff-perfused rat hearts to assess cardiac electrophysiology after MEHP exposure compared with controls. MEHP dose was chosen based on reported blood concentrations after an exchange transfusion procedure.

RESULTS

Thirty-minute exposure to MEHP increased the atrioventricular node (147 versus 107 ms) and ventricular (117 versus 77.5 ms) effective refractory periods, compared with controls. Optical mapping revealed prolonged action potential duration at slower pacing cycle lengths, akin to reverse use dependence. The plateau phase of the action potential duration restitution curve steepened and became monophasic in MEHP-exposed hearts (0.18 versus 0.06 slope). Action potential duration lengthening occurred during late-phase repolarization resulting in triangulation (70.3 versus 56.6 ms). MEHP exposure also slowed epicardial conduction velocity (35 versus 60 cm/s), which may be partly explained by inhibition of Na_v1.5 (874 and 231 µmol/L half-maximal inhibitory concentration, fast and late sodium current).

CONCLUSIONS

This study highlights the impact of acute MEHP exposure, using a clinically relevant dose, on cardiac electrophysiology in the intact heart. Heightened clinical exposure to plasticized medical products may have cardiac safety implications-given that action potential triangulation and electrical restitution modifications are a risk factor for early after depolarizations and cardiac arrhythmias.

A Review of Biomonitoring of Phthalate Exposures

Phthalates (diesters of phthalic acid) are widely used as plasticizers and additives in many consumer products. Laboratory animal studies have reported the endocrine-disrupting and reproductive effects of phthalates, and human exposure to this class of chemicals is a concern. Several phthalates have been recognized as substances of high concern. Human exposure to phthalates occurs mainly via dietary sources, dermal absorption, and air inhalation. Phthalates are excreted as conjugated monoesters in urine, and some phthalates, such as di-2-ethylhexyl phthalate (DEHP), undergo secondary metabolism, including oxidative transformation, prior to urinary excretion. The occurrence of phthalates and their metabolites in urine, serum, breast milk, and semen has been widely reported. Urine has been the preferred matrix in human biomonitoring studies, and concentrations on the order of several tens to hundreds of nanograms per milliliter have been reported for several phthalate metabolites. Metabolites of diethyl phthalate (DEP), dibutyl- (DBP) and diisobutyl- (DiBP) phthalates, and DEHP were the most abundant compounds measured in urine. Temporal trends in phthalate exposures varied among countries. In the United States (US), DEHP exposure has declined since 2005, whereas DiNP exposure has increased. In China, DEHP exposure has increased since 2000. For many phthalates, exposures in children are higher than those in adults. Human epidemiological studies have shown a significant association between phthalate exposures and adverse reproductive outcomes in women and men, type II diabetes and insulin resistance, overweight/obesity, allergy, and asthma. This review compiles biomonitoring studies of phthalates and exposure doses to assess health risks from phthalate exposures in populations across the globe.

Effect of the Plasticizer DEHP in Blood Collection Bags on Human Plasma Fraction Unbound Determination for Alpha-1-Acid Glycoprotein (AAG) Binding Drugs

Fraction unbound (f_u) is a critical drug distribution parameter commonly utilized for modeling efficacious dosage and safety margin predictions. An over-estimation of f_u for 13 chemically diverse small molecule drugs primarily bound to alpha-1-acid glycoprotein (AAG) in human plasma was discovered when in vitro results from our screening lab were compared to literature values. Di-(2-ethylhexyl) phthalate (DEHP), a plasticizer known to be used in the manufacture of blood collection bags, was extracted from plasma obtained through three common techniques that allowed contact with DEHP, and drug f_u values in plasma from each collection method were estimated using the HTDialysis protein binding methodology. Additionally, f_u of test compounds in plasma spiked with varying concentrations of DEHP (0-800 μM) was determined, and DEHP extractions were performed from plasma stored in Terumo bags over 7 days. Blood stored in Terumo bags, blood collected in Terumo bags, but immediately transferred to conical vials, and vacutainer-collected blood yielded DEHP concentrations of 300-1000 μM, 1-10 μM, and 0.1-2 μM, respectively. This finding corresponded with the f_u of tested drugs in DEHP-spiked plasma increasing between 2- and 5-fold. Additionally, DEHP was discovered to leach from the Terumo bag, with concentrations increasing 10-fold over a 7-day test period. In summary, the presence of DEHP in commercially available blood collection bags confounds in vitro f_u estimation for drugs that bind primarily to AAG. It is recommended that vacutainer-collected human plasma, which contains negligible DEHP, be used for the most accurate estimation of f_u in human plasma.

Biocompatibility of Blood Tubings

We studied hemocompatibility of various blood tubings with C3a anaphylatoxin measurement and comparative electron scanning microscopy.

The following tubing materials were tested: polyvinylchloride (PVC) plasticised with phthalate (PVC), pvc plasticised with phthalate coextruded with polyurethane (PIV), and two phathalate-free lines: pvc plasticised with trimellitate coextruded with polyurethane (TRI) and pvc plasticised with LT 360 (LTP).

Results of C3a generation rate showed a significant activation by all blood tubings, with a reduced rate with PIV when compared to all others.

Electron scanning microscopy showed marked alterations of PIV surface on tubings stored for 6 months. Protein deposits on internal surfaces after dialysis were similar whatever tubing material was tested, but adhesive cell number was greater with TRI when compared to PVC and LTP.

Hemocompatibility is unchanged with phthalate-free tubings when compared to phthalate plasticised ones. In contrast with phthalate plasticised PVC there is no beneficial effect of polyurethane coextrusion with trimellitate plasticised PVC in regard to C3a generation.

Phthalates impact human health: Epidemiological evidences and plausible mechanism of action

Disregarding the rising alarm on the hazardous nature of various phthalates and their metabolites, ruthless usage of phthalates as plasticizer in plastics and as additives in innumerable consumer products continues due low their cost, attractive properties, and lack of suitable alternatives. Globally, in silico computational, in vitro mechanistic, in vivo preclinical and limited clinical or epidemiological human studies showed that over a dozen phthalates and their metabolites ingested passively by man from the general environment, foods, drinks, breathing air, and routine household products cause various dysfunctions. Thus, this review addresses the health hazards posed by phthalates on children and adolescents, epigenetic modulation, reproductive toxicity in women and men; insulin resistance and type II diabetes; overweight and obesity, skeletal anomalies, allergy and asthma, cancer, etc., coupled with the description of major phthalates and their general uses, phthalate exposure routes, biomonitoring and risk assessment, special account on endocrine disruption; and finally, a plausible molecular cross-talk with a unique mechanism of action. This clinically focused comprehensive review on the hazards of phthalates would benefit the general population, academia, scientists, clinicians, environmentalists, and law or policy makers to decide upon whether usage of phthalates to be continued swiftly without sufficient deceleration or regulated by law or to be phased out from earth forever.

Isomeric separation and quantitation of di-(2-ethylhexyl) trimellitates and mono-(2-ethylhexyl) trimellitates in blood by LC-MS/MS

A new and fast HPLC-method for the simultaneous determination of tri-(2-ethylhexyl) trimellitate (TOTM or TEHTM), its diesters 2,4-di-(2-ethylhexyl) trimellitate (2,4-DEHTM), 1,4-di-(2-ethylhexyl) trimellitate (1,4-DEHTM), 1,2-di-(2-ethylhexyl) trimellitate (1,2-DEHTM) and monoesters 1-mono-(2-ethylhexyl) trimellitate (1-MEHTM), 2-mono-(2-ethylhexyl) trimellitate (2-MEHTM) and 4-mono-(2-ethylhexyl) trimellitate (4-MEHTM) together with di-(2-ethylhexyl) phthalate (DEHP) and its primary metabolite mono-(2-ethylhexyl) phthalate (MEHP) in blood was developed and validated. The analytes are extracted from blood using liquid-liquid extraction and are chromatographically separated by reversed-phase HPLC using core shell material. Quantitative assessment was performed by ESI-tandem mass spectrometry in negative ionization mode using stable isotope dilution. In less than 30min six postulated primary metabolites of TOTM along with the DEHP metabolite MEHP can be selectively and sensitively quantified. Additionally, the method enables the determination of the parent plasticizers TOTM and DEHP. The detection limits in blood were found to range between 0.7-5.5μg/L for all TOTM analytes. Precision and repeatability of the method were proven by relative standard deviations between 0.9% and 8.7%. TOTM, an alternative plasticizer to DEHP, is already increasingly used for medical devices. Nevertheless, data about the human metabolism of TOTM are still limited. The presented method is the first one enabling the simultaneous determination of the parent plasticizers TOTM and DEHP together with their primary degradation products (DEHTM, MEHTM, MEHP) and can thus be applied manifold including the investigation of the human metabolism of TOTM.

Comparative study on the migration of di-2-ethylhexyl phthalate (DEHP) and tri-2-ethylhexyl trimellitate (TOTM) into blood from PVC tubing material of a heart-lung machine

Medical devices like blood tubing often consist of PVC material that requires the addition of plasticizers. These plasticizers may migrate into the blood leading to an exposure of the patients. In this study the migration behavior of three different blood tubing sets (PVC material with two different plasticizers and silicone as control material) applied on a heart-lung machine standardly used for cardiopulmonary bypass (CPB) in children was studied. We analyzed the total plasticizer migration by analysis of both, the parent compounds as well as their primary degradation products in blood. Additionally, the total mass loss of the tubing over perfusion time was examined. The PVC tubing plasticized with DEHP (di-2-ethylhexyl phthalate) was found to have the highest mass loss over time and showed a high plasticizer migration rate. In comparison, the migration of TOTM (tri-2-ethylhexyl trimellitate) and its primary degradation products was found to be distinctly lower (by a factor of approx. 350). Moreover, it was observed that the storage time of the tubing affects the plasticizer migration rates. In conclusion, the DEHP substitute TOTM promises to be an effective alternative plasticizer for PVC medical devices particularly regarding the decreased migration rate during medical procedures.

The adverse cardiac effects of Di(2-ethylhexyl)phthalate and Bisphenol A

The ubiquitous nature of plastics has raised concerns pertaining to continuous exposure to plastic polymers and human health risks. Of particular concern is the use of endocrine-disrupting chemicals in plastic production, including di(2-ethylhexyl)phthalate (DEHP) and bisphenol A (BPA). Widespread and continuous exposure to DEHP and BPA occurs through dietary intake, inhalation, dermal and intravenous exposure via consumer products and medical devices. This article reviews the literature examining the relationship between DEHP and BPA exposure and cardiac toxicity. In vitro and in vivo experimental reports are outlined, as well as epidemiological studies which examine the association between these chemicals and cardiovascular outcomes. Gaps in our current knowledge are also discussed, along with future investigative endeavors that may help resolve whether DEHP and/or BPA exposure has a negative impact on cardiovascular physiology.

The effects of environmental chemicals on renal function

The global incidence of chronic kidney disease (CKD) is increasing among individuals of all ages. Despite advances in proteomics, genomics and metabolomics, there remains a lack of safe and effective drugs to reverse or stabilize renal function in patients with glomerular or tubulointerstitial causes of CKD. Consequently, modifiable risk factors that are associated with a progressive decline in kidney function need to be identified. Numerous reports have documented the adverse effects that occur in response to graded exposure to a wide range of environmental chemicals. This Review summarizes the effects of such chemicals on four aspects of cardiorenal function: albuminuria, glomerular filtration rate, blood pressure and serum uric acid concentration. We focus on compounds that individuals are likely to be exposed to as a consequence of normal consumer activities or medical treatment, namely phthalates, bisphenol A, polyfluorinated alkyl acids, dioxins and furans, polycyclic aromatic hydrocarbons and polychlorinated biphenyls. Environmental exposure to these chemicals during everyday life could have adverse consequences on renal function and might contribute to progressive cumulative renal injury over a lifetime. Regulatory efforts should be made to limit individual exposure to environmental chemicals in an attempt to reduce the incidence of cardiorenal disease.

A review of alternatives to di (2-ethylhexyl) phthalate-containing medical devices in the neonatal intensive care unit

OBJECTIVE

To conduct an extensive literature and toxicological database review on substitute compounds and available alternative medical products to replace polyvinyl chloride (PVC) and/or di(2-ethylhexyl) phthalate (DEHP), and conduct a DEHP-medical inventory analysis at a large metropolitan neonatal intensive care unit (NICU).

STUDY DESIGN

A systematic search for DEHP-free alternative products was performed using online databases. An informal audit of a large metropolitan NICU was undertaken in 2005 and 2006; 21 products were identified that could potentially contain DEHP. Availability of DEHP-free alternatives was determined through company websites and phone interviews.

RESULT

Two alternative approaches are available for replacing DEHP in NICU medical products: (1) replacement by DEHP-free plasticizers; and (2) replacement of PVC entirely through the use of other polymers. Both approaches seem to provide less harmful substitutes to DEHP, but support PVC-free polymers as the preferred alternative. However, significant data gaps exist, particularly for the alternative polymers. In all, 10 out of 21 (48%) products in the NICU audit were DEHP-free; six consisted of alternative polymers and four of alternative plasticizers. Of the remaining 11 products, only three were available without DEHP at the time of the audit.

CONCLUSION

Because of significant data gaps, systematic toxicological testing of DEHP-free alternatives is imperative. Continued development of alternative products is also needed.

Phthalate esters used as plasticizers in packed red blood cell storage bags may lead to progressive toxin exposure and the release of pro-inflammatory cytokines

Phthalate esters (PE's) are plasticizers used to soften PVC-based medical devices. PE's are the most abundant man-made pollutants and increase the risk of developing an allergic respiratory disease or a malignancy. The leaching of PE's in donated packed red blood cells (PRBC) during storage was assessed. PRBC transfusion bags containing CPD/AS-1 (ADSOL) buffer were analyzed. Samples were collected on storage day 1 and day 42. Two PE's, di-(2-ethylhexyl) phthalate (DEHP) and mono-(2-ethylhexyl) phthalate (MEHP), were measured by liquid chromatography coupled to mass spectrometry (LCMS). Interleukin-8 (IL-8) was measured by standard ELISA techniques. DEHP significantly increased from 34.3 µM (±20.0 SD) on day 1 to 433.2 µM (±131.2 SD) on day 42, a 12.6-fold increase. Similarly, MEHP significantly increased from 3.7 µM (±2.8 SD) on day 1 to 74.0 µM (±19.1 SD) on day 42, a 20.2-fold increase. Also, DEHP and MEHP increased the release of IL-8 from human umbilical vein endothelial cells (HUVEC). The transfusion of older units of PRBC could lead to an accumulation of PE's possibly resulting in inflammation and other effects. This accumulation could be exacerbated due to the decreased metabolism of PE's since trauma patients have a lower esterase activity, the enzymes responsible for metabolizing PE's. The effect of oxidative stress caused by PE's is discussed as a potential mechanism for increases in inflammation caused by older units of PRBC.

Selective phthalate activation of naturally occurring human constitutive androstane receptor splice variants and the pregnane X receptor

Phthalates and other endocrine-disruptive chemicals are manufactured in large quantities for use as plasticizers and other commercial applications, resulting in ubiquitous human exposure and thus, concern regarding their toxicity. Innate defense against small molecule exposures is controlled in large part by the constitutive androstane receptor (CAR) and the pregnane X receptor (PXR). The human CAR gene undergoes multiple alternative splicing events resulting in the CAR2 and CAR3 variant receptors. Recent studies from our laboratory show that CAR2 is potently and specifically activated by di(2-ethylhexyl) phthalate (DEHP). We hypothesized that alternative splicing is a mechanism for increasing CAR's functional diversity, broadening the human receptors' repertoire of response to environmental xenobiotics. In these studies, we examine the interaction of alternatively spliced CARs and PXR with a range of suspected endocrine disruptors, including phthalates, bisphenol A (BPA), and 4-N-nonylphenol (NP). Transactivation and two-hybrid studies in COS-1 cells revealed differential selectivity of endocrine-disrupting chemicals for the variant CAR and PXR. Ex vivo studies showed DEHP and di-isononyl phthalate potently induced CYP2B6 and CYP3A4 expression in human hepatocytes. Mutation analysis of CAR2, in silico modeling, and ligand docking studies suggested that the SPTV amino acid insertion of CAR2 creates a unique ligand-binding pocket. Alternative gene splicing results in variant CAR receptors that selectively recognize phthalates and BPA. The interaction of phthalates with CAR and PXR suggests a xenobiotic response that is complex and biologically redundant.

Human body burdens of chemicals used in plastic manufacture

In the last decades, the availability of sophisticated analytical chemistry techniques has facilitated measuring trace levels of multiple environmental chemicals in human biological matrices (i.e. biomonitoring) with a high degree of accuracy and precision. As biomonitoring data have become readily available, interest in their interpretation has increased. We present an overview on the use of biomonitoring in exposure and risk assessment using phthalates and bisphenol A as examples of chemicals used in the manufacture of plastic goods. We present and review the most relevant research on biomarkers of exposure for phthalates and bisphenol A, including novel and most comprehensive biomonitoring data from Germany and the United States. We discuss several factors relevant for interpreting and understanding biomonitoring data, including selection of both biomarkers of exposure and human matrices, and toxicokinetic information.

An exposure assessment of di-(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DBP) in human semen

Levels of the phthalates such as di(2-ethylhexyl) phthalate (DEHP), mono(2-ethylhexyl) phthalate (MEHP, a major metabolite of DEHP), di-n-butyl phthalate (DBP), mono-n-butyl phthalate (MBP, a major metabolite of DBP), and phthalic acid (P, (a common metabolite of phthalates, including DEHP and DBP) were determined in the semen samples of 99 healthy volunteers without known prior medicosurgical history. Samples were obtained from young men (age 20-25 yr) who visited a clinic, and the semen concentrations of phthalates were measured using ultra-performance liquid chromatography (UPLC) and tandem mass spectrometry (MS/MS). UPLC/MS/MS showed that mean concentrations in semen samples were 1.07 microg/ml for MEHP, 0.61 microg/ml for DEHP, 0.39 microg/ml for PA, 0.06 microg/ml for MBP, and 0.003 microg/ml for DBP. The concentration of MEHP (the metabolite of DEHP) was highest, and the concentrations of the metabolites including MEHP, MBP, and PA were higher than actual concentrations of parent DEHP and DBP. These findings suggest the detection of phthalates in healthy human semen might require further investigation for effects on human fertility.

Extraction of the plasticizers diethylhexylphthalate and polyadipate from polyvinylchloride nasogastric tubes through gastric juice and feeding solution

OBJECTIVES

Except for polyadipate, which is used as an alternative in polyvinylchloride (PVC) feeding tubes, diethylhexylphthalate (DEHP) is the plasticizer used almost exclusively in PVC medical products. A clear response to the chronic intake of DEHP has been shown in several organ systems from different species. In the present study, we compared the extraction of DEHP and polyadipate from PVC gastric tubes.

METHODS

An in vivo setting was simulated. We used 5 cm of PVC nasogastric tubes containing DEHP or polyadipate, which were incubated with gastric juice for 1 week and a feeding solution for 4 weeks. The leakage of these plasticizers was measured daily in the gastric juice group and weekly in the feeding solution group. The amount of plasticizer extracted was compared between groups and days.

RESULTS

In the feeding solution group, the extraction of DEHP ranged from 200 to 542 microg after 1 week and from 660 to 1700 microg after 4 weeks. The extraction of polyadipate was 10 times lower than that of DEHP. In the gastric juice group, extracted DEHP ranged from 635 to 1043 microg, whereas the extraction of polyadipate was 100 times lower.

CONCLUSIONS

Within 1 week, the extraction of DEHP from a 5-cm PVC tube reaches up to 1 mg. Extrapolated, this represents an in vivo load of up to 4 mg. The load accumulated by a newborn in an intensive care unit can therefore easily reach several milligrams of DEHP per day. Polyadipate nasogastric tubes may therefore be an alternative and help to reduce the daily load of DEHP.

High-throughput determination of mono- and di(2-ethylhexyl)phthalate migration from PVC tubing to drugs using liquid chromatography-tandem mass spectrometry

The risk assessment of di(2-ethylhexyl) phthalate (DEHP) that migrated from polyvinyl chloride (PVC) medical devices is an important issue for hospitalized patients. Many studies have been conducted to determine the level of DEHP migration. A recent report has indicated that DEHP in blood bags was hydrolyzed by esterase to mono(2-ethylhexyl) phthalate (MEHP). Therefore, a method for the simultaneous determination of DEHP and MEHP was developed. The migration of DEHP and MEHP from PVC tubing to drugs was examined. Although we detected MEHP in the drugs, we found no enzymatic activity involved in the migration process. Some reports have indicated that hydrolysis may have occurred during sterilization by autoclaving. However, we did not perform any heat treatment. It is speculated that the MEHP migrated directly from the PVC tubing. The simultaneous determination of DEHP and MEHP is required for risk assessment, as MEHP may be even more toxic than the parent compound.

Evaluation of the direct toxicity of trioctyltrimellitate (TOTM), di(2-ethylhexyl) phthalate (DEHP) and their hydrolysis products on isolated rat hepatocytes

Plasticizers are added to polyvinyl chloride (PVC) to confer flexibility to the polymer. Di(2-ethylhexyl) phthalate (DEHP) is the most commonly used of them. However, due to its non covalent bond to the PVC, DEHP tends to vaporize easily. A significant exposure has been recorded in dialyzed patients since medical tubings. Most animal species metabolize DEHP rapidly into monoethylhexyl phthalate (MEHP) and 2-ethylhexanol (2-EH). Because of the suspected toxicity of DEHP, an alternative plasticizer, trioctyltrimellitate (TOTM) has aroused increasing interest. The aim of this study was to determine on isolated rat hepatocytes in vitro, the direct hepatotoxic potential of both DEHP and TOTM and their hydrolytic products. To evaluate the possible toxic liver risk resulting from exposure to DEHP and TOTM, isolated rat hepatocytes were incubated with either DEHP, TOTM, MEHP or their common metabolite (2-EH) for 3 hours. Cell viability was periodically estimated thanks to trypan blue tests (15 - 180 min). The activity of lactate dehydrogenase (LDH) was also monitored (1h, 2h, 3h). The results obtained with trypan blue test and with direct LDH activity measurements, were satisfactorily correlated. Hepatocytes treated with both plasticizers and metabolites on the one hand, and the controls (untreated suspension) on the other hand, showed important differences as for cell viability. The acute toxicity on hepatocytes is mainly due to MEHP. Among DEHP, TOTM, MEHP, 2-EH and after intraperitoneal injection of those compounds, only DEHP and MEHP were able to induce a significant hydrogen peroxide (H2O2) production by the rat hepatocytes. These observations enable us to confirm the hypothesis according to which DEHP and MEHP cause an imbalance between the synthesis and the degradation of H2O2. Our results suggest a short-term in vitro cytotoxicity of MEHP. Even if trypan blue and LDH tests offered good results and were easily branded, further assays as well as MTT-tests should performed in order to confirm the cytotoxicity of the compounds tested.

HPLC determination of residual monomers released from heat-cured acrylic resins

HPLC was used to examine the leachability of three non-phthalic and four phthalic post-polymerized residual monomers from three commercially available heat-cured acrylic resins. Specimens of equal dimensions were constructed from each brand of material by following the standardized procedure and were stored under three different conditions, namely, distilled water, artificial saliva, and a binary mixture of ethanol/water. The resulting liquids provided samples for analysis by HPLC. Three different experiments were performed for each brand of acrylic and each storage condition in order to examine the effects of parameters, particularly time and temperature. The results obtained from this study suggest that a wide spectrum of residues diffuse out of the three examined acrylic resin materials. The non-phthalic compounds were leached at high concentrations, whereas all the phthalates examined exhibited different degrees of elusion commensurate with the storage condition, brand of material, and type of experiment. It seems that a significant quantity of non-phthalic and phthalic residues diffuse out of the acrylic resin materials examined. The main component extracted was methyl methacrylate, the level of which seems to be time-dependent and decreases for a period of up to 5 days when resins are stored in distilled water at room temperature.

Role of PPARα in mediating the effects of phthalates and metabolites in the liver

Phthalate esters belong to a large class of compounds known as peroxisome proliferators (PP). PP include chemicals that activate different subtypes of the peroxisome proliferator-activated receptor (PPAR) family. The ability of phthalate esters and their metabolites to activate responses through different PPAR subtypes is not fully characterized. We investigated the ability of two phthalate esters di-(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DBP) and selected metabolites to activate PPAR (alpha, beta/delta, gamma) using a transient transfection assay. The monoester of DEHP, mono-(2-ethylhexyl) phthalate (MEHP) activated all three subtypes of PPAR, but preferentially activated PPARalpha. A second metabolite of DEHP, 2-ethylhexanoic acid (2-EHXA) was a weaker activator of all three subtypes. DBP, but not the primary metabolite mono-n-butyl phthalate weakly activated all three PPAR subtypes. MEHP and DBP but not DEHP and MBP interacted directly with human PPARalpha and PPARgamma as determined by scintillation proximity assays. Both DEHP and DBP activated expression of PP-inducible gene products in wild-type but not PPARalpha-null mice suggesting that both of these phthalates exert their effects by activation of PPARalpha in vivo. The preferential activation of PPARalpha by phthalate ester metabolites suggests that these phthalates mediate their toxic effects in rodent liver in a manner indistinguishable from other PP.

Determination of di(2-ethylhexyl)phthalate and mono(2-ethylhexyl)phthalate in human serum using liquid chromatography-tandem mass spectrometry

Concentrations of mono(2-ethylhexyl)phthalate (MEHP), and di(2-ethylhexyl)phthalate (DEHP), in serum of healthy volunteers were determined by high performance liquid chromatography (HPLC) with tandem mass spectrometry (LC/MS/MS). The serum was extracted with acetone, followed by hexane extraction under acidic conditions, and then applied to the LC/MS/MS. Recoveries of 20 ng/ml of MEHP and DEHP were 101+/-5.7 (n=6) and 102+/-6.5% (n=6), respectively. The limits of quantification (LOQ) of MEHP and DEHP in the method were 5.0 and 14.0 ng/ml, respectively. The concentration of MEHP in the serum was at or less than the LOQ. The concentration of DEHP in the serum was less than the LOQ. Contaminations of MEHP and DEHP from experimental reagents, apparatus and air during the procedure were less than the LOQ and were estimated to be <1.0 and 2.2+/-0.6 ng/ml, respectively. After subtraction of the contamination, the net concentrations of MEHP and DEHP in the serum were estimated at or <5 and <2 ng/ml, respectively. To decrease contamination by DEHP, the cleanup steps and the apparatus and solvent usage were minimized in the sample preparation procedures. The high selectivity of LC/MS/MS is the key for obtaining reliable experimental data from in the matrix-rich analytical samples and for maintaining a low level contamination of MEHP and DEHP in this experimental system. This method would be a useful tool for the detection of MEHP and DEHP in serum.

The male reproductive system and its susceptibility to endocrine disrupting chemicals

In the past years, there has been increased interest in assessing the relationship between impaired male fertility and environmental factors. Human male fertility is a complex process and therefore a great variety of sites may be affected by exogenous noxae. Lifestyle factors as well as various environmental and occupational agents may impair male fertility. Many studies have been published reporting on reproductive dysfunctions in male animals and humans. Especially environmental pollutants with endocrine activity are discussed as a possible cause of this detrimental development. Evidence from animal experiments show that substances with oestrogenic and antiandrogenic properties may cause hypospadia, cryptorchidism, reduction of sperm density and an increase of testicular tumours. Many adverse effects on animal male fertility have been documented for phthalates and some chlorinated hydrocarbons such as polychlorinated biphenyls and polychlorinated dibenzo-p-dioxins. For other chemicals such as bisphenol A and nonylphenols animal data are conflicting. Environmental pollutants may mediate their effects by receptor binding, modulation of hormone-regulated mechanisms or direct toxic effects. Data on environmental chemicals and human male fertility are scarce, and risk assessment is mostly based on the results of animal studies. However, there are indications that exposure to endocrine active chemicals during early development may alter hormone responsiveness in adulthood. Furthermore, some of the chemicals are found in fluids that are associated with human reproduction, such as follicular fluid, seminal fluid and cervical mucus. Recent studies suggest a correlation between pesticide exposure and standard semen parameters as well as in vitro fertilization rates.

Extraction of di-ethylhexyl-phthalate from perfusion lines of various material, length and brand by lipid emulsions

BACKGROUND

The plasticizer di-ethylhexyl-phthalate (DEHP) is extracted especially by lipid emulsions from polyvinylchloride infusion systems. The aim of this study was to systematically examine the extraction from perfusion lines commonly used in our hospital for lipid emulsion infusions.

METHODS

Perfusion lines made from polyvinylchloride of various lengths and brands, polyethylene, polyvinylchloride/polyethylene (PVC/PE) and polyvinylchloride/polyurethane (PVC/PU), were perfused with lipid emulsions according to the circumstances of newborns on an intensive care unit, i.e. high temperature, 24-hour duration and low quantities. Concentration of di-ethylhexyl-phthalate was determined with gas chromatograph mass spectrometry.

RESULTS

The lipid emulsions before perfusion had a contamination with DEHP of 0.82 microg/ml. Pure PVC lines of 1.5 m length leached between 74 microg/ml and 107 microg/ml. Sterilization of the lines did not influence DEHP extraction. After perfusion of DEHP-free PVC lines and PVC-free lines, the emulsions had a contamination with DEHP of 0.23 microg/ml and 0.11 microg/ml, respectively. PVC/PU co-extruded lines leached 73 microg/ml. PVC/PE lines leached 41.6 microg/ml.

CONCLUSIONS

Lipid emulsions contain a production-inherent load of DEHP. Perfusion through PVC-perfusion lines extracts a varying large amount of DEHP depending on length and brand of the perfusion lines. Co-extruded PVC/PU and PVC/PE lines, intended to avoid DEHP contamination, leach a similar amount of DEHP and thus do not avoid the DEHP toxicity issue. The load accumulated by a baby on an intensive care unit easily reaches several milligrams of DEHP per day. As its effect upon biologic systems has been proven, and alternatives (PE or PU perfusion lines) are available, PVC and PVC co-extruded perfusion lines should be abandoned for infusions, especially in babies.

High-throughput analysis of phthalate esters in human serum by direct immersion SPME followed by isotope dilution?fast GC/MS

Solid-phase microextraction (SPME) coupled to gas chromatography/mass spectrometry (GC/MS) was applied to the determination of phthalate esters in human serum. The present method decreased the sample preparation time by a factor of 50 by using direct immersion SPME with an 85-microm polyacrylate fiber to extract phthalate esters from the matrix. The use of fast GC/MS further improves total analysis time when compared to other techniques. Isotope dilution was successfully applied to improve the precision, reproducibility, and repeatability of the SPME method. The linear dynamic range spans several orders of magnitude from low ppb to ppm levels, and the LOD for the method is 15 pg microL(-1) on average with RSDs less than 4% for the six phthalate esters included in this study.

Exposure to di-(2-ethylhexyl) phthalate among premature neonates in a neonatal intensive care unit

OBJECTIVE

Premature neonates who spend time in a neonatal intensive care unit may be at increased risk of adverse health effects from exposure to di-(2-ethylhexyl) phthalate (DEHP) because of their increased risk of high exposure, their small body size, and their physical condition. DEHP, a reproductive toxicant in animals, is a major component in polyvinyl chloride (PVC) plastics, which are frequently used in medical tubing and blood storage bags. DEHP is not covalently bound to PVC, and it may be easily released from the PVC medical devices. The objective of this study was to determine whether premature infants who undergo medical procedures, such as blood transfusions, intravenous therapy, enteral and parenteral nutrition support, and dialysis, are at increased risk of exposure to DEHP than the general population. Because of their smaller size, children and especially premature and small infants may receive a larger dose of DEHP on a milligram per kilogram basis than adults when the same-size medical device is used for all ages.

METHODS

Premature neonates who seemed to have the potential to be on intravenous infusion for >2 weeks and were expected to survive were eligible for enrollment in the study. We assessed exposure to DEHP in 6 premature newborns by measuring in 41 urine samples the levels of 3 DEHP metabolites: mono-(2-ethylhexyl) phthalate (mEHP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (mEHHP), and mono-(2-ethyl-5-oxohexyl) phthalate (mEOHP).

RESULTS

mEHHP and mEOHP were detected in all 41 urine samples, and mEHP was detected in 33. Because only 33 of the samples had detectable amounts for all 3 metabolites, statistical analyses were limited to those 33. The levels of all 3 DEHP metabolites varied widely, and the urinary mean and median concentrations of mEOHP and mEHHP were 1 order of magnitude higher than those for mEHP. Furthermore, the geometric mean urinary concentrations of mEOHP (1617 ng/mL), mEHHP (2003 ng/mL), and mEHP (100 ng/mL) in these 6 premature infants who underwent intensive therapeutic interventions were found to be severalfold higher than in the US general population (for mEHP, geometric mean in those 6 years and older was 3.43 ng/mL).

CONCLUSIONS

This study provides the first quantitative evidence confirming that newborns who undergo intensive therapeutic medical interventions are exposed to higher concentrations of DEHP than the general population. Although the overall benefits of medical procedures using PVC devices outweigh the risks associated with exposure to DEHP, more research is needed to determine whether infants and children who undergo intensive therapeutic interventions using DEHP-containing devices are at higher risk for altered health outcomes than infants and children who undergo similar treatments but are not potentially exposed to DEHP.

Risk assessment of di(2-ethylhexyl)phthalate released from PVC blood circuits during hemodialysis and pump–oxygenation therapy

This study deals with in vitro investigation of the release of di(2-ethylhexyl)phthalate (DEHP) during hemodialysis and pump-oxygenation therapy using medical grade PVC tubing. High resolution GC-MS analysis showed that the release of DEHP was time-dependently increased by circulation of bovine blood into a major system for the hemodialysis that is used in Japan, and the amount of DEHP released into the blood had reached 7.3 mg by 4 h of circulation. No significant difference was observed in the release patterns of DEHP under the conditions with and without fluid removal treatment during hemodialysis, indicating that the treatment seems not to be effective for eliminating DEHP from the blood through the hemodialysis membrane. Mono(2-ethylhexyl)phthalate (MEHP) analysis revealed that a small amount of DEHP (3-4%) was converted to MEHP by hydrolysis during the circulation of blood. A considerable amount of DEHP was also released from the PVC circuit mimicking the pump-oxygenation system, and 7.5-12.1 mg of DEHP had migrated into bovine blood from the circuit by 6 h. It was noticed, however, that the release was obviously suppressed by covalently coating the inner surface of the PVC tubing with heparin, though this effect was not observed with ionic bond type-heparin coating. Covalent bond type-heparin coating of PVC tubing seems to offer the advantage of decreasing the amount of DEHP exposure to patients during treatment using a PVC circuit.

Induction of propranolol metabolism in isolated rats hepatocytes treated by di(2-ethylhexyl) phthalate (DEHP) and mono(2-ethylhexyl) phthalate (MEHP)

Blood lines of polyvinyl chloride (PVC) for hemodialysis usually contain di(2-ethylhexyl) phthalate (DEHP) as a plasticizer. Previous studies show that 1 mg/kg of this plasticizer can leach into the blood during one dialysis session. It is rapidly metabolized in the liver. Mono(2-ehtylhexyl) phthalate (MEHP), its main metabolite can be detected as well. After oral administration to rodents, both compounds caused a variety of adverse biological effects such as testicular atrophy, peroxisome proliferation and hepatic peroxisomal enzyme induction. Male wistar rats were treated intraperitoneally by DEHP and MEHP using twice the dose of that involved in human exposure during a dialysis session. Propranolol metabolism by hepatocytes was investigated after fresh isolation from treated and untreated rats by means of reverse phase HPLC. The choice of propranolol as a substrate was made because of its rather quick liver metabolisation. Phenobarbital was chosen in the study as a reference of enzymatic inducer to evaluate the inducing effect of DEHP and MEHP. Propranolol was metabolized by the hepatocytes of both treated and untreated rats. Hepatocytes isolated from rats treated by phenobarbital, MEHP and DEHP were shown to have a higher speed constant of metabolism indicating a rapid metabolism of propranolol. Under these conditions, in fact, propranolol metabolisation was found to be respectively 6, 2.7, 2 times faster than the propranolol metabolisation of untreated rats. The hypothesis that DEHP and MEHP are enzymatic inducers, particularly cytochrome P450 (CYP) inducers of the xenobiotics metabolism on the intact liver after IP administration has become been found to be valid. The results obtained in this study confirm the value of isolated hepatocytes as an in vivo drug metabolism predictive model.

Donor exposure to the plasticizer di(2-ethylhexyl)phthalate during plateletpheresis

BACKGROUND

Di(2-ethylhexyl)phthalate (DEHP) is a plasticizer that is contained in most PVC devices, including apheresis disposables. Because DEHP can be extracted from apheresis disposables as the blood passes through the apheresis device, DEHP exposure was determined in healthy donors undergoing plateletpheresis performed with commercially available apheresis systems.

STUDY DESIGN AND METHODS

The study population consisted of 36 healthy PLT donors undergoing plateletpheresis with either continuous or discontinuous apheresis devices. Serum concentrations of DEHP were determined from peripheral blood obtained before and after plateletpheresis, with gas chromatography-mass spectroscopy.

RESULTS

Plateletpheresis performed with standard collection disposables resulted in a median increase of 232 percent of serum DEHP compared to levels before apheresis, corresponding to a total amount of DEHP exposed during a single apheresis of a median of 6.46 (range, 1.8-20.3) microg per kg of body weight. Endogenous levels of triglycerides showed a positive correlation with the amount of DEHP released. Increase in serum DEHP was short-term as serum DEHP rapidly returned to levels obtained before apheresis within 3 hours after completion of the apheresis course. Donor exposure to DEHP led to no variation in liver cell function within 48 hours after plateletpheresis.

CONCLUSION

Commercial plateletpheresis disposables release considerable amounts of DEHP during the apheresis procedure, but the total dose of DEHP retained by the donor is within the normal range of DEHP exposure of the general population.

Diethyl phthalate, a chemotactic factor secreted by Helicobacter pylori

The structure of a small-molecule, non-peptide chemotactic factor has been determined from activity purified to apparent homogeneity from Helicobacter pylori supernatants. H. pylori was grown in brucella broth media until one liter of solution had 0.9 absorbance units. The culture was centrifuged, and the bacteria re-suspended in physiological saline and incubated at 37 degrees C for 4 h. A monocyte migration bioassay revealed the presence of a single active chemotactic factor in the supernatant from this incubation. The chemotactic factor was concentrated by solid phase chromatography and purified by reverse phase high pressure liquid chromatography. The factor was shown to be indistinguishable from diethyl phthalate (DEP) on the basis of multiple criteria including nuclear magnetic resonance spectroscopy, electron impact mass spectroscopy, UV visible absorption spectrometry, GC and high pressure liquid chromatography retention times, and chemotactic activity toward monocytes. Control experiments with incubated culture media without detectable bacteria did not yield detectable DEP, suggesting it is bacterially derived. It is not known if the bacteria produce diethyl phthalate de novo or if it is a metabolic product of a precursor molecule present in culture media. DEP produced by H. pylori in addition to DEP present in man-made products may contribute to the high levels of DEP metabolites observed in human urine. DEP represents a new class of chemotactic factor.

Comparative study of the leachability of di(2-ethylhexyl) phthalate and tri(2-ethylhexyl) trimellitate from haemodialysis tubing

The leachability of both Di(2-ethylhexyl) phthalate (DEHP) and Tri(2-ethylhexyl) trimellitate (TEHTM) or Trioctyl trimellitate (TOTM) from haemodialysis tubing was investigated in 20 patients with chronic renal failure undergoing maintenance haemodialysis. The blood tubing made of common polyvinyl chloride (PVC) plasticized with DEHP (group 1 patients) were replaced with tubing plasticized with TOTM-DEHP (group 2 patients). The patient blood obtained from the inlet and the outlet of the dialyzer was analyzed during a 4 h-dialysis session. Thus, the circulating concentrations of both DEHP and TOTM resulting from the release from dialyzer tubes were estimated using High-performance Liquid chromatograph (HPLC). With the common PVC-DEHP blood tubing, a DEHP quantity of 122.95+/-33.94 mg was extracted from tubing during a single dialysis session (ranging from 55 to 166.21 mg). During the same period, the total amounts of DEHP retained by the patients were 27.30+/-9.22 mg (ranging from 12.50 to 42.72 mg). As for blood tubing plasticized with TOTM-DEHP, 41.80+/-4.47 mg of DEHP and 75.11+/-25.72 mg of TOTM were extracted. During the same period, the amounts of DEHP and TOTM retained by the patients were 3.42+/-1.37 mg and 4.87+/-2.60 mg, respectively. The extraction rate both plasticizers was correlated with serum lipid content (cholesterol+triglyceride) (r(2)=0.75 for DEHP and r(2)=0.64 for TOTM). In the present investigation, less TOTM and DEHP were apparently released from haemodialysis tubing plasticized with TOTM-DEHP than DEHP released from haemodialysis tubing plasticized with DEHP only. TOTM seems to be a superior alternative to DEHP for use in medical devices because of its potential lower leachability. To recommend it as an alternative plasticizer, its possible toxicity towards human body should be investigated before it can be used routinely. However, patients undergoing haemodialysis using tubing plasticized with DEHP only are regularly exposed to non negligible amounts of DEHP. In view of several biological effects previously reported, it is time to reconsider the use of DEHP only as a plasticizer.

Simultaneous analysis of the di(2-ethylhexyl)phthalate metabolites 2-ethylhexanoic acid, 2-ethyl-3-hydroxyhexanoic acid and 2-ethyl-3-oxohexanoic acid in urine by gas chromatography-mass spectrometry

A gas chromatographic-mass spectrometric method was developed for the quantitative analysis of the three Di(2-ethylhexyl)phthalate (DEHP) metabolites, 2-ethylhexanoic acid, 2-ethyl-3-hydroxyhexanoic acid and 2-ethyl-3-oxohexanoic acid in urine. After oximation with O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine hydrochloride and sample clean-up with Chromosorb P filled glass tubes, all three organic acids were converted to their tert.-butyldimethylsilyl derivatives. Quantitation was done with trans-cinnamic acid as internal standard and GC-MS analysis in the selected ion monitoring mode (SIM). Calibration curves for all three acids in the range from 20 to 1,000 microg/l showed correlation coefficients from 0.9972 to 0.9986. The relative standard deviation (RSD) values determined in the observed concentration range were between 1.3 and 8.9% for all three acids. Here we report for the first time the identification of 2-ethyl-3-hydroxyhexanoic acid and 2-ethyl-3-oxohexanoic acid in human urine next to the known DEHP metabolite 2-ethylhexanoic acid. In 28 urine samples from healthy persons we found all three acids with mean concentrations of 56.1 +/- 13.5 microg/l for 2-ethylhexanoic acid, 104.8 +/- 80.6 microg/l for 2-ethyl-3-hydroxyhexanoic acid and 482.2 +/- 389.5 microg/l for 2-ethyl-3-oxohexanoic acid.

Health risks posed by use of Di-2-ethylhexyl phthalate (DEHP) in PVC medical devices: a critical review

BACKGROUND

Polyvinyl chloride plastics (PVC), made flexible through the addition of di-2-ethylhexyl phthalate (DEHP), are used in the production of a wide array of medical devices. From the late 1960s, leaching of DEHP from PVC medical devices and ultimate tissue deposition have been documented.

METHODS

A critical review of DEHP exposure, metabolism, and toxicity data from human and animals studies was undertaken. A brief analysis of alternatives to DEHP-plasticized PVC for use in medical device manufacture was completed.

RESULTS

DEHP leaches in varying concentrations into solutions stored in PVC medical devices. Certain populations, including dialysis patients and hemophiliacs may have long-term exposures to clinically important doses of DEHP, while others, such as neonates and the developing fetus, may have exposures at critical points in development. In vivo and in vitro research links DEHP or its metabolites to a range of adverse effects in the liver, reproductive tract, kidneys, lungs, and heart. Developing animals are particularly susceptible to effects on the reproductive system. Some adverse effects in animal studies occur at levels of exposure experienced by patients in certain clinical settings. DEHP appears to pose a relatively low risk of hepatic cancer in humans. However, given lingering uncertainties about the relevance of the mechanism of action of carcinogenic effects in rodents for humans and interindividual variability, the possibility of DEHP-related carcinogenic responses in humans cannot be ruled out.

CONCLUSIONS

The observed toxicity of DEHP and availability of alternatives to many DEHP-containing PVC medical devices presents a compelling argument for moving assertively, but carefully, to the substitution of other materials for PVC in medical devices. The substitution of other materials for PVC would have an added worker and community health benefit of reducing population exposures to DEHP, reducing the creation of dioxin from PVC production and disposal, and reducing risks from vinyl chloride monomer exposure.

Polyvinylchloride infusion lines expose infants to large amounts of toxic plasticizers

PURPOSE

The purpose of this study was to evaluate whether infusion lines are able to leach plasticizers in substantial amounts and thus be a candidate substance for hepatotoxic effects during long-term total parenteral nutrition (TPN).

METHODS

TPN solutions, blood products, and selected drugs typical for preterm infants concerning amount, content, and infusion time were perfused through common polyvinylchloride (PVC) infusion lines. Concentration of diethylhexyl-phthalate (DEHP) before and after perfusion was determined by gas chromatography/mass spectrometry.

RESULTS

Daily quantities of DEHP by 24-hour infusions were Lipid emulsion 20%: 10185.6 microg; aminoacid/glucose-solution: 116.2 microg; midazolaminfusion for sedation: 26.4 microg; fentanyl for sedation: 132.5 microg; propofol for sedation: 6561.0 microg. The amount of DEHP by single doses of blood products (20 mL) were packed red blood cells: 144-608 microg; platelet rich plasma: 928 microg; and fresh frozen plasma: 552-8108 microg. The dose of DEHP for a typical preterm neonate requiring TPN and additional therapy like sedation or blood products is at minimum 10 mg and can easily reach 20 mg/d.

CONCLUSION

This large amount of DEHP is especially disturbing, because it effects the most vulnerable patients (neonates). Whether there is a relation to TPN-induced hepatobiliary dysfunction remains to be elucidated and is under investigation. With respect to recent literature, a biological effect of these doses must be assumed.

A pharmacokinetic interpretation of increasing concentrations of DEHP in haemodialysed patients

The degree of exposure to DEHP was assessed in 11 patients with chronic renal failure undergoing maintenance haemodialysis. The amount of DEHP leached from the dialyser during a 4-h dialysis session was estimated by monitoring the DEHP blood concentration using a HPLC method. When a patient undergoes a dialysis treatment, the concentration of di-2-ethylhexyl phthalate (DEHP) in venous blood is increased when the blood crosses through the dialysis apparatus. This increase may be explained either because DEHP is not extracted by the dialyser or because DEHP comes from the dialysis bath due to contact of blood against plasticized pipes. To explain the increasing concentration of DEHP during treatment of renal failure using plasticized tubing, we propose a pharmacokinetic compartmental model in order to fit raw data obtained from dialysed patients and to get the amount of DEHP which enters the body by AUC calculations. Results obtained after HPLC analysis show a high degree of interpatient variability in DEHP retained. This amount can reach a toxicity level because of repetitive dialysis treatments over prolonged periods of time. In the coming years, it seems necessary to reconsider the use of DEHP as a plasticizer in medical devices. Highly unacceptable amounts of DEHP leached during the dialysis session could be easily avoided by careful selection of haemodialysis tubing.

Identification of plasticizers in medical products by a combined direct thermodesorption--cooled injection system and gas chromatography--mass spectrometry

The combination of a new thermodesorption module with a cooled injection system now provides a powerful system for direct analysis of volatile trace compounds in gaseous, liquid and solid samples by gas chromatography-mass spectrometry (GC-MS). As a cooled injection system is used for the cryofocusing of the desorbed volatiles the GC-MC system still can be used for the regular analysis of liquid samples. Although plasticizers usually are analyzed by GC-MS after solvent extraction, contaminated solvents and glassware are very well known problems. Analysis of plasticizers in plastic materials by direct thermodesorption instead saves time and avoids cross contaminations. Many medical products are made of plasticized polyvinyl chloride. Extraction of the common plasticizer di(2-ethylhexyl) phthalate (DEHP) into blood will occur, and harmful effects of DEHP in the human body have been suggested. We therefore analyzed 21 different plastic devices which are used for various invasive techniques in medicine by direct thermodesorption GC-MS. In some of the plastics up to 30 different components were identified. By far the most common plasticizer found was DEHP, followed by diethyl and dibutyl phthalates.

A cancer risk assessment of di(2-ethylhexyl)phthalate: application of the new U.S. EPA Risk Assessment Guidelines

The current United States Environmental Protection Agency (EPA) classification of di(2-ethylhexyl)phthalate (DEHP) as a B2 "probable human" carcinogen is based on outdated information. New toxicology data and a considerable amount of new mechanistic evidence were used to reconsider the cancer classification of DEHP under EPA's proposed new cancer risk assessment guidelines. The total weight-of-evidence clearly indicates that DEHP is not genotoxic. In vivo administration of DEHP to rats and mice results in peroxisome proliferation in the liver, and there is strong evidence and scientific consensus that, in rodents, peroxisome proliferation is directly associated with the onset of liver cancer. Peroxisome proliferation is a transcription-mediated process that involves activation by the peroxisome proliferator of a nuclear receptor in rodent liver called the peroxisome proliferator-activated receptor (PPARalpha). The critical role of PPARalpha in peroxisomal proliferation and carcinogenicity in mice is clearly established by the lack of either response in mice genetically modified to remove the PPARalpha. Several mechanisms have been proposed to explain how, in rodents, peroxisome proliferation can lead to the formation of hepatocellular tumors. The general consensus of scientific opinion is that PPARalpha-induced mitogenesis and cell proliferation are probably the major mechanisms responsible for peroxisome proliferator-induced hepatocarcinogenesis in rodents. Oxidative stress appears to play a significant role in this increased cell proliferation. It triggers the release of TNFalpha by Kupffer cells, which in turn acts as a potent mitogen in hepatocytes. Rats and mice are uniquely responsive to the morphological, biochemical, and chronic carcinogenic effects of peroxisome proliferators, while guinea pigs, dogs, nonhuman primates, and humans are essentially nonresponsive or refractory; Syrian hamsters exhibit intermediate responsiveness. These differences are explained, in part, by marked interspecies variations in the expression of PPARalpha, with levels of expression in humans being only 1-10% of the levels found in rat and mouse liver. Recent studies of DEHP clearly indicate a nonlinear dose-response curve that strongly suggests the existence of a dose threshold below which tumors in rodents are not induced. Thus, the hepatocarcinogenic effects of DEHP in rodents result directly from the receptor-mediated, threshold-based mechanism of peroxisome proliferation, a well-understood process associated uniquely with rodents. Since humans are quite refractory to peroxisomal proliferation, even following exposure to potent proliferators such as hypolipidemic drugs, it is concluded that the hepatocarcinogenic response of rodents to DEHP is not relevant to human cancer risk at any anticipated exposure level. DEHP should be classified an unlikely human carcinogen with a margin of exposure (MOE) approach to risk assessment. The most appropriate and conservative point of reference for assessing MOEs should be 20 mg/kg/day, which is the mouse NOEL for peroxisome proliferation and increased liver weight. Exposure of the general human population to DEHP is approximately 30 microg/kg body wt/day, the major source being from residues in food. Higher exposures occur occupationally [up to about 700 microg/kg body wt/day (mainly by inhalation) based on current workplace standards] and through use of certain medical devices [e.g., up to 457 microg/kg body wt/day for hemodialysis patients (intravenous)], although these have little relevance because the routes of exposure bypass critical activation enzymes in the gastrointestinal tract.

Exposure of hemodialysis patients to di-2-ethylhexyl phthalate

The migration of di-2-ethylhexyl phthalate (DEHP) from dialyzers was studied in 21 patients with chronic renal failure undergoing maintenance hemodialysis. The circulating concentrations of DEHP were measured by high performance liquid chromatography in blood of patients obtained from the inlet and the outlet of the dialyzer during a 4-h dialysis session. During treatment of renal failure using plasticized tubing, the plasma level of DEHP increased. On average, an estimated 75.2 mg of DEHP was extracted from the dialyzer during a single dialysis session, with a range of 44.3-197. 1 mg. On the other hand, the total amount of DEHP retained by the patient during the dialysis session was evaluated by the difference between the AUCout and the AUCin and ranged from 3.6 to 59.6 mg. The rate of extraction of DEHP from the dialyzer was correlated (r=0.705, P<0.05) with serum lipid content (cholesterol and triglyceride).So, we confirmed that patients on hemodialysis are always regularly exposed to considerable amounts of DEHP. However, several metabolic effects have been reported in various animal species following treatment with DEHP, such as changes in lipid metabolism and in hepatic microsomal drug-metabolizing enzyme activities. DEHP is now a well-known hepatic peroxisomal proliferator in rodents and an inducer of many peroxisomal and non-peroxisomal enzymes. So, lipid metabolism modifications and hepatic changes observed in hemodialysis patients could be explained from chronic exposition to DEHP. In the coming years, it seems necessary to reconsider the use of DEHP as a plasticizer in medical devices. Highly unacceptable amounts of DEHP leached during the dialysis session could be easily avoided by careful selection of hemodialysis tubing.