1-(1-methyl-2-propoxyethoxy)propan-2-ol

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

An oral gavage reproductive/developmental toxicity screening test in rats is available. The study was conducted under GLP and according to OECD guideline 421. Supporting data are available through read-across within the category from a 2-generation reproductive toxicity study on propylene glycol methyl ether (PGME) via inhalation in rats.

Link to relevant study records

Reference

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

March 21, 2006 - June 11, 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to OECD TG 421 and in accordance with the principles of GLP.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 421 (Reproduction / Developmental Toxicity Screening Test)

Version / remarks:

USEPA OPPTS 870.3550

Deviations:

no

Principles of method if other than guideline:

not applicable

GLP compliance:

yes

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

Animals: CD (Crl: CD(SD)IGS BR) rats were obtained from Charles River Laboratories, Inc (Portage, MI). They were acclimated to the laboratory at least one week prior to treatment, and were approximately 8 weeks old at the beginning of the study. Animals were housed two to three per cage during acclimation, one per cage after assignment or two per cage (one per sex during breeding) in stainless steel cages. Dams were housed one per cage (with litter) in plastic cages with ground corn cob nesting material from approximately gestation day 19 through lactation, under a 12 hour light/dark photocycle. Room humidity and temperature were maintained at 40-70% and 22 +/- 1 degrees C. Room air was exchanged approximately 12-15 times/hour. Animals were allowed free access to food (LabDiet Certified Rodent Diet #5002, PMI Nutrition International, St. Louis, MO) and municipal water. There were no contaminants in the feed or water that would interfere with the study.

Route of administration:

oral: gavage

Vehicle:

other: 0.5% methylcellulose

Details on exposure:

Groups of 12 male and 12 female CD rats randomly assigned to four treatment groups and were gavaged with 0 (control), 100, 300 and 1000 mg/kg/day test material in 0.5% methylcellulose vehicle (4 ml/kg bw). Females were dosed daily for two weeks prior to breeding, through breeding (two weeks), gestation (three weeks), and through postpartum day 4 (one day prior to necropsy). The males were dosed for two weeks prior to breeding and continuing through breeding (two weeks) up until necropsy (test Day 29). Dose volumes were adjusted weekly using the most current body weight. Dosing suspensions were prepared periodically throughout the study period based on stability.

Details on mating procedure:

Breeding commenced after approximately 2 weeks of treatment. During breeding, each female was caged with a male from the same group until pregnancy occurred (presence of sperm in vaginal lavage sample evaluated daily or presence of a copulatory plug) or two weeks had elapsed. The day on which pregnancy was detected was considered gestation day 0. The sperm- or plug-positive females were then separated from the males and returned to their home cages.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The low- and high-dose suspensions from the first mix of the main study were analyzed by GC/FID to confirm homogeneous distribution of the test material prior to the start of the study. The relative standard deviations were 1.1 and 1.7%, respectively, confirming homogeneous distribution. Concentrations in suspensions taken concomitantly with the homogeneity analyses were 101. 7 - 103.2% of targets. Stability of the test material (0.250, 2.50 and 250 mg/ml) in the vehicle was determined prior to study start. The material was stable for 39 days at the tested concentrations.

Duration of treatment / exposure:

Females were dosed daily for two weeks prior to breeding, through breeding (two weeks), gestation (three weeks), and through postpartum day 4. The males were dosed for two weeks prior to breeding and continuing through breeding (two weeks) up until necropsy (test Day 29)

Frequency of treatment:

once/day

Details on study schedule:

not applicable

Dose / conc.:

100 mg/kg bw/day (nominal)

Dose / conc.:

300 mg/kg bw/day (nominal)

Dose / conc.:

1 000 mg/kg bw/day (nominal)

No. of animals per sex per dose:

12

Control animals:

yes, concurrent vehicle

Details on study design:

The high-dose level was based upon data obtained from the preliminary range-finding study and was expected to induce some toxic effects, but not
death or obvious suffering. The lower dose levels were selected to provide dose response data for any toxicity that may have been observed among the high-dose group rats and to establish a NOEL.

Positive control:

No data

Parental animals: Observations and examinations:

Cage-side examinations (activity, repetitive behaviour, vocalization, incoordination/limping, injury, neuromuscular function, altered respiration blue/pale skin and mucous membranes, severe eye injury (rupture), fecal consistency and fecal/urinary quantity were conducted twice daily. All animals were observed for morbidity, mortality and the availability of food and water at least twice daily. Clinical exams (hand-held examination of the animals with an evaluation of the abnormalities in the eyes, urine, feces, GI tract, extremities, movement, posture, reproductive system, respiration, skin/hair coat mucous membranes, general behaviour, injuries or palpable masses/swellings) were conducted once daily. Females were observed for signs of parturition on or about gestation day 20. Females that delivered received clinical examinations on lactation days 0, 1 and 4. Females that failed to mate or deliver were subjected to hand-held evaluations weekly.

All rats were weighed prior to exposure and on the first day of dosing. Male body weights were recorded weekly throughout the study and females were weighed weekly prior to gestation. Presumed pregnant females were weighed on gestation day 0, 7, 14 and 20. Females that delivered litters were weighed on lactation days 1 and 4. Females that failed to mate or deliver a litter were weighed at least weekly until termination.

Feed consumption was determined once a week during the pre-breeding phase. It was not determined during breeding. After breeding, it was determined on gestation days 0, 7, 14, and 20 for mated females. After parturition, feed consumption was measured on lactation days 1 and 4. Feed consumption was not recorded for females that failed to mate or deliver a litter of for males after breeding.

Oestrous cyclicity (parental animals):

not applicable

Sperm parameters (parental animals):

Weights of the epididymides and testes were calculated. The histopathological examination of the testes included a qualitative assessment of stages of spermatogenesis.

Litter observations:

Females were observed for signs of parturition beginning on or about gestation day 20. If possible, parturition was observed for signs of difficulty or unusual duration. The day of delivery was recorded as lactation day 0. All litters were examined as soon as possible after delivery. The litter size on lactation day 0, numbers of live and dead pups on postpartum days (PND) 0, 1 and 4, and sex and weight of each pup on lactation days 1 and 4 were recorded. Physical abnormalities or demeanor changes in the neonates were recorded as observed during the lactation period. Pup clinical observations were recorded on each litter on PND 0 through 4. Any pups found dead were sexed and examined grossly for external and visceral defects.

Postmortem examinations (parental animals):

On the day prior to the scheduled necropsy, all males and females in each group were fasted overnight. At necropsy (test day 29 for males or lactation days 5-7 for females), the animals were anesthetized with CO2 and decapitated. Females that did not deliver were terminated and necropsied at least 24 days after the last day of the mating period.

Post-mortem examinations included a gross necropsy of all adults (which included a gross examination of the eyes, brain and pituitary, and external and visceral tissues). The histopathological examination of the testes included a qualitative assessment of states of spermatogenesis. The uteri of all females were stained with a 10% solution of sodium sulfide and the number of implantation sites recorded. Weights of the testes, epdidymides, kidneys and liver were recorded and organ to body weight ratios calculated.

Samples of the cervix, coagulating glands, epididymides, gross lesions, kidneys, liver, mammary gland (females), ovaries, oviducts, pituitary, prostate, seminal vesicles, testes, uterus and vagina were collected and preserved from adults surviving to study termination. These tissues plus the adrenals, aorta, auditory sebaceous glands, bone and bone marrow, brain, cecum, colon, cranial nerve, duodenum, esophagus, eyes, heart, ileum, jejunum, lacrimal/Harderian glands, larynx, lungs, mediastinal lymph node and tissues, mesenteric lymph node and tissues, nasal turbinates/pharynx, oral tissues, pancreas, parathyroid glands, peripheral nerve, rectum, salivary glands, skeletal muscle, skin and subcutis, spinal cord, spleen, stomach, thymus, thyroid gland, tongue, trachea, urinary bladder were collected from rats found moribund. All tissues collected from control and high dose animals and rats found moribund were examined histologically. Liver, kidneys and relevant gross lesions were examined from low and mid dose rats.

Postmortem examinations (offspring):

All pups surviving to PND 4 were euthanized by i.p. administration of sodium pentobarbital and examined for gross external alterations. Any pups found dead were also examined (if possible).

Statistics:

Parental body weights, gestation and lactation body weight gains, litter mean body weights, feed consumption and organ weights were first evaluated by Bartlett’s test for homogeneity. Parametric and nonparametric data were then analyzed by the appropriate analysis of variance (ANOVA). If the ANOVA was significant at alpha = 0.05, a Dunnett’s test (alpha = 0.05) or the Wilcoxon Rank Sum test with Bonferroni’s correction was performed. Feed consumption data were excluded if the feed was spilled or scratched.

Gestation length, average time to mating, and litter size were analyzed using a non-parametric ANOVA. If the ANOVA was significant, the Wilcoxon Rank Sum test with Bonferroni’s correction was performed. Statistical outliers (alpha = 0.02) were identified and excluded from the analysis only for documented, scientifically sound reasons. Mating, conception, fertility and gestation indices were analyzed by the Fisher exact probability test, with Bonferroni’s correction. The neonatal sex ratio was analyzed using the binomial distribution test. Genders of pups found dead were included in the ratio. Survival indices, post-implantation loss and other neonatal incidence data were analyzed using the litter as the experimental unit by the censored Wilcoxon test (alpha = 0.05). Females failing to deliver a litter were excluded from the appropriate analyses.

Reproductive indices:

Female and male mating indices, female and male conception indices, female and male fertility indices, gestation index, post-implantation loss, sex ratio

Offspring viability indices:

Gestation survival index, Day 1 or 4 pup survival index

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Excess salivation immediately after dosing (all males and majority of females) in high dose group.

Mortality:

mortality observed, non-treatment-related

Description (incidence):

One high dose male was terminated on test day 18 due to labored respiration. This animal had changes indicative of aspiration after dosing.

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Endocrine findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Very slight hepatocellular hypertrophy (11/12 males and 12/12 females) and very slight hyaline droplet formation in proximal renal kidney tubules of males (9/12) in high dose group

Other effects:

not examined

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

effects observed, treatment-related

Reproductive performance:

effects observed, treatment-related

Description (incidence and severity):

Increased post implantation loss (11.26% vs. 6.47% in control), decreased litter size (14.0 vs. 14.4 live pups/litter in control not significant but considered to be related to treatment) in high dose group. The mean litter size would have been lower (13.4) if it had not been for one animal that had a very large litter (20 pups). Four of 11 (36%) high dose litters had three or more resorptions (maximum in control litters was two). One female had a difficult birth and retained the placenta.

No effects were noted at 300 or 100 mg/kg bw/day.

Dose descriptor:

NOEL

Effect level:

300 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

organ weights and organ / body weight ratios

histopathology: non-neoplastic

Critical effects observed:

yes

System:

hepatobiliary

Organ:

liver

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

presumably yes

Clinical signs:

not examined

Mortality / viability:

mortality observed, treatment-related

Description (incidence and severity):

1000 mg/kg: Decreased gestation survival (97.5% vs. 98.9% in control), consistent with increased postimplantation loss.

Body weight and weight changes:

not examined

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

malformations noted. No effects were noted at 300 or 100 mg/kg bw/day.

Dose descriptor:

NOEL

Generation:

F1

Effect level:

300 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

mortality

Critical effects observed:

no

Reproductive effects observed:

yes

Lowest effective dose / conc.:

1 000 mg/kg bw/day (nominal)

Treatment related:

yes

Relation to other toxic effects:

reproductive effects as a secondary non-specific consequence of other toxic effects

Dose response relationship:

yes

Relevant for humans:

not specified

None

Conclusions:

Based on the results, the no-observed-effect level (NOEL) for DPnP for parental and reproductive toxicity was 300 mg/kg/day.

Executive summary:

Groups of 12 male and 12 female Crl:CD(SD) rats were administered Dipropylene Glycol n-Propyl Ether (DPnP) daily, by gavage at dose levels of 0 (control), 100, 300, or 1000 mg/kg/day. Females were dosed once daily for two weeks prior to breeding, through breeding (two weeks), gestation (three weeks), and lactation up to postpartum day 4.

 

Females were necropsied on postpartum day 5. Males were dosed two weeks prior to breeding and continuing through breeding (two weeks) until necropsy (test day 29). Effects on reproductive function as well as general toxicity were evaluated. In addition, postmortem examinations included a gross necropsy of the adults with collection of organ weights and histopathologic examination of tissues. Litter size, pup survival, sex, body weight, and the presence of gross external abnormalities were also assessed.

 

Administration of 1000 mg/kg/day of DPnP resulted in treatment-related parental toxicity in males and females consisting of increases in the incidence of hepatocellular hypertrophy and corresponding increases in absolute and relative liver weights. In addition, absolute and relative kidney weights were increased in males and females at this dose level. Microscopic examination of the kidneys revealed hyaline droplet formation in the proximal renal tubules of males given 1000 mg/kg/day, but there were no treatment-related histopathologic findings in the kidneys of high-dose females. Transient, excess salivation was noted in the majority of high-dose males and females immediately after dosing, but was considered to be a local response and of no toxicological significance.

 

Accompanying the parental toxicity at 1000 mg/kg/day was a slight increase in post implantation loss, along with a corresponding slight increase in gestation survival and very slight decrease in litter size. One high-dose female also had a difficult birth and retained placentae, although the relationship of this finding to treatment is equivocal. There was no parental or reproductive toxicity at 300 or 100 mg/kg/day.

 

Based on these results, the no-observed-effect level (NOEL) for parental and reproductive toxicity was 300 mg/kg/day.

Effect on fertility: via oral route

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

300 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

Good

Effect on fertility: via inhalation route

Endpoint conclusion:

no adverse effect observed

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

In the absence of a full reproductive toxicity study on DPGPE, data available for the structurally related propylene glycol methyl ether (PGME) will be used, along with data from DPGPE, to predict the reproductive toxicity potential of DPGPE. PGME and DPGPE are closely related in molecular structure and physicochemical properties and thus, the potential for toxicological effects. No major differences in the toxicological profile have been observed between propylene glycol ethers e.g. mono-, di- and tri-propylene glycol methyl ethers and mono-, di- and tri-propylene glycol n-propyl ethers).

The justification for using data on structurally related substances is provided in the category document attached to Section 13 of the IUCLID dossier.

Data available for DPGPE:

Groups of 12 male and 12 female Crl:CD(SD) rats were administered Dipropylene Glycol n-Propyl Ether (DPnP) daily, by gavage at dose levels of 0 (control), 100, 300, or 1000 mg/kg/day. Females were dosed once daily for two weeks prior to breeding, through breeding (two weeks), gestation (three weeks), and lactation up to postpartum day 4.

Females were necropsied on postpartum day 5. Males were dosed two weeks prior to breeding and continuing through breeding (two weeks) until necropsy (test day 29). Effects on reproductive function as well as general toxicity were evaluated. In addition, postmortem examinations included a gross necropsy of the adults with collection of organ weights and histopathologic examination of tissues. Litter size, pup survival, sex, body weight, and the presence of gross external abnormalities were also assessed.

Administration of 1000 mg/kg/day of DPnP resulted in treatment-related parental toxicity in males and females consisting of increases in the incidence of hepatocellular hypertrophy and corresponding increases in absolute and relative liver weights. In addition, absolute and relative kidney weights were increased in males and females at this dose level. Microscopic examination of the kidneys revealed hyaline droplet formation in the proximal renal tubules of males given 1000 mg/kg/day, but there were no treatment-related histopathologic findings in the kidneys of high-dose females. Transient, excess salivation was noted in the majority of high-dose males and females immediately after dosing, but was considered to be a local response and of no toxicological significance.

Accompanying the parental toxicity at 1000 mg/kg/day was a slight, treatment-related increase in post implantation loss, along with a corresponding slight increase in gestation survival and very slight decrease in litter size. One high-dose female also had a difficult birth and retained placentae, although the relationship of this finding to treatment is equivocal. There was no parental or reproductive toxicity at 300 or 100 mg/kg/day.

Based on these results, the no-observed-effect level (NOEL) for parental and reproductive toxicity was 300 mg/kg/day.

Data available for PGME:

The objective of this two-generation inhalation reproduction study was to evaluate the effects of propylene glycol monomethyl ether (PGME) on the reproductive capability and neonatal growth and survival of rats. Groups of 30 male and 30 female Sprague-Dawley rats were exposed to 0, 300, 1000 or 3000 ppm PGME via inhalation, for 6 hours/day, 5 days/week prior to mating and 6 hours/day, 7 days/week during mating, gestation and lactation for two generations. Inhalation exposure of adult male and female rats to 1000 (females only) and 3000 (males and females) ppm PGME resulted in dose-related parental effects. Toxicity in 3000 ppm PGME P1 and P2 males and females was evidenced primarily as an increased incidence of sedation for several weeks early in the exposure regimen and significant decreases in body weights, which achieved decrements of as much as 20 and 21% relative to controls, respectively. Decreased body weights in the P1 and P2 high concentration females generally persisted throughout the pre-breeding, gestation and lactation phases of the study. Additional effects noted among P1 and P2 adult females exposed to 3000 ppm PGME included lengthened estrous cycles, decreased fertility, decreased ovary weights and an increased incidence of histologic ovarian atrophy. The effects on fertility, estrous cyclicity and ovarian weight/histology appeared to be interrelated and associated with the significant decreases in 3000 ppm PGME female body weights and general toxicity/nutritional stress throughout the test period. No treatment-related differences in sperm counts or motility were observed among P1 or P2 adult males. Neonatal effects observed at 3000 ppm PGME consisted of decreased pup body weights, reduced pup survival and litter size, increased time to vaginal opening or preputial separation, and histopathologic observations in the liver and thymus of weanling rats. These neonatal effects also were considered secondary to maternal toxicity, particularly with respect to the compromised nutritional status of the maternal animals of the 3000 ppm PGME group. In the 1000 ppm PGME group, mild parental toxicity was evidenced by slightly decreased pre-mating body weights among P1 and P2 females, but was not accompanied by any statistically significant effects on parental reproduction or neonatal survival, growth or development. There were no treatment-related parental or neonatal effects related to exposure of rats to 300 ppm PGME. In conclusion, the no-observed-effect-level (NOEL) for fertility and reproductive effects in this two-generation inhalation reproduction study was 1000 ppm PGME.

Summary:

Although there are no full reproductive toxicity studies available for DPGPE, there is sufficient data available for a structurally related substance (PGME) along with reproductive screening data on DPGPE to make a conclusion about the reproductive toxicity of DPGPE to support classification and risk assessment.

The no-observed-effect-level (NOEL) for fertility and reproductive effects in the two-generation inhalation reproduction study on PGME was 1000 ppm. The NOAEL for paternal toxicity is 300 ppm and for offspring toxicity is 1000 ppm.  Effects appear secondary to parental weight loss. The reproductive NOEL from the OECD 421 oral screening study on DPGPE was 300 mg/kg/day. Accompanying the parental toxicity at 1000 mg/kg/day was a slight, treatment-related increase in post implantation loss, along with a corresponding slight increase in gestation survival and very slight decrease in litter size. One high-dose female also had a difficult birth and retained placentae, although the relationship of this finding to treatment is equivocal. There was no parental or reproductive toxicity at 300 or 100 mg/kg/day. Based on these results, the no-observed-effect level (NOEL) for parental and reproductive toxicity and was 300 mg/kg/day. 

Effects on developmental toxicity

Description of key information

A dermal embryotoxicty/teratogenicity study in rabbits is available. This is a GLP study conducted according to OECD 414 (Prenatal Developmental Toxicity Study). In addition there is a key developmental toxicity study available for category member, DPnB (dermal, rat).  There are also rat develomental studies on PnP (inhalation rat) and DPM (inhalation rat and rabbit). Justification for using these studies is included in the catgory document attached to the IUCLID.

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

yes

Remarks:

Minor deviations were observed and reported and these did not negatively impact the quality or integrity of the data nor the outcome of the study.

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.3700 (Prenatal Developmental Toxicity Study)

Deviations:

yes

Remarks:

Minor deviations were observed and reported and these did not negatively impact the quality or integrity of the data nor the outcome of the study.

Principles of method if other than guideline:

not applicable

GLP compliance:

yes

Limit test:

no

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Covance Research Products, Inc., Denver, Pennsylvania
- Age at study initiation: 5.5 months old upon receipt
- Weight at study initiation: 3084 g to 4442 g
- Housing: Upon arrival, all rabbits were housed individually in clean, stainless steel cages suspended above ground corncob bedding (Pel-O’Cobs®; The Andersons, Industrial Products Division, Maumee, Ohio). The bedding was changed at least twice each week. Nesting material was not required, as the females were euthanized prior to the date of expected parturition. Animals were maintained in accordance with the Guide for the
Care and Use of Laboratory Animals (National Research Council, 1996). The animal facilities at WIL Research Laboratories, LLC are fully accredited by the Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC International).
- Diet (e.g. ad libitum): The basal diet (PMI Nutrition International, LLC, Certified Rabbit LabDiet® 5322) was offered 3 times at 25 g on the day of arrival, 3 times at 50 g on the day after arrival and ad libitum on all subsequent days until euthanasia.
- Water (e.g. ad libitum): Reverse osmosis-purified (on-site) drinking water, delivered by an automatic watering system was provided ad libitum during the study.
- Acclimation period: not specified in the report

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 66 ± 5°F (19 ± 3°C), Actual mean daily temperature ranged from 65.6°F to 66.5°F (18.7°C to 19.2°C)
- Humidity (%): 50 ± 20% relative humidity, Actual mean daily relative humidity ranged from 43.5% to 54.8%
- Air changes (per hr): Air handling units were set to provide approximately 10 fresh air changes per hour.
- Photoperiod (hrs dark / hrs light): Light timers were calibrated to provide a 12-hour light (6 a.m. to 6 p.m.)/12-hour dark photoperiod

Route of administration:

dermal

Vehicle:

unchanged (no vehicle)

Details on exposure:

TEST SITE
- Area of exposure: The appropriate volume of the test or control article was applied evenly over the shaved, intact dorsal skin of each animal (approximately 10 cm x 15 cm) using a syringe and stainless steel cannulae (16-gauge).
- % coverage: The area dosed corresponded to approximately 5.3% to 7.2% of the body surface area (cm2).
- Type of wrap if used: A bandage of absorbent gauze was placed over the dosing area followed by a layer of non-absorbant material (polyethylene plastic). These 2 layers were held in place with tape. The treated area and the 2 layers of material were then secured by wrapping the torso with gauze bandaging and secured with Durapore® wrap.
- Time intervals for shavings or clipplings: One day prior to the initiation of dose administration and throughout the study as necessary (at least 1 time each week), a section slightly larger than the dosing area of the scapular and lumbar regions of each rabbit was shaved with Oster® small animal clippers.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): Following the 6-hour exposure period each day, the collars and wrappings were removed. The test sites were gently washed with disposable paper towels and deionized water to remove any residual test article, and then gently dried.
- Time after start of exposure: 6 hours/day

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): The dosage volumes were 1.1, 0.55, 0.83 and 1.1 mL/kg for the control, 500, 750 and 1000 mg/kg/day groups, respectively.

USE OF RESTRAINERS FOR PREVENTING INGESTION: yes. The duration of the exposure was 6 hours, during which Elizabethan collars were
applied to each animal to prevent ingestion of the test article and/or wrappings.

Analytical verification of doses or concentrations:

no

Details on analytical verification of doses or concentrations:

As the test article was administered undiluted, analyses to confirm stability, homogeneity and concentration of the test article were not conducted.

Details on mating procedure:

- Impregnation procedure: purchased timed pregnant

Duration of treatment / exposure:

The control and test article were administered by dermal application for 6 hours, once daily during gestation days 6-28.

Frequency of treatment:

The control and test article were administered by dermal application for 6 hours, once daily during gestation days 6-28.

Duration of test:

The control and test article were administered by dermal application for 6 hours, once daily during gestation days 6-28.

Dose / conc.:

500 mg/kg bw/day (nominal)

Dose / conc.:

750 mg/kg bw/day (nominal)

Dose / conc.:

1 000 mg/kg bw/day (nominal)

No. of animals per sex per dose:

25 time mated rabbits per dose

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: based on the results of a range finding study, there was no maternal toxicity or embryo/fetal lethality observed at the limit dose of 1000 mg/kg/day.

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: All rabbits were observed twice daily, once in the morning and once in the afternoon, for moribundity and mortality. Animals were also observed for signs of toxicity approximately 1-2 hours following dose administration.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Individual detailed clinical observations were recorded from the day of receipt through gestation day 29 (prior to dose administration during the treatment period).

DERMAL OBSERVATIONS: Yes
- Time schedule: Application sites were examined for erythema, edema, scaling, fissuring and other dermal findings daily within approximately 1 hour (target time between 30 and 60 minutes) after the end of each 6-hour exposure

BODY WEIGHT: Yes
- Time schedule for examinations: Individual maternal body weights were recorded on gestation days 0 (by supplier), 4 and 6-29 (daily).

FOOD CONSUMPTION: Yes
- Time schedule: Individual food consumption was recorded daily on gestation days 4-29. Food intake was reported as g/animal/day and g/kg/day for the corresponding body weight change intervals and also for gestation days 6-9, 9-12, 12-15, 15-18, 18-21, 21-25, 25-29 and 6-29.

WATER CONSUMPTION: No

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 29
- Organs examined: rabbits were euthanized on gestation day 29 by an intravenous injection of sodium pentobarbital via the marginal ear vein. The thoracic, abdominal and pelvic cavities were opened by a ventral mid-line incision, and the contents were examined. In all instances, the post mortem findings were correlated with the ante mortem comments and any abnormalities were recorded.

OTHER: Liver weights were recorded for all does. Maternal tissues were preserved in 10% neutral-buffered formalin for possible future histopathologic examination only as indicated by the gross findings. The carcass of each female was then discarded.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: Uteri with no macroscopic evidence of implantation were opened and subsequently placed in 10% ammonium sulfide solution for detection of early implantation loss.

Fetal examinations:

- External examinations: Yes: [all per litter]
- Soft tissue examinations: Yes: [all per litter]
- Skeletal examinations: Yes: [all per litter]
- Head examinations: Yes: [half per litter]

Statistics:

Standard statistical procedures were used.

Indices:

Postimplantation loss, viable fetuses affected/litter

Historical control data:

yes

Clinical signs:

no effects observed

Dermal irritation (if dermal study):

effects observed, treatment-related

Description (incidence and severity):

Slight to severe scaling and slight fissuring was noted for a majority of animals in the 1000 mg/kg/day group. The incidence of these findings was highest mid-way through dosing, and decreased in severity and incidence generally throughout the remainder of the study. The control, 500 and 750 mg/kg/day groups also experienced slight scaling, but the incidence was greatly reduced compared to the 1000 mg/kg/day group. Moderate erythema was noted in 1 and 4 females in the 750 and 1000 mg/kg/day groups, respectively. Slight erythema was noted in all treatment groups, with the highest occurrence in the 1000 mg/kg/day group. The incidence of very slight erythema (barely perceptible) was similar between the control and 500 mg/kg/day group; however, this finding was noted up to approximately twice as often in the 750 and 1000 mg/kg/day groups throughout the treatment period. Very slight to slight edema was noted for multiple females in the 500, 750 and 1000 mg/kg/day groups, compared to a single occurrence of very slight edema in the control group; no dose-related trend was evident. The dermal findings in this study were generally considered test article-related, but because the severity and incidence decreased substantially or were absent by the end of the dose administration period, the dermal findings were not considered adverse.

Mortality:

no mortality observed

Description (incidence):

All animals survived to the scheduled necropsy.

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Water consumption and compound intake (if drinking water study):

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Details on maternal toxic effects:

Other than the dermal irritation described above, no test article-related clinical or macroscopic findings were noted at any dose level. Mean maternal body weights, body weight changes, net body weights, net body weight changes, gravid uterine weights and food consumption were unaffected by test article administration.

Dose descriptor:

NOAEL

Based on:

test mat.

Remarks on result:

not determinable due to absence of adverse toxic effects

Abnormalities:

no effects observed

Fetal body weight changes:

no effects observed

Reduction in number of live offspring:

no effects observed

Changes in sex ratio:

no effects observed

Changes in litter size and weights:

no effects observed

Anogenital distance of all rodent fetuses:

not specified

Changes in postnatal survival:

no effects observed

External malformations:

no effects observed

Skeletal malformations:

no effects observed

Visceral malformations:

not examined

Other effects:

no effects observed

Details on embryotoxic / teratogenic effects:

Intrauterine growth and survival in the test article-treated groups were similar to the control group. There were no test article-related malformations or developmental variations observed in any fetus evaluated in this study.

Dose descriptor:

NOAEL

Based on:

test mat.

Sex:

male/female

Remarks on result:

not determinable due to absence of adverse toxic effects

Abnormalities:

no effects observed

Developmental effects observed:

no

None

Conclusions:

Based on the results of this study, the dermal application of 1000 mg/kg/day (the limit dose based on OPPTS 870.3700 Guidelines) was considered to be the no-observed-adverse-effect level (NOAEL) for maternal systemic toxicity; however, dermal irritation (local toxicity) was transiently observed at all dosage levels. A dosage level of 1000 mg/kg/day was considered to be the NOAEL for prenatal development when DPnP was administered by dermal exposure to pregnant rabbits.

Executive summary:

The objective of the study was to determine the potential maternal toxicity (local and systemic) and/or prenatal developmental toxicity of the test article, dipropylene glycol n-propyl ether (DPnP), when administered by dermal exposure to pregnant rabbits throughout the period of major organogenesis up to a limit dose of 1000 mg/kg/day and to determine a NOAEL (no-observed-adverse-effect level) for maternal toxicity and developmental toxicity.

All animals survived to the scheduled necropsy. Slight to severe scaling and slight fissuring was noted for a majority of animals in the 1000 mg/kg/day group. The incidence of these findings were highest mid-way through dosing, and decreased in severity and incidence generally throughout the remainder of the study. The control, 500 and 750 mg/kg/day groups also experienced slight scaling, but the incidence was greatly reduced compared to the 1000 mg/kg/day group. Moderate erythema was noted in 1 and 4 females in the 750 and 1000 mg/kg/day groups, respectively. Slight erythema was noted in all treatment groups, with the highest occurrence in the 1000 mg/kg/day group. The incidence of very slight erythema (barely perceptible) was similar between the control and 500 mg/kg/day group; however, this finding was noted up to approximately twice as often in the 750 and 1000 mg/kg/day groups, respectively, throughout the

treatment period. Very slight to slight edema was noted for multiple females in the 500, 750 and 1000 mg/kg/day groups, compared to a single occurrence of very slight edema in the control group; no dose-related trend was evident. No maternal systemic toxicity (clinical observations, body weight, food consumption, macroscopic findings or liver weights) was observed at any dosage level in this study. Dermal irritation (local toxicity) was transiently observed at all dosage levels. Intrauterine growth and survival in the test article-treated groups were similar to the control group. There were no test article-related malformations or developmental variations observed in any fetus evaluated in this study.

Based on the results of this study, the dermal application of 1000 mg/kg/day (the limit dose based on OPPTS 870.3700 Guidelines) was considered to be the no-observed-adverse-effect level (NOAEL) for maternal systemic toxicity; however, dermal irritation (local toxicity) was transiently observed at all dosage levels. A dosage level of 1000 mg/kg/day was considered to be the NOAEL for prenatal development when DPnP was administered by dermal exposure to pregnant rabbits.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Species:

rabbit

Quality of whole database:

good

Additional information

There is a developmental toxicity study in rabbits which has been performed with DPGPE but not in rat.

In the absence of developmental toxicity data on DPGPE in rat, data from the structurally related dipropylene glycol butyl ether (DPGBE), which has undergone developmental toxicity testing in rat, can be used. Along with DPGBE, other developmental rat studies with structurally related DPGME and PGPE can be used to support DPGPE. DPGME, DPGPE, PGPE and DPGBE are closely related in molecular structure and physicochemical properties and thus, the potential for toxicological effects. No major differences in the toxicological profile have been observed between propylene glycol ethers e.g. mono-, di- and tri-propylene glycol n-butyl ethers and mono-, di- and tri-propylene glycol n-propyl ethers).

The justification for using data on structural related substances is provided in the category document attached to Section 13 of the IUCLID dossier.

Data available for DPGPE:

The objective of the study was to determine the potential maternal toxicity (local and systemic) and/or prenatal developmental toxicity of the test article, dipropylene glycol n-propyl ether (DPnP), when administered by dermal exposure to pregnant rabbits throughout the period of major organogenesis up to a limit dose of 1000 mg/kg/day and to determine a NOAEL (no-observed-adverse-effect level) for maternal toxicity and developmental toxicity. The Dermal route was selected as this is the most relevant route for human exposure to this substance.

 

All animals survived to the scheduled necropsy. Slight to severe scaling and slight fissuring was noted for a majority of animals in the 1000 mg/kg/day group. The incidence of these findings were highest mid-way through dosing, and decreased in severity and incidence generally throughout the remainder of the study. The control, 500 and 750 mg/kg/day groups also experienced slight scaling, but the incidence was greatly reduced compared to the 1000 mg/kg/day group. Moderate erythema was noted in 1 and 4 females in the 750 and 1000 mg/kg/day groups, respectively. Slight erythema was noted in all treatment groups, with the highest occurrence in the 1000 mg/kg/day group. The incidence of very slight erythema (barely perceptible) was similar between the control and 500 mg/kg/day group; however, this finding was noted up to approximately twice as often in the 750 and 1000 mg/kg/day groups, respectively, throughout the treatment period. Very slight to slight edema was noted for multiple females in the 500, 750 and 1000 mg/kg/day groups, compared to a single occurrence of very slight edema in the control group; no dose-related trend was evident. No maternal systemic toxicity (clinical observations, body weight, food consumption, macroscopic findings or liver weights) was observed at any dosage level in this study. Dermal irritation (local toxicity) was transiently observed at all dosage levels. Intrauterine growth and survival in the test article-treated groups were similar to the control group. There were no test article-related malformations or developmental variations observed in any fetus evaluated in this study.

 

Based on the results of this study, the dermal application of 1000 mg/kg/day (the limit dose based on OPPTS 870.3700 Guidelines) was considered to be the no-observed-adverse-effect level (NOAEL) for maternal systemic toxicity; however, dermal irritation (local toxicity) was transiently observed at all dosage levels. A dosage level of 1000 mg/kg/day was considered to be the NOAEL for prenatal development when DPnP was administered by dermal exposure to pregnant rabbits.

 

Data available for DPGBE:

Dipropylene glycol n-butyl ether (DPGBE) was applied daily to the skin of pregnant rats on gestation days 6 through 15. DPGBE was applied to the clipped skin of two groups of Wistar rats (>20/sex/dose level) at various dilutions in propylene glycol (PG) equivalent to doses of 0 (PG-only; 1.5 ml/kg bw/day), 0.3 or 1.0 ml DPGBE/kg bw/day. These doses equate to 0, 273, or 910 mg DPGBE/kg bw/day. Rats wore neck collars to prevent grooming and ingestion of test material. Solutions were applied unoccluded since the low vapor pressure of DPGBE and PG precluded evaporative loss. Slight skin reactions were found in the dams from all treatment groups and thus were not considered to be treatment related. No maternal toxicity was found: clinical signs and organ or body weights did not differ between treatment and controls groups. No deaths occurred in any groups over the course of the study. Fecundity was comparable among groups. No embryo- or fetotoxicity was evident since pre- and post-implantation loss, number of viable fetuses, and fetal weights and lengths were comparable between treatment and control groups. DPGBE did not cause developmental toxicity in skeletal or soft tissue. Skeletal malformations were observed only in the control group and skeletal variants were observed in all dose groups. The high dose group did exhibit a slight increase (not statistically significant) in the incidence of supernumerary rudimentary thoracic ribs when compared to controls. However, this finding was not considered biologically significant since the incidence was within normal limits for this species. In conclusion, DPGBE is not maternally toxic, embryo- or fetotoxic, or teratogenic in Wistar rats receiving dermal doses up to 1.0 ml/kg bw/day during organogenesis (days 6 - 15). The NOAEL for maternal toxicity, embryo- or fetal toxicity, or developmental toxicity is 1.0 ml/kg bw/day (910 mg/kg bw/day), the highest dose level on the study.

 

 

In the studies using DPM, no treatment related adverse effects - no maternal toxicity, no embryo-/fetotoxicity and no teratogenicity - were observed in rats or rabbits at the highest attainable concentration of dipropylene glycol methyl ether. The studies in both species are of good quality and reliable without restrictions. The no observed adverse effect level for dipropylene glycol methyl ether is 300 ppm in both species.

In studies using DPnP, maternal toxicity was seen in both rat and rabbit at the highest dose level (1500 ppm) with very minor effects observed in the rat developmental study (in conjunction with maternal toxicity) and the absence of developmental effects in the rabbit study at this exposure level.  The no observed effect level for propylene glycol proyl ether is 300 ppm for material toxicity in both species along with develpmental toxicity in rats; with 1500 ppm being the NOEL for developmental toxicity in rabbits.

As such, there are data available for multiple category members, via multiple dose routes and using rodent and non rodent species that demonstrate an absence of developmental toxicity.

 

Toxicity to reproduction: other studies

Additional information

No other studies available

Justification for classification or non-classification

There were no effects observed in the dermal developmental study at any dose level. In the reproductive screening study there were some minor effects at the high dose on pup survival and some evidence of post implantation loss, however the effects were very minor and accompanied some maternal toxicty. Therefore based on the results of the studies and Guidance to Regulation (EC) No. 1272/2008 on Classification, Labelling and Packaging of substances and mixtures, dipropylene glycol n-propyl ether will not be classified for reproduction toxicity.