Impact of the Di(2-Ethylhexyl) Phthalate Administration on Trace Element and Mineral Levels in Relation of Kidney and Liver Damage in Rats

Di(2-ethylhexyl) phthalate (DEHP) is a widely used synthetic polymer in the industry. DEHP may induce reproductive and developmental toxicity, obesity, carcinogenesis and cause abnormal endocrine function in both human and wildlife. The aim of this study was to investigate trace element and mineral levels in relation of kidney and liver damage in DEHP-administered rats. Therefore, prepubertal male rats were dosed with 0, 100, 200, and 400 mg/kg/day of DEHP. At the end of the experiment, trace element and mineral levels, glucose-6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6-PGD), glutathione reductase (GR) and glutathione S-transferase (GST) enzyme activities were evaluated in the serum, liver, and kidney samples of rats. Furthermore, serum clinical biochemistry parameters, organ/body weight ratios and histological changes were investigated to evaluate impact of DEHP more detailed. Our data indicated that sodium (Na), calcium (Ca), potassium (K), lithium (Li), rubidium (Rb) and cesium (Cs) levels significantly decreased, however iron (Fe) and selenium (Se) concentrations significantly increased in DEHP-administered groups compared to the control in the serum samples. On the other hand, upon DEHP administration, selenium concentration, G6PD and GR activities were significantly elevated, however 6-PGD activity significantly decreased compared to the control group in the kidney samples. Decreased G6PD activity was the only significant change between anti-oxidant enzyme activities in the liver samples. Upon DEHP administration, aberrant serum biochemical parameters have arisen and abnormal histological changes were observed in the kidney and liver tissue. In conclusion, DEHP may induce liver and kidney damage, also result abnormalities in the trace element and mineral levels.

Metabolism and urinary excretion kinetics of di(2-ethylhexyl) terephthalate (DEHTP) in three male volunteers after oral dosage

Di(2-ethylhexyl) terephthalate (DEHTP) is used as a substitute for di(2-ethylhexyl) phthalate (DEHP), an ortho-phthalate-based plasticizer that is classified and labeled due to its toxicity to reproduction. In this study the metabolism and urinary excretion kinetics of DEHTP were investigated by single oral dosage of 50 mg DEHTP to three male volunteers (resulting in individual dosages between 0.55 and 0.59 mg/kg body weight). Separate urine samples were consecutively collected for 48 h. In analogy to DEHP, we quantified specific side-chain-oxidized monoester metabolites of DEHTP (5OH-MEHTP, 5oxo-MEHTP, 5cx-MEPTP and 2cx-MMHTP) by HPLC-MS/MS with online sample clean-up and isotope dilution. All postulated metabolites were detectable in all samples after dosage. The predominant, specific urinary metabolite was 5cx-MEPTP representing about 13.0 % of the applied dose as mean of the three volunteers (range 7.0-20.4 %) in urine, followed by 5OH-MEHTP (mean: 1.8 %; range 1.3-2.4 %) and 5oxo MEHTP (mean: 1.0 %; range 0.6-1.6 %). 2cx-MMHTP was a minor metabolite representing only 0.3 % (range 0.2-0.4 %). In total, about 16.1 % of the dose was recovered in urine as the above investigated specific metabolites within 48 h with the major share (95 %) being excreted within the first 24 h. Investigation of the glucuronidation patterns revealed that the carboxy-metabolites are excreted almost completely in their free form (>90 %), whereas for 5OH-MEHTP and 5oxo-MEHTP, glucuronidation is preferred (>70 %). With this study we provide reliable urinary excretion factors to calculate DEHTP intakes based on metabolite concentrations in environmental and occupational studies.

DEHP induces obesity and hypothyroidism through both central and peripheral pathways in C3H/He mice

OBJECTIVE

Di(2-ethylhexyl) phthalate (DEHP) is reported to cause obesity and hypothyroidism in both humans and rodents, but the underlying mechanisms were largely unknown. This study was designed to clarify the effects and the mechanisms of DEHP on the pathogenesis of obesity and hypothyroidism and to discover the relationship between them.

METHODS

Male C3H/He mice were treated with DEHP for 5 weeks, and the body weight, food intake, and body temperature were recorded during the exposure. After exposure, key organs and serum were analyzed by Q-PCR, Western blot, and ELISA.

RESULTS

DEHP induced significant body weight gain and adipogenesis in all exposure groups except for 0.05 mg/kg. Marked hyperphagia and daytime hypothermia were also observed, which were accompanied by disturbed hypothalamic neuropeptide expression and reduced BAT UCP1 expression. In addition, WAT lipid metabolism was significantly deceased at low dose (0.5 mg/kg) and increased at high dose (50 and 200 mg/kg). DEHP also induced hypothyroidism, which was probably attributed to the combined effects of hepatic CAR activation and hypothalamic TRH inhibition induced by hypothalamic leptin resistance.

CONCLUSIONS

Chronic DEHP exposure could induce obesity by interrupting energy homeostasis, which is probably due to the synergistic effects of hypothyroidism and hypothalamic leptin resistance.

The effects on steroidogenesis and histopathology of adult male Japanese quails (Coturnix coturnix japonica) testis following pre-pubertal exposure to di(n-butyl) phthalate (DBP)

In the present study, we have investigated the effects of 30-day dietary (pre-pubertal) exposure to different doses (0 (control), 1, 10, 50, 200 and 400 mg/kg bodyweight/day) of di(n-butyl) phthalate (DBP) on Leydig cells of adult male Japanese quails by quantifying the transcript levels for P450 side-chain cleavage (p450scc), P450c17 (CYP17), and 3β- and 17β-hydroxysteroid dehydrogenase (hsd) using quantitative (real-time) polymerase chain reaction (qRT-PCR). In addition, the plasma testosterone levels were analysed using radioimmunoassay (RIA) and testis was examined for evidence of gross pathology and histopathology. Our data showed that pre-pubertal exposure to DBP produced alterations in testicular architecture as evident by poorly developed or mis-shaped testis, and altered spermatogenesis due to tubular degeneration and atrophy of seminiferous tubules especially in the high DBP dose (200 and 400 mg/kg) treated groups. In addition, DBP altered several key enzymes involved in testicular steroidogenesis pathways in an apparent dose-dependent manner. For example, biphasic effects of DBP were observed for P450scc and 3β-hsd mRNA, that were generally increasing at low dose 10 mg/kg, and thereafter, an apparent dose-dependent decrease between 50 and 400mg/kg. The steroidogenic acute regulatory (StAR) protein was at the lowest detectable limits and therefore not quantifiable. These effects did not parallel the non-significant changes observed for plasma testosterone levels. The present data is consistent with previous reports showing that DBP modulates Leydig cell steroidogenesis in several species, with a potential negative effect on reproduction in those avian species that are vulnerable to endocrine disrupting chemicals.

In utero exposure to the endocrine disruptor di-(2-ethylhexyl) phthalate induces long-term changes in gene expression in the adult male adrenal gland

The plasticizer di-(2-ethylhexyl) phthalate (DEHP) is used to add flexibility to polyvinylchloride polymers and as a component of numerous consumer and medical products. DEHP and its metabolites have been detected in amniotic fluid and umbilical cord blood, suggesting fetal exposure. In the present study, we used an in utero exposure model in which pregnant rat dams were exposed to 1- to 300-mg DEHP/kg·d from gestational day 14 until birth. We previously reported that this window of exposure to environmentally relevant doses of DEHP resulted in reduced levels of serum testosterone and aldosterone in adult male offspring and that the effects on aldosterone were sustained in elderly rats and resulted in decreased blood pressure. Here, we characterized the long-term effects of in utero DEHP exposure by performing global gene expression analysis of prepubertal (postnatal d 21) and adult (postnatal d 60) adrenal glands. We found that the peroxisome proliferator-activated receptor and lipid metabolism pathways were affected by DEHP exposure. Expression of 2 other DEHP targets, hormone-sensitive lipase and phosphoenolpyruvate carboxykinase 1 (Pck1), correlated with reduced aldosterone levels and may account for the inhibitory effect of DEHP on adrenal steroid formation. The angiotensin II and potassium pathways were up-regulated in response to DEHP. In addition, the potassium intermediate/small conductance calcium-activated channel Kcnn2 and 2-pore-domain potassium channel Knck5 were identified as DEHP targets. Based on this gene expression analysis, we measured fatty acid-binding protein 4 and phosphoenolpyruvate carboxykinase 1 in sera from control and DEHP-exposed rats and identified both proteins as putative serum biomarkers of in utero DEHP exposure. These results shed light on molecular targets that mediate DEHP long-term effects and, in doing so, provide means by which to assess past DEHP exposure.

Derivation of an oral reference dose (RfD) for the nonphthalate alternative plasticizer 1,2-cyclohexane dicarboxylic acid, di-isononyl ester (DINCH)

1,2-Cyclohexanedicarboxylic acid, 1,2-diisononylester (DINCH), a polyvinyl chloride plasticizer, has food, beverage, and medical device applications that may result in general population exposure. Although no apparent toxicity information in humans was identified, there is a substantial data set in lab animals to serve as the basis of hazard identification for DINCH. Target tissues associated with repeated dietary DINCH exposure in lab animals included liver, kidney, and thyroid and mammary glands. In contrast to some phthalate ester plasticizers, DINCH did not show evidence of hepatic peroxisomal proliferation, testicular toxicity, or liver tumors in rats. Liver and thyroid effects associated with DINCH exposure were attributed to compensatory thyroid stimulation secondary to prolonged metabolic enzyme induction. The toxicological significance of mammary fibroadenomas in female rats is unclear, given that this common benign and spontaneously occurring tumor type is unique to rats. The weight of evidence suggests DINCH is not genotoxic and the proposed mode of action (MOA) for thyroid gland lesions was considered to have a threshold. No adverse reproductive effects were seen in a two-generation study. An oral reference dose (RfD) of 0.7 mg/kg-d was derived from a human equivalent BMDL₁₀ of 21 mg/kg-d for thyroid hypertrophy/hyperplasia seen in adult F₁ rats also exposed in utero. The total uncertainty factor of 30x was comprised of intraspecies (10×) and database (3×) factors. An interspecies extrapolation factor was not applied since rodents are more sensitive than humans with respect to the proposed indirect MOA for thyroid gland lesions.

Prepubertal mouse testis growth and maturation and androgen production are acutely sensitive to di-n-butyl phthalate

Phthalates are plasticizers with widespread industrial, domestic, and medical applications. Epidemiological data indicating increased incidence of testicular dysgenesis in boys exposed to phthalates in utero are reinforced by studies demonstrating that phthalates impair fetal rodent testis development. Because humans are exposed to phthalates continuously from gestation through adulthood, it is imperative to understand what threat phthalates pose at other life stages. To determine the impact during prepuberty, we assessed the consequences of oral administration of 1 to 500 mg di-n-butyl phthalate (DBP)/kg/d in corn oil to wild-type (C57BL/6J) male mice from 4 to 14 days of age. Dose-dependent effects on testis growth correlated with reduced Sertoli cell proliferation. Histological and immunohistochemical analyses identified delayed spermatogenesis and impaired Sertoli cell maturation after exposure to 10 to 500 mg DBP/kg/d. Interference with the hypothalamic-pituitary-gonadal axis was indicated in mice fed 500 mg DBP/kg/d, which had elevated circulating inhibin but no change in serum FSH. Increased immunohistochemical staining for inhibin-α was apparent at doses of 10 to 500 mg DBP/kg/d. Serum testosterone and testicular androgen activity were lower in the 500 mg DBP/kg/d group; however, reduced anogenital distance in all DBP-treated mice suggested impaired androgen action at earlier time points. Long-term effects were evident, with smaller anogenital distance and indications of disrupted spermatogenesis in adult mice exposed prepubertally to doses from 1 mg DBP/kg/d. These data demonstrate the acute sensitivity of the prepubertal mouse testis to DBP at doses 50- to 500-fold lower than those used in rat and identify the upregulation of inhibin as a potential mechanism of DBP action.

Two generations of fall armyworm (Lepidoptera: Noctuidae) contamination by di-n-butylphthalate

The effects of di-n-butylphthalate (DnBP) were investigated with respect to bioaccumulation and whether these effects occurred over a second generation in the fall armyworm Spodoptera frugiperda (J.E. Smith, 1797). The concentrations of DnBP in males and females of the second generation were higher than those in first one. However, frequency of mortality of exposed individuals in the second generation was approximately 57% less but the reduction in size and weight was more pronounced than in the first generation.

Exposure to di(2-ethyl-hexyl) phthalate (DEHP) in utero and during lactation causes long-term pituitary-gonadal axis disruption in male and female mouse offspring

The present study examined the effects in mice of exposure to di(2-ethyl-hexyl) phthalate (DEHP) throughout pregnancy and lactation on the development and function of the pituitary-gonadal axis in male and female offspring once they have attained adulthood. Groups of two to three dams were exposed with the diet from gestational d 0.5 until the end of lactation, at 0, 0.05, 5, and 500 mg DEHP/kg · d. The experiment was repeated three times (total: seven to 10 dams per treatment). The 500-mg dose caused complete pregnancy failure, whereas exposure to doses of 0.05 and 5 mg did not affect pregnancy and litter size. In total, about 30 male and 30 female offspring per group were analyzed. Offspring of the DEHP-treated groups, compared with controls, at sexual maturity showed: 1) lower body weight (decrease 20-25%, P < 0.001); 2) altered gonad weight (testes were ∼13% lighter and ovaries ∼40% heavier; P < 0.001); 3) poor germ cell quality (semen was ∼50% less concentrated and 20% less viable, and ∼10% fewer oocytes reached MII stage, P < 0.001); 4) significant lower expression of steroidogenesis and gonadotropin-receptor genes in the gonads; and 5) up-regulated gonadotropin subunit gene expression in the pituitary. In conclusion, our findings suggest that, in maternally exposed male and female mice, DEHP acts on multiple pathways involved in maintaining steroid homeostasis. Specifically, in utero and lactational DEHP exposure may alter estrogen synthesis in both sexes. This, in turn, induces dysregulation of pituitary-gonadal feedback and alters the reproductive performance of exposed animals.

[Toxicity effects of phthalate substitute plasticizers used in toys]

Phthalate esters are widely used as plasticizers in polyvinyl chloride products. Because of human health concerns, regulatory authorities in Japan, US, Europe and other countries control the use of di(2-ethylhexyl) phthalate, diisononyl phthalate, di-n-butyl phthalate, butylbenzyl phthalate, diisodecyl phthalate and di-n-octyl phthalate for the toys that can be put directly in infants' mouths. While these regulatory actions will likely reduce the usage of phthalate esters, there is concern that other plasticizers that have not been sufficiently evaluated for safety will be used more frequently. We therefore collected and evaluated the toxicological information on di(2-ethylhexyl) terephthalate (DEHT), 1,2-cyclohexanedicarboxylic acid, diisononyl ester (DINCH), diisononyl adipate (DINA), 2,2,4-trimetyl-1,3-pentanediol diisobutyrate (TXIB), tri-n-butyl citrate (TBC) and acetyl tri-n-butyl citrate (ATBC) which were detected at a relatively high frequency in toys. The collected data have shown that chronic exposure to DEHT affects the eye and nasal turbinate, and DINCH exerts effects on the thyroid and kidney in rats. DINA and TXIB have been reported to have hepatic and renal effects in dogs or rats, and ATBC slightly affected the liver in rats. The NOAELs for repeated dose toxicity are relatively low for DINCH (40 mg/kg bw/day) and TXIB (30 mg/kg bw/day) compared with DEHT, DINA and ATBC. DEHT, TXIB and ATBC have been reported to have reproductive/developmental effects at relatively high doses in rats. For DINA and TBC, available data are insufficient for assessing the hazards, and therefore, adequate toxicity studies should be conducted. In the present review, the toxicity information on 6 alternatives to phthalate plasticizers is summarized, focusing on the effects after oral exposure, which is the route of most concern.

[Study on the effect of di-(2-ethylhexyl) phthalate on pregnant rats and the protection of zinc against it in pregnancy]

OBJECTIVE

To investigate the effect of di-(2-ethylhexyl) phthalate (DEHP) on pregnant rat and the protection of zinc.

METHODS

Fifty rats were randomized equally into 5 groups consisting of blank (given 1 ml 0.9% sodium chloride), corn oil (given 1 ml corn oil), zinc (given 1 ml zinc gluconate including 1.2 mg zinc), DEHP (given 50 mg×kg(-1)×d(-1) DEHP) and DEHP + zinc (given 50 mg×kg(-1)×d(-1) DEHP + zinc gluconate). At the beginning of the experiment (about 7 d before pregnancy), the female rats were administered with corresponding drugs everyday. The pregnant rats were killed and the fetal rats were removed on 19th day. The following results in each group were recorded: the body weight and the organic weight of the female rats, the number and the weight of fetus rats and the placental weight.

RESULTS

The weight and the coefficient of female rats' kidney/body, spleen/body, brain/body, and heart/body in DEHP group compared with other groups were not statistical significance (all P > 0.05). The coefficient of female rats' liver/body, uterus/body, and ovary/body of blank group were (4.4 ± 0.7)%, (1.26 ± 0.09)%, (0.083 ± 0.009)% respectively, corn oil group were (4.5 ± 0.6)%, (1.29 ± 0.10)%, (0.084 ± 0.008)%, zinc group were (4.4 ± 0.4)%, (1.26 ± 0.08)%, (0.084 ± 0.009)%, DEHP group were (5.4 ± 1.0)%, (1.11 ± 0.08)%, (0.074 ± 0.012)%, and DEHP + zinc group were (4.4 ± 1.0)%, (1.28 ± 0.10)%, (0.082 ± 0.007)%; in DEHP group the coefficient of female rats' liver/body, uterus/body, and ovary/body compared with other groups was statistical significance (P < 0.05). The fetal quantity, fetal weight and placental weight of female rats of blank group were 12.8 ± 2.7, (6.03 ± 0.16) g, (1.00 ± 0.03) g respectively, corn oil group were 13.6 ± 3.1, (6.07 ± 0.20) g, (1.00 ± 0.04) g, zinc group were 13.3 ± 3.1, (6.16 ± 0.18) g, (1.00 ± 0.05) g, DEHP group were 9.2 ± 4.1, (4.03 ± 0.09) g, (0.95 ± 0.03) g, and zinc + DEHP group were 12.1 ± 2.9, (6.09 ± 0.17) g, (0.99 ± 0.03) g. In DEHP group the fetal quantity, fetal weight and placental weight of female rats compared with other groups were statistical significance (P < 0.05).

CONCLUSION

DEHP can damage female rats and fetal rats in gestation period. Zinc supplied before pregnancy can relieve the influence by DEHP.

Developmental toxicity and uterotrophic studies with di-2-ethylhexyl terephthalate

BACKGROUND

These studies were conducted to evaluate the potential adverse effects of di-2-ethylhexyl terephthalate (DEHT) exposure on in utero development in mice and rats. In addition, a uterotrophic assay for estrogenic activity was conducted in sexually immature rats.

METHODS

In the developmental toxicity studies, diet containing DEHT was fed to four groups of mated female Crl:CD(SD)IGS BR rats (25/group) from gestation day (GD) 0-20 or Crl:CD1(ICR) mice (25/group) from GD 0-18. Concentrations within the feed were 0, 0.3, 0.6, and 1.0% for the rats and 0, 0.1, 0.3, and 0.7% for the mice. Laparohysterectomies were carried out on the last day of exposure and the numbers of fetuses, early and late resorptions, total implantations, and corpora lutea were recorded. The fetuses were weighed, sexed, and examined for external, visceral and skeletal malformations, and developmental variations. The dose rate from dietary DEHT exposure was 0, 226, 458, and 747 mg/kg/day in the rats and 197, 592, and 1382 mg/kg/day in the mice for the control, low, mid, and high-exposure groups, respectively.

RESULTS

DEHT exposure did not affect clinical observations. A slight reduction in body weight gain was noted in the high-dose level rat group; the remaining groups were unaffected. At necropsy, increased liver weights were noted in the high-dose rat group and the mid- and high-dose mouse groups. Mean numbers of implantation sites and viable fetuses, mean fetal weights, and mean litter proportions of preimplantation loss, early resorptions, late resorptions, and fetal sex ratios were unaffected by DEHT exposures. No test article-related malformations or variations were observed at any concentration level in the rat and mouse developmental toxicity studies. In the uterotrophic assay for estrogenic activity, sexually immature female rats received oral gavage doses 20, 200, or 2000 mg DEHT/kg bw/day from postnatal day (PND) 19-21. A slight reduction in rate of body weight gain was noted on the first day of dosing in the high dose group, but no other indications of toxicity were evident. DEHT exposure did not affect wet or blotted uterine weight parameters in any of these dose groups. The NOEL for developmental toxicity in rats was 747 mg/kg/day and 1382 mg/kg/day in mice. The NOEL for estrogenic activity was 2000 mg/kg/day. The NOEL for maternal toxicity was 458 mg/kg/day in rats and 197 mg/kg/day in mice.

CONCLUSIONS

The lack of adverse developmental effects with DEHT exposure are in contrast to the adverse developmental effects noted after di-2-ethylhexyl phthalate (DEHP) exposure. The difference between the effects noted with the ortho-constituent (DEHP) and the lack of effects reported with the para-constituent (DEHT) is due most likely to differences in metabolism and the formation of the stable monoester, mono-2-ethylhexyl phthalate (MEHP) from the DEHP moiety.

Early pre-pubertal exposure to low-dose oral di(2-ethylhexyl) phthalate does not affect sperm plasma membrane stability, acrosomal integrity or chromatin structure in the post-pubertal boar

This study aimed to determine whether pre-pubertal exposure in boars to di(2-ethylhexyl) phthalate (DEHP), a plasticizer reported to have toxic effects on rodent reproduction, would affect the sperm ability to undergo capacitation and acrosome reaction (AR) in vitro or give rise to a higher degree of chromatin instability associated with acid-induced denaturation. Spermatozoa were collected from 16 boars (n=8/group) 8-9 months of age, exposed to 300mg/kg body weight of DEHP or placebo per os three times a week, from 3 to 7 weeks of age. The spermatozoa were cryopreserved and examined post-thaw by flow cytometry for their ability to capacitate in vitro when exposed to the effector bicarbonate and to acrosome-react when exposed to calcium ionophores, using the lipid stain Merocyanine-540 (m-540), and peanut agglutinin-fluorescein isothiocyanate, respectively, as probes. The ability of the DNA to sustain denaturation in vitro was tested using a sperm chromatin structure assay (SCSA). No significant differences between the DEHP-exposed group and controls were found for any of the sperm attributes examined. Frozen-thawed spermatozoa showed similar rates of non-capacitated cells between groups, and were capacitated at similar rates. Rates of induced ARs were also similar. Values of DNA denaturation were low and showed no differences between groups. In conclusion, pre-pubertal exposure to DEHP does not seem, under the conditions of the present experiment, to affect the ability of frozen-thawed spermatozoa collected post-puberty to capacitate or acrosome-react (the main requisites for fertilization) or to present damage in their nuclear genome.

Single-layer transdermal film containing lidocaine: Modulation of drug release

We have recently described an innovative drug delivery system, a water-based and vapor permeable film intended for dermal and/or transdermal delivery. The aim of this work was to modulate the delivery of the model drug lidocaine hydrochloride from the transdermal film across rabbit ear skin. The effect of drug loading, of film-forming polymer type and content, of adhesive and plasticizer on lidocaine transport across the skin was evaluated. Additional objective was to evaluate the effect of occlusion on the kinetics of lidocaine transport, by applying an occlusive backing on the surface of the transdermal film. From the data obtained it can be concluded that the transdermal film acts as a matrix controlling drug delivery. The film-forming polymer molecular weight had a negligible effect on drug penetration, while its content was more effective. The choice of the adhesive seems to be the most important variable governing drug transport. In particular, the presence of lauric acid combined with a basic drug, such as lidocaine, can produce a relevant improvement in permeation, because of the formation of an ion pair. Concerning the kinetics, drug depletion is responsible for the declining permeation rates observed in the late times of permeation.

Identification of differentially expressed genes in the testis of Sprague-Dawley rats treated with di(n-butyl) phthalate

The aim of this study was to identify the di(n-butyl) phthalate (DBP)-induced differentially expressed genes (DEGs) using a novel annealing control primer system in the testes of Sprague-Dawley male rats. Animals (4 weeks of age) were administered orally either corn oil only (vehicle control) or DBP (250, 500, or 750 mg/kg/day) for 30 days. Total RNA was isolated from the rat testes and GeneFishing PCR was used to determine the differential gene expression levels. Using this technique, a total of 59 DEG mRNA fragments were observed in the testes treated with DBP 750 mg/kg/day compared to vehicle control. Of these 59 genes, 31 genes were significantly altered after exposing rats to high dose DBP (750 mg/kg/day), and their sequences cloned. Based on the Basic Local Alignment Search Tool (BLAST), 4 expressed sequence tags (EST), 27 cloned genes (Insl3, pgrp, H1SHR, etc.) and 3 genes (LDHA, lactate dehydrogenase A; Spag4, sperm associated antigen 4 and PBR, peripheral-type benzodiazepine receptor) were found to be involved in spermatogenesis and steroidogenesis. In addition, the expression patterns of the steroidogenesis-related genes such as scavenger receptor class B-1 (SR-B1), steroidogenic acute regulated protein (StAR), P450 side chain cleavage (P450scc), CYP17, and CYP19 were further analyzed by RT-PCR. Significant increases in the mRNA levels of steroidogenesis-related genes (PBR, SR-B1, StAR, P450scc, and CYP17) were observed in the high dose DBP-treated rats. However, DBP significantly decreased the CYP19 mRNA levels compared with controls. DBP (750 mg/kg/day) significantly increased the TR-alpha1 and PPARgamma expression in testes, whereas the AR and ERbeta protein levels were significantly reduced in the same group. These data indicate that the steroidogenesis- or spermatogenesis-related genes identified in this study may provide insights into the molecular mechanisms underlying environmental pollutants-mediated male infertility.

Airway inflammation and adjuvant effect after repeated airborne exposures to di-(2-ethylhexyl)phthalate and ovalbumin in BALB/c mice

BACKGROUND

Epidemiological studies have suggested an association between exposure to phthalate plasticizers, including di-(2-ethylhexyl)phthalate (DEHP), and increased prevalence of asthma, rhinitis or wheezing. Furthermore, studies in mice have demonstrated an adjuvant effect from DEHP after parenteral administration with the model allergen ovalbumin (OVA).

OBJECTIVE

Exposures to DEHP were investigated for adjuvant effects and airway inflammation in a mouse inhalation model.

METHODS

BALB/cJ mice were exposed to aerosols of 0.022-13 mg/m(3) DEHP and 0.14 mg/m(3) OVA 5 days/week for 2 weeks and thereafter weekly for 12 weeks. Mice exposed to OVA alone or OVA+Al(OH)(3) served as control groups. Finally, all groups were exposed to a nebulized 1% OVA solution on three consecutive days. Serum, bronchoalveolar lavage (BAL) fluid, and draining lymph nodes were collected 24h later.

RESULTS

In the OVA+Al(OH)(3) group, significantly increased levels of OVA-specific IgE and IgG1 in serum as well as of eosinophils in BAL fluid were observed. DEHP affected OVA-specific IgG1 production in a concentration-dependent manner, whereas little effect was seen on IgE and IgG2a. Dose-dependent increases in inflammatory cells were observed in BAL fluids, leading to significantly higher lymphocyte, neutrophil and eosinophil numbers in the OVA+13 mg/m(3) DEHP group. Ex vivo cytokine secretion by cultures of draining lymph nodes suggested that DEHP has a mixed Th1/Th2 cytokine profile.

CONCLUSION

Airborne DEHP is able to increase serum IgG1 and lung inflammatory cell levels, but only at very high concentrations. Realistic DEHP levels do not have an adjuvant effect or induce allergic lung inflammation in the present mouse model.

A dose–response study following in utero and lactational exposure to di-(2-ethylhexyl) phthalate (DEHP): Reproductive effects on adult female offspring rats

Di(2-ethylhexyl) phthalate (DEHP) is used in numerous consumer products, mainly imparting flexibility and durability to polyvinyl chloride (PVC) based plastics. It is a known reproductive and developmental toxicant in male rodents. However, data regarding effects of DEHP on female reproductive health are particularly sparse. We performed an extensive dose-response study following developmental exposure to DEHP and evaluated the effects on adult female reproductive function. Two wide ranges of doses, low and high, were tested. Female Wistar rats were treated daily with DEHP and peanut oil (vehicle control) by gavage from gestation day 6 to lactation day 21. The low doses were: 0.015, 0.045, 0.135, 0.405 and 1.215mgDEHP/kg/bw/day and the high doses were: 5, 15, 45, 135 and 405mg DEHP/kg/bw/day. At the doses tested, no effects on organ (liver, kidney, spleen, thymus, thyroid, ovary and uterus) or body weights were detected. Female offspring presented a normal pattern of estrous cyclicity with no hormonal alterations (serum estradiol and progesterone). A statistically significant increase in tertiary atretic follicles was observed at the highest dose (405mgDEHP/kg/day). Morphometric analysis indicated that uterus and vagina luminal epithelial cell height were unaffected by treatment. An increase in the number of ovarian atretic tertiary follicles was the only effect observed in adult female offspring exposed in utero and during lactation to DEHP.

Development and characterization of film forming polymeric solutions for skin drug delivery

Film forming polymeric solutions as a novel approach for skin drug delivery were developed and characterized concerning their mechanical properties and water vapor permeability. They were developed by varying type and content of the film forming polymer as well as nature and content of the plasticizer. The resulting formulations were evaluated according to five criteria: drying time, cosmetic attractiveness, outward stickiness, integrity on skin (after 18 h) and viscosity. Among the 14 tested polymers 10 film formers yielded formulations with a positive evaluation in all five test criteria. Selected formulations were then investigated for tensile strength and elongation at break in vitro and for water vapor permeability in vitro (WVP) and in vivo (TEWL). Their mechanical properties determined in vitro were found to be not predictive for the flexibility and abrasion resistance observed on living skin. Similar to this, the results derived from the WVP and the TEWL methods were not in accordance with each other. Obviously, the investigated in vitro methods do not characterize the properties of the thin films on living skin satisfactorily. Nevertheless, the identified film forming solutions are a promising approach and will provide the basis for the further development of this novel dosage form.

Peroxisome Proliferator–Activated Receptor α Protects against Glomerulonephritis Induced by Long-Term Exposure to the Plasticizer Di-(2-Ethylhexyl)Phthalate

Safety concerns about di-(2-ethylhexyl)phthalate (DEHP), a plasticizer and a probable endocrine disruptor, have attracted considerable public attention, but there are few studies about long-term exposure to DEHP. DEHP toxicity is thought to involve peroxisome proliferator-activated receptor alpha (PPARalpha), but this contention remains controversial. For investigation of the long-term toxicity of DEHP and determination of whether PPARalpha mediates toxicity, wild-type and PPARalpha-null mice were fed a diet that contained 0.05 or 0.01% DEHP for 22 mo. PPARalpha-null mice that were exposed to DEHP exhibited prominent immune complex glomerulonephritis, most likely related to elevated glomerular oxidative stress. Elevated NADPH oxidase, low antioxidant enzymes, and absence of the PPARalpha-dependent anti-inflammatory effects that normally antagonize the NFkappaB signaling pathway accompanied the glomerulonephritis in PPARalpha-null mice. The results reported here indicate that PPARalpha protects against the nephrotoxic effects of long-term exposure to DEHP.

Dietary di(2-ethylhexyl)phthalate-impaired glucose metabolism in experimental animals

The effects of chronic intake of di(2-ethylhexyl)phthalate (DEHP) on the main intermediate glycolytic metabolites in liver and gastrocnemius muscle were investigated in experimental animals. Male Wistar rats (90-100 g) were fed for 21 days either with a standard chow or the same diet supplemented with 2% (w/w) of DEHP. The DEHP-fed rats had an altered in vivo glucose tolerance associated with abnormal glucose intermediate metabolite contents in liver and skeletal muscle. In these rats, the hepatic content of glucose-6-phosphate (G-6-P), fructose-6-phosphate, pyruvate, lactate, glucose-1-phosphate and glycogen decreased. At the same time, the G-6-P content decreased while the pyruvate and lactate levels increased in skeletal muscle. These data, along with the high plasma glucose concentration and the normal lactate blood levels of this group, could indicate that DEHP-fed rats could present a deficiency in muscle glucose and lactate transport, a reduction of the flux through muscle hexokinase and hepatic glucokinase, and a reduction in glycogen synth-

Effect of di-(2-ethylhexyl) phthalate on N-cadherin and catenin protein expression in rat testis

This study investigated the effect of DEHP exposure on N-cadherin and alpha-, beta- and p120-catenin immunoreactivities in the rat testis. DEHP was administered by daily gavage to 25-day-old male Sprague-Dawley rats at a dose of 2 g DEHP/5 ml corn oil/kg body weight for 2 days or 7 days. Control rats were treated with corn oil vehicle under the same conditions. Animals were killed at 24h after the last treatment. Another group of rats treated with DEHP or corn oil vehicle (control group) for 2 days were held for 30 days without treatment to observe recovery. Testes were analyzed for histopathology, TUNEL staining, immunofluorescence (IF) and Western blot analyses. Animals exposed to DEHP for 2 days or 7 days showed severe alterations of seminiferous tubules characterized by germ cell sloughing. Animals from the longer term recovery group treated with DEHP showed foci of delayed spermatogenesis. A linear and continuous pattern of N-cadherin was observed in the basal compartment of the seminiferous tubules. A similar pattern but with higher IF intensity was observed for N-cadherin in rats treated with DEHP for 2 days or 7 days, compared to control animals. The alpha-, beta- and p120-catenins were detected in the basal compartment of seminiferous tubules in similar localization and IF pattern for DEHP and control groups. A significant increase in testicular N-cadherin and alpha-catenin levels was detected by Western blot analysis in DEHP-exposed versus control rats. No variations in N-cadherin or catenin expression were detected in the recovery groups. These findings demonstrate that DEHP induces an up-regulation of N-cadherin and alpha-catenin expression and may perturb cell-cell adhesion phenomena in the seminiferous tubule.

The effect of pressurized carbon dioxide as a temporary plasticizer and foaming agent on the hot stage extrusion process and extrudate properties of solid dispersions of itraconazole with PVP-VA 64

The aim of the current research project was to explore the possibilities of combining pressurized carbon dioxide with hot stage extrusion during manufacturing of solid dispersions of itraconazole and polyvinylpyrrolidone-co-vinyl acetate 64 (PVP-VA 64) and to evaluate the ability of the pressurized gas to act as a temporary plasticizer as well as to produce a foamed extrudate. Pressurized carbon dioxide was injected into a Leistritz Micro 18 intermeshing co-rotating twin-screw melt extruder using an ISCO 260D syringe pump. The physicochemical characteristics of the extrudates with and without injection of carbon dioxide were evaluated with reference to the morphology of the solid dispersion and dissolution behaviour and particle properties. Carbon dioxide acted as plasticizer for itraconazole/PVP-VA 64, reducing the processing temperature during the hot stage extrusion process. Amorphous dispersions were obtained and the solid dispersion was not influenced by the carbon dioxide. Release of itraconazole from the solid dispersion could be controlled as a function of processing temperature and pressure. The macroscopic morphology changed to a foam-like structure due to expansion of the carbon dioxide at the extrusion die. This resulted in increased specific surface area, porosity, hygroscopicity and improved milling efficiency.

The Effects of Subacute Inhalation of Di (2‐ethylhexyl) Phthalate (DEHP) on the Testes of Prepubertal Wistar Rats

In animal studies using oral dosing for short periods, di (2-ethylhexyl) phthalate (DEHP) is well known for its reproductive toxicity, especially for its testicular toxicity. However, extending the period of DEHP exposure in prepubertal rats resulted in significant increases in testosterone. This suggests that the reproductive effect of DEHP might be associated with the timing and the term of exposure. Moreover, the route of exposure may induce differences in its effect because tissue levels of metabolites of DEHP after inhalation are thought to be different from those after oral administration. We researched the effects of inhalation of DEHP on testes of prepubertal rats. Our results showed that inhalation of DEHP by 4-wk-old male Wistar rats at doses of 5 or 25 mg/m(3), 6 h per day, for 4 and 8 wk significantly increased the concentration of plasma testosterone and weight of seminal vesicles. However, the concentration of luteinizing hormone (LH), follicular stimulating hormone (FSH) and the expression of mRNAs of androgen biosynthesis enzyme, cytochrome P450 cholesterol side-chain-cleavage enzyme (P450scc), 3beta-hydroxysteroid dehydrogenase (3beta-HSD), cytochrome P450 17alpha-hydroxylase/17, 20 lyase (CYP17) and aromatase (CYP19) did not change. Rats with precocious testes did not increase in any of the DEHP groups. We also found that the estimated effective dose in this study was less than those reported in previous studies which used oral dosing. Our study showed that inhaled DEHP increased plasma testosterone concentrations in prepubertal rats and suggested that their effects were more sensitive to inhalation of DEHP than oral dosing.

Probabilistic risk characterization: An example with di(2-ethylhexyl) phthalate

While probabilistic methods gain attention in hazard characterization and are increasingly used in exposure assessment, full use of the available probabilistic information in risk characterization is still uncommon. Usually, after probabilistic hazard characterization and/or exposure assessment, percentiles from the obtained distributions are used as point estimates in risk characterization. In this way, all information on variability and uncertainty is lost, while these aspects are crucial in any risk assessment. In this paper, we present a method to integrate the entire distributions from probabilistic hazard characterization and exposure assessment into one risk characterization plot. This method is illustrated using di(2-ethylhexyl) phthalate as an example. The final result of this probabilistic risk assessment is summarized in a single plot, containing two pieces of information: the confidence we may have in concluding there is no risk, and the fraction of the population this conclusion applies to. This information leads to a better informed conclusion on the risk of a substance, and may be very useful to define the necessary measures for risk reduction.

Risk assessment of oral exposure to diisononyl phthalate from children's products

Dialkyl phthalates are plasticizers used in household products made from polyvinyl chloride (PVC). Diisononyl phthalate (DINP) is the principal phthalate in soft plastic toys. Because DINP is not tightly bound to PVC, it may be released when children mouth PVC products. The potential chronic health risks of phthalate exposure to infants have been under scrutiny by regulatory agencies in Europe, Canada, Japan, and the U.S. This report describes a risk assessment of DINP exposure from children's products, by the U.S. Consumer Product Safety Commission (CPSC) staff. This report includes the findings of a CPSC Chronic Hazard Advisory Panel (CHAP) which: (1) concluded that DINP is unlikely to present a human cancer hazard and (2) recommended an acceptable daily intake (ADI) level of 120 microg/kg-d, based on spongiosis hepatis in rats. The risk assessment incorporates new measurements of DINP migration rates from 24 toys and a new observational study of children's mouthing activities, with a detailed characterization of the objects mouthed. Probabilistic methods were used to estimate exposure. Mouthing behavior and, thus, exposure depend on the child's age. Approximately 42% of tested soft plastic toys contained DINP. Estimated DINP exposures for soft plastic toys were greatest among children 12-23 months old. The mean exposure for this age group was 0.08 (95% confidence interval 0.04-0.14) microg/kg-d, with a 99th percentile of 2.4 (1.3-3.2) microg/kg-d. The authors conclude that oral exposure to DINP from mouthing soft plastic toys is not likely to present a health hazard to children. The opinions expressed by the authors have not been reviewed or approved by, and do not necessarily reflect the views of, the U.S. Consumer Product Safety Commission. Because this material was prepared by the authors in their official capacity, it is in the public domain and may be freely copied or reprinted.

Subacute oral toxicity study of diethylphthalate based on the draft protocol for “Enhanced OECD Test Guideline no. 407”

We performed a 28-day repeated-dose toxicity study of diethylphthalate based on the draft protocol of the "Enhanced OECD Test Guideline 407" to investigate whether it has endocrine-mediated properties according to this assay. Diethylphthalate was orally administered to SD rats at doses of 0, 40, 200, and 1,000 mg/kg/day for at least 28 days, but no endocrine-mediated effects were detected based on any of the parameters examined, suggesting that diethylphthalate does not possess endocrine properties according to this assay.

Neuropathological studies of rats following multiple exposure to tri-ortho-tolyl phosphate, chlorpyrifos and stress

Adult male Long-Evans rats were exposed to 2 neurotoxic organophosphates in a setting of chronic stress, over a 63-day period. The organophosphates were tri-ortho-tolyl phosphate (TOTP) administered in 14 gavage doses of 75, 150 or 300 mg/kg, and chlorpyrifos, given in two 60 mg/kg subcutaneous exposures. Corticosterone was added to the drinking water at 400 microg/ml, to model aspects of chronic stress. These compounds/dosages were administered individually and in combination, with appropriate controls, giving rise to 16 experimental groups. The major neuropathologic change was the presence of axonal degeneration progressing to myelinated fiber degeneration, mainly in distal regions of selected fiber tracts and peripheral nerve, seen in animals sacrificed on experimental day 63. The cervical spinal cord and medullary levels of the sensory gracile fasciculus were most prominently affected. This axonopathy/fiber degeneration was TOTP dose-related at the 300 and 150 mg/kg levels. There was association of this lesion with inhibition of the enzyme neurotoxic esterase in hippocampal tissue from TOTP-treated rats. Such an association categorizes this disease process as organophosphate ester-induced delayed neuropathy. Neither chlorpyrifos nor corticosterone appeared to contribute to the neuropathic events or the enzyme inhibition. A cohort of rats was maintained on the corticosterone dosing, but without additional exposure to TOTP or chlorpyrifos, for an additional 27 days. When these rats were examined on day 90, the nerve fiber degeneration had progressed in all experimental groups administered the 300 mg/kg dose of TOTP (lower doses were not studied at the 90-day interval), although hippocampal neurotoxic esterase had returned to control values.

Evaluation of anti-androgenic activity of di-(2-ethylhexyl)phthalate

DEHP is a widely used platiciser in the manufacture of PVC-based materials. It is known to disrupt the reproductive tract development in male rats. We have performed the Hershberger assay with DEHP on an immature castrated rat model to check if DEHP antagonise the testosterone propionate androgenic effect on the accessory sex organs development. DEHP significantly decreased the BC/LA muscles, the prostate, and the seminal vesicles relative weights from 100, 200, and 400 mg/kg bw/day, respectively. DEHP increased the liver relative weight from 100 mg/kg bw/day. A study was also performed on MDA-MB453 cell line stably transfected with pMMTVneo-Luc with DEHP and its major metabolites (MEHP and metabolites VI and IX) to identify anti-androgenic activity. Neither DEHP nor MEHP antagonised DHT activity in the MDA-MB453 transfected cells. In contrast, metabolites VI and IX were anti-androgenic in vitro. DEHP appeared not to be a 5alpha-reductase inhibitor and acted in an independent mechanism from the testicular production in the young rat.

INFLUENCE OF DI-(2-ETHYLHEXYL)PHTHALATE ON FETAL TESTICULAR DEVELOPMENT BY ORAL ADMINISTRATION TO PREGNANT RATS

Influence of di-(2-ethylhexyl)phthalate (DEHP) on testicular development was studied by oral administration of DEHP at doses of 500 and 1000 mg/kg/day to pregnant rats on gestational days (G) 7 to 18. Ethinyl estradiol (EE) at dose levels of 0.25 and 0.5 mg/kg/day was used as a reference substance. Each 5-6 pregnant rats were sacrificed and their fetuses were examined on G12, 14, 16, 18 and 20. Fetal deaths averaging 20-36% were observed at every examination in the group receiving 1000 mg/kg of DEHP. Increases of fetal deaths over 50% were also observed in the reference group that received 0.5 mg/kg of EE. Microscopic examination of the fetal testis in groups treated with DEHP revealed degeneration of germ cells in G16 fetuses and localized proliferation or hyperplasia of interstitial cells in G18 and 20 fetuses. Germ cells having more than two nuclei were observed in a few cases including the control testes of G14 fetuses. These multinucleated cells were observed frequently in G20 fetuses treated with DEHP. Examination of testes of naturally delivered offspring of dams treated with 1000 mg/kg of DEHP at 7 weeks of age revealed scattered atrophy or dilatation of seminiferous tubules. Another experiment was carried out to confirm the dose of DEHP affecting testicular development and spermatogenesis. DEHP was given to pregnant rats at doses of 125, 250 and 500 mg/kg/day during G7-18. Similar histopathological changes were observed in fetal testes of the group exposed to 500 and 250 mg/kg of DEHP, but not in those exposed to 125 mg/kg. In postnatal examinations, however, no abnormality was found in the testes at 5 and 10 weeks after birth in any of the treated groups. Furthermore, no abnormal findings were observed in the function of sperm, sperm counts and sperm morphology in the offspring of the group treated with DEHP during the fetal period at 10 weeks of age. Thus, 125 mg/kg/day is considered the no-observed-effect-level of DEHP on testicular development of rats by exposure in utero during the period of organogenesis.

Effects of In Utero Exposure to Bisphenol A on mRNA Expression of Arylhydrocarbon and Retinoid Receptors in Murine Embryos

To evaluate the effects of bisphenol A (BPA), a candidate endocrine disruptor (ED), on embryonic development, we examined the mRNA expression levels of the arylhydrocarbon receptor (AhR), which binds with many EDs and plays crucial roles in xenobiotic metabolism, and of the retinoic acid receptor (RAR) alpha and retinoid X receptor (RXR) alpha, key factors in nuclear receptor-dependent retinoid signal transduction, in murine embryos exposed in utero to BPA (0.02, 2, 200, and 20,000 microg/kg/day) at 6.5-13.5 or 6.5-17.5 days post coitum (dpc), using the real-time reverse transcription-polymerase chain reaction (RT-PCR) method. Extremely low-dose BPA (0.02 microg/kg/day; 1/100 the dose of environmental exposure) remarkably increased AhR mRNA expression in the cerebra, cerebella, and gonads (testes and ovaries) of male and female 14.5- and 18.5-dpc-embryos. In utero exposure to BPA at 2, 200, and 20,000 microg/kg/day also increased levels of AhR mRNA. In gonads of 14.5-dpc-embryos, AhR mRNA levels were elevated and showed diphasic (U) dose-response curves following exposure to BPA, but inverted U dose-response curves were obtained for 18.5-dpc-embryos. Exposure to BPA increased expression levels of RARalpha and RXRalpha mRNAs in the cerebra, cerebella, and gonads of male and female 14.5- and 18.5-dpc-embryos. Extremely low-dose BPA (0.02 microg/kg/day) increased RARalpha mRNA expression in the cerebella of male and female 14.5- and 18.5-dpc-embryos and in the gonads of female 14.5-dpc-embryos, and significantly increased RXRalpha mRNA expression in the cerebra and cerebella of male and female 14.5-dpc-embryos. The present findings confirm that in utero exposure to an extremely low dose of BPA up-regulates the mRNA expression of AhR, RARalpha, and RXRalpha in murine embryos and disrupts the receptor-dependent signal transducing systems, and will contribute to the assessment of the toxic effects of BPA on xenobiotic metabolism and retinoid signals in embryogenesis.

In vitro and in vivo characterization of scleral implant of indomethacin: role of plasticizer and cross-linking time

Film-type scleral implants of indomethacin using sodium alginate and PEG 400 and 600 (3, 5, 8, and 10% w/w w.r.t. sodium alginate) as plasticizers were fabricated by solvent casting. The prepared implants were cross-linked by treatment with calcium chloride 10, 20, and 30% w/v solution, for periods between 1 to 24 hr. Uniformity of thickness, weight, and drug content and surface pH of the implants were evaluated. The influence of plasticizer type/concentration and crosslinking time/concentration of calcium chloride on indomethacin release was studied on a static dissolution setup developed by us. Selected batches of the implants were subjected to pharmacodynamic studies, after scleral placement, in uveitis-induced (intravitreal injection of bovine serum albumin 50 microg/ml) rabbit eyes. The release of indomethacin from the implants was influenced by the concentration and nature of plasticizers used. Chemical cross-linking with calcium chloride was successful in retarding the drug release. The pharmacodynamic studies showed a marked improvement in the various clinical parameters (congestion, keratitis, flare, clot, aqueous cells, and synechias) in the implanted eye when compared with the control eye in the rabbits. The implants survived for 2 weeks in vivo.

Tri-ortho-cresyl phosphate (TOCP) decreases the levels of cytoskeletal proteins in hen sciatic nerve

Tri-ortho-cresyl phosphate (TOCP) is an organophosphorus ester. It is capable of producing organophosphorus ester induced delayed neurotoxicity (OPIDN) in human being and sensitive animals, which is characterized by ataxia that progresses to paralysis after 1-3 weeks following exposure to some organophosphorus ester. In present study, 18 adult hens were divided randomly into three groups, i.e. two experimental groups and control group (n = 6 each group). All hens were 10 months old and weighted 1.5-2.0 kg. The hens in two experimental groups were treated with TOCP by gavage at single dosages of 375 and 750 mg/kg respectively. TOCP was dissolved in corn oil and administered at 0.65 ml/kg. Six control hens received an equivalent volume of corn oil by gavage. All hens were sacrificed after 21 days of treatment and the sciatic nerves were dissected, homogenized and used for the determination of cytoskeletal proteins by western blotting. The levels of neurofilament (NF) subunits were decreased both in supernatant and pellet of sciatic nerves, and the most noticeable decrease in levels of NF subunits protein was observed in neurofilament medium (NF-M). Compared to the control hens, neurofilament heavy (NF-H) level decreased by 36 and 38% (P < 0.01) in the pellet and by 27 and 26% (P < 0.05) in the supernatant of sciatic nerves of hens treated with 375 and 750 mg/kg TOCP respectively. The reduction of NF-M were 36 and 68% (P < 0.01) in pellet, 50 and 67% (P < 0.01) in supernatant at 375 and 750 mg/kg dosage respectively. The neurofilament light (NF-L) lessened slightly, but the relative percentage of integrated optical density (IOD) was no significant alteration when compared to the control hens. There were significant decreases in levels of alpha-tubulin, beta-tubulin in pellet and alpha-tubulin, beta-tubulin, beta-actin in supernatant of sciatic nerves in TOCP-treated hens. Thus, the decreases of cytoskeletal proteins suggested the possible involvement of them in delayed neurotoxicity.

Final report on the safety assessment of acetyl triethyl citrate, acetyl tributyl citrate, acetyl trihexyl citrate, and acetyl trioctyl citrate

Acetyl Triethyl Citrate, Acetyl Tributyl Citrate, Acetyl Trihexyl Citrate, and Acetyl Trioctyl Citrate all function as plasticizers in cosmetics. Additionally, the Trihexyl and Trioctyl forms are described as skin-conditioning agents-emollients, although there are currently no reported uses of Acetyl Trihexyl Citrate or Acetyl Trioctyl Citrate. Acetyl Triethyl Citrate and Acetyl Tributyl Citrate are used in nail products at concentrations up to 7%. Recognizing that there are no reported uses of Acetyl Trihexyl or Trioctyl Citrate, if they were to be used in the future, their concentration of use is expected to be no higher than that reported for Acetyl Triethyl and Tributyl Citrate. These ingredients were sufficiently similar in structure that safety test data on one were considered applicable to all. Approximately 99% of orally administered Acetyl Tributyl Citrate is excreted-intermediate metabolites include acetyl citrate, monobutyl citrate, acetyl monobutyl citrate, dibutyl citrate, and acetyl dibutyl citrate. In acute, short-term, subchronic, and chronic feeding studies, these ingredients were relatively nontoxic. Differences from controls were either not statistically significant or not related to any organ toxicity. Ocular exposures produced moderate reactions that cleared by 48 hours after instillation. Dermal application was not toxic in rabbits. In a guinea pig maximization test, Acetyl Triethyl Citrate was a sensitizer whereas Acetyl Tributyl Citrate was not. Limited clinical testing of Acetyl Triethyl Citrate and Acetyl Tributyl Citrate was negative for both skin irritation and sensitization. These clinical data were considered more relevant than the guinea pig maximization data, suggesting to the Cosmetic Ingredient Review Expert Panel that none of these ingredients would be a sensitizer. Physiologic effects noted with intravenous delivery of Acetyl Triethyl Citrate or Acetyl Tributyl Citrate include dose-related decreases in blood pressure and intestinal muscular spasms. These ingredients were not genotoxic in bacterial or mammalian test systems. No significant differences in tumor induction (lymphomas) were noted in rats fed Acetyl Tributyl Citrate for 2 year. Acetyl Tributyl Citrate was not a developmental or reproductive toxicant in studies in mice and rats. Based on all the available data, these ingredients were considered safe as used in cosmetics.

Estimated daily intake of plasticizers in 1-week duplicate diet samples following regulation of DEHP-containing PVC gloves in Japan

Duplicate hospital diet samples obtained over 1 week in 2001 were analysed to estimate the daily intake of plasticizers and the results were compared with those obtained in 1999. The plasticizers quantified in this study were: dibutyl phthalate, butylbenzyl phthalate (BBP), di(2-ethylhexyl) phthalate (DEHP), diisononyl phthalate (DINP), di(2-ethylhexyl) adipate (DEHA), diisononyl adipate (DINA) and O-acetyl tributyl citrate (ATBC). Dipropyl, dipentyl, dihexyl and dicyclohexyl phthalate were also analysed but not detected. The analytical procedure for this follow-up study was essentially the same as in the previous one. Detection limits were 0.1-15.6 ng g(-1) for each plasticizer. One-week duplicate diet samples provided by three hospitals in three remote prefectures of Japan were analysed as individual meals. DEHP was detected at 6-675 ng g(-1) in 62 of 63 meals, significantly lower levels compared with those detected in 1999. Levels of DEHA and DINP also decreased. The mean intake of plasticizers estimated from all samples was 160 microg DEHP day(-1), 12.5 microg DEHA day(-1), 4.7 microg DINP day(-1) and 3.4 microg BBP day(-1). Levels of DINA were relatively high in meals from one hospital: in those meals, the average daily intake was 1338 microg day(-1). Those of ATBC were also higher in meals from another hospital: the average daily intake was 1228 microg day(-1). The sources of DINA and ATBC can be cling-film or sausage packaging.

Adjuvant effect of di-n-butyl-, di-n-octyl-, di-iso-nonyl- and di-iso-decyl phthalate in a subcutaneous injection model using BALB/c mice

During the last decades, the prevalence of the allergic airway diseases, asthma and rhinitis, has increased world-wide. Introduction of environmental chemicals with adjuvant effect may play a role in this increase. In the present study, the adjuvant effects of di-n-butyl-, di-n-octyl-, di-iso-nonyl- and di-iso-decyl phthalate are studied in a screening model. Ovalbumin, used as the model antigen, was injected subcutaneously in the neck region of BALB/cJ mice with the selected phthalate in concentrations from 2-2000 microg/ml. Additionally, the mice were boosted once or twice with ovalbumin alone. Immunization with ovalbumin alone, the ovalbumin control group, served as the baseline for antibody production, whereas aluminium hydroxide served as the positive control. The levels of ovalbumin-specific IgE, IgG1 and IgG2a antibodies in sera were determined. Adjuvant effect was accepted to be present if a statistical increase in antibody production occurred in a test group as compared to an ovalbumin control group together with the fulfillment of dose-response relationships. Adjuvant effect varied strongly between the phthalates investigated. Phthalates with 8 or 9 carbon atoms in the alkyl side chains were the stronger adjuvants whereas phthalates with shorter or longer alkyl side chains possessed less adjuvant activity. Adjuvant effects were apparent either from the IgE or the IgG1 response or both, whereas no effect was seen on the IgG2a response. Additional studies with airborne exposure are required to establish whether the hazards also result in a significant risk for the development of allergy in man.

Reproductive and neurobehavioural toxicity study of bis(2-ethylhexyl) phthalate (DEHP) administered to mice in the diet

Bis(2-ethylhexyl) phthalate (DEHP) was given in the diet to provide levels of 0 (control), 0.01, 0.03, and 0.09% from 5 weeks of age of the F0 generation to 9 weeks of age of the F1 generation in mice, and selected reproductive and neurobehavioural parameters were measured. There were no adverse effects of DEHP on either litter size, litter weight or sex ratio at birth. The average body weight of male offspring was significantly decreased in the low-dose group at birth. In behavioural developmental parameters, surface righting at PND 4 was significantly delayed in the low- and middle-dose group in female offspring, and those effects were slightly dose related (P < 0.05). Surface righting at PND 7 was significantly depressed in the high-dose group of male offspring, and those effects were significantly dose related (P < 0.001). That of female offspring was significantly depressed in the low-dose group. The dose level of DEHP in the present study produced few adverse effects in reproductive and neurobehavioural parameters in mice.

The effects of plasticizers and titanium dioxide on the properties of poly(vinyl alcohol) coatings

Poly(vinyl alcohol) has not previously been examined in much detail as a controlled release polymer for use in pharmaceutical formulations. However, this food grade polymer has barrier and tensile properties which make it attractive for such applications. The effects of several diluents and fillers on Poly(vinyl alcohol) (PVAL) coatings have been determined using both mechanical property and water vapor permeability measurements. It has been found that the alcohol ethoxylate Neodol 23-6.5 (CH3(CH2)11-O-(CH2-CH2-O)6-H) acts as a plasticizer for PVAL only up to 15-20 wt% in contrast to 600 molecular weight Polyethylene Glycol (PEG 600), which continuously plasticizes PVAL. The effects of Neodol on PVAL mechanical properties and water vapor permeability at higher concentrations can be explained in terms of Neodol phase separation and has been confirmed with DSC. The inert filler and whitener titanium dioxide (TiO2) monotonically degrades film mechanical properties and increases water vapor permeability of the coating. Attempts to correlate coating dust generated during particle attrition tests with mechanical property measurements were unsuccessful. A correlation between accelerated granule stability and water vapor permeability of the PVAL coating was established.

Eleven phthalate esters and di(2-ethylhexyl) adipate in oneweek duplicate diet samples obtained from hospitals and their estimated daily intake

Plasticizers in duplicate diet samples obtained over 1 week were analysed in order to estimate daily intake. The phthalate esters were as follows: diethyl, dipropyl, dibutyl, dipentyl, dihexyl, butylbenzyl, dicyclohexyl, di(2-ethylhexyl), dioctyl, diisooctyl (mixture of isomers) and diisononyl (mixture). Di(2-ethylhexyl) adipate was also determined. Homogenized samples of composite meals were extracted with acetonitrile, lipids were removed by extraction into n-hexane and the acetonitrile layer was cleaned using Florisil and Bondesil PSA dual layer column. Phthalates were determined by GC/MS (SIM). Phthalate recovery from the fortified food mixture by this method was 62.5-140.8%. Quality assurance as assessed by three laboratories indicated coefficient of variance in the levels of detected phthalates in same lot samples as below 10%. Detection limits were 0.1-23 ng/g for each phthalate. One-week duplicate diet samples provided by three hospitals in three remote prefectures of Japan were analysed as individual meals. In all 63 samples, DEHP was present at the highest level among all phthalates in the range 10-4400 ng/g. The intake of plasticizers estimated from all samples was 519 microg DEHP/day, 86 microg DEHA/day, 65 microg DINP/day, and 4.7 microg BBP/day. Calculated DEHP in 2-day samples out of 21 days exceeded EU TDI for a person of 50 kg body weight (1850 microg per day). Disposable PVC gloves used during the preparation of meals were suspected as the source of the high DEHP content. One-day intake of the other phthalates and DEHA was below 7% of TDI in all cases. High concentrations of DEHP (5990 ng/g) was found in baby food used in quality assurance work. The source of contamination was the PVC-tube used during production and was effectively reduced by replacing the tube by one made of stainless steel.

Two-generation reproduction studies in Rats fed di-isodecyl phthalate

Di-isodecyl phthalate (DIDP) is a commercial plasticizer with low toxicity in many animal studies. The effects of dietary DIDP administration on fertility and developmental parameters were assessed in Sprague-Dawley rats utilizing two generation reproductive toxicity studies generally consistent with current regulatory guidelines. Dietary levels ranged from 0.02 to 0.8% (or approximately 15 to 600 mg/kg/day). In the reproductive studies, there were no effects on fertility, but there were decreases in adult body weight along with corresponding increases in liver and kidney weights and histopathologic changes indicative of peroxisomal proliferation. There were no effects on live birth index, but reduced offspring survival was observed at postnatal days 1 to 4. This reduced survival was more pronounced in the F2 generation in which statistical significance was achieved at levels of 0.2% DIDP and greater. There were also transient decreases in offspring body weights prior to weaning, corresponding to rapid offspring growth, and high levels of food consumption. There were no notable alterations in developmental landmarks. Overall, these studies provided experimentally defined No-Observed-Adverse-Effect Levels (NOAELs) of 0.06% (approximately 50 mg/kg/day) for F2 offspring survival and 0.8% (approximately 600 mg/kg/day) for fertility, other measures of reproductive function, and developmental landmarks. Statistical evaluation of the data from both studies identified 108 mg/kg/day with a 95% lower bound value of 86 mg/kg/day as a theoretical NOAEL for reduced F2 offspring survival.

Effect of butyl benzyl phthalate in Sprague-Dawley rats after gavage administration: a two-generation reproductive study

Butyl benzyl phthalate (BBP), a plasticizer, has been shown in in vitro studies to be weakly estrogenic, and in in vivo studies to possess testicular toxicity and teratogenicity, but few experimental data on BBP multigeneration effects on reproduction in mammals are available. The present two-generation reproductive study was conducted in male and female Sprague-Dawley rats using oral doses of 0, 20, 100, and 500 mg/kg/day BBP. Endpoints were chosen in order to evaluate both subchronic and reproductive toxicity. In the parent animals (F(0)), a decrease in body weight gain was observed in males in the 500 mg/kg/day group, although no significant decrease in food consumption was found. No dose-related changes were observed in estrous cyclicity, fertility, or lactation. A dose-dependent increase in kidney weight in rats of both sexes, an increase in liver weight in males, and a decrease in the weight of the ovaries in females were observed. No macroscopic or microscopic changes were found in the reproductive system of males or females. Oral administration of BBP caused a decrease in the serum concentration of testosterone, and an increase in FSH. In the next generation (F(1)), the body weight of male and female offspring at birth in the 100 and 500 mg/kg groups was significantly decreased, and the body weight in the 500 mg/kg group was lower throughout the study, while viability was not affected. Anogenital distance (AGD) at birth was decreased in male pups and was increased in female pups of the 500 mg/kg/day group. Preputial separation for male offspring in the 500 mg/kg/day group was delayed, while vaginal opening for female offspring in this group was not affected. BBP did not affect reproductive ability, including delivery and lactation, at any dose whereas macroscopic and microscopic changes of the testis, and decreased serum concentrations of testosterone were observed in male offspring of the 500 mg/kg/day group after puberty. From these data, it would appear that 20 mg/kg BBP is a no observed adverse effect level (NOAEL) for reproductive effects on parent animals and the next generation.

Influence of relative humidity on the mechanical and drug release properties of theophylline pellets coated with an acrylic polymer containing methylparaben as a non-traditional plasticizer

The purpose of this study was to investigate the influence of relative humidity (RH) on the mechanical and dissolution properties of theophylline pellets coated with Eudragit((R)) RS 30 D/RL 30 D containing methylparaben (MP) as a non-traditional plasticizer. The coated beads were stored at 23 degrees C and at different relative humidities (0, 29, 51, 75 and 84% RH). The effect of storage conditions on the rate of drug release from coated beads was determined in pH 7.4 phosphate buffer solution. The mechanical properties, including tensile strength and Young's modulus, of individual beads were determined by a diametral compression method with a Chatillon((R)) tension/compression apparatus. The morphology of the intact and fractured beads was investigated using scanning electron microscopy (SEM). The moisture content of the polymeric films was determined using a Karl Fischer coulometric moisture analyzer. The results from the mechanical studies demonstrated that an increase in the relative humidity resulted in a decrease in the tensile strength and Young's modulus of the coated beads. SEM photographs showed that coated beads stored at 0% RH exhibited brittle fracture failure. The coated beads stored at 84% RH showed ductile behavior, which was attributed to the hydroplasticization effect on the acrylic polymer due to the uptake of moisture. The moisture content in the films was also shown to influence the rate of drug release from Eudragit((R)) RS 30 D/RL 30 D coated beads containing MP as the plasticizer. The change in release profiles could be minimized when the relative humidity was reduced to zero. The dissolution rate of theophylline from the coated beads decreased when stored at high relative humidities. This trend was reversed when the coated beads that were stored at 84% RH for 5 weeks, were then equilibrated at 0% RH.

Influence of additives on the release profile of nifedipine from poly(DL-lactide-co-glycolide) microspheres

Nifedipine-containing poly(DL-lactide-co-glycolide) (PLGA) microspheres of various sizes and drug contents were prepared by the solvent evaporation method. The in vitro release profiles of nifedipine from PLGA microspheres and the degradation pattern of the polymer were evaluated. Four additives were incorporated in the microspheres: two non-fatty plasticizers: diethylphthalate and triacetin, and two fatty substances: isopropyl myristate and Myvacet. Diethylphthalate and Myvacet increased the nifedipine release rate while isopropyl myristate and triacetin had no influence on it. Triacetin seems to be very poorly incorporated into the microspheres. These additives did not modify the degradation rate of the polymer. Differential scanning calorimetry detected a decrease of the glass transition temperature of diethylphthalate-containing microspheres, a small variation with Myvacet, and very little change when triacetin or isopropyl myristate were incorporated. This variation of the glass transition temperature (Tg) tends to imply that nifedipine is released by a diffusion process through the polymer matrix which is enhanced when additives decrease the Tg. Scanning electron microscopy allowed the vizualization of the highly porous structure of microspheres containing the oily substances, and the unchanged smooth surface of diethylphthalate-containing microspheres.

Subchronic inhalation toxicity study of 2-ethylhexanol vapour in rats

A 90-day subchronic inhalation toxicity study was performed on Wistar rats in accordance to OECD testing guidelines to evaluate the toxicological profile of 2-ethylhexanol, potential target organs, and a no-observable-adverse-effect-level (NOAEL). 10 males and 10 females per group were exposed to 2-ethylhexanol vapours at concentrations of 15, 40 and 120 ppm (the latter corresponding to the vapour saturation at 20 degrees C) 6 hours/day for 90 days. The respective controls inhaled clean air under the same conditions. No substance-related adverse effects were observed for body weight, body weight gain, mortality, organ weights, clinical biochemistry and haematological parameters including clotting time. Cyanide-insensitive palmitoyl-CoA oxidation, a marker for peroxisome proliferation, was found elevated in a subchronic study in Fischer 344 rats after gavage application of 500 mg/kg but not under the conditions of this 90-day subchronic inhalation study. There were no findings related to the treatment with 2-ethylhexanol either at necropsy or at histological examination. The highest concentration tested under these conditions (120 ppm) was found to be the NOAEL for male and female rats.

Prechronic toxicity studies on 2-ethylhexanol in F334 rats and B6C3F1 mice

Data on the subchronic toxicity of 2-ethylhexanol (2EH) were required to establish the dose vehicle and dose levels for oncogenicity studies. In preliminary studies 2EH was given subacutely (11 days) to male and female Fischer 344 rats and B6C3F1 mice as an aqueous emulsion by oral gavage (0, 100, 330, 1000, and 1500 mg/kg/day). Clinical observations were made, body weights, food consumption, clinical chemistries, hematologies, and selected organ weights were measured, and gross and micropathologies were performed. Target organs were the central nervous system, liver, forestomach, spleen, thymus, and kidney in rats and the central nervous system, liver, and forestomach in mice. 2EH was then administered by oral gavage to male and female F344 rats and B6C3F1 mice as an aqueous emulsion (0, 25, 125, 250, and 500 mg/kg/day) for 13 weeks. At 500 mg/kg/day in the rat there was reduced body weight gain (6% male, 7% female), increased relative liver (29% male, 15% female), kidney (16% male, 6% female), stomach (11% male, 16% female), and testes (6%) weights, and moderate gross and microscopic changes in the liver and forestomach. There were no behavioral effects or effects on the spleen or thymus. A no-effect level for target organ effects in the rat was 125 mg of 2EH/kg/day. At 500 mg of 2EH/kg/day in the mouse the only effects were increased relative stomach weights in males (13%) and a low incidence of gross and microscopic findings in the forestomach (male and female) and liver (female). A no-effect level for target organ effects in the mouse was 125 mg of 2EH/kg/day. 2EH was a peroxisome proliferator in the rat but not in the mouse at subchronic dose levels of 500 mg/kg/day. Dose levels in oncogenicity studies were set at 50 mg/kg/day for the absence of treatment-related effects in rats and mice, and 500 and 750 mg/kg/day, respectively, in rats and mice as high doses producing minimal toxicity without altering the life span.

Behavioral changes with alterations of choline acetyltransferase immunoreactivities induced by N-butyl benzenesulfonamide

N-butyl benzenesulfonamide (NBBS), one of the sulfonamide plasticizers, induced characteristic effects to Wistar rats after acute repeated exposures (300 mg/kg body weight, ip every 6 h). The signs were pica, staggering gait with hindlimb-paresis and splaying, teeth-grinding, self paw-biting and coma. The motor activity parameters showed generalized decreased mobility. The gait and hindlimb abnormalities coexisted with changes of lower motoneuron activity, ie decreased immunoreactivity of choline acetyltransferase in the lumbar spinal cord. The effects became more overt with repeated exposure to NBBS and the severity was increased. These effects were short-lived and the animals soon recovered.

Absorption of sunscreens and other compounds through human skin in vivo: derivation of a method to predict maximum fluxes

PURPOSE

The goal of this study was to quantify the transdermally absorbed amounts of the sunscreens octyl dimethyl p-aminobenzoic acid, oxybenzone, 4-isopropyl-dibenzoylmethane, 3-(4-methylbenzylidene)-camphor, isoamyl-4-methoxycinnamate, the repellent and plasticizer dibutyl phthalate, the antioxidant 3.5-di-t-butyl-4-hydroxyanisol, and the antimicrobial compounds butyl-4-hydroxybenzoate, biphenyl-2-ol, and 2,4,4'-tri-chlor-2'-hydroxydiphenylether (triclosane). Permeabilities PB and maximum fluxes Jmax should be correlated with relevant physicochemical properties.

METHODS

Saturated solutions of the above-mentioned compounds in a propylene glycol/water mixture were applied to the skin using glass chambers which were fixed to the upper arms of volunteers. Maximum fluxes were calculated from concentration decreases in the vehicle.

RESULTS

A linear relationship between the logarithms of permeabilities PB of the penetrants (0.02-0.28 cm h-1) and the corresponding octanol/vehicle partition coefficients PCOct/V (166-186,208) was found. Consequently, the influence of aqueous boundary layers could be neglected. However, the slope of the resulting straight line of 0.38 is considerably smaller than unity indicating that PCOct/V does not represent the lipophilicity of the stratum corneum adequately. Maximum fluxes range from 0.5 to 130 micrograms cm-2 h-1. A general equation for the calculation of Jmax was derived based on experimental data taking into account the PCOct/V and the solubilities CsV of the respective penetrants in the vehicle.