New metabolites of di(2-ethylhexyl)phthalate (DEHP) in human urine and serum after single oral doses of deuterium-labelled DEHP

The metabolism of di(2-ethylhexyl)phthalate (DEHP) in humans was studied after three doses of 0.35 mg (4.7 g/kg), 2.15 mg (28.7 g/kg) and 48.5 mg (650 g/kg) of D4-ring-labelled DEHP were administered orally to a male volunteer. Two new metabolites, mono(2-ethyl-5-carboxypentyl)phthalate (5cx-MEPP) and mono[2-(carboxymethyl)hexyl]phthalate (2cx-MMHP) were monitored for 44 h in urine and for 8 h in serum for the high-dose case, in addition to the three metabolites previously analysed: mono(2-ethyl-5-hydroxyhexyl)phthalate (5OH-MEHP), mono(2-ethyl-5-oxohexyl)phthalate (5oxo-MEHP) and mono(2-ethylhexyl)phthalate (MEHP). For the medium- and low-dose cases, 24 h urine samples were analysed. Up to 12 h after the dose, 5OH-MEHP was the major urinary metabolite, after 12 h it was 5cx-MEPP, and after 24 h it was 2cx-MMHP. The elimination half-lives of 5cx-MEHP and 2cx-MMHP were between 15 and 24 h. After 24 h 67.0% (range: 65.8–70.5%) of the DEHP dose was excreted in urine, comprising 5OH-MEHP (23.3%), 5cx-MEPP (18.5%), 5oxo-MEHP (15.0%), MEHP (5.9%) and 2cx-MMHP (4.2%). An additional 3.8% of the DEHP dose was excreted on the second day, comprising 2cx-MMHP (1.6%), 5cx-MEPP (1.2%), 5OH-MEHP (0.6%) and 5oxo-MEHP (0.4%). In total about 75% of the administered DEHP dose was excreted in urine after two days. Therefore, in contrast to previous studies, most of the orally administered DEHP is systemically absorbed and excreted in urine. No dose dependency in metabolism and excretion was observed. The secondary metabolites of DEHP are superior biomonitoring markers compared to any other parameters, such as MEHP in urine or blood. 5OH-MEHP and 5oxo-MEHP in urine reflect short-term and 5cx-MEHP and 2cx-MMHP long-term exposure. All secondary metabolites are unsusceptible to contamination. Furthermore, there are strong hints that the secondary oxidised DEHP metabolites—not DEHP or MEHP—are the ultimate developmental toxicants.     

Intravenous exposure to di(2-ethylhexyl)phthalate (DEHP): metabolites of DEHP in urine after a voluntary platelet donation

In this study we investigated human metabolism and excretion of DEHP after intravenous exposure. For this purpose we determined the five major DEHP metabolites in urine samples of a volunteer before and after a platelet donation (dual-needle technique). Plateletpheresis procedures are known to cause a significant DEHP exposure. We observed a sharp increase in urinary DEHP metabolite concentrations after the procedure. Maximum concentrations of 5OH-MEHP, 5oxo-MEHP, 5cx-MEPP and MEHP observed 4 h after the procedure were 822, 729, 577 and 388 μg/l respectively. 2cx-MMHP was excreted at highest concentrations after 8 h (201 μg/l). Due to longer elimination half-times, 5cx-MEPP and 2cx-MMHP were the major metabolites excreted in urine 24 h after the exposure. The 24-h-cumulative excretion of 363 μg 5cx-MEPP, 353 μg 5OH-MEHP, 309 μg 5oxo-MEHP, 178 μg MEHP and 133 μg 2cx-MMHP indicates an absolute exposure of our volunteer of about 2.6 mg DEHP. Related to the body weight this equals a dose of 31.6 μg/kg body weight/day. This indicates that current risk or preventive limit values for DEHP such as the RfD of the US EPA (20 μg/kg/day) and the TDI of the European Union (20–48 μg/kg/day) can be exceeded on the day of the plateletpheresis. The amount of the dose excreted in urine, distribution of the metabolites in urine and all other elimination characteristics after intravenous DEHP exposure are comparable to oral exposure. There are no indications that toxicokinetic behaviour and the toxicity of DEHP are fundamentally different after the two routes of exposure. Therefore, toxicological endpoints observed for DEHP after oral application should also be considered relevant for medical procedures causing intravenous DEHP exposure, like apheresis procedures. Especially women in their reproductive age need to be protected from DEHP exposures exceeding the above mentioned preventive limit values.     

Di(2-ethylhexyl)phthalate (DEHP) metabolites in human urine and serum after a single oral dose of deuterium-labelled DEHP

Human metabolism of di(2-ethylhexyl)phthalate (DEHP) was studied after a single oral dose of 48.1 mg to a male volunteer. To avoid interference by background exposure the D4-ring-labelled DEHP analogue was dosed. Excretion of three metabolites, mono(2-ethyl-5-hydroxyhexyl)phthalate (5OH-MEHP), mono(2-ethyl-5-oxohexyl)phthalate (5oxo-MEHP) and mono(2-ethylhexyl)phthalate (MEHP), was monitored for 44 h in urine and for 8 h in serum. Peak concentrations of all metabolites were found in serum after 2 h and in urine after 2 h (MEHP) and after 4 h (5OH-MEHP and 5oxo-MEHP). While the major metabolite in serum was MEHP, the major metabolite in urine was 5OH-MEHP, followed by 5oxo-MEHP and MEHP. Excretion in urine followed a multi-phase elimination model. After an absorption and distribution phase of 4 to 8 h, half-life times of excretion in the first elimination phase were approximately 2 h with slightly higher half-life times for 5OH- and 5oxo-MEHP. Half-life times in the second phase—beginning 14 to 18 h post dose—were 5 h for MEHP and 10 h for 5OH-MEHP and 5oxo-MEHP. In the time window 36 to 44 h, no decrease in excreted concentrations of 5OH- and 5oxo-MEHP was observed. In the first elimination phase (8 to 14 h post dose), mean excretion ratios of MEHP to 5oxo-MEHP and MEHP to 5OH-MEHP were 1 to 1.8 and 1 to 3.1. In the second elimination phase up to 24 h post dose mean excretion ratios of MEHP to 5oxo-MEHP to 5OH-MEHP were 1 to 5.0 to 9.3. The excretion ratio of 5OH-MEHP to 5oxo-MEHP remained constant through time at 1.7 in the mean. After 44 h, 47% of the DEHP dose was excreted in urine, comprising MEHP (7.3%), 5OH-MEHP (24.7%) and 5oxo-MEHP (14.9%).     

Studies on the effects of orally administered di-(2-ethylhexyl) phthalate in the ferret

A target-organ study of the effects of the phthalate ester di-(2-ethylhexyl) phthalate (DEHP) has been conducted in mature male albino ferrets. DEHP treatment caused a loss of body weight when administered as a 1% (w/w) diet for 14 months. Additionally, marked liver enlargement with associated morphological and biochemical changes was observed. These changes consisted of liver cell enlargement, lysosomal changes, dilatation of the endoplasmic reticulum and the depression of a number of marker enzyme activities. The only other tissue observed to be affected by DEHP treatment was the testes where histological evidence of tissue damage was observed in some animals.Studies on the metabolism of [¹⁴C]DEHP in the ferret indicated that the diester was metabolised to derivatives of mono-(2-ethylhexyl) phthalate which were excreted in the urine both unconjugated and as glucuronides.The results obtained have been compared with previous studies in the rat and it is concluded that DEHP is hepatotoxic in both species.     

A twenty-volunteer study using deuterium labelling to determine the kinetics and fractional excretion of primary and secondary urinary metabolites of di-2-ethylhexylphthalate and di-iso-nonylphthalate

This study has obtained estimates of the kinetics and fractional excretion factors of metabolism of DEHP and DINP to their main primary and secondary metabolites. Samples were obtained from an open-label, fixed sequence, single oral dose study in 10 male and 10 female subjects. The dosed substances were deuterated di-2-ethylhexylphthalate (D₄-DEHP) and di-isononylphthalate (D₄-DINP) at two dose levels. Urine samples were collected at intervals up to 48 h post-dose. LC-MS/MS was used to measure metabolite concentrations. Excreted amounts were then calculated using urine volumes. Metabolite half-lives were estimated to be 4-8 h with more than 90% of metabolites in the first 24 h of urine collections and the remainder in the 24-48 h period. The four metabolites of DEHP amounted to 47.1 ± 8.5% fractional excretion on a molar basis. For DINP the identified metabolites totalled 32.9 ± 6.4%. For both DEHP and DINP the metabolites were in the abundance order -monoester < -oxo < -carboxy < -hydroxy. These robust fractional excretion values for the main primary and secondary phthalate metabolites along with estimates of their uncertainty can be used in future surveys of human exposure to DEHP and DINP.     

Urinary phthalate monoesters concentration in couples with infertility problems

The widespread use of phthalates results in human exposure: phthalates are rapidly metabolized to their respective monoesters and other oxidative products, which are glucuronidated and excreted through the urine and feces. Several in vivo studies showed that some phthalates, in particular diethyl-hexyl phthalate (DEHP), diethyl phthalate (DEP), di(n-butyl)phthalate (DnBP) and n-butylbenzylphthalate (BBzP), are able to interact with the human endocrine system, interfering with the reproduction ability. In this study, 56 couples were recruited from a centre of assisted reproduction. Spot urine samples were collected and five urinary metabolites of the above phthalates were determined using an HPLC/MS/MS analytical method with isotopic dilution. The results were compared with those of 56 couples of parents of one or more children and the statistical analysis revealed a significant difference between the two groups in terms of urinary concentrations of phthalates metabolites. A further step will be the correlation of these results with information on the life styles and working conditions collected through a specifically designed questionnaire.     

Interaction of di-(2-ethylhexyl) phthalate with the pharmacological response and metabolic aspects of ethanol in mice

The interactions of di-(2-ethylhexyl) phthalate (DEHP) with the pharmacological response and metabolic aspects of ethanol in mice were investigated at oral doses of DEHP of 1.5, 3.0 and 7.5 g/kg or intraperitoneal doses of 3.7, 7.5 and 18.9 g/kg, administered once or daily for 7 days. A single oral or intraperitoneal administration of DEHP resulted in a significant increase in the ethanol-induced sleeping time, associated with an inhibition of alcohol dehydrogenase activity in liver; the effect of intraperitoneal administration was significant only at the highest dose. The activities of high and low Km aldehyde dehydrogenases in mouse liver were not affected by a single dose of DEHP by either route. Repeated oral doses of DEHP produced significant reductions in the ethanol-induced sleeping time and increases in the activities of alcohol and aldehyde dehydrogenases, whereas repeated intraperitoneal doses of DEHP significantly increased the sleeping time and decreased the activity of alcohol dehydrogenase, without any perceptible effect on the activities of aldehyde dehydrogenases. In vitro studies with mouse liver preparations revealed significant inhibition of alcohol dehydrogenase activity by mono-(2-ethylhexyl) phthalate and 2-ethylhexanol and of high and low Km aldehyde dehydrogenase activities by DEHP and mono-(2-ethylhexyl) phthalate at concentrations ranging from 0.03 to 1.00 mM. In all cases, in vitro enzyme inhibition by mono-(2-ethylhexyl) phthalate was most pronounced.     

Assessment of the teratogenicity of di(2-ethylhexyl)phthalate and mono(2-ethylhexyl)phthalate in mice

Di(2-ethylhexyl)phthalate (DEHP) and mono(2-ethylhexyl)phthalate (MEHP) were administered PO or IP to pregnant ICR mice at varying doses on days 7, 8, and 9 of gestation. In groups given DEHP orally, resorptions and malformed fetuses increased significantly at 1,000 mg/kg. Fetal weights were also significantly suppressed. Anterior neural tube defects (anencephaly and exencephaly) were the malformations most commonly produced. No teratogenic effects were revealed by IP doses of DEHP and PO or IP doses of MEHP, although high doses were abortifacient and lethal to pregnant females. Thus DEHP is highly embryotoxic and teratogenic in mice when given PO but not IP. The difference in metabolism, disposition, or excretion by the route of administration may be responsible for the difference in DEHP teratogenicity. Although MEHP is a principal metabolite of DEHP and is several times more toxic than DEHP to adult mice, it seems that MEHP and its metabolites are not teratogenic in ICR mice.     

The occurrence of phthalic acid esters in various samples of commercially available sodium chloride injections (Indian Pharmacopoeia)

Conclusive evidence for the presence of di(2-ethylhexyl) phthalate (DEHP) in 15 out of 17 commercially available sodium chloride injection (Indian Pharmacopoeia) samples was obtained and concentration levels as high as 11.0 mg/500 ml of saline were detected. The presence of such contaminants in i.v. fluids, avoidable by the institution of appropriate quality control measures before manufacturing and marketing, is a matter of serious concern. Stipulated specifications in different pharmacopoeias are meant only to ensure sterility and pyrogenicity, and it is advisable that cognisance be taken of the presence of toxic contaminants e.g. di(2-ethylhexyl) phthalate.     

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.     

Teratogenicity of di-(2-ethylhexyl)phthalate in mice

Fetotoxicity of di-(2-ethylhexyl)phthalate (DEHP) was studied in a random strain (ddY-Slc♀ × CBA ♂) of mice. A single oral administration of DEHP 0.05 ml/kg on day 7 of gestation resulted in a decrease in body weight of live fetuses, but there were no dead, gross, or skeletal abnormal fetuses. At 0.1 ml/kg and above DEHP decreased fetal body weight and the fetuses were dead or deformed. The fetotoxicity was dose dependent and a straight line Y = 51.9 log X + 61.6 was obtained where Y = the rate of death(%) and X = the dose of DEHP administered (ml/kg). The LD₅₀ and the non-effective aximum dose which induced fetal death was 0.60 ml/kg and 0.065 ml/kg, respectively. The non-effective maximum doses which resulted in gross and skeletal abnormalities were 0.80 and 0.68 ml/kg, respectively.     

Effect of di(2-ethylhexyl)phthalate (DEHP) on hepatic mixed function oxidases in different animal species

Administration of 2000 mg/kg of di(2-elhylhexyl)phthalate (DEHP) for a period of 7 or 15 days in rats, mice, guinea pigs and rabbits produced a differential effect as judged by alterations in body weight gain, liver weight and activities of mixed function oxidases. DEHP exposure for 7 days caused an increase in the activity of aniline hydroxylase, arylhydrocarbon hydroxylase and ethylmorphine N-demethylase in rats, mice and guinea pigs, but a decrease in that of rabbits. However, exposure for 15 days produced a smaller degree of increase in the activity of these enzymes in rats and mice and even produced a decrease in the activity of these enzymes in guinea pigs. This differential response of DEHP in various animal species suggests a species difference in the toxicity of the plasticizer.     

Blood burden of di(2-ethylhexyl) phthalate and its primary metabolite mono(2-ethylhexyl) phthalate in pregnant and nonpregnant rats and marmosets

A comparison of the dose-dependent blood burden of di(2-ethylhexyl) phthalate (DEHP) and mono(2-ethylhexyl) phthalate (MEHP) in pregnant and nonpregnant rats and marmosets is presented. Sprague-Dawley rats and marmosets were treated orally with 30 or 500 mg DEHP/kg per day, nonpregnant animals on 7 (rats) and 29 (marmosets) consecutive days, pregnant animals on gestation days 14-19 (rats) and 96-124 (marmosets). In addition, rats received a single dose of 1000 mg DEHP/kg. Blood was collected up to 48 h after dosing. Concentrations of DEHP and MEHP in blood were determined by GC/MS. In rats, normalized areas under the concentration-time curves (AUCs) of DEHP were two orders of magnitude smaller than the normalized AUCs of the first metabolite MEHP. Metabolism of MEHP was saturable. Repeated DEHP treatment and pregnancy had only little influence on the normalized AUC of MEHP. In marmosets, most of MEHP concentration-time courses oscillated. Normalized AUCs of DEHP were at least one order of magnitude smaller than those of MEHP. In pregnant marmosets, normalized AUCs of MEHP were similar to those in nonpregnant animals with the exception that at 500 mg DEHP/kg per day, the normalized AUCs determined on gestation days 103, 117, and 124 were distinctly smaller. The maximum concentrations of MEHP in blood of marmosets were up to 7.5 times and the normalized AUCs up to 16 times lower than in rats receiving the same daily oral DEHP dose per kilogram of body weight. From this toxicokinetic comparison, DEHP can be expected to be several times less effective in the offspring of marmosets than in that of rats if the blood burden by MEHP in dams can be regarded as a dose surrogate for the MEHP burden in their fetuses.     

Disposition of orally administered di-(2-ethylhexyl) phthalate and mono-(2-ethylhexyl) phthalate in the rat

The dispositon of di-(2-ethylhexyl) phthalate (DEHP) and mono-(2-ethylhexyl) phthalate (MEHP) was studied in the rat. Three hours after a single oral dose of DEHP (2.8 g/kg), plasma concentrations of 8.8±1.7 g/ml DEHP and 63.2±8.7 g/ml MEHP were reached. MEHP levels declined with a half-life of 5.2±0.5 h. The ratio of the area under the plasma concentration-time curve of MEHP to that of DEHP was 16.1±6.1. When ¹⁴CDEHP was administered, 19.3±3.3% of the radioactivity was excreted in the urine within 72 h, the rest being excreted in the faeces. The urinary excretion rate of total radioactivity declined with a half-life of 7.9±0.5 h. Single administration of MEHP (0.4 g/kg) resulted in plasma concentrations of 84.1±14.9 g/ml 3 h after dosing; the half-life of MEHP was 5.5±1.1 h. Multiple dosing with DEHP (2.8 g/kg/day) for 7 consecutive days produced no accumulation of DEHP or MEHP in plasma.     

Effects of co-administration of Di(2-ethylhexyl)phthalate and testosterone on several parameters in the testis and pharmacokinetics of its mono-de-esterified metabolite

The administration of 1 g/kg di(2-ethylhexyl) phthalate (DEHP) or 5 mg/kg testosterone for 1 week did not affect the testicular and prostatic gland weights in rats. However, co-administration of DEHP and testosterone induced severe testicular atrophy accompanied by a decrease of zinc concentration in the testis and reduction of the activity of testicular specific lactate dehydrogenase isozyme. These changes were similar to the results of high dose administration of DEHP alone. Values of biological half-life and area under the concentration-time curve (AUC) of mono(2-ethylhexyl)phthalate, the main metabolite of DEHP, in testes after a single co-administration of DEHP (p.o.) and testosterone (i.p.) were higher than those after DEHP administration alone. Results suggest that the co-administration of DEHP and testosterone enhanced the adverse effects of DEHP on testes as the result of changes in pharmacokinetic values of MEHP.     

A dose-response study following in utero and lactational exposure to di-(2-ethylhexyl) phthalate (DEHP): effects on androgenic status, developmental landmarks and testicular histology in male offspring rats

An extensive dose-response study following in utero and lactational exposure to di-(2-ethylhexyl) phthalate (DEHP) was conducted. A wide range of low and high DEHP doses were tested. Reproductive effects were evaluated on male offspring rats. Female Wistar rats were treated daily with DEHP and peanut oil by gavage from gestation day 6 to lactation day 21 at doses of 0.015, 0.045, 0.135, 0.405 and 1.215 mg DEHP/kg body weight (bw)/day (low doses) and at 5, 15, 45, 135 and 405 mg DEHP/kg bw/day (high doses). Nipple retention and reduced anogenital distance, both sensitive markers of anti-androgenic effects during development, were only seen in males exposed to the highest dose (405 mg/kg/day). Delayed preputial separation was observed in animals exposed to 15 mg DEHP/kg/day and higher doses. Histopathological examination of the testis on postnatal days (PNDs) 1 and 22 revealed changes at 135 and 405 mg DEHP/kg/day. The most prominent finding on PND 1 was the presence of bi- and multinucleated gonocytes. On PND 22 signs of reduced germ cell differentiation in seminiferous tubules of exposed animals were observed. Testis weight on PND 22 was significantly increased at 5, 15, 45 and 135 mg/kg/day, an effect that qualitatively differs from exposure to higher doses. The current results show that DEHP acts as an anti-androgen at a high dose exposure (405 mg/kg/day). However, these results also indicate that other subtle developmental effects occur at lower DEHP doses.     

Long‐term exposure to bis(2‐ethylhexyl)phthalate (DEHP) inhibits growth of guppy fish (Poecilia reticulata)

Bis(2‐ethylhexyl)phthalate (DEHP) is a widely used plasticizer that is a commonly found contaminant of aquatic environments. However, little is known about the long‐term effects of DEHP on fish development, as previous studies yielded conflicting results and mostly investigated the effects of concentrations higher than those found in natural habitats. We thus aimed to investigate the effects of DHEP (i) at concentrations present in the environment, and (ii) under conditions that might accentuate any deleterious consequences (larvae rather than adult fish, use of higher temperature). Different concentrations of DEHP (0.1–10 µg l^?1rpar; applied continuously for 91 days were tested on guppy fish that were less than one week old at the beginning of the treatment. As early as 14 days after the start of exposure, guppies treated with 10 µg l^?1 DEHP showed significantly reduced body length as compared with control fish. The inhibitory effect of DEHP was concentration‐dependent and increased with time, leading to a maximal reduction in body length of 15 and 40% at 1 and 10 µg l^?1 DEHP, respectively. The effect was even more pronounced for body weight, which was diminished by up to 40 and 70% at 1 and 10 µg l^?1 DEHP, respectively. The reduction in growth was still significant at 91 days of DEHP treatment, whereas the Fulton's condition factor was unaffected. While DEHP significantly blocked growth in both male and female guppies, no shift in the sexual development was observed. These data show that DEHP, at concentrations present in aquatic environments, can profoundly affect development in fish. Copyright © 2009 John Wiley & Sons, Ltd.     

Di-(2-ethylhexyl) phthalate enhances the release of lysosomal enzymes from alveolar macrophages during phagocytosis

Lung tissue damage, histologically similar to protease induced lung lesions, has been previously demonstrated in animals exposed to the plasticizer, di-(2-ethylhexyl)phthalate (DEHO). In an attempt to identify the mechanism responsible for this damage, we have examined the effect of DEHP on alveolar macrophages. Serum solubilized DEHP has a significant effect on both the phogocytosis of latex particles and lysosomal enzyme released from rabbit alveolar macrophages. Pre-exposure to 2 mg% DEHP caused a 2-fold increase in the rate of phagocytosis and an 8-fold and 10-fold increase, respectively, in the release of the lysosomal hydrolases β-glucuronidase and acid phosphatase. Although exposure to 2 mg% DEHP caused an 8-fold increase in in vitro cell death, pre-exposure to DEHP had only minimal effect on death during subsequent cell culture, as indicated by measurement of dye exclusion and the release of the cytosolic enzyme lactate dehydrogenase. The relationship between the DEHP induced increase in lysosomal enzyme release from alveolar macrophages and the pathological and histological effects of DEHP on pulmonary tissue is discussed, particularly with respect to patients receiving multiple blood transfusions.     

Effects of maternal exposure to di(2-ethylhexyl)phthalate (DEHP) during pregnancy on susceptibility to neonatal asthma

Di(2-ethylhexyl) phthalate (DEHP) is used as a plasticizer and is widely dispersed in the environment. In this study, we investigated the effects of maternal exposure to DEHP during pregnancy on neonatal asthma susceptibility using a murine model of asthma induced by ovalbumin (OVA). Pregnant BALB/c mice received DEHP from gestation day 13 to lactation day 21. Their offspring were sensitized on postnatal days (PNDs) 9 and 15 by intraperitoneal injection of 0.5 μg OVA with 200 μg aluminum hydroxide. On PNDs 22, 23 and 24, live pups received an airway challenge of OVA for 30 min. Offspring from pregnant mice that received DEHP showed reductions in inflammatory cell count, interleukin (IL)-4, IL-13, and eotaxin in their bronchoalveolar lavage fluid and in total immunoglobulin E and OVA-specific IgE in their plasma compared with offspring from pregnant mice that did not receive DEHP treatment. These results were consistent with histological analysis and immunoblotting. Maternal exposure to DEHP reduces airway inflammation and mucus production in offspring, with a decrease in inducible nitric oxide synthase (iNOS) in the lung tissue. This study suggests that maternal exposure to DEHP during pregnancy reduces asthmatic responses induced by OVA challenge in offspring. These effects were considered to be closely related to the suppression of Th2 immune responses and iNOS expression.     

Elimination,distribution and metabolism of di-(2-ethylhexyl)adipate (deha) in rats

The excretion, retention, distribution and metabolism of di-(2-ethylhexyl)adipate (DEHA) have been studied in the rat.After oral administration of [¹⁴C]DEHA, almost all the dose was excreted within 48 h, predominantly in the urine and as respiratory carbon dioxide. The faecal excretion was low. There was no evidence of the accumulation of radioactivity in any organs or tissues. Adipic acid (AA) was found to be the main urinary metabolite; it was also detected in the digestive tract, blood and liver.In vitro, DEHA was hydrolyzed at a significant rate by tissue preparations prepared from liver, pancreas and small intestine of the rat.These results suggest that orally administered DEHA is rapidly hydrolyzed in the body to form AA without any accumulation of mono-(2-ethylhexyl)adipate (MEHA).