2-isopropoxyethanol

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Link to relevant study records

Reference

Endpoint:

multi-generation reproductive toxicity

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1988

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods

Remarks:

Well documented publication which meets basic scientific principles”. Full study report also available

Qualifier:

according to guideline

Guideline:

other: National Toxicology Programme Continuous Breeding Protocol

Deviations:

yes

Remarks:

, F1 tests were only carried out with the control and low dose groups

GLP compliance:

yes

Limit test:

no

Species:

mouse

Strain:

CD-1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Kingston NY
- Age at study initiation: (P) x 11wks; (F1): 74+/-10 days
- Housing: by sex in solid bottom polypropylene or polycarbonate cages with stainless steel wire lids, then subsequently in breeding pairs. Ad-Sorb-Dri bedding used.
- Diet (ad libitum): NIH-07
- Water (ad libitum): tap
- Acclimation period: 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-25
- Photoperiod (hrs dark / hrs light): 10/14

Route of administration:

oral: drinking water

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: Each dosing solution formulated directly. No loss of compound after 3 days at room temperature and only 0.9% after 21 days lost. Consequently, fresh solutions prepared every 2 weeks.

Details on mating procedure:

- M/F ratio per cage: 1:1
- Length of cohabitation: 7-day pre-mating period and a 98-day cohabitation period.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analysis on days 1, 6, 10 and 14. All doses found to be within 97-104% of expected values.

Duration of treatment / exposure:

14 weeks

Frequency of treatment:

continuous

Details on study schedule:

At the completion of the continuous breeding phase, the F0 breeding pairs were separated and housed individually and exposure to 2-butoxyethanol continued. When the last litter was weaned from the continous breeding phase F0 males and females from the 1 % dose group were mated with male and female control animals in a one-week crossover mating study to determine any sex-related reproductive effects of 2-butoxyethanol.

Remarks:

Doses / Concentrations:
0 0.5, 1.0 or 2.0 %
Basis:
nominal in water

Remarks:

Doses / Concentrations:
0, 720, 1340 and 2050 mg/kg bw
Basis:
actual ingested

No. of animals per sex per dose:

20. 40 in control

Control animals:

other: Yes. Control males and females were also mated for comparative purposes.

Details on study design:

-The study itself consisted of three phases:
Phase 1 = continous breeding phase
Phase 2 = F0 males and females mated with control animals
Phase 3 = F1 males and females mated

Exposure to 2-butoxyethanol was discontinued during the one-week mating period and then reintroduced at 1 % dose level (estimated daily intake 1830 mg/kg bw). Control males and females were also mated for comparative purposes. The proportion of successful copulations from the breeding pairs was similar in all groups. However, the number of fertile females was significantly reduced in the group where treated females were mated with control males.

A final phase was conducted to assess the fertility and reproductive effects of 2-butoxyethanol in second generation (F1) pups. The pups selected were those born after the CBP and when the maternal animals were individually housed. As there were insufficient pups in the 1 and 2 % dose groups, only the pups from the 0.5 % dose group were used. The F1 generation pups were nursed, weaned and reared to sexual maturity. After weaning, the mice received 0.5 % 2-butoxyethanol in their drinking water (estimated daily intake 950 mg/kg bw). At 74 ± 10 days of age, the F1 animals from different litters were mated. The animals were necropsied after delivery.

Positive control:

No

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes

DETAILED CLINICAL OBSERVATIONS: Yes

BODY WEIGHT: Yes

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes

Oestrous cyclicity (parental animals):

F0 Females Mated with Control Males
-When evaluated over the 7 day period prior to necropsy, proportionally more females (7/13) in the 1 % treated group than controls (9/38) had oestrus cycles longer than 7 days.

Sperm parameters (parental animals):

Parameters examined in P and F1 male parental generations

Litter observations:

Parameters examined in P and F1 generations

Postmortem examinations (parental animals):

Parameters examined in P and F1 generations

Postmortem examinations (offspring):

Parameters examined in F1 and F2 generations

Statistics:

Cochran-Armitage test for dose related trends in fertility. Chi-square test for differences in fertility among groups. Pairwise comparisons between dose groups and control using Fisher's exact test. Reproductive indices between groups compared using Kruskal-Wallis test and ordered differences using Jonckheere's test. Pairwise comparisons of treatment groups perfomed using Wilcoxon-Mann-Whitney U test. Pup number per litter corrected for when calculating average pup weight.

Reproductive indices:

The numbers of fertile pairs from the surviving pairs of the continuous breeding phase were 38/39, 19/19, 13/14 and 5/7 at 0, 0.5, 1.0 and 2.0 % dose levels, respectively.

Offspring viability indices:

no further information

Mortality:

mortality observed, treatment-related

Description (incidence):

-During the 98 day cohabitation period, deaths occurred in the female mice: 13/20 in the 2 % group, 6/20 in the 1 % dose group, 1/20 in the 0.5 % dose group and 1/40 in the control group. In the male mice, no deaths occurred.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

-The average body weights in the female 2 % dose group were consistently lower than the controls. Male groups experienced weight loss (1-2 % of initial body weight) in the two highest doses.
-At necropsy, male and female mice from the 1 % dose group had significantly lower body weights.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

-Reduced fluid consumption was observed at all dose levels in both sexes (22 %, 18 % and 36 % reduction relative to controls at 0.5 %, 1.0 % and 2.0 %, respectively after 14 weeks of dosing).

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

-In the only histopathological examination carried out on the treated females, no treatment related kidneys lesions were observed.

Histopathological findings: neoplastic:

not examined

Reproductive function: oestrous cycle:

no effects observed

Description (incidence and severity):

-In the 1% group no significant differences were observed between the control and treated animals for the average oestrous cycle length and frequency.
-No treatment-related changes in the oestrous cycle length and frequency were noted in the F1 generation.

Reproductive function: sperm measures:

no effects observed

Description (incidence and severity):

-In the 1% group no significant differences were observed between the control and treated animals for the weights of reproductive organs, sperm motility or morphology.
-No treatment-related changes in the weights of reproductive organs, sperm motility or morphology were noted in the F1 generation.

Reproductive performance:

effects observed, treatment-related

Description (incidence and severity):

-Significant reduction in reproductive performance occurred at 1 and 2 % dose levels as indicated by dose-related decrease in number of litters per fertile pair, litter sizes, pup viability and live pup weight.
-No significant fertility and reproductive effects were observed in the F1 animals as indicated by the proportions of successful copulation and fertile females, litter size, pup viability and live pup weights.

Dose descriptor:

NOAEL

Effect level:

720 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

mortality

body weight and weight gain

reproductive performance

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Relative liver and kidney weights were increased in the dose group receiving 2-butoxyethanol (0.5%)

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

no effects observed

Reproductive performance:

no effects observed

Description (incidence and severity):

On the P1 generation (low dose and control only tested) , there were no effects on mating and fertility indices or any other reproductive parameter.

Dose descriptor:

LOAEL

Effect level:

635 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

organ weights and organ / body weight ratios

Critical effects observed:

no

Lowest effective dose / conc.:

635 mg/kg bw/day (actual dose received)

System:

other: see organs

Organ:

kidney

liver

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

A small but significant reduction (by 3 %) of live F1 pup weight was also observed in the 0.5 % dose group without other significant reproductive effects but no effect was seen in the pups born to the F1 generation.

Sexual maturation:

no effects observed

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Histopathological findings:

no effects observed

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

720 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

There were no significant differences in F2 litter size, pups numbers or weights.

Dose descriptor:

NOAEL

Generation:

F2

Effect level:

> 720 mg/kg bw/day

Sex:

male/female

Remarks on result:

not determinable due to absence of adverse toxic effects

Remarks:

Observations limited by maternal toxicity

Reproductive effects observed:

not specified

The continuous breeding first generation study showed that treatment significantly affected fertility at the mid and high dose levels and marginally affected pup weight at the lowest level. The cross-breeding results suggest that the fertility effects were only due to effects on the female mice. In the cross-over study there were no effecting on mating index (number with copulatory plugs/number co-habited), however for females that co-habited with control males the fertility index (number fertile/number with copulatory plugs) ws significantly reduced compared to the controls and other cross-over group. Similarly, the number of live pups/litter of the 1% treated females/control males fell. These effects may have been an indirect consequence of the severe general systemic toxicity rather than a direct effect of 2-butoxyethanol on the reproductive organs.

The top dose exceeded the MTD in the first generation animals.

Conclusions:

In this study, effects were seen on fertility only at doses which were severely toxic to the animals (1340 and 2050 mg/kg bw/d). A NOAEL of 720 mg/kg bw/day can be identified for fertility effects by oral route in mice. Marginal pup weight reductions at this dose were not repeated in the second generation and therefore not regarded as a significant finding.

Executive summary:

In a continuous breeding study carried out to an NTP protocol, mice were exposed for a period of 14 weeks to the oral drinking water routes to 2 -butoxyethanol at doses from 720 to 2050mg/kg. Significant adverse reproductive effects were observed in the females at very high dose levels (1340 mg/kg and above) which also caused severe general toxicity, including death. At the lowest dose studied, the only adverse finding was a marginal statistically significant reduction in pup weight. However, since this reduction was only 3% compared to controls and was not repeated in the F1 generation, it was not considered a significant adverse finding.

No NOAEL or LOAEL can be determined for systemic parental toxicity because this kind of study is not designed to assess systemic toxicity although it is of note that there were effects (reduced fluid consumption) even at the lowest dosage of 720 mg/kg/day. Under the conditions of the study, the NOAEL for reproductive toxicity of 2-butoxyethanol (fertility) can be set as 720 mg/kg/day.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

650 mg/kg bw/day

Species:

mouse

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

A preliminary reproductive toxicity screening test of 2-isopropoxyethanol by oral administration in rats was carried out in accordance with the OECD test guideline 421. After the first administration, haematuria appeared in both sexes at 125 mg/kg. It was also observed in a single and in females at 30 mg/kg. As this was only seen on day 1 and then disappeared, it is not taken into account in deriving the NOAEL for non reproductive effects. At the end of the administration period, spleen weights were increased in both sexes at 125 mg/kg. No other alteration was observed regarding body weights, food consumption or any reproductive or developmental parameters. The NOELs for repeated dose toxicity were considered to be 30 mg/kg/day for non-reproductive effects and 125 mg/kg/day, the maximum dose tested, for reproductive parameters.

There is no multi-generation reproductive toxicity study available using isopropoxyethanol as the test substance. There is data available on a close structural analogue. In a continuous breeding study carried out to an NTP protocol, mice were exposed to 2-butoxyethanol for a period of 14 weeks by oral drinking water at doses from 720 to 2050mg/kg. Significant adverse reproductive effects were observed in the females at very high dose levels (1340 mg/kg and above) which also caused severe general toxicity, including death. At the lowest dose studied, the only adverse finding was a marginal statistically significant reduction in pup weight. However, since this reduction was only 3% compared to controls and was not repeated in the F1 generation, it was not considered a significant adverse finding. No NOAEL or LOAEL can be determined for systemic parental toxicity because this kind of study is not designed to assess systemic toxicity although it is of note that there were effects (reduced fluid consumption) even at the lowest dosage of 720 mg/kg/day. Under the conditions of the study, the NOAEL for reproductive toxicity of 2-butoxyethanol (fertility) can be set as 720 mg/kg/day. This would be equivalent to a dose of 650mg/kg/day of isopropoxyethanol.

There is additional and relevant supporting data on this source substance from other studies: In a study designed to assess the potential for testicular toxicity, rats were exposed by inhalation to isopropoxyethanol for two weeks at concentrations of 0, 300 and 1000ppm. Whilst there were marked signs of toxicity in the high dose animals (reduced weight gain and haematological effects), there were no effects on the testes. In a reliable 90 day repeat dose study using oral exposures via drinking water up to 450 -470mg/kg/day in male and female rats, a number of reproductive parameters were examined in the animals that survived to termination. In males, a decrease in epididymal weights was noticed but this was in proportion to overall reduced body weight. Sperm concentrations were also reduced by approximately 5 -10% in all dose groups but there was no dose response relationship evident. There were no effects on estrous length but some evidence that the two highest dose group animals spent more time in the diestrus stage. This correlated with the smaller uterine size, which was attributed to a secondary consequence of reduced body weight gain. In addition, the lack of effect on overall estrous cycle length and absence of histopathologic lesions suggest that the effects on estrous cycle length are unlikely to indicate a specific treatment-related reproductive effect. Thus, the effects on male and female rat reproductive endpoints are not considered to be indications of selective reproductive system toxicity.  The effects seen were minor in nature, not seen in males and only occurred in the presence of other significant systemic toxicity (i.e., decreased body weights, marked haematotoxicity).  In conclusion, the study does not indicate any primary effects on fertility that can be directly attributed to treatment.

For this end point, a sub-category approach is a viable solution and glycol ethers are cited as an example of this approach in the R-6 ECHA guidance on grouping of chemicals and are also proposed in the work of Yamada (J Toxicol Sci, 37(3), 503-15, 2012) on effects from repeated exposure to glycol ethers. A full justification is attached as a document to the read across object in this chapter.

 

In a study designed to assess the potential for testicular toxicity, rats were exposed by inhalation to isopropoxyethanol for two weeks at concentrations of 0, 300 and 1000ppm. Whilst there were marked signs of toxicity in the high dose animals (reduced weight gain and haematological effects), there were no effects on the testes.

Overall, the data available from both analogues with supporting data from the substance itself provides sufficient evidence to meet the data requirements for this end point and to conclude that the substance does not show any significant reprotoxic effects.

Short description of key information:
2 generation study (surrogate substance, oral drinking water); NOAEL=650mg/kg by extrapolation
Screening study, oral gavage, NOAEL (reproductive effects)>125mg/kg. NOAEL (parental effects) 30mg/kg

Effects on developmental toxicity

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

March-April 1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OTS 798.4900 (Prenatal Developmental Toxicity Study)

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Raleigh, NV, USA.
- Age at study initiation: Males 10 weeks, females 8 weeks (10 on GD0)
- Weight at study initiation: females 217-299 on GD0
- Fasting period before study:
- Housing: single housing during pregnancy period in plastic shoebox cages except during inhalation period
- Diet (ad libitum except during exposure): NIH-7, ex Zeigler brother Inc, Gardners, PA, USA
- Water (ad libitum including during exposure): deionised water
- Acclimation period: 14 day quarantine

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18.3 - 21.2 across all chambers. Average 19.8
- Humidity (%): 35 - 64 across all chambers. Average 48.
- Photoperiod (hrs dark / hrs light):12/12

IN-LIFE DATES: From: To: 10th March to 17th April 1997

Route of administration:

inhalation: vapour

Type of inhalation exposure (if applicable):

whole body

Vehicle:

unchanged (no vehicle)

Details on exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: 1 m3 stainless steel and glass chambers
- Method of holding animals in test chamber: none
- System of generating vapour: liquid EGiPE was vapourised into air carrier gas in a J-tube and then further diluting and mixing it into the incoming chamber airflow. A liquid metering pump was used to meterthe substance from a stainless steel reservoir into a J-shaped stainless steel tube filled with 6 mm glass beads. The tube was warmed to between
125-164°C to aid vaporisation. The system controlled the exposure concentration via a feedback loop.
- Temperature, humidity, pressure in air chamber: - Temperature (°C): 18.3 - 21.2 across all chambers. Average 19.8. - Humidity (%): 35 - 64 across all chambers. Average 48.
- Air change rate: 12-15 ACH

TEST ATMOSPHERE
- Brief description of analytical method used: Gas Chromatograph equipped with a flame ionization detector and a Gas Sampling Valve was used to monitor the exposure chamber concentration and room air.
- Samples taken from breathing zone: No: Concentrations were measured at the center of each chamber during the exposure, The chamber concentration of the test substance was analyzed one to two times per hour in each chamber during each daily exposure period. Prior to the start of the range-finding study, each chamber had been checked and confirmed for uniformity of distribution of test compound by measuring the concentration at nine positions.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Gas Chromatograph validated for the substance and equipped with a flame ionization detector and a Gas Sampling Valve, measured once or twice per hour during exposure periods. A sample of the atmosphere from each chamber was continuously pulled through the sample probe. A stream selector valve was used to conduct the atmosphere from the sample lines one at a time, into the sample loop of the GC.

Details on mating procedure:

- Impregnation procedure: Cohoused
- If cohoused:
- M/F ratio per cage: 1:1
- Length of cohabitation: Each morning following start of cohabitation period and each morning thereafterfemales were examined for the presence of vaginal sperm and/or vaginal or dropped copulation. Sperm-negative females were retained in the same male's cage and checked for sperm on successive mornings until insemination occurred.This process was continued until sufficient pregnant femailes were available (excess animals used).
- Proof of pregnancy: sperm in vaginal smear referred to as GD0

Duration of treatment / exposure:

6 hours per day for 10 consecutive days from GD6 to GD15

Frequency of treatment:

Daily

Duration of test:

10 days exposure

Dose / conc.:

99.5 ppm (analytical)

Remarks:

nominal 100

Dose / conc.:

299.8 ppm (analytical)

Remarks:

nominal 300

Dose / conc.:

599.5 ppm (analytical)

Remarks:

nominal 600

No. of animals per sex per dose:

25

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale: Based on a dose range finder using the same exposures where 600 and 300 ppm resulted in demonstrable maternal toxicity and possible (not statistically significant) developmental toxicity, and I00 ppm resulted in minimal maternal toxicity and no developmental toxicity. The highest exposure concentration level, 600 ppm, was therefore chosen to induce overt maternal toxicity and the lowest no developmental effects.
- Rationale for animal assignment (if not random): stratified randomisation method to provide uniform mean body weights across dose groups.

Maternal examinations:

CLINICAL OBSERVATIONS: Yes
- Time schedule: During exposure period: twice, immediately before and after exposures. Once per day at other times.

BODY WEIGHT: Yes / No / No data
- Time schedule for examinations:DG 0, 6, 9, 12, 15, 18, 20 (day of sacrifice)

FOOD CONSUMPTION AND COMPOUND INTAKE: Yes
- Food consumption for each animal determined and mean diet consumption calculated as g food/kg body weight/day: Yes, over periods GD 0-6, 6-9, 9-12, 12-15, 15-18, 18-20.

POST-MORTEM EXAMINATIONS: Yes / No / No data
- Sacrifice on gestation day # 20
- Organs examined: liver, spleen, thymus and uterus

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 resorptions: Yes
- Other: Number of live/dead fetuses.

Blood sampling:

- Plasma: No
- Serum: No

Fetal examinations:

- External examinations: Yes, all
- Soft tissue examinations: Yes, half per litter
- Skeletal examinations: Yes, half per litter
- Head examinations: Yes, half per litter
- Anogenital distance of all live rodent pups: not specified
- All fetuses were confirmed for sex.

Statistics:

The unit of comparison was the pregnant female or the litter. Quantitative continuous data were compared among the three treatment groups against the one air only control group by the use of Bartlett's test for homogeneity of variances. If Bartlett's test indicated lack of homogeneity of variances, then nonparametric statistical tests were employed for the continuous variables. If Bartlett's test indicated homogeneous variances (i.e., p>0.001) , then parametric statistical tests were employed for the continuous variables.

Historical control data:

Data available and include with main report.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

300 and 600ppm: Blood in bedding, on tail and fur after exposures on gd 6 and 7 with a concentration-related incidence, and more severe on gd 6. General clinical observations (not assigned to specific dams) also indicated blood in catch pans (under the cages in the cage racks in the inhalation chamber and immediately after exposure) over a 4 day period which corresponded to the first through the last gd 6 and possibly through gd 9 (last date corresponds to gd 9 for dams with the earliest gd 6 date). Rust-colored fur on head and neck (probably from chromodacryorrhea from the Harderian glands behind the eyes groomed onto the head and/or neck) was observed gd 7-1 2,. Piloerection was observed at 600 pprn on gd 7-1 3 and 16 (1 -14 dams) and at 300 ppm on gd 9-13, and 15 (1-4 dams).

Rust-colored fur was also observed on the neck of control animals gd 9 and 13.

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Clinical weight loss (>5.0 g within a weigh period) was observed in ten dams at 600 ppm, three dams at 300 ppm, and one dam at 100 ppm on gd 9 (for interval gd 6-9), and in one control dam on gd 12 (for interval gd 9-12). Based on means, the difference was greatest GD 6-9 (~ -7% at 600ppm) It was only statistically significant GD 6-15 @ 600ppm and only GD6-9 @ 300ppm.) GD6-9 there was a clear dose response.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

When the data were expressed as glkglday, maternal feed consumption at 600 ppm was reduced for gd 6-9 and 6-15. GD 6-9 was most marked at -34%. At 300 ppm, feed consumption as glkglday was significantly reduced only for gd 6-9 and significantly increased for gd 12-15. At 100 ppm, maternal feed consumption as glkglday was significantly reduced only for gd 6-9. Over the whole exposure period, there was no significant reduction.

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

not examined

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

Description (incidence and severity):

Maternal spleen weights, absolute and relative to terminal body weight, were significantly increased at 600 pprn. (30% increase in relative spleen weight). Maternal absolute thymus weight was significantly reduced at 300 pprn but not at 600 ppm, and maternal relative thymus weight was unchanged across groups. This was not regarded as treatment related.

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

one dam at 300 pprn exhibited pale kidney but this was not seen in any other dose group.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Number of abortions:

no effects observed

Pre- and post-implantation loss:

effects observed, treatment-related

Description (incidence and severity):

Whilst the absolute number of adversely affected implants per litter was not statistically significantly elevated, in the top dose this was statistically significantly increased from 3.8%in controls to 7.6% in the top dose group.

Total litter losses by resorption:

no effects observed

Early or late resorptions:

no effects observed

Dead fetuses:

no effects observed

Changes in pregnancy duration:

no effects observed

Changes in number of pregnant:

no effects observed

Other effects:

no effects observed

Description (incidence and severity):

Corpora lutea per dam

Dose descriptor:

NOAEC

Effect level:

300 ppm (analytical)

Based on:

test mat.

Basis for effect level:

pre and post implantation loss

Dose descriptor:

NOAEC

Effect level:

100 ppm (analytical)

Based on:

test mat.

Basis for effect level:

body weight and weight gain

clinical signs

food consumption and compound intake

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 examined

Changes in postnatal survival:

not examined

External malformations:

effects observed, non-treatment-related

Description (incidence and severity):

One fetus at 600 ppm exhibited cleft palate. One fetus at 300 ppm exhibited three external malformations: cleft palate, anasarca (whole body edema) and
micromelia (short limbs). One fetus at 100 ppm exhibited short, thread-like tail. Fetal external variations were limited to one fetus at 0 pprn (dam no. 80, fetus no. 11, female) with a hematoma on the neck.

Skeletal malformations:

effects observed, non-treatment-related

Description (incidence and severity):

Only one fetal skeletal malformation was observed; one fetus at 300 ppm, the same fetus with multiple external malformations, exhibited cartilage of sternum split (a finding present in the historical control dataset). Fetal skeletal variations included misaligned sternebrae and changes in cartilage and bone in the thoracic centra, and predominantly extra rib (full or rudimentary) on Lumbar I, and short rib). These are common fetal findings and were distributed across all dose groups examined.

Visceral malformations:

effects observed, non-treatment-related

Description (incidence and severity):

Fetal visceral malformations were almost exclusively limited to hydronephrosis and hydroureter distributed across all groups. This is a very common finding in term rodent fetuses. One fetus from the control group exhibited kidneys fused with one ureter. Fetal visceral variations were distributed across all groups with no treatment- or exposure-related pattern; they included predominantly enlarged lateral ventricles of the cerebrum, and distended ureters, both common findings in term fetuses

Dose descriptor:

NOAEC

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

Developmental toxicity was seen at 600 ppm but only as a small but significant increase in adversely affected implants per litter. However, there were no significant increases in any other developmental parameters. There was no evidence of treatment-related teratogenicity at any exposure concentration evaluated. There were no significant embryolfetal effects observed at 300 or I00 ppm. All of the fetal malformation and variation findings in this study were those commonly observed in historical control C rat fetuses in the performing laboratory.

Executive summary:

Groups of 25 pregnant female SD rats were exposed in a guideline developmental toxicity study by inhalation to vapour concentrations of 100, 300 and 600ppm of ethylene glycol isopropyl ether (EGiPE) 6hrs/day over the period GD6 -15. Animals were sacrificed on GD20 for a detailed examination of the parent animals and pups.

Pregnancy rates were high and approximately equivalent across all groups. No dams died, aborted, delivered early, or were removed from study. Maternal body weights were significantly reduced at 600 ppm (whole exposure period) and at 300 pprn on gd 9; maternal weight change was significantly reduced at 300 and 600 pprn for gd 6-9 and at 600 pprn for the whole exposure period. Maternal spleen weights, absolute and relative, were significantly increased at 600 ppm. Maternal feed consumption in was significantly reduced in g/kgbw/day at 600 pprn during the exposure period. Treatment-related clinical observations at 300 and 600 pprn included blood in urine early in the exposure period (gd 6-7) and piloerection at 600 ppm. There were no treatment-related effects on gestational parameters, iother than a slightly adversely affected implants per litter (which encompassed resorptions, dead fetuses, and malformed fetuses) was significantly increased at 600 pprn in the absence of any increased incidences of the component parameters. There were no treatment-related statistically or biologically significant changes in the incidence of external, visceral, skeletal, or total fetal malformations or variations.

In conclusion, EGiPE administered by inhalation of the vapor during major organogenesis in CD rats resulted in maternal toxicity at 300 and 600 ppm, and developmental toxicity at 600 ppm. There was no evidence for teratogenicity at any concentration tested. The NOAEL for maternal toxicity was at or about 100 pprn and for developmental toxicity was 300 ppm

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no adverse effect observed

Additional information

Groups of 25 pregnant female SD rats were exposed in a guideline developmental toxicity study by inhalation to vapour concentrations of 100, 300 and 600ppm of ethylene glycol isopropyl ether (EGiPE) 6hrs/day over the period GD6 -15. Animals were sacrificed on GD20 for a detailed examination of the parent animals and pups. Pregnancy rates were high and approximately equivalent across all groups. No dams died, aborted, delivered early, or were removed from study. Maternal body weights were significantly reduced at 600 ppm (whole exposure period) and at 300 pprn on gd 9; maternal weight change was significantly reduced at 300 and 600 pprn for gd 6-9 and at 600 pprn for the whole exposure period. Maternal spleen weights, absolute and relative, were significantly increased at 600 ppm. Maternal feed consumption in was significantly reduced in g/kgbw/day at 600 pprn during the exposure period. Treatment-related clinical observations at 300 and 600 pprn included blood in urine early in the exposure period (gd 6-7) and piloerection at 600 ppm. There were no treatment-related effects on gestational parameters, iother than a slightly adversely affected implants per litter (which encompassed resorptions, dead fetuses, and malformed fetuses) was significantly increased at 600 pprn in the absence of any increased incidences of the component parameters. There were no treatment-related statistically or biologically significant changes in the incidence of external, visceral, skeletal, or total fetal malformations or variations. EGiPE administered by inhalation of the vapor during major organogenesis in CD rats resulted in maternal toxicity at 300 and 600 ppm, and developmental toxicity at 600 ppm. There was no evidence for teratogenicity at any concentration tested. The NOAEL for maternal toxicity was at or about 100 pprn and for developmental toxicity was 300 ppm

There is no data on the developmental toxicity of EGiPE to rabbits. There is however data on closely related substances that can be used to predict the toxicity of EGiPE. Female rabbits were exposed to n-propoxyethanol by inhalation at 0, 125, 250 or 500ppm for 6 hr per day during days 6 -18 of gestation. Maternal effects included a slight reduction in weight gain at the 500ppm level and red-colored urine in one animal at 500ppm following the second exposure. Hematologic determinations, absolute and relative organ weights, and observations at necropsy revealed no treatment-related maternal effects. Reproductive indices were not affected and the test substance was not teratogenic. The NOAEL could be concluded as 250ppm for maternal toxicity and >= 500ppm, the maximum tested dose, for teratogenicity. In a GLP developmental toxicity study, pregnant rabbits were exposed to 2 -butoxyethanol vapour at concentrations up to 200ppm during GD6 -18. The results indicated that exposures of up to 100ppm were without effect but exposures of 200ppm produced both maternal toxicity, manifest as reduced body weight and gravid uterine weight, and toxicity to the conceptus (embryotoxicity), manifest as as fewer viable implants. There was no evidence of teratogenicity. From these studies it can be concluded that EGiPE is unlikely to exhibit developmental toxicity in rabbits. A full and detailed justification for a this analogue read across approach is attached to the relevant record in the IUCLID chapter.

Justification for classification or non-classification

There is no evidence from the information available to suggest that classification for either reprotoxic or developmental toxicity is required.