Registration Dossier

Administrative data

Description of key information

Four studies were performed to assess the repeated dose toxicity properties of propylene glycol methyl ether by oral route. None was conducted according to GLP and guidelines. For dermal exposure, a GLP-study equivalent to OECD guideline 410 is available for propylene glycol methyl ether. This study is supported by two non-GLP studies similar to OECD guideline 411. Numerous GLP and non-GLP studies are available for repeated inhalation exposure to propylene glycol methyl ether according or equivalent to OECD guidelines 412, 413 and 453.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records
Reference
Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Published data with limited information on the methods and results.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 409 (Repeated Dose 90-Day Oral Toxicity in Non-Rodents)
GLP compliance:
not specified
Species:
other: rat & dog
Strain:
other: CFE (rats)
Sex:
male
Route of administration:
oral: feed
Duration of treatment / exposure:
13 weeks
Frequency of treatment:
5 times per week
Remarks:
Doses / Concentrations:
459.5; 919; 1836; 3672 mg/kg
Basis:

Control animals:
not specified
Details on study design:
Post-exposure period: no data
Dose descriptor:
NOAEL
Effect level:
< 459.5 mg/kg bw/day (nominal)
Sex:
not specified
Dose descriptor:
LOAEL
Effect level:
459.5 mg/kg bw/day (nominal)
Sex:
not specified
Critical effects observed:
not specified

Rats: Mild to severe central nervous system depression were observed. This  caused a growth depression because of the reduced food intake. 

The livers  became enlarged, especially at doses > 919 mg/kg. Cell necrosis in the  liver mainly in the peripheral parts of the lobules. 

Minor kidney injury at higher doses.

Dogs: Mild to severe central nervous system depression in a dose-related manner  was observed. 

Male dogs developed numerous spermiophages in the epididymis. Minor kidney injury at higher doses. As no data is available on purity, the relevance of spermiophages in the epididymis is unclear. As this effect was not seen in the well performed fertility studies and only in dogs in this study it can be considered to be not related to propylene glycol methyl ether.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
LOAEL
460 mg/kg bw/day
Study duration:
subchronic
Species:
rat
Quality of whole database:
acceptable

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records
Reference
Endpoint:
chronic toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1998
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study was conducted in accordance with GLP and OECD guideline 453 and TSCA guideline part 798
Qualifier:
according to
Guideline:
OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)
Qualifier:
according to
Guideline:
other: TSCA Guideline Part 798
Principles of method if other than guideline:
Method: other: OECD 453
GLP compliance:
yes
Limit test:
no
Species:
rat
Strain:
Fischer 344
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River breeding Laboratories, Inc., Kingston, NY
- Age at study initiation: Approximately 6-7 weeks
- Weight at study initiation: Approximately 140-150 gms (male) and 110-120 - gms (female)
- Fasting period before study: None
- Housing: 2/cage in stainless steel wire cages
- Diet (ad libitum): Except during exposure
- Water (ad libitum): Except during exposure
- Acclimation period: 1 week


ENVIRONMENTAL CONDITIONS
- Temperature (°C): Standard conditions
- Humidity (%): Standard conditions
- Air changes (per hr): Standard conditions



Route of administration:
inhalation: vapour
Type of inhalation exposure:
whole body
Vehicle:
other: unchanged (no vehicle)
Details on inhalation exposure:
See the attachment-1
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
See the attachment-1
Duration of treatment / exposure:
2 years whole body exposure
Frequency of treatment:
6 hours/day, 5 days/week
Remarks:
Doses / Concentrations:
300 ppm
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
1000 ppm
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
3000 ppm
Basis:
nominal conc.
No. of animals per sex per dose:
50 animals/sex/dose
Control animals:
yes
Details on study design:
See the attachment-1
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily (except weekends) for signs of toxicity and checked daily for mortality (including weekends)

DETAILED CLINICAL OBSERVATIONS: Yes
These observation were made only rats belonging to group A
- Time schedule: Prior to start of exposure and weekly thereafter


BODY WEIGHT: Yes
- Time schedule for examinations: All animals were weighed prior to the initial exposure and weekly intervals for the first 13 weeks and at approximately 4- weeks thereafter.

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations:
- Dose groups that were examined: Prior to start of exposure and prior to necropsy in all animals dose group A.


HAEMATOLOGY: Yes
- Time schedule for collection of blood: After 6 months, 12 months and 18 months of exposure
- Anesthetic used for blood collection: Yes (identity) Methoxyflurane
- Animals fasted: Yes
- How many animals: For interim collection (6, 12, 18 months) 10 rats/sex/exposure randomly selected
- Parameters checked in table [No.?] were examined.


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: After 6 months, 12 months and 18 months of exposure
- Anesthetic used for blood collection: Yes (identity) Methoxyflurane
- Animals fasted: Yes
- How many animals: For interim collection (6, 12, 18 months) 10 rats/sex/exposure randomly selected
- Parameters checked in table [No.?] were examined.


URINALYSIS: Yes
- Time schedule for collection of urine: 1-6 days prior to 6, 12, 18 months blood collection and 1 day prior to 24 month blood collection
- Metabolism cages used for collection of urine: No
- Animals fasted: No
- Parameters checked in table [No.?] were examined.






Sacrifice and pathology:
GROSS PATHOLOGY: Yes
All surviving animals were fasted overnight and necropsied after approximately 24 months of exposure to PGME. Each animal was weighed, anesthetized with methoxyflurane and trachea exposed and clamped prior to decapitation. The eyes were visually examined throgh a moistened glass slide pressed against the corneal surface. Weight of brain, heart, lungs, liver, kidneys, adrenals and testes were recorded and the organ weights to final body weight ratios were calculated. The lungs were intratracheally infused to an approximately normal inspiratory volume with neutral phosphate buffered 10 % formalin. The nasal cavity was flushed by a similar method via the pharyngeal duct. Representative samples of tissues and any masses or lesions observed during necropsy were preserved in formalin. A similar procedure was followed for rats which died or were sacrificed in a moribund condition, except that blood samples, terminal body weights and organ weight data were not be collected.
HISTOPATHOLOGY: Yes
Tissues were prepared for light microscopic evaluation by procedures, sectioned at approximately 6µm and stained with hematoxylin and eosin. A complete histopathologic evaluation of all tissues was conducted on all control and 3000 ppm PGME exposure rats and from rats that died or were sacrificed in a moribund during the course of the study. In addition, microscopic examination of tissues from the low and middle exposure groups included the liver, kidneys, lungs, nasal tissues and all gross lesions.
Other examinations:
Organ weights: Weight of brain, heart, lungs, liver, kidneys, adrenals and testes were recorded.
Statistics:
See the attchment-1
Clinical signs:
effects observed, treatment-related
Mortality:
mortality observed, treatment-related
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
no effects observed
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
no effects observed
Details on results:
CLINICAL SIGNS AND MORTALITY: Overall survival was excellent for the 2 year study with mortality never exceeding 58 % for any treatment group. For males, a slight increase in mortality was observed following 700 days exposure to 3000 ppm PGME vs. controls. At study termination, the cumulative mortality in males was 40, 32, 40 and 58 % for the control, 300, 1000, 3000 ppm groups respectively. For females no treatment related increase in mortality was observed. At study termination, the cumulative mortality in females was 22, 30, 28 and 16 % for the control, 300, 1000, 3000 ppm groups respectively.
At 3000 ppm PGME the sedative effects, characterized by decreased activity and incoordination, were observed in both sexes during the first week of exposures. The animals generally recovered within hours following the six hour exposure periods. During the second week of exposures, the animals appeared to have accommodated to the test material as no further observation of sedative effects thought the first year exposures were noted. Other clinical observations were in general consistent with age related changes commonly observed in chronic studies with Fischer 344 rats and not due to PGME exposures. A number of rats in each group had external masses or nodules in various locations of the skin, subcutaneous tissues and in preputial or clitoral glands areas. These masses/nodules were distributed across all groups without regard to treatment.

BODY WEIGHT AND WEIGHT GAIN: For male rats, there were numerous instances of treatment groups having a statistically significant difference in body weights or weight gain vs controls. These differences included decreases as well as increases and did not display a dose response relationship. For females, occasional statistically identified differences from controls were also observed but lacked dose response during the 13 weeks of study. However, by 118 days treatment, the mean body weights females exposed to 3000 ppm PGME were consistently and statistically lower than control values by approximately 3-7 %. This effect on the body weights of female rats was considered to be treatment related.

OPHTHALMOSCOPIC EXAMINATION: There were no ophthalmologic abnormalities noted in any of the group A study animals that were considered to be treatment related.


HAEMATOLOGY: There were no hematological effects in male and female rats that were attributable to PGME exposures. Occasional statistical significant differences were observed that lacked dose response, were not reproducible (between the 6, 12, 18 and 24 month sampling intervals) or differed in a manner in which that was not toxicologically relevant. The only statistically identified hematological change was an increase in total leukocyte counts in 300 ppm PGME males at 6 months which was not considered treatment related as it represented an increase and not a decrease in counts, was not observed at other time points, and lacked any histopathological correlate. No effects were observed in WBC differential counts. The only statistically identified changes included, elevated leukocyte counts in females exposed to 300 and 1000 ppm PGME for 6 months, but not at 3000 ppm PGME or at later time periods, increased erythrocyte and platelet counts in females exposed to 3000 ppm PGME after 6 months but not at later times periods and slight decrease in platelet counts in females exposed to 3000 ppm PGME for 12 months but not at 18 or 24 months. These changes were all considered to be a reflection of normal biological variability. As with the males, no treatment related effects were observed in WBC differential counts and blood cell morphology.


CLINICAL CHEMISTRY: Occasional findings of statistically significant but not treatment related included, elevated BUN in rats exposed to 1000 ppm for 6 months, elevated cholesterol in rats exposed to 1000 and 3000 ppm for 6 months, elevated triglycerides levels in rats exposed to 300 and 1000 ppm for 6 months or 3000 ppm for 24 months, increased creatinine levels in rats exposed to 3000 ppm at 6, 12 and 24 months, decreased creatinine phosphokinase activity in rats exposed to 1000 ppm only for 24 months. In addition, the mean calcium level in male rats exposed to 1000 ppm for 6 months was statistically identified as elevated and the phosphorous level of rats exposed to 3000 ppm for 18 months was identified as decreased relative to controls. All of those statistically identified differences were considered to be a result of normal variability and unrelated to PGME exposure since they were not either reproducible, lacked a dose response relationship or lacked histopathological correlate. Elevated serum alkaline phosphatase activities were also observed in male rats exposed to 3000 ppm PGME for 6, 12 and 24 months or to 1000 ppm for 24 months. This enzyme is typically associated with degenerative changes or obstruction of the biliary duct system, which was morphologically unaffected by PGME exposure. Changes observed in electrolytes were statistically identified but not treatment related and lacked a dose response relationship.


URINALYSIS: The slight changes in urinalysis parameters that were observed in two weeks i.e. increased urine pH in male rats exposed to 3000 ppm PGME but these changes were not apparent in this study following 6, 12, 18, and 24 months of exposure. There were no treatment related effects evident in urinalysis including microscopic examinations of urine micro sediment from male and female rats.


ORGAN WEIGHTS: A statistically significant increase in liver weights (18.6 % absolute and 21.2 % relative to body weight) was observed in high exposure group males, relative to controls at the terminal 24 month sacrifice, similar increases were present at earlier time points. For female rats, there were no significant liver weight differences observed in the high concentration group at the terminal sacrifice, however there were statistically significant liver weight increases at earlier time points. Kidney weights were elevated in males exposed to 3000 ppm PGME following 6, 12, 18 and 24 months of exposure. At 24 months, this increase averaged 22 % for absolute kidney weights and 28 % for kidney weights relative to their body weights. Although statistically identified at all time periods were slight <5 % absolute and did not correlate to any histopathological changes in renal tissues. No other changes in organ weights interpreted to be treatment related were observed in male or female rats.


GROSS PATHOLOGY: A slight increase in the incidence of dark foci in the livers of male rats exposed to 1000 and 3000 ppm PGME for 2 years was correlated with the presence of altered hepatocellular foci observed histologically .All other gross pathological observations and the occurrence of palpable mass were distributed across all groups, including controls and were typical for rats of this age and strain.


HISTOPATHOLOGY: The major toxicological effects of exposure were observed in the liver and kidneys. Effects of lesser importance were observed in nasal tissues and lungs. The clinical pathology data did not indicate significant treatment related hepatotoxicity. The lack of dose response in the incidence of tumors in males does not suggest a treatment related effect.

Dose descriptor:
NOEL
Effect level:
300 ppm
Sex:
male/female
Basis for effect level:
other: overall effects
Critical effects observed:
not specified
Conclusions:
In conclusion, PGME did not cause a dose related increase in tumors in male and female rats exposed to 0, 300, 1000 and 3000 ppm PGME vapors for 6 hours/day, 5 days/week for up to 2 years. A NOEL of 300 ppm PGME was established for this study.
Executive summary:

Groups of 50 male and 50 female Fischer 344 per sex per concentration were whole body exposed to targeted vapor concentrations of 0, 300, 1000 and 3000 ppm PGME (colorless liquid) under dynamic airflow conditions 6 hours/day, 5 days/week for up to 2 years.

Rats were received frombreeding Laboratories,. Mice were kept for acclimatization for 1 week period. At study initiation rats were of approximately 6 -7 weeks old. Rats were housed 2/sex/cage in stainless steel cages with wire bottoms. A standard laboratory diet (Purina Certified Laboratory Chow, Ralston Purina Co.) supplied to rats adlibitum except during exposure. Adlibitum water was supplied to rats except during exposure.

 

Monitored for effects included clinical observations, body weights, hematology, clinical chemistry, urinalysis, opthalmoscopy, necropsy, organ weights, gross pathology and histopathology.

Overall survival was excellent for the 2 year study with mortality never exceeding 58 % for any treatment group. For males, a slight increase in mortality was observed following 700 days exposure to 3000 ppm PGME vs. controls. At study termination, the cumulative mortality in males was 40, 32, 40 and 58 % for the control, 300, 1000, 3000 ppm groups respectively. For females no treatment related increase in mortality was observed. At study termination, the cumulative mortality in females was 22, 30, 28 and 16 % for the control, 300, 1000, 3000 ppm groups respectively. At 3000 ppm PGME the sedative effects, characterized by decreased activity and incoordination, were observed in both sexes during the first week of exposures. The animals generally recovered within hours following the six hour exposure periods. During the second week of exposures, the animals appeared to have accommodated to the test material as no further observation of sedative effects thought the first year exposures were noted. Other clinical observations were in general consistent with age related changes commonly observed in chronic studies with Fischer 344 rats and not due to PGME exposures. A number of rats in each group had external masses or nodules in various locations of the skin, subcutaneous tissues and in preputial or clitoral glands areas. These masses/nodules were distributed across all groups without regard to treatment.

For male rats, there were numerous instances of treatment groups having a statistically significant difference in body weights or weight gain vs controls. These differences included decreases as well as increases and did not display a dose response relationship. For females, occasional statistically identified differences from controls were also observed but lacked dose response during the 13 weeks of study. However, by 118 days treatment, the mean body weights females exposed to 3000 ppm PGME were consistently and statistically lower than control values by approximately 3-7 %. This effect on the body weights of female rats was considered to be treatment related.

There were no ophthalmologic abnormalities noted in any of the group A study animals that were considered to be treatment related.

There were no hematological effects in male and female rats that were attributable to PGME exposures. Occasional statistical significant differences were observed that lacked dose response, were not reproducible (between the 6, 12, 18 and 24 month sampling intervals) or differed in a manner in which that was not toxicologically relevant. The only statistically identified hematological change was an increase in total leukocyte counts in 300 ppm PGME males at 6 months which was not considered treatment related as it represented an increase and not a decrease in counts, was not observed at other time points, and lacked any histopathological correlate. No effects were observed in WBC differential counts. The only statistically identified changes included, elevated leukocyte counts in females exposed to 300 and 1000 ppm PGME for 6 months, but not at 3000 ppm PGME or at later time periods, increased erythrocyte and platelet counts in females exposed to 3000 ppm PGME after 6 months but not at later times periods and slight decrease in platelet counts in females exposed to 3000 ppm PGME for 12 months but not at 18 or 24 months. These changes were all considered to be a reflection of normal biological variability. As with the males, no treatment related effects were observed in WBC differential counts and blood cell morphology.

Occasional findings of statistically significant but not treatment related included, elevated BUN in rats exposed to 1000 ppm for 6 months, elevated cholesterol in rats exposed to 1000 and 3000 ppm for 6 months, elevated triglycerides levels in rats exposed to 300 and 1000 ppm for 6 months or 3000 ppm for 24 months, increased creatinine levels in rats exposed to 3000 ppm at 6, 12 and 24 months, decreased creatinine phosphokinase activity in rats exposed to 1000 ppm only for 24 months. In addition, the mean calcium level in male rats exposed to 1000 ppm for 6 months was statistically identified as elevated and the phosphorous level of rats exposed to 3000 ppm for 18 months was identified as decreased relative to controls. All of those statistically identified differences were considered to be a result of normal variability and unrelated to PGME exposure since they were not either reproducible, lacked a dose response relationship or lacked histopathological correlate. Elevated serum alkaline phosphatase activities were also observed in male rats exposed to 3000 ppm PGME for 6, 12 and 24 months or to 1000 ppm for 24 months. This enzyme is typically associated with degenerative changes or obstruction of the biliary duct system, which was morphologically unaffected by PGME exposure. Changes observed in electrolytes were statistically identified but not treatment related and lacked a dose response relationship.

The slight changes in urinalysis parameters that were observed in two weeks i.e. increased urine pH in male rats exposed to 3000 ppm PGME but these changes were not apparent in this study following 6, 12, 18, and 24 months of exposure. There were no treatment related effects evident in urinalysis including microscopic examinations of urine micro sediment from male and female rats.

There were no changes observed in organ weights related to PGME exposure.There were no gross pathological findings attributable to PGME exposure in male and female rats. The gross lesions observed were generally distributed across all groups or occurred sporadically and were typical for rats of this age and strain.

There were no histopathological findings attributable to PGME exposure in male and female rats. The histopathological lesions observed were generally distributed across all groups or occurred sporadically and were typical for rats of this age and strain. The major toxicological effects of exposure were observed in the liver and kidneys. Effects of lesser importance were observed in nasal tissues and lungs. The clinical pathology data did not indicate significant treatment related hepatotoxicity. The lack of dose response in the incidence of tumors in males does not suggest a treatment related effect.

 In conclusion, PGME did not cause a dose related increase in tumors in male and female rats exposed to 0, 300, 1000 and 3000 ppm PGME vapors for 6 hours/day, 5 days/week for up to 2 years. A NOEL of 300 ppm PGME was established for this study.

 

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
NOAEC
1 122 mg/m³
Study duration:
chronic
Species:
rat
Quality of whole database:
Good (Klimisch 1)

Repeated dose toxicity: inhalation - local effects

Link to relevant study records
Reference
Endpoint:
chronic toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1998
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study was conducted in accordance with GLP and OECD guideline 453 and TSCA guideline part 798
Qualifier:
according to
Guideline:
OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)
Qualifier:
according to
Guideline:
other: TSCA Guideline Part 798
Principles of method if other than guideline:
Method: other: OECD 453
GLP compliance:
yes
Limit test:
no
Species:
rat
Strain:
Fischer 344
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River breeding Laboratories, Inc., Kingston, NY
- Age at study initiation: Approximately 6-7 weeks
- Weight at study initiation: Approximately 140-150 gms (male) and 110-120 - gms (female)
- Fasting period before study: None
- Housing: 2/cage in stainless steel wire cages
- Diet (ad libitum): Except during exposure
- Water (ad libitum): Except during exposure
- Acclimation period: 1 week


ENVIRONMENTAL CONDITIONS
- Temperature (°C): Standard conditions
- Humidity (%): Standard conditions
- Air changes (per hr): Standard conditions



Route of administration:
inhalation: vapour
Type of inhalation exposure:
whole body
Vehicle:
other: unchanged (no vehicle)
Details on inhalation exposure:
See the attachment-1
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
See the attachment-1
Duration of treatment / exposure:
2 years whole body exposure
Frequency of treatment:
6 hours/day, 5 days/week
Remarks:
Doses / Concentrations:
300 ppm
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
1000 ppm
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
3000 ppm
Basis:
nominal conc.
No. of animals per sex per dose:
50 animals/sex/dose
Control animals:
yes
Details on study design:
See the attachment-1
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily (except weekends) for signs of toxicity and checked daily for mortality (including weekends)

DETAILED CLINICAL OBSERVATIONS: Yes
These observation were made only rats belonging to group A
- Time schedule: Prior to start of exposure and weekly thereafter


BODY WEIGHT: Yes
- Time schedule for examinations: All animals were weighed prior to the initial exposure and weekly intervals for the first 13 weeks and at approximately 4- weeks thereafter.

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations:
- Dose groups that were examined: Prior to start of exposure and prior to necropsy in all animals dose group A.


HAEMATOLOGY: Yes
- Time schedule for collection of blood: After 6 months, 12 months and 18 months of exposure
- Anesthetic used for blood collection: Yes (identity) Methoxyflurane
- Animals fasted: Yes
- How many animals: For interim collection (6, 12, 18 months) 10 rats/sex/exposure randomly selected
- Parameters checked in table [No.?] were examined.


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: After 6 months, 12 months and 18 months of exposure
- Anesthetic used for blood collection: Yes (identity) Methoxyflurane
- Animals fasted: Yes
- How many animals: For interim collection (6, 12, 18 months) 10 rats/sex/exposure randomly selected
- Parameters checked in table [No.?] were examined.


URINALYSIS: Yes
- Time schedule for collection of urine: 1-6 days prior to 6, 12, 18 months blood collection and 1 day prior to 24 month blood collection
- Metabolism cages used for collection of urine: No
- Animals fasted: No
- Parameters checked in table [No.?] were examined.






Sacrifice and pathology:
GROSS PATHOLOGY: Yes
All surviving animals were fasted overnight and necropsied after approximately 24 months of exposure to PGME. Each animal was weighed, anesthetized with methoxyflurane and trachea exposed and clamped prior to decapitation. The eyes were visually examined throgh a moistened glass slide pressed against the corneal surface. Weight of brain, heart, lungs, liver, kidneys, adrenals and testes were recorded and the organ weights to final body weight ratios were calculated. The lungs were intratracheally infused to an approximately normal inspiratory volume with neutral phosphate buffered 10 % formalin. The nasal cavity was flushed by a similar method via the pharyngeal duct. Representative samples of tissues and any masses or lesions observed during necropsy were preserved in formalin. A similar procedure was followed for rats which died or were sacrificed in a moribund condition, except that blood samples, terminal body weights and organ weight data were not be collected.
HISTOPATHOLOGY: Yes
Tissues were prepared for light microscopic evaluation by procedures, sectioned at approximately 6µm and stained with hematoxylin and eosin. A complete histopathologic evaluation of all tissues was conducted on all control and 3000 ppm PGME exposure rats and from rats that died or were sacrificed in a moribund during the course of the study. In addition, microscopic examination of tissues from the low and middle exposure groups included the liver, kidneys, lungs, nasal tissues and all gross lesions.
Other examinations:
Organ weights: Weight of brain, heart, lungs, liver, kidneys, adrenals and testes were recorded.
Statistics:
See the attchment-1
Clinical signs:
effects observed, treatment-related
Mortality:
mortality observed, treatment-related
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
no effects observed
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
no effects observed
Details on results:
CLINICAL SIGNS AND MORTALITY: Overall survival was excellent for the 2 year study with mortality never exceeding 58 % for any treatment group. For males, a slight increase in mortality was observed following 700 days exposure to 3000 ppm PGME vs. controls. At study termination, the cumulative mortality in males was 40, 32, 40 and 58 % for the control, 300, 1000, 3000 ppm groups respectively. For females no treatment related increase in mortality was observed. At study termination, the cumulative mortality in females was 22, 30, 28 and 16 % for the control, 300, 1000, 3000 ppm groups respectively.
At 3000 ppm PGME the sedative effects, characterized by decreased activity and incoordination, were observed in both sexes during the first week of exposures. The animals generally recovered within hours following the six hour exposure periods. During the second week of exposures, the animals appeared to have accommodated to the test material as no further observation of sedative effects thought the first year exposures were noted. Other clinical observations were in general consistent with age related changes commonly observed in chronic studies with Fischer 344 rats and not due to PGME exposures. A number of rats in each group had external masses or nodules in various locations of the skin, subcutaneous tissues and in preputial or clitoral glands areas. These masses/nodules were distributed across all groups without regard to treatment.

BODY WEIGHT AND WEIGHT GAIN: For male rats, there were numerous instances of treatment groups having a statistically significant difference in body weights or weight gain vs controls. These differences included decreases as well as increases and did not display a dose response relationship. For females, occasional statistically identified differences from controls were also observed but lacked dose response during the 13 weeks of study. However, by 118 days treatment, the mean body weights females exposed to 3000 ppm PGME were consistently and statistically lower than control values by approximately 3-7 %. This effect on the body weights of female rats was considered to be treatment related.

OPHTHALMOSCOPIC EXAMINATION: There were no ophthalmologic abnormalities noted in any of the group A study animals that were considered to be treatment related.


HAEMATOLOGY: There were no hematological effects in male and female rats that were attributable to PGME exposures. Occasional statistical significant differences were observed that lacked dose response, were not reproducible (between the 6, 12, 18 and 24 month sampling intervals) or differed in a manner in which that was not toxicologically relevant. The only statistically identified hematological change was an increase in total leukocyte counts in 300 ppm PGME males at 6 months which was not considered treatment related as it represented an increase and not a decrease in counts, was not observed at other time points, and lacked any histopathological correlate. No effects were observed in WBC differential counts. The only statistically identified changes included, elevated leukocyte counts in females exposed to 300 and 1000 ppm PGME for 6 months, but not at 3000 ppm PGME or at later time periods, increased erythrocyte and platelet counts in females exposed to 3000 ppm PGME after 6 months but not at later times periods and slight decrease in platelet counts in females exposed to 3000 ppm PGME for 12 months but not at 18 or 24 months. These changes were all considered to be a reflection of normal biological variability. As with the males, no treatment related effects were observed in WBC differential counts and blood cell morphology.


CLINICAL CHEMISTRY: Occasional findings of statistically significant but not treatment related included, elevated BUN in rats exposed to 1000 ppm for 6 months, elevated cholesterol in rats exposed to 1000 and 3000 ppm for 6 months, elevated triglycerides levels in rats exposed to 300 and 1000 ppm for 6 months or 3000 ppm for 24 months, increased creatinine levels in rats exposed to 3000 ppm at 6, 12 and 24 months, decreased creatinine phosphokinase activity in rats exposed to 1000 ppm only for 24 months. In addition, the mean calcium level in male rats exposed to 1000 ppm for 6 months was statistically identified as elevated and the phosphorous level of rats exposed to 3000 ppm for 18 months was identified as decreased relative to controls. All of those statistically identified differences were considered to be a result of normal variability and unrelated to PGME exposure since they were not either reproducible, lacked a dose response relationship or lacked histopathological correlate. Elevated serum alkaline phosphatase activities were also observed in male rats exposed to 3000 ppm PGME for 6, 12 and 24 months or to 1000 ppm for 24 months. This enzyme is typically associated with degenerative changes or obstruction of the biliary duct system, which was morphologically unaffected by PGME exposure. Changes observed in electrolytes were statistically identified but not treatment related and lacked a dose response relationship.


URINALYSIS: The slight changes in urinalysis parameters that were observed in two weeks i.e. increased urine pH in male rats exposed to 3000 ppm PGME but these changes were not apparent in this study following 6, 12, 18, and 24 months of exposure. There were no treatment related effects evident in urinalysis including microscopic examinations of urine micro sediment from male and female rats.


ORGAN WEIGHTS: A statistically significant increase in liver weights (18.6 % absolute and 21.2 % relative to body weight) was observed in high exposure group males, relative to controls at the terminal 24 month sacrifice, similar increases were present at earlier time points. For female rats, there were no significant liver weight differences observed in the high concentration group at the terminal sacrifice, however there were statistically significant liver weight increases at earlier time points. Kidney weights were elevated in males exposed to 3000 ppm PGME following 6, 12, 18 and 24 months of exposure. At 24 months, this increase averaged 22 % for absolute kidney weights and 28 % for kidney weights relative to their body weights. Although statistically identified at all time periods were slight <5 % absolute and did not correlate to any histopathological changes in renal tissues. No other changes in organ weights interpreted to be treatment related were observed in male or female rats.


GROSS PATHOLOGY: A slight increase in the incidence of dark foci in the livers of male rats exposed to 1000 and 3000 ppm PGME for 2 years was correlated with the presence of altered hepatocellular foci observed histologically .All other gross pathological observations and the occurrence of palpable mass were distributed across all groups, including controls and were typical for rats of this age and strain.


HISTOPATHOLOGY: The major toxicological effects of exposure were observed in the liver and kidneys. Effects of lesser importance were observed in nasal tissues and lungs. The clinical pathology data did not indicate significant treatment related hepatotoxicity. The lack of dose response in the incidence of tumors in males does not suggest a treatment related effect.

Dose descriptor:
NOEL
Effect level:
300 ppm
Sex:
male/female
Basis for effect level:
other: overall effects
Critical effects observed:
not specified
Conclusions:
In conclusion, PGME did not cause a dose related increase in tumors in male and female rats exposed to 0, 300, 1000 and 3000 ppm PGME vapors for 6 hours/day, 5 days/week for up to 2 years. A NOEL of 300 ppm PGME was established for this study.
Executive summary:

Groups of 50 male and 50 female Fischer 344 per sex per concentration were whole body exposed to targeted vapor concentrations of 0, 300, 1000 and 3000 ppm PGME (colorless liquid) under dynamic airflow conditions 6 hours/day, 5 days/week for up to 2 years.

Rats were received frombreeding Laboratories,. Mice were kept for acclimatization for 1 week period. At study initiation rats were of approximately 6 -7 weeks old. Rats were housed 2/sex/cage in stainless steel cages with wire bottoms. A standard laboratory diet (Purina Certified Laboratory Chow, Ralston Purina Co.) supplied to rats adlibitum except during exposure. Adlibitum water was supplied to rats except during exposure.

 

Monitored for effects included clinical observations, body weights, hematology, clinical chemistry, urinalysis, opthalmoscopy, necropsy, organ weights, gross pathology and histopathology.

Overall survival was excellent for the 2 year study with mortality never exceeding 58 % for any treatment group. For males, a slight increase in mortality was observed following 700 days exposure to 3000 ppm PGME vs. controls. At study termination, the cumulative mortality in males was 40, 32, 40 and 58 % for the control, 300, 1000, 3000 ppm groups respectively. For females no treatment related increase in mortality was observed. At study termination, the cumulative mortality in females was 22, 30, 28 and 16 % for the control, 300, 1000, 3000 ppm groups respectively. At 3000 ppm PGME the sedative effects, characterized by decreased activity and incoordination, were observed in both sexes during the first week of exposures. The animals generally recovered within hours following the six hour exposure periods. During the second week of exposures, the animals appeared to have accommodated to the test material as no further observation of sedative effects thought the first year exposures were noted. Other clinical observations were in general consistent with age related changes commonly observed in chronic studies with Fischer 344 rats and not due to PGME exposures. A number of rats in each group had external masses or nodules in various locations of the skin, subcutaneous tissues and in preputial or clitoral glands areas. These masses/nodules were distributed across all groups without regard to treatment.

For male rats, there were numerous instances of treatment groups having a statistically significant difference in body weights or weight gain vs controls. These differences included decreases as well as increases and did not display a dose response relationship. For females, occasional statistically identified differences from controls were also observed but lacked dose response during the 13 weeks of study. However, by 118 days treatment, the mean body weights females exposed to 3000 ppm PGME were consistently and statistically lower than control values by approximately 3-7 %. This effect on the body weights of female rats was considered to be treatment related.

There were no ophthalmologic abnormalities noted in any of the group A study animals that were considered to be treatment related.

There were no hematological effects in male and female rats that were attributable to PGME exposures. Occasional statistical significant differences were observed that lacked dose response, were not reproducible (between the 6, 12, 18 and 24 month sampling intervals) or differed in a manner in which that was not toxicologically relevant. The only statistically identified hematological change was an increase in total leukocyte counts in 300 ppm PGME males at 6 months which was not considered treatment related as it represented an increase and not a decrease in counts, was not observed at other time points, and lacked any histopathological correlate. No effects were observed in WBC differential counts. The only statistically identified changes included, elevated leukocyte counts in females exposed to 300 and 1000 ppm PGME for 6 months, but not at 3000 ppm PGME or at later time periods, increased erythrocyte and platelet counts in females exposed to 3000 ppm PGME after 6 months but not at later times periods and slight decrease in platelet counts in females exposed to 3000 ppm PGME for 12 months but not at 18 or 24 months. These changes were all considered to be a reflection of normal biological variability. As with the males, no treatment related effects were observed in WBC differential counts and blood cell morphology.

Occasional findings of statistically significant but not treatment related included, elevated BUN in rats exposed to 1000 ppm for 6 months, elevated cholesterol in rats exposed to 1000 and 3000 ppm for 6 months, elevated triglycerides levels in rats exposed to 300 and 1000 ppm for 6 months or 3000 ppm for 24 months, increased creatinine levels in rats exposed to 3000 ppm at 6, 12 and 24 months, decreased creatinine phosphokinase activity in rats exposed to 1000 ppm only for 24 months. In addition, the mean calcium level in male rats exposed to 1000 ppm for 6 months was statistically identified as elevated and the phosphorous level of rats exposed to 3000 ppm for 18 months was identified as decreased relative to controls. All of those statistically identified differences were considered to be a result of normal variability and unrelated to PGME exposure since they were not either reproducible, lacked a dose response relationship or lacked histopathological correlate. Elevated serum alkaline phosphatase activities were also observed in male rats exposed to 3000 ppm PGME for 6, 12 and 24 months or to 1000 ppm for 24 months. This enzyme is typically associated with degenerative changes or obstruction of the biliary duct system, which was morphologically unaffected by PGME exposure. Changes observed in electrolytes were statistically identified but not treatment related and lacked a dose response relationship.

The slight changes in urinalysis parameters that were observed in two weeks i.e. increased urine pH in male rats exposed to 3000 ppm PGME but these changes were not apparent in this study following 6, 12, 18, and 24 months of exposure. There were no treatment related effects evident in urinalysis including microscopic examinations of urine micro sediment from male and female rats.

There were no changes observed in organ weights related to PGME exposure.There were no gross pathological findings attributable to PGME exposure in male and female rats. The gross lesions observed were generally distributed across all groups or occurred sporadically and were typical for rats of this age and strain.

There were no histopathological findings attributable to PGME exposure in male and female rats. The histopathological lesions observed were generally distributed across all groups or occurred sporadically and were typical for rats of this age and strain. The major toxicological effects of exposure were observed in the liver and kidneys. Effects of lesser importance were observed in nasal tissues and lungs. The clinical pathology data did not indicate significant treatment related hepatotoxicity. The lack of dose response in the incidence of tumors in males does not suggest a treatment related effect.

 In conclusion, PGME did not cause a dose related increase in tumors in male and female rats exposed to 0, 300, 1000 and 3000 ppm PGME vapors for 6 hours/day, 5 days/week for up to 2 years. A NOEL of 300 ppm PGME was established for this study.

 

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Study duration:
chronic
Species:
rat
Quality of whole database:
Good (Klimisch 1)

Repeated dose toxicity: dermal - systemic effects

Link to relevant study records
Reference
Endpoint:
sub-chronic toxicity: dermal
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1953
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: This study was conducted prior to GLP and similar to OECD guideline 411.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 411 (Subchronic Dermal Toxicity: 90-Day Study)
GLP compliance:
no
Limit test:
no
Species:
rabbit
Strain:
not specified
Sex:
male
Details on test animals and environmental conditions:
Not specified in the report
Type of coverage:
occlusive
Vehicle:
water
Details on exposure:
Route of Administration: dermal
- Area of exposure: Shaved abdomen
- Type of wrap if used: A pad of absorbent cotton about 3"By 3" in size and sufficiently thick to just absorb the volume of the test material was applied to the shaved abdomen of the rabbit. The proper dose of the compound was added to the cotton and then covered with an impervious saran film about 5" by 5".This saran film was covered with a heavy cloth and the whole application was then strapped onto the animal with adhesive tape.



Analytical verification of doses or concentrations:
not specified
Details on analytical verification of doses or concentrations:
Not specified in the report
Duration of treatment / exposure:
90 days
Frequency of treatment:
5 days/week
Remarks:
Doses / Concentrations:
2 ml/kg (1838 mg/kg)
Basis:
nominal per unit body weight
Remarks:
Doses / Concentrations:
4 ml/kg (3676 mg/kg)
Basis:
nominal per unit body weight
Remarks:
Doses / Concentrations:
7 ml/kg (6433 mg/kg)
Basis:
nominal per unit body weight
Remarks:
Doses / Concentrations:
10 ml/kg (9190 mg/kg)
Basis:
nominal per unit body weight
No. of animals per sex per dose:
5 animals/control, 2 ml/kg- 6 animals, 4 ml/kg- 7 animals, 7 ml/kg- 9 animals, 10 ml/kg- 11 animals
Control animals:
yes
Details on study design:
Post-exposure period: no data
- Rationale for animal assignment : Random
- Post-exposure recovery period : None
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
DETAILED CLINICAL OBSERVATIONS: No data
DERMAL IRRITATION (if dermal study): No
BODY WEIGHT: Yes
FOOD CONSUMPTION: Yes
HAEMATOLOGY: Yes
Time schedule for collection of blood: Prior to exposure and on day 30th and 90 th.
URINALYSIS: No

Sacrifice and pathology:
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
On 90th day the rabbits were autopsied and tissues were taken from the liver, kidney, spleen, adrenal, heart, lungs and occasionally from stomach for histological examination. These sections were stained with hematoxylin and eosin.
Other examinations:
Organ weights: At autosy weights of liver, kidney, adrenal, spleen, lungs and heart.
Statistics:
The possible significance between mean cell counts, body weights and organ weights was determined by use of student's test of "t".
Clinical signs:
effects observed, treatment-related
Dermal irritation:
not specified
Mortality:
mortality observed, treatment-related
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
no effects observed
Details on results:
CLINICAL SIGNS AND MORTALITY: The mortalities resulting from the repeated applications of PGME to the skin of rabbits for a period 90 days as below.
1/6, 2/7, 8/9 and 11/11 for 2, 4, 7 and 10 ml/kg respectively. The higher doses i.e. 7 ml/kg and 10 ml/kg of PGNME produced narcosis which generally led to the death of the animal. Dose group with 2ml/kg and 4 ml/kg were associated with only slight mortality but that was due to respiratory infection and in no way attributable to exposure of PGME.The animals which showed narcosis during the early portion of the experimental period which disappeared as the applications were repeated. The animals had developed a tolerance for the materials.


BODY WEIGHT AND WEIGHT GAIN: There were no significant differences in body weights between control and treated animals of 2ml/kg and 4 ml/kg dose groups. The animals treated with 7ml/kg and 10 ml/kg dose levels showed terminal loss in body weights probably due to decreased food consumption.

FOOD CONSUMPTION: Food consumption was decreased in the animals of 7ml/kg and 10 ml/kg dose groups.

HAEMATOLOGY: There were no PGME exposure related effects on any of the measured hematology parameters in rabbits.

ORGAN WEIGHTS: There were also no statistically significant differences in organ weights of rabbits exposed to PGME

GROSS PATHOLOGY: Gross examination of animals surviving the 90 day period of treatment, irrespective of dose, revealed normal lungs, heart, liver, kidney, adrenal, testes, stomach and intestines. These organs were also normal grossly in rabbits that became narcotized and died, with the exception that the stomach was usually filled with food and marked distended. This gastric retention appeared to be correlated with the narcotic effect. Occasionally, small hemorrhagic areas were noted in the gastric mucosa of such animals.


HISTOPATHOLOGY: Upon histological examination of tissues from surviving animals, the liver, lung, heart, adrenal, spleen, testes and stomach were within normal limits. Death from narcosis was often related to pneumonia and empyema.Occasionally, pyelonephritis or early interstitial nephritis was observed. Renal tubular necrosis of moderate to marked severity was observed in three rabbits that died from the 7 ml/kg and 10 ml/kg doses of PGME.However, other rabbits that died showed only a slight granular degeneration in the tubules
Dose descriptor:
NOAEL
Effect level:
1 838 mg/kg bw/day
Sex:
male
Basis for effect level:
other: overall effects
Dose descriptor:
LOAEL
Effect level:
3 676 mg/kg bw/day
Sex:
male
Basis for effect level:
other: overall effects
Critical effects observed:
not specified
Conclusions:
Based on the results of this study NOAEL for male rabbits is (2.0 ml/kg) 1838 mg/kg/day and LOAEL for male rabbits is (4.0 ml/kg) 3676 mg/kg/day..
Executive summary:

Four groups of male rabbits each were applied by repeated dermal doses, five days per week of PGME (colorless liquid) for a period of 90 days. A total of 65 daily doses were applied to shaved abdomen of rabbit’s equivalent to 10.0 ml/kg, 7.0 ml/kg, 4.0 ml/kg, and 2.0 ml/kg. A fifth matched group of five male rabbits served as a control group for the experiment.

Monitored for effects included clinical observations, body weights, food consumption, hematology, necropsy, organ weights, gross pathology and histopathology.

The mortalities resulting from the repeated applications of PGME to the skin of rabbits for a period 90 days as below.1/6, 7/2, 9/8 and 111/11 for 2, 4, 7 and 10 ml/kg respectively. The higher doses i.e. 7 ml/kg and 10 ml/kg of PGNME produced narcosis which generally led to the death of the animal. Dose group with 2ml/kg and 4 ml/kg were associated with only slight mortality but that also due to respiratory infection and in no way attributable to exposure of PGME.The animals which showed narcosis during the early portion of the experimental period which disappeared as the applications were repeated. The animals had developed a tolerance for the materials.

There were no significant differences in body weights between control and treated animals of 2 ml/kg and 4 ml/kg dose groups. The animals treated with 7ml/kg and 10 ml/kg dose level showed terminal loss in body weights probably due to decreased food consumption. Food consumption was decreased in the animals of 7ml/kg and 10 ml/kg dose groups.

There were no PGME exposure related effects on any of the measured hematology parameters in rabbits. There were also no statistically significant differences in organ weights of rabbits exposed to PGME.

Gross examination of animals surviving the 90 day period of treatment, irrespective of dose, revealed normal lungs, heart, liver, kidney, adrenal, testes, stomach and intestines. These organs were also normal grossly in rabbits that became narcotized and died, with the exception that the stomach was usually filled with food and marked distended. This gastric retention appeared to be correlated with the narcotic effect. Occasionally, small hemorrhagic areas were noted in the gastric mucosa of such animals.

Upon histological examination of tissues from surviving animals, the liver, lung, heart, adrenal, spleen, testes and stomach were within normal limits. Death from narcosis was often related to pneumonia and empyema.Occasionally, pyelonephritis or early interstitial nephritis was observed. Renal tubular necrosis of moderate to marked severity was observed in three rabbits that died from the 7 ml/kg and 10 ml/kg doses of PGME.However, other rabbits that died showed only a slight granular degeneration in the tubules.

Based on the results of this study NOAEL for male rabbits is (2.0 ml/kg) 1838 mg/kg/day and LOAEL for male rabbits is (4.0 ml/kg) 3676 mg/kg/day

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
NOAEL
1 840 mg/kg bw/day
Study duration:
subchronic
Species:
rabbit
Quality of whole database:
acceptable

Additional information

Inhalation

Rat

In a 2-week study by inhalation (not GLP) rats were exposed to PGME 5h/day 5d/week at doses of 2500, 5000 and 10000 ppm (9.4 – 18.7 – 37.5 mg/l) (Goldberg et al., 1964). Animals in the 5000 and 10,000 ppm group displayed a transient nonspecific depression of behaviour for the first several exposures, followed by rapid development of tolerance. Decreased growth rate was seen at 10,000 ppm. In this study the NOAEC was 2500 ppm for behavioural effects (acute narcotic effects) and 5000 ppm for general RDT toxicity..

In a GLP two-week study by inhalation route, PGME was administered to Fischer 344 rats (9 exposures) at doses of 0, 300, 1000 and 3000 ppm (0 - 1.1 – 3.75 – 11.2 mg/l) (Miller et al., 1981). No deaths occurred during PGME exposure. Rats in the 3000 ppm groups appeared to be anaesthetised or sedated during exposure. There were no gross pathologic observations or histopathologic changes in the liver or kidneys in all groups. Liver weights of rats in the 3000 ppm group were higher than controls.,. The NOAEC in this study was 1000 ppm based on effects seen at 3000 ppm.

In a two-week study by inhalation (9 exposure in 11 days), Fischer 344 rats were exposed to an unique 3000 ppm (11.2 mg/l) concentration of PGME (Stott, 92). A control untreated group was also included. Exposure to 3000 ppm produced sedation in male and female rats during the first week of exposure. Resolution of sedation correlated with increases in relative liver weights. Increases in the rate of hepatocellular proliferation (mitotic response) was observed after the first week in male rats. No other histopathologic changes were noted in the livers of exposed rats. Relative kidney weights of both sexes were slightly, but statistically increased, following two weeks of exposure. Kidney weight changes in males was accompanied by the deposition of alpha 2µ-globulin characteristic of male rat specific “protein droplet nephropathy”.

In a GLP 13-week study by inhalation route (performed according to OECD guideline 413) Fischer 344 rats were exposed to PGME at doses of 300, 1000 and 3000 ppm (1.1 – 3.75 – 11.2 mg/l), 6h daily and 5 d/week (Landry et al., 1983). No treatment related effects were found in animals exposed to 300 or 1000 ppm. At 3000 ppm clinical observations indicated a transient central nervous system depression, relative liver weight increased slightly concomitant with non degenerative (adaptive) histological effects. Body weight gain was slightly decreased in females. For this study the NOAEC was 1000 ppm.

In a GLP study, Fischer 344 rats were exposed by inhalation to PGME during 13 weeks 6 hours daily and 5 days/week at doses of 0 – 300 and 3000 ppm (1.1 – 11.2 mg/l) (Cieszlak et al., 1996). Exposure to 3000 ppm produced sedation in male and female rats during first week of exposure that was ameliorated by increased hepatic mixed function oxidase activity and hepatocellular proliferation which is a normal physiologic adaptation to increased metabolic demand. No sedation or adaptive hepatic effects were observed at 300 ppm. A male rat specific alpha 2µ-globulin nephropathy was observed at 3000 ppm and to a slight extent at 300 ppm. PGME produced effects at all doses in males leading to a LOAEC of 300 ppm. In females the NOAEC was 300 ppm.

In a 6 month study performed on rats by inhalation route, PGME was administered during 7h/day 5d/week (Rowe et al., 1954). A NOAEC greater than 1500 ppm was observed.

In a chronic GLP toxicity/carcinogenicity study (see section 4.1.2.8), animals were exposed 2 years at PGME concentrations of 0, 300, 1000 and 3000 ppm (0 - 1.1 – 3.75 – 11.2 mg/l) (Cieszlak et al., 1998a). PGME-induced sedation at 3000 ppm resolved in all animals during the second week of exposure in conjunction with the appearance of adaptive changes in the liver (MFO induction and hepatocellular proliferation-from previous work). MFO activities (PROD) subsequently dropped to near control values by week 52, coinciding with a return of sedation at 3000 ppm PGME. In male rats, the loss of metabolic adaptation was followed by a dose-related increase in eosinophilic foci of altered hepatocytes after two years of exposure to 1000 or 3000 ppm PGME. Kidney toxicity was observed in male rats only, which was confirmed immunohistochemically as an alpha 2µ-globin nephropathy. The 300 ppm exposure level was established as an NOAEL in rats based on liver effects.

Mouse

B6C3F1 mice were exposed to PGME by inhalation route at concentrations of 0, 300, 1000 and 3000 ppm (0 - 1.1 – 3.75 – 11.2 mg/l) 6h/day during 11 days (9 exposure) (Miller et al., 1981). This test was performed according GLP. No deaths occurred during PGME exposure. Mice in the 3000 ppm groups appeared to be anaesthetised or sedated during exposure. There were no gross pathologic observations or histopathologic changes in the liver or kidneys in all groups. All affected parameters (relative liver weight of female mice at 3000 ppm) recovered to normal levels after 6 weeks. In this study the NOAEC was 1000 ppm based on effects seen at 3000 ppm.

PGME was administered by inhalation during 2 weeks (9 exposures in 11 days) to B6C3F1 mice at doses of 0 and 3000 ppm (11.2 mg/l) 6 hours daily (Stott, 92). Exposure to 3000 ppm produced sedation in male and female mice during the first week of exposure. Resolution of sedation correlated with increases in relative liver weights. Increases in the rate of hepatocellular proliferation (mitotic response) was observed after the first week in both sexes, and after the second week of exposures in females. No other histopathologic changes were noted in the livers of exposed mice.

In a GLP study, B6C3F1 mice were exposed by inhalation to PGME during 13 weeks 6 hours daily and 5 days/week (Cieszlak et al., 1996). Two groups were evaluated in this study: a first subgroup for standard subchronic toxicity assessment and dosed with 0, 300, 1000 or 3000 ppm (0 - 1.1 – 3.75 – 11.2 mg/l) and a second subgroup evaluated for enzyme induction and cellular proliferation (dose levels: 300 and 3000 ppm). Exposure to 3000 ppm produced sedation in male and female mice during the first three days of exposure. An accelerated atrophy of the X zone of the adrenal gland of female mice was observed at 3000 ppm and to a very slight degree at 1000 ppm. A slight numerical increase in renal and hepatic cellular proliferation, significantly increased hepatic enzyme induction was observed at 3000 ppm in both sexes; increased liver weight (females only) was also observed at 3000 ppm. No effects were observed at 300 ppm. The NOAEC in this study was 1000 ppm (whichever the subgroup). Atrophy of the X-zone of the adrenal gland was described as an age related event in mice and was considered to be a non-specific, non adverse effect.

In a chronic GLP toxicity/carcinogenicity study (see section 4.1.2.8), animals were exposed 2 years at PGME concentrations of 0, 300, 1000 and 3000 ppm (0 - 1.1 – 3.75 – 11.2 mg/l) (Cieszlak et al., 1998b). A transient sedation of mice inhaling 3000 ppm PGME during the first week of exposures was observed; however, this resolved during the second week concomitant with adaptive changes in the livers of these animals (previous study results). Mice exposed to 3000 ppm had increased mortality (males), decreased in-life body weights and body weight gains relative to controls, over much of the exposure period, as well as minimal increases in absolute and relative liver weights and hepatic MFO activity. No treatment-related histopatholgical changes accompanied these liver effects, nor were histopathological changes observed in any other tissues. These data, along with the occurrence of chronic, albeit small increases in hepatocellular proliferation in mice inhaling 3000 ppm suggested minimal regenerative response in the liver, likely related to shorted life span metabolically stressed hepatocytes. Minimal decreases in body weights (average 3%) were also observed, in both sexes exposed to 1000 ppm but less consistently than in the high exposure mice. A NOAEL of 1000 ppm was established based on an increased mortality in the high dose (3000 ppm) male group that may have been related to minimal liver toxicity. Effects seen on the body weight were not taken into account because they were minimal and not accompanied with other toxicological effects.

Rabbit

In a 3-6 months inhalation study performed on rabbits, PGME was administered at doses of 800, 1500, 3000 and 6000 ppm (3 – 5.6 – 11.2 – 22.3 mg/l) 7h/day, 5d/week (Rowe et al., 1954). Toxicological effects from repeated vapour exposures were Slightly increased liver weights in females and slight histological changes of liver and lungs at 1500, 3000 and 6000 ppm (no histological changes of the liver for the only animal of the 6000 ppm group. There were no observable treatment-related effects with repeated exposure to 800 ppm. In this study, the NOAEC was 800 ppm based on effects seen at 1500 ppm.

In a 13-week study by inhalation route, rabbits were exposed to PGME by inhalation route at doses of 0, 300, 1000 and 3000 ppm (0 - 1.1 – 3.75 – 11.2 mg/l), 6 hours daily and 5d/week (Landry et al., 1983). This test was performed according to OECD guideline 413 and was GLP. No treatment related effects were found in animals exposed to 300 or 1000 ppm. At 3000 ppm clinical observations indicated a transient central nervous depression and serum alkaline phosphatase was increased. The NOAEC was 1000 ppm based on effects seen at 3000 ppm.

Guinea pig

In a six-month study by inhalation, guinea-pigs were exposed 7 h/days, 5 d/week at PGME concentration of 0, 1500 and 3000 ppm (0 – 3.75 – 11.2 mg/l) (Rowe et al., 1954). No effects were seen at the highest dose tested.

Monkey

Monkey (strains unknown) were exposed during 6 months 7h daily and 5d/week to 0, 800, 1500 and 3000 ppm (0 - 3 – 5.6 – 11.2 mg/l) of PGME (Rowe, 1957). The NOAEC was reported to be 800 ppm with a LOAEC of 1500 ppm (no more details available for this study).

Summary inhalation route :

In the majority of the studies, transient CNS depression was seen at doses of 3000 ppm leading to a NOAEL of 1000 ppm for this effect (acute effect). In rats evidence of specific male nephropathy was noticed in almost all studies, this effect is not relevant for human and will therefore not be taken into account for the risk assessment. The main toxicological effects noticed in rats were liver effects: increases in liver and relative liver weight, induction of hepatic enzyme and cellular proliferation. Concerning this effect, a NOAEC of 300 ppm (1122 mg/m3) is derived from a well performed 2-year rat study.

Dermal

In a 21 day dermal study, New Zealand White rabbits were applied daily a dose of 0 or 1000 mg/kg PGME (15 applications) (Calhoun and Johnson, 1984). Rabbits receiving 1000 mg/kg PGME showed no signs of systemic effects in various parameters including hematologic analysis and histopathology. The only treatment related effect was slight scaling and minimal inflammation with a protective thickening response of the skin. In this study the NOAEL was not determined due to the effect seen at the only dose tested.

In a 90 day dermal study, rabbits were administered PGME at doses of 0 to 10 ml/kg 5d/week (Rowe et al., 1954). Larger doses (7 to 10 ml/kg) produced narcosis which generally led to the death of the animal (8/9 deaths at 7 ml/kg, 11/11 deaths at 10 ml/kg). Repeated applications in doses of 1 to 5 ml/kg were generally without effect. Histologic examination of tissues of surviving animals were within normal limits. Slight narcosis at 3676 mg/kg (4 ml/kg) was observed. In this study a NOAEL of 2 ml/kg bw was taken regarding the effects seen at 4 ml/kg bw.

Oral

Rat

In a 35 day study by oral route, rats were administered PGME by gavage at doses of 0, 91.9, 275.7, 919 and 2757 mg/kg (Rowe et al., 1954). No mortalities were found. At 2757 mg/kg, some animals initially lost body weight, but they recovered quickly. The final body weight was not significantly different from that of controls. 2757 mg/kg produced only minor effects on liver and kidney.

In a 13 weeks oral route study, CFE rats were exposed to PGME at concentrations of 459.5, 919, 1836 and 3672 mg/kg (Stenger et al., 1972). Mild to severe central nervous system depression was observed. This caused a growth depression due to reduced feed intake. Livers were enlarged, especially at doses > 919 mg/kg. Cell necrosis was observed, mainly in the peripheral portions of the lobules. There was minor kidney injury at higher doses. In this study, no NOAEL could be identified because effects were seen at the lowest dose tested (459.5 mg/kg).

Rabbit

Three rabbits were dosed orally with 1840 mg/kg/d of PGME (BASF, 65). Only three animals were used for this study. One animal died after 9 applications. The treatment led to a slight decrease of erythrocytes and lymphocytes. PGME had no effect on the testes.

Dog

Male Dogs were feed orally with PGME at doses of 0.5; 1; 3 and 3 ml/kg/d (459.5; 919; 1836 and 3672 mg/kg) for a period of 14 weeks (5 treatments a week) (Stenger et al., 1972). Mild to severe central nervous system depression in a dose-related manner was observed. Male dogs developed numerous spermiophages in the epididymis. There were minor kidney changes at higher doses. In this study the NOAEL was found to be lower than 459.5 mg/kg based on effects seen at 459.5 mg/kg. As no data is available on purity, the relevance of spermiophages in the epididymis is unclear. As this effect was not seen in the well performed fertility studies and only in dogs in this study it can be consider to be not related to PGME.

Summary RDT oral route:

Only four studies were performed to assess the repeated dose toxicity properties of PGME by oral route. None was made according GLP and guidelines. Overall for oral route, a LOAEL of 460 mg/kg can be taken into account (from a rat and a dog study) based on slight CNS depression seen from this dose in rats and dogs (13-week study for rats and 14-week study for dogs) and a NOAEL of 919 mg/kg by oral route for systemic effects (hepatic effects).

Conclusions:

Animals exposed to PGME via inhalation and oral route have developed central nervous systems effects (sedation).

Hepatic mixed function oxidase activity and hepatocellular proliferation were increased at high doses, sometimes accompanied with mild degenerative changes or necrosis (in rare cases).

Minimal nephropathy in male rats was sometimes described with specific alpha-2-μ-globulin deposition in the kidney. Therefore, these renal effects are not relevant to humans.

By dermal route, local effects were reported at doses of about 1 g/kg (the only dose tested): scaling, minimal inflammation, and skin thickening. No systemic effects were reported at this level of dose leading to a NOAEL of 1000 mg/kg. The LOAEL for local effects was 1000 mg/kg/d.

By inhalation, a NOAEC of 300 ppm for liver effects is derived from a well performed 2-year rat study (6 h exposure for 5 days a week). Based on the molecular weight and assuming a temperature of between 20 and 25 degrees celcius, this concentration is converted to 1122 mg/m3.

By dermal route, a NOAEL of 1000 mg/kg was found for systemic effects based on a 21-day study in rabbits, however a higher NOAEL of 1840 mg/kg bw was determined in the longer 90 -day dermal study. This will be taken forward to the risk assessment. By oral route, a LOAEL of 460 mg/kg can be taken into account for CNS effects in rats and dogs (13-week study for rats and 14 -week study for dogs) and a NOAEL of 919 mg/kg by oral route for systemic effects (hepatic effects).


Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
This is the critical study for transient CNS depression effects following oral adminsitration; NOEL for systemic toxicity (not CNS) is 919 mg/kg bw

Justification for selection of repeated dose toxicity inhalation - systemic effects endpoint:
This study duration covered 2 years (longer duration as compared to a 13-week study) and was conducted in accordance with GLP and OECD guideline 453 and TSCA guideline part 798.

Justification for selection of repeated dose toxicity inhalation - local effects endpoint:
This study duration covered 2 years (longer duration as compared to a 13-week study) and was conducted in accordance with GLP and OECD guideline 453 and TSCA guideline part 798.

Justification for selection of repeated dose toxicity dermal - systemic effects endpoint:
reliable and well reported study.

Repeated dose toxicity: via oral route - systemic effects (target organ) digestive: liver; neurologic: central nervous system

Repeated dose toxicity: inhalation - systemic effects (target organ) digestive: liver

Repeated dose toxicity: dermal - systemic effects (target organ) neurologic: central nervous system

Justification for classification or non-classification

The no observed adverse effect levels for propylene glycol methyl ether exceed the values triggering classification via all routes of exposure. Therefore no classification for prolonged exposure is required.