Abstract  Immunologic studies were conducted on sera from workers exposed to phthalic-anhydride (85449) (PA), methyltetrahydrophthalic-anhydride (26590205) (MTHPA), and hexahydrophthalic-anhydride (85427) (HHPA). The workers were exposed at four different facilities that produced alkyd resins, rocket guns, and electronic components. The effect of conjugates with different hapten densities (HD) on the outcome of skin prick tests, RAST of specific immunoglobulin-E (IgE) antibodies, and ELISA tests of specific immunoglobulin-G (IgG) antibodies were presented. The correlation between skin prick tests and RAST was examined. Human serum albumin conjugates (HSA) were prepared. Skin prick reactions to MTHPA increased with rising HD over the range of 6 to 13 moles/mole. The achieved HD was tested by spectrometric and gas chromatographic methods. In RAST of IgE antibodies MTHPA-HSA with HD six and 25 showed significantly lower bindings than conjugates with intermediate HD. A good correlation was obtained between skin prick tests and RAST. Of 234 workers tested, 45 had a skin prick reaction of over 50% of the histamine reaction. All but two of these were RAST positive. Nine RAST positive workers had no obvious skin prick reaction. However, their RAST values were low. In exposed workers, the ELISA value of specific IgG antibodies to MTHPA/HSA showed optimal values when tested with the HD 13 conjugate. The specific antibodies in workers exposed to either MTHPA or HHPA/MHHPA showed a marked cross reactivity to MTHPA/HSA, HHPA/HSA, and MHHPA/HSA as proven by skin prick tests, RAST, and RAST inhibition. In workers exposed to PA there was less cross reactivity to the other anhydrides.

Abstract  Methoxyacetic acid (MAA) is one of the metabolites of phthalate esters which are commonly used as plasticizers of plastics. Jcl:ICR mice at day 10.5 or 11.0 (VP = day 0) were orally treated with 0, 0.5, or 0.8 mL/kg of MAA and their embryos were examined at various intervals after the MAA treatment. Observations at day 15.5 showed that MAA at 0.8 mL/kg induced various limb malformations. The results indicated that forelimbs were more sensitive to MAA than hindlimbs, and day 11.0 limbs were more severely affected than day 10.5 limbs. Main pathogenetic changes were cell death in the mesenchyme as well as in the AER. The final pattern of limb defects is considered to be determined by the amount and distribution of cell death together with regenerative capacity of surviving cells.

Abstract  Di-n-butyl phthalate (DBP), a common plasticizer, was tested for developmental toxicity in Wistar rats. Pregnant rats were orally given DBP at a dose of 0.5, 0.63, 0.75 or 1.0 g/kg on days 7-15 of pregnancy (day 0 sperm positive). Maternal death and complete resorption of implanted embryos in all surviving dams were observed at 1.0 g/kg. Increased postimplantation loss and decreased fetal weight were found at doses of 0.63 and 0.75 g/kg. A significantly increased incidence of fetal malformations was detected at 0.75 g/kg. Cleft palate was predominantly observed. To evaluate the susceptible period for teratogenicity of DBP, pregnant rats were orally given DBP at a dose of 0.75, 1.0 or 1.5 g/kg on days 7-9, 10-12 or 13-15 of pregnancy. Postimplantation loss was 100% for each period of dosing at 1.5 g/kg. A significant increase in postimplantation loss was found in dams given DBP at doses of 0.75 and 1.0 g/kg regardless of the days of treatment. No evidence of teratogenicity was detected when DBP was given on days 10-12. Treatment on days 7-9 with DBP at doses of 0.75 and 1.0 g/kg caused a significant increase in incidences of skeletal malformations, such as deformity of vertebral column in cervical and thoracic regions and of ribs, but neither external nor internal malformations. Treatment on days 13-15 at 0.75 or 1.0 g/kg resulted in a significantly increased incidence of fetuses with external and skeletal malformations, such as cleft palate and fusion of sternebrae. The highest incidence of malformed fetuses occurred after treatment with DBP on days 13-15. It could be concluded that developing embryo has biphasic susceptibility to teratogenicity of DBP in rats.

Abstract  Bis(tributyltin)phthalate (TBTP) dissolved in sesame oil was administered orally to pregnant rats (Crj:Wistar) via stomach tube at the daily dose of 30 mg/kg at different times of the fetal organogenesis, i.e. 6th to 8th day, 9th to 11th day, 12th to 14th day and 15th to 17th day, and the critical period on teratogenicity of TBTP was examined in the fetuses. Gross malformations, such ascleft palate and general edema were observed in 9th to 11th day (0.6%), 12th to 14th day (10.1%) and 15th to 17th day (0.6%) treated groups. The highest incidence of gross malformation was observed in the 12th to 14th day treated group. The incidence of internal anomalies increased in 6th to 8th day (25.8%), 9th to 11th day (35.5%), 12th to 14th day (54.7%) and 15th to 17th day (24.5%) treated groups. Highest incidence of internal organ malformation was observed in 12th to 14th day treated group. Various types of skeletal anomalies were observed in 6th to 8th day (48.8%), 9th to 11th day (77.5%), 12th to 14th day (74.0%) and 15th to 17th day (32.5%) treated groups. Highest incidence of skeletal anomalies was observed in 9th to 11th day treated group. It is concluded that the critical period in induction of gross and internal malformation by administration of TBTP exists between 12th and 14th day of gestation. However, critical period in skeletal anomaly exist between the 9th and 11th day.

Abstract  A reproductive assessment by continuous breeding study of di(n-butyl)-phthalate (DBP) was conducted by the US National Toxicology Program (NTP). When this plasticizing agent was administered continuously to rats of both sexes, fertility and reproductive tract effects were detected in adult F1 offspring, not in the F0 parents. The present study investigated the potential adverse effects on reproduction of in utero and lactational exposure of rats to DBP at dose levels similar to the NTP study, but with a shorter dosing period and production of a single litter. Pregnant CD rats (sperm-positive = gestation day (GD) 0; 10 dams/dose) were given DBP by gavage at 0, 250, 500 or 750 mg/kg body weight/day from GD 3 throughout pregnancy and lactation until the offspring were at postnatal day (PND) 20. Maternal body weights throughout the dosing period were not significantly affected by DBP treatment, and no clinical signs of toxicity were observed. DBP treatment had no apparent effect on parturition. Litter size was decreased in the 750 mg/kg/day group (9.0 +/- 0.7 vs 12.7 +/- 0.8 pups/litter in the control group). The number of implantation sites (on PND 21), proportion of pups born alive, sex ratio of live pups, and weight at birth were comparable in all groups. Adverse effects on the male reproductive system were induced in a dose-dependent manner. Anogenital distance on PND 2 was significantly decreased in males from dams treated with 500 and 750 mg DBP/kg/day. Undescended testes on PND 40 were observed in 0, 13, 29, and 25% of litters at 0, 250, 500, and 750 mg/kg/day, respectively. Small malformed prepuces and penises occured in 86 and 50% of litters at 500 and 750 mg/kg/day, respectively. The age at onset of vaginal opening and preputial separation was comparable in all groups, including gross morphologically normal males at 500 and 750 mg/kg/day. Decreased testicular size and poorly developed or absent epididymis were observed in all DBP groups. Lack of patent vagina and malformed or absent uteri and ovaries occured at 500 and 750 mg DBP/kg/day. Thus, exposure to high doses of DBP in utero and during the entire lactational period induced profound reproductive tract malformations in rats similar to those observed in the NTP study.

Abstract  Di-(2-ethylhexyl) phthalate (DEHP) is a commonly used plasticizer and solvent which constantly leaches into the environment. It is a reproductive and developmental toxicant in animal models. Human exposure to DEHP is significant and greater than 75% of the general population have measurable levels of its metabolite (MEHP) in their urine. Our group showed that DEHP at 1 g/kg body weight in vivo, and the active metabolite MEHP at 50-100 uM in vitro inhibit aromatase induction and consequently, the production of estradiol by rat granulosa cells. Given that urinary MEHP has been measured at 0.24 uM in humans, we set out to determine the lowest dose that causes an effect in rat granulosa cells. Immature female rats were injected with 15 IU of PMSG and granulosa cell cultures were established 24 hours later. Cells were cultured in serum free medium with testosterone, FSH, and MEHP (0, 0.001, 0.01, 0.1, 0.5, 1, 2, or 5 uM). Media were changed after the first 24 h. Media and cells were collected at 51 h and media were assayed for estradiol (RIA). Aromatase mRNA was measured (real-time PCR) in a subset of cells (0, 1, and 5 uM). Total protein, as a measure of cell number at 51 h, was not affected by dose of MEHP. Estradiol was reduced to 82% of control at 1 uM MEHP (p<0.05) and to 66% of control at 5 uM MEHP (p<0.002). Levels of aromatase mRNA paralleled the estradiol data and tended to be lower at 1 uM (p = 0.054) and were significantly reduced at 5 uM MEHP (p<0.05). These results indicate that MEHP impairs rat granulosa cell function in vitro at doses 100 fold lower than previously established and only 4 fold higher than urinary levels in humans. The mechanism of action appears to be similar to high doses of MEHP. The recognition that low, pharmacologically and environmentally relevant doses affect granulosa cell steroidogenesis calls attention to DEHP exposure of the general population and not only of occupationally exposed humans. These data underline the importance to further study the effects of phthalates on the female reproductive system.

Abstract  Cryptorchidism is a fairly common human malformation, being displayed in 1-3 males per 100 at birth. Since only a small percentage of these lesions can be linked to known genetic defects, developmental exposure to man-made chemicals has been implicated in the increase in this reproductive malformation. Phthalate esters are high production volume, ubiquitous environmental chemicals some of which induce reproductive malformations in rats when administered during sexual differentiation. Recently we have shown that malformations in gubernacular ligament development induced by high doses of DEHP are associated with decreased insl3 gene expression, a gene critical for proper gubernacular ligaments formation. In the current study, DEHP (0, 100, 300, 600, or 900 mg/kg/day) was administered orally to Spague Dawley dams on gestation days (GD) 8 through 18. On GD18, fetal testes were evaluated for hormone production and changes in gene expression. Each fetal testis was incubated ex vivo in 500 ul medium for 3 hours. Medium was collected for analysis of steroid hormone levels. Testis tissue was also collected on GD 18 and mRNA prepared to assess expression of several genes by real-time rt-PCR including insl3, SF-1, StAR, and enzymes in the steroid pathway. Results to date indicate that DEHP induced a dose dependent decrease in testosterone production that, when analyzed on a mean per litter basis, was statistically significant at 300, 600 and 900 mg/kg. Progesterone production was decreased significantly at 900 mg/kg. Insl3 gene expression was also decreased in a dose dependent manner. Effects on the expression of other testicular genes and on production of other steroid hormones are currently being examined. Thus far, the changes demonstrated are consistent with the malformations previously observed in male offspring after in utero exposure to similar doses of DEHP. Disclaimer: This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.

Abstract  Male infertility has become a major health problem in many Western countries. In Denmark more than 6% of all children are now born after assisted reproduction. Unfortunately the causes are not known in most cases, although spermatogenic failure can be due to Y microdeletions and other rare genetic causes. In addition, testicular cancer, which is a disease of young adults, is becoming more common in industrialized countries. We propose that male infertility, undescended testis, hypospadias and testicular cancer may all be symptoms of one underlying entity, the testicular dysgenesis syndrome (TDS). The most severe form of the syndrome is gonadal dysgenesis in intersex patients and the less severe phenotype may present itself as subfertility due to decreased sperm count. We assume that not only genetic abnormalities cause maldevelopment of the male gonad, but also environmental factors may contribute to an increasing occurrence of TDS. In fact, it has been repeatedly shown that TDS-like symptoms can be produced in rats exposed to phthalates in utero. Our preliminary data from an ongoing study suggests that phthalate exposure via breast milk may lead to decreased Leydig cell function in newborn boys. However, current research raises more questions than answers: Is there a biologically significant chemical exposure of the unborn child through placenta and breast milk. May it affect reproductive function during puberty and adult life? Are we, in the industrialized world, currently witnessing a process, where human fecundity is declining due to adverse environmental exposures?

Abstract  TMA is an organic acid anhydride that is widely used in industry. It can induce specific IgE and cause occupational asthma in sensitized individuals. Persistent occupational asthma, even with antigen/hapten avoidance can be seen is approximately 20% of the cases. Duration of both circulating TMA-specific IgE and specific airway responsiveness was studied in a TMA sensitized Brown Norway rat asthma model as possible contributory factors to persistent asthma. TMA powder (4 mg) was applied to 4 anesthetized rats? backs (clipped with scissors) on days 0, 7, 14 and 21 and washed off after 4 hrs. Specific IgE analyses and airway challenge with TMA (40 mg/m3 for 10 min) were performed on day 35 and day 386. The ELISA OD values for TMA-specific IgE were 0.46?0.07 and 0.12?0.02 on day 35 and day 386, respectively (non-specific binding from control sera OD=0.08?0.002). Dual, early- (EAR) and late-phase (LAR) airway responses (indicated by enhanced pause, an index of airway resistance) were observed on day 35. A dual response was noted upon rechallenge on day 386 in 3 rats and LAR-only in the 4th rat. These results demonstrate the persistence of specific airway responsiveness to TMA, even though circulating specific-IgE had drastically declined.

Abstract  Given the potential vulnerability of children to the effects of environmental exposures, understanding the relationship between children?s health outcomes and environmental exposures is an important research need to reduce uncertainty in risk assessment. Over the past 8 years, significant research activities have been initiated at the USEPA to increase understanding of children?s vulnerabilities and to better characterize children?s exposures to chemical stressors in the environment. Research efforts include development of models, methods, and data to quantitatively describe ways that children are exposed to environmental stressors. Current and recently completed studies include large field studies to measure children?s exposures to chemicals in their homes and daycare centers as well as targeted studies to better understand the determinants of exposure. CTEPP, a study of 260 preschool-age children, has recently been completed and data are being analyzed to identify important exposure factors and pathways. A longitudinal children?s study of 60 infants and toddlers is being implemented over the next couple of years to assess exposures to current-use pesticides, phthalates, and BFRs. As a result of these and other Agency initiatives, important data are being collected and assessment approaches are being developed and used to improve the scientific basis of exposure assessments for children. Despite this significant progress, there are many important gaps associated with how to effectively measure and characterize exposure for health studies and risk assessment. In this presentation, ongoing and recent USEPA initiatives aimed at evaluating children?s exposures and health risks will be discussed, including issues associated with characterizing cumulative risks from exposures to multiple environmental stressors. The information and data obtained from these efforts will help identify the most important exposures for children and enable decision to prioritize environmental health related activities.

Abstract  Malaria infections among seafarers have been regularly reported from Denmark, Germany, France, Belgium, Italy, Poland, The Netherlands, United Kingdom and other countries. No statistics are available on malaria infections among crews of ships flying "flags of convenience". The estimated number of malaria cases in international seafarers may be between 500 and 1,000 each year, some of which are fatal. In the strategy of malaria prevention in this occupational group, the most important objective is to prevent death caused by severe Plasmodium falciparum infections in which clinical manifestations occur during a ship's voyage, and where diagnosis and treatment are delayed. Protective measures against malaria on ships and the benefits, risks and limitations of chemoprophylaxis are discussed. See also CIS 99-2066. Topics: dimethyl phthalate; diethyltoluamide; drugs; endemic diseases; infection control; information of personnel; malaria; prophylaxis; risk awareness; sea transport; tropical diseases.

Abstract  Aminated resin (NDA-101) and oxidized resin (NDA-702) were synthesized to remove Dimethyl phthalate (DMP) from the contaminated water. The equilibrium and heat properties in the course of adsorption process were examined and compared with two commercial heterogeneous adsorbents, namely an acrylic ester resin (Amberlite XAD-7) and a coal-based granular activated carbon (AC-750). The associated equilibrium isotherms can be well fitted by Freundlich equation and the adsorption capacities for DMP followed the order: NDA-702 NDA-101 AC-750 XAD-7. The surface of XAD-7 was demonstrated to be relatively homogeneous through surface energy heterogeneity analysis, offering the sole hydrogen bonding interaction. Contrarily, heterogeneous surface of oxidized resins NDA-702 and the aminated resins NDA-101 exhibited a promising adsorption capacity and affinity toward DMP probably derived by multiple hydrogen bonding, ... stacking, and micropore filling interactions. (ProQuest: ... denotes formulae/symbols omitted.)

Abstract  Soils are commonly exposed to phthalic acid esters (PAEs) due to their wide usage in a large variety of fields. Several PAEs have been categorized as priority pollutants due to their environmental impact. Therefore, characterizing the sorption behavior of PAEs on soils is very important. Soil column chromatography was utilized to study sorption of dimethyl phthalate (DMP) and diethyl phthalate (DEP) on European and Chinese reference soils. The influence of different environmental conditions such as ionic strength, temperature and pH on the sorption process was investigated. Results show the organic carbon (OC) content in soil plays a main role in the sorption of DMP and DEP. Ionic strength and cation type influenced sorption of DMP and DEP on the two soils, however, in a different manner suggesting that OC in these two soils might be differently affected by the presence of ions. The sorption of DMP and DEP was also found to depend on the investigated pH range of mobile phase with significant relative changes of sorption coefficients in both soils. The influence of temperature on sorption to both soils was small and derived sorption enthalpies indicated that van der Waal's forces dominate the sorption of DMP and DEP, which leads us to propose that additional specific interactions such as hydrogen bonding only play a negligible role.

Abstract  It has been hypothesized that oils containing high levels of omega-3 polyunsaturated fatty acids, such as canola and fish oil, could counteract some of the adverse effects induced by phthalates. In the present study, the influence of different oily vehicles on di-butyl phthalate (DBP)-induced testicular toxicity and lipid profile was investigated. Pregnant Wistar rats were treated by oral gavage from gestation days 13 to 20 with DBP (500 mg/kg/day) diluted in three different vehicles: corn, canola or fish oil. Male fetuses were analyzed on gestation day 20. DBP exposure lowered intratesticular testosterone levels and anogenital distance, regardless of the vehicle used. The percentage of seminiferous cords containing multinucleated gonocytes and cord diameter was increased in DBP-exposed groups, compared with vehicle controls, with no difference between the three DBP-exposed groups. Clustering of Leydig cells was seen in all DBP groups. Lipid profile indicated that administration of canola and fish oil can increase the content of omega-3 fatty acids in rat testis. However, content of omega-3 was diminished in DBP-treated groups. Overall, our results indicate that different oily vehicles did not alter fetal rat testicular toxicity induced by a high DBP dose.

Abstract  Dibutyl phthalate (DBP), a widely used phthalate, is known to cause many serious diseases, especially in the reproductive system. However, little is known about the effects of its metabolite, mono-n-butyl phthalate (MBP), on preimplantation embryo development. In the present study, we found that treatment of embryos with 10⁻³ M MBP impaired developmental competency, whereas exposure to 10⁻⁴ M MBP delayed the progression of preimplantation embryos to the blastocyst stage. Furthermore, reactive oxygen species (ROS) levels in embryos were significantly increased following treatment with 10⁻³ M MBP. In addition, 10⁻³ M MBP increased apoptosis via the release of cytochrome c, whereas immunofluorescent analysis revealed that exposure of preimplantation embryos to MBP concentration-dependently (10⁻⁵, 10⁻⁴ and 10⁻³ M) decreased DNA methylation. Together, the results indicate a possible relationship between MBP exposure and developmental failure in preimplantation embryos.

Abstract  The distribution of di(ethylhexyl)phthalate (117817) (DEHP) in plasma and plasma proteins after fractionation was examined in blood contaminated by storage in plastic. The DEHP content of freshly drawn human plasma, of plasma samples stored in polyethylene containers which did not contain phthalate plasticizers, and of plasma stored over 7 days at 4 degrees-C and at -20 degrees-C was measures. The effects of thawing and refreezing a contaminated sample on DEHP content were studied. Plasma samples were dried after the addition of methanol. The residue, with added internal standard, was suspended in methanol and mixed with toluene. Water was added, the mixture was centrifuged, and the aqueous phase was removed. The toluene layer was analyzed by electron capture gas chromatography for DEHP. The limit of detection was 0.5 micrograms (microg) DEHP per milliliter (ml) of plasma. The relative standard deviation was about 3.7 percent. The DEHP content of freshly drawn plasma did not differ from that of a blank. The DEHP concentration in plasma stored in plastic bags varied between 16 and 120microg/ml. Samples stored in polyethylene containers had high concentrations of DEHP. The DEHP content of plasma increased over 7 days from near zero to 70microg/ml at 4 degrees-C, and from 4 to 26microg/ml at -20 degrees-C. No increase was noted in the thawed and refrozen sample. After fractionation, the major part of DEHP was found in the lipoprotein fraction. Contamination with DEHP ranged from 3 to 18microg/ml in fibrinogen, from 5 to 25microg/ml in albumin, and from 3 to 160microg/ml in immunoglobulin-G. The authors conclude that DEHP is present in very minute amounts (if at all) in human plasma, and that contamination from plastic bags concentrates in the lipoprotein fraction.

Abstract  Di (2-ethylhexyl) phthalate (DEHP) is used as a plasticizer in polyvinyl chloride plastics. Routes of exposure for humans include inhalation, ingestion, and through medical fluids such as saline and blood. DEHP is a suspected endocrine disrupter and may have adverse effects following in utero exposure. In this report, we extend our previous findings showing multiple toxic effects following in utero exposure to DEHP which included testicular and reproductive deficits. The current study administered DEHP at a dose of 1000 mg/kg/bw from GD 8 and #150; 21. We assessed two measures of endocrine disruption following exposure to DEHP: anogenital distance (AGD) and nipple retention in neonatal males. DEHP reduced AGD in males (p<0.001), but had no significant effects in females. DEHP-exposed males showed increased nipple retention on PND 11 which occurred in 75% of pups (p<0.001). These results are most likely an outcome of DEHP acting as an antiandrogen. It should also be noted that since toxic effects in animal studies typically occur at high doses, the question of likely exposure levels in humans is often raised. Recently however, Swan et al. (2005, Env Hlth Perspectives, 113, 1056) reported a decrease in anogenital distance in male human infants related to their prenatal body burden of phthalates.

Abstract  In order to investigate the developmental effects of chemicals in mixture, three compounds were combined using five dosages of each agent (a 5x5x5 design). Due to the large number of treatment groups (125), the experiment was divided into five replicates, each consisting of five blocks. To date, four of the five blocks have been completed with over 1200 rats treated and 1000 litters examined. F-344 rats were gavaged on gestation days (GD) 6-15 with TCE (0, 10.1, 32, 101, and 320 mg/kg/d), DEHP (0, 24.7, 78, 247, and 780 mg/kg/d), and HEPT (0, 0.25, 0.8, 2.5, and 8.0 mg/kg/d) in corn oil. The dams were allowed to deliver and their pups were weighed and examined on days 1 and 6. Implants were counted to determine prenatal loss. Linear and logistic regression models were used to analyze continuous and proportional endpoints, respectively. Preliminary data analysis after four replicates revealed TCE and DEHP main effects and synergism for reduced maternal weight gain during GD 6-8; however, DEHP and HEPT were antagonistic. Full-litter resorptions were associated with main effects and a two-way synergism of DEHP and HEPT. Eye defects were associated with TCE and DEHP main effects. Decreased pup weights were associated with a main effect of each agent and DEHP antagonisms with the other two agents. Post-natal loss was associated with a HEPT main effect and a TCE-DEHP-HEPT three-way synergism. Results will be discussed in terms of study design and implications for risk assessment.

Abstract  A suitable worker population was sought to conduct a retrospective cohort mortality study for occupational exposure to di-2-(ethylhexyl)phthalate (117817) (DEHP). Companies were contacted regarding annual DEHP consumption or production, types of processes for which DEHP was used, the size of the potentially exposed workforce, and the length of time DEHP had been used. The Society of the Plastics Industry stated that the major use of DEHP was as a plasticizer in polyvinyl-chloride (9002862) (PVC) products. The highest potential source of worker exposures was during the formulating and compounding of the plastic resin. Surveys were then conducted of a plastics manufacturer, a PVC plastic sheet processing facility, and two aerosol filter testing facilities. Field monitoring was conducted of worker exposures to DEHP. The authors conclude that the populations exposed to DEHP were too small and not employed long enough to offer a suitable study cohort. Field monitoring showed worker exposures of less than 0.5 milligrams per cubic meter which was well below the OSHA standard of 5mg/m3. It is recommended that a retrospective mortality study not be pursued at this time.

Abstract  A NIOSH hazard review of di-2-ethylhexyl-phthalate (117817) (DEHP) and possible alternative test agents used for respiratory quantitative fit testing are presented. The toxicity of DEHP is considered. DEHP has been shown to be toxic only when administered to laboratory animals at high doses. The median lethal doses range from 14.2 to 33.9 grams per kilogram. No definite evidence of teratogenicity or mutagenicity has been found. In bioassays with B6C3F1-mice and female Fischer-344-rats, a treatment related excess incidence of hepatocellular carcinomas occurred. Mechanisms by which DEHP induces liver neoplasms are unclear. Alternative test substances should be substituted for DEHP in respirator quantitative fit testing if feasible. The toxicities of di-2-ethylhexyl-sebacate (122623), dimethyl-polysiloxane (9006659), refined corn oil, and mineral oil are considered. All except mineral oil appear to be suitable as substitutes for DEHP in quantitative fit testing of respirators. Mineral oil is eliminated as it tends to accumulate in lungs. Refined corn oil appears to be the best candidate for replacing DEHP as it has a very low order of toxicity, and extensive negative data on its carcinogenic potential exists.

Abstract  Phthalate esters are high production volume, ubiquitous environmental chemicals some of which induce reproductive malformations in rats when administered during sexual differentiation. Recently we have shown that malformations in gubernacular ligament development induced by high doses of DEHP are associated with decreased insl3 gene expression, a gene critical for proper gubernacular ligament formation. In study one, DEHP (0, 100, 300, 600, or 900 mg/kg/day) was administered orally to Sprague-Dawley dams on gestation days (GD) 8 through 18. On GD18, fetal testes were evaluated for hormone production and changes in gene expression. Results indicate that DEHP induced a dose dependent linear decrease in testosterone production that was significant at 300, 600 and 900 mg/kg. Progesterone production was decreased at 900 mg/kg. Insl3 gene expression was also decreased in a dose dependent manner. To investigate the ontogeny of gene changes associated with these effects, a second study dosed dams orally with 0 (vehicle only) or 750 mg/kg/day DEHP beginning on GD8. Testes RNA was prepared from fetuses of 3 litters each on GD 16.5, 17, and 18. Microarray analysis was conducted on these samples using Affymetrix gene chips. Preliminary results indicate significant (p0.05) changes in several genes associated with Leydig cell steroidogenesis and peptide hormone production such as CYP17, StAR and Insl3 beginning, in some cases, as early as GD 16.5. A more thorough analysis of gene chip results is underway but, thus far, the changes demonstrated are consistent with the malformations previously observed in male offspring after in utero exposure to similar doses of DEHP.