Butyl 2,3-epoxypropyl ether

Endpoint summary

Description of key information

The 10 -week NOAEC for repeated dose inhalation toxicity was determined to be 0.2 mg/L based on severe pneumonia and slight patchy atrophy of the testis.

The 28 -day NOAEC for repeated dose inhalation toxicity was determined to be 0.1 mg/L based on observed degeneration of the olfactory mucosa and hyperplastic/metaplastic changes of the ciliated respiratory epithelium.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Reason / purpose for cross-reference:

reference to same study

Principles of method if other than guideline:

To evaluate the inhalation repeated dose toxicity of the test substance male rats were exposed to 50 7-hour exposures to 4 different vapour concentrations.

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

not specified

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Diablo Laboratories
- Weight at study initiation: 57 - 97 gram before acclimatization, at the start of experiment 90 -120 gram.
- Housing: Two to a cage
- Diet: Standard green feed from Simonsen Laboratories,
- Acclimation period: 2 weeks

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

air

Details on inhalation exposure:

The exposures were made in metal chambers, 200 litres in capacity, and the air flow ranged from 10 to 20 litres per minute, depending on the vapour concentration used. The constant metering device delivered the compound to the evaporator where it was vaporized in the air entering the chamber.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The vapour concentrations were monitored at intervals ranging from twice daily to once weekly, by analysis of air drawn from the sampling port of each chamber. The vapour was absorbed from the air in pyridine, and reacted with pyridinium chloride; the amount of acid consumed was then measured.

Duration of treatment / exposure:

7 hours

Frequency of treatment:

daily except weekends

Dose / conc.:

38 ppm (nominal)

Dose / conc.:

75 ppm (nominal)

Dose / conc.:

150 ppm (nominal)

Dose / conc.:

300 ppm (nominal)

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Observations and examinations performed and frequency:

The animals were observed at intervals during exposure as well as before and after placement in the chamber, for signs of toxicity or aberrations from normal behaviour. They were weighed once weekly.

Sacrifice and pathology:

At the end of the experimental period the survivors were decapitated under light ether anaesthesia for necropsy. After thorough gross inspection, the lungs, livers, and kidneys of all animals were freed of connective tissue blotted lightly to remove excess moisture and weighted for calculation of organ/bodyweight ratios. Sections of these tissues were preserved for microscopic examination. Sections were also preserved from alternate animals of brain, thyroid, thymus, heart, stomach, intestine, pancreas, adrenal, testis, seminal vesicles, and urinary bladder.
Microscopic examination was made of the tissues of 10 animals in each group, with the exceptions of those exposed to 300 ppm, only five of which survived 50 exposures. Tissues of one animal in this group that died after 40 exposures were included.

Statistics:

Organ/body weight rations and percentage weight gains were statistically compared by the Student t-test.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Animals in the 300 ppm group developed an emaciated appearance, and were ill-kempt in appearance, but showed no overt signs of toxicity. At 150 ppm, surviving animals were without further signs of toxicity except that weight gain was retarded.

Mortality:

mortality observed, treatment-related

Description (incidence):

At 300 ppm, there were 5 deaths, all occurring between the twentieth and thirty-fifth exposures. At the level of 150 ppm, there was one death after 20 exposures. At 38 and 27 ppm, there were no deaths.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

A decrease in bodyweight gain was significant (p=0.05) in the 300 ppm group and in the 150 ppm groups. At lower doses there was no significance.

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:

not examined

Haematological findings:

not examined

Clinical biochemistry 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):

The only significant difference in organ/body weight ratios occurred in the kidneys and lungs of rats in the 300 ppm group, which were heavier than those of the control group (p=0.05). The record of the organ weights for the 75 ppm group was lost in a laboratory accident, but it may be assumed that there were no differences, since there were none at 150 ppm.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

There were few findings at necropsy, other than general decrease in body fat. One rat exposed to 150 ppm had tan discoloration of the thymus, and 2 others had small areas of atelectasis in the lung. One rat exposed to 300 ppm had a consolidated lobe in the lung; one had atelectasis of a lobe; another had very small testes; and another a brown discoloration of the thymus. No abnormalities were seen in the other exposure groups.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Atelectasis was the most common finding, appearing in the lungs of 4 controls and 18 of 35 experimental animals. Lung congestion was noted in 2 controls and 4 experimental animals. These lesions would not appear to be related to the treatment. There were no other findings among controls or animals exposed to 39 ppm.
One animal exposed to 75 ppm had severe pneumonia and slight patchy atrophy of the testis. Five animals exposed to 150 ppm had bronchopneumonia. Three of the five survivors in the 300 ppm group had pneumonia; two of these had atrophic testes, and one had also focal liver necrosis. Both the other animals had atrophic testes and atelectasis of the lungs, and one had focal liver necrosis.
The rat that died after 40 exposures had testicular atrophy, and pneumonia with a foreign-body reaction.

Histopathological findings: neoplastic:

no effects observed

Other effects:

not specified

Key result

Dose descriptor:

NOAEC

Effect level:

38 ppm (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

histopathology: non-neoplastic

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

200 mg/m³

Study duration:

subchronic

Species:

rat

Organ:

lungs

testes

Repeated dose toxicity: inhalation - local effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)

GLP compliance:

no

Limit test:

no

Specific details on test material used for the study:

Name used in report: TK-10408 (Butyl glycidyl ether)

Species:

rat

Strain:

other: C-G TIF:RAIF

Sex:

male/female

Route of administration:

inhalation: vapour

Type of inhalation exposure:

nose only

Vehicle:

air

Details on inhalation exposure:

The three concentrations of the test substance were generated using three separate vapour generators each connected to a separate nose-only exposure chamber. The nose-only exposure chambers were of the Battelle flow-past design (Cannon et al., 1984). The vapour generation system used 500 mL fritted bubbler wash bottles containing the test substance through which air was passed. The airflows were measured using rotameters calibrated against primary standards. After the bubblers, additional dilution air was added, to produce the required concentrations of the test substance in air.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The primary calibration of the concentration of the vapour to which the animals were exposed was performed using a Hewlett-Packard model S700A gas chromatograph (GC) using an automated gas injection loop. This mode of GC operation involves passing the atmosphere to be sampled through a loop of known volume. Analysis was performed by quickly switching the sampling loop into the GC column at the point of entry of the carrier gas.
The gas chromatograph was equipped with a flame ionization detector. The column used was 10 ft by 1/8 in stainless steel packed with 10% FFAP (Carbowax 20M-2 nitroterephthalic acid reaction product) on 80/100 mesh, and acid washed DMCS (dimethylchlorosilane) Chromosorb W. An electronic integrator was used for measuring area under the peak.
At the high exposure concentrations (> 5 mg/I) initially thought necessary for this study this method of calibration was used for day to day sampling. However, with the considerably lower concentrations that were actually used this method was not ideal due to the very small amounts of butyl glycidyl ether that would have to be injected using a microliter syringe.Therefore, a more precise determination of the exposure concentrations was made by measuring the weight difference of the test substance in the vaporizer before and after the exposure (weight differential method). To confirm the concentrations by the weight differential method, we measured the concentration in the chamber air with the calibrated gas chromatograph. These data were used to validate our weight differential method of determining concentration.
During the study the exposure conditions were monitored in two ways: 1) Determination of the exposure concentration by the weight differential method which had been validated as described above and 2) each 20 minutes during the exposure, the concentration in one chamber was measured as well as the sequentially low, medium and high dose. These data were used as a rough estimate of exposure concentration homogeneity because the gas chromatograph was not calibrated during the exposure with known quantities of the test substance. When comparisons were made between the weight differential method and the calibrated gas chromatograph method, the results of the weight differential method were within 2% of the results of calibrated gas chromatographic method.

Duration of treatment / exposure:

28 days

Frequency of treatment:

Daily

Dose / conc.:

0.1 mg/L air (nominal)

Dose / conc.:

0.5 mg/L air (nominal)

Dose / conc.:

1 mg/L air (nominal)

No. of animals per sex per dose:

Main study: 10
Reversibility study: 5 (only controls and high dose)

Control animals:

yes, concurrent vehicle

Details on study design:

RANGE-FINDING STUDY
Prior to the start-up of the 28-day inhalation study a range-finding study was performed as an aid to establishing the concentrations for the 28-day study. Groups of 2 males and 2 females were exposed to the test substances at doses of 11, 17, 23, and 28 mg/L air. The respirable atmospheres for this pretest were produced using a Hospitek Nebulizer operated at an air pressure of 1 at., and with a flow rate of 9 L of air per min. This aerosol was diluted to obtain the desired test concentration. The mortalities in these exposures exhibited lung congestion and consolidation. The LC50 was determined to be 14 mg/Lair with the 95% confidence limits of 10-20 mg/L air.
Based on a four hour vapor only exposure made at 3.5 mg/litre air, where the animals were estimated to be still too stressed to stand repeated 6 hour exposures, the test concentrations were chosen for the 28-day study.
A reversibility study with the high dose and control groups was included.

Positive control:

no

Observations and examinations performed and frequency:

The general health and behaviour of the animals was observed on each exposure day during the study.

BODY WEIGHT: Yes, daily

HAEMATOLOGY: Yes, hemaglobin, mean cell volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, white blood cell differential count, volume oxygen, methemoglobin, carboxyhemoglobin, oxyhemoglobin, prothrombin time.

CLINICAL CHEMISTRY: Yes, glucose, aspartate transferase

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
Necropsies were performed after sacrificing the animals under ether anesthesia and the following organs were collected in 10% buffered formalin:
nose, larynx, esophagus, trachea, lungs, liver, kidneys, adrenal glands, stomach, small intestine, large intestine, pancreas, urinary bladder, thymus, lymph nodes, salivary glands, lacrimal glands, femur with joint, sternum and ribs, bone marrow, skeletal muscle, spinal cord, sciatic nerve, skin, testes/ovaries, thyroid gland, mammary gland, uterus, vagina, spleen. Before fixation, the lungs, liver, kidneys, brain, testes/ovaries, adrenal glands, heart, thyroid gland and thymus were weighed.
In order to obtain a standard degree of alveolar expansion, lungs were inflated with fixative through the lower part of the trachea under a pressure of 25 cm of water. All organs from the animals in the control and high dose groups were embedded in paraplast in pre-labelled cassettes and 5 micron sections were made. In animals from the low dose and medium dose groups this preparation was restricted to the nasal passages which were the only organs to show treatment-related changes at the high dose level.
Nasal passages were sectioned at three levels in order to observe different types of epithelia (respiratory and olfactory); the larynx was sectioned transversally just anterior to the ventral saccule. Transverse and longitudinal sections of the trachea were prepared and the left lung lobe was sectioned longitudinally at the level of the main-stem bronchus. All other organs were sectioned routinely, with a maximum of 3-4 organs per slide. Tissue sections were stained with haemalum-phloxin-saffron trichromic stain, microscopically observed and the resulting pathologic data collected directly using the Xybion Path/Tax computer program.

Clinical signs:

no effects observed

Description (incidence and severity):

There were no observations made which indicated that the animals were negatively affected by the treatment. All animals were reported "normal, no remarkable findings" during the entire study.

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The body weights of the male animals in the high dose level group were significantly decreased compared with controls after the second week of exposure.
There was also some decrease in the body weights of female rats in the high dose level group but this was less apparent than in the males and was not consistently significantly different from control animals.

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:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

Haemoglobin: There was a small but statistically significant increase in haemoglobin in male animals exposed to the high dose of the test substance (control = 16.08; high dose = 16.9 g/100 mL blood). In addition, at the end of the reversibility phase, the reversibility high dose group showed a decrease in haemoglobin with respect to the study high dose group (rev. high dose = 15.9; study high dose = 16.9 g/100 mL blood). This is interpreted as a reversible treatment related change.
Indices: The mean cell volume (MeV) was slightly but statistically significantly increased in medium and high dose females (control = 88 µ; high dose = 90.0 µ; medium dose = 31 µ). Some changes were also seen in the reversibility groups. This small increase has no biological significance and is purely related to the homogeneity of the data. There was a decrease in mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) (rev. high dose:: 31.4; high dose = 34.0 µg/µm³) in reversibility high dose males when compared to study high dose (res. high dose = 28.8; high dose = 31 µg). These changes may reflect the return to normal of haematological parameters after mild toxic effects of treatment with the test substances for 28 days. There were no other changes in the haematological data which seemed of biological significance.
White Blood Cell Differential Count: In male animals the lymphocytes were significantly increased in the low and medium dose groups and increased, but not significantly, in the high dose group. No significant differences were observed between controls and treated animals in the male reversibility groups or in any of the female groups. No other changes were observed in the differential WBC analysis.
IL - co-oximeter: There were no changes seen which were of biological consequence in the parameters measured in this section. These included Volume % oxygen (Vol % O2 ), Methemoglobin (Methb), Carboxyhemoglobin (COHb). Oxyhemoglobin (02Hb), and Prothrombin Time (PTME).

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Glucose: There was a statistically significant decrease in fasting glucose in the high dose males reversibility group when compared to reversibility control (control: 5.3± 0.9, mean: standard deviation; rev. controls 4.67± 0.18 mM/L). Even though not statistically significant, the high dose males had on the average about one millimole/litre less fasting glucose than the controls. No histopathological changes were seen in the pancreas.
Aspartate Transferase (AST): Both male and female high dose level animals show elevated AST levels (male Controls = 58.4, high dose male = 70.8; female controls = 59.4; high dose female = 77.0 IU/L). Only the females have statistically significant changes. These changes without concomitant changes in alanine transferase might be suggestive of heart, kidney or pancreatic damage. No other data in this study suggest changes in heart or kidney. Some small decrease was seen in the male high dose reversibility groups in fasting glucose levels possibly implicating the pancreas. There are slight non-significant increases in alanine transferase in the high dose males and females which might become significant upon further treatment. No haemolysis of blood samples was noted in the samples used for these determinations. No other changes were seen in the blood chemistry determinations.

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):

There are no statistical differences between groups for absolute organ weights. The organ to body weight ratio indicates a statistically significant increase for brain/body weight in high dose males reflecting the lower body weight in these animals (see also clinical observations) .
The organ weight/brain weight ratio shows a statistically significant difference between groups only in high dose females where a decreased liver/brain ratio is noted. However, no microscopic changes were observed in the liver.

Gross pathological findings:

no effects observed

Description (incidence and severity):

No gross pathological findings were observed at necropsy.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

The only histopathological changes found during the microscopic evaluation which can be related to the treatment by inhalation with the test substance were observed in the nasal cavity. Two types of changes, both dose-related, were observed; a degeneration of the olfactory mucosa and hyperplastic/metaplastic changes of the ciliated respiratory epithelium.
The degeneration of the neuro-epithelium of the olfactory mucosa affected all animals from high and medium dose groups. The severity of the lesions, scored on a 0 to 5 scale, was found to be more marked in the high dose than in the medium dose. Males appeared to be slightly more affected than females. In one animal the olfactory epithelium degeneration was accompanied by a squamous metaplasia of the olfactory mucosa. After the reversibility period the frequency and severity of the olfactory epithelium degeneration in the high dose group were reduced, indicating that the changes are reversible. Animals from the low dose group did not show the olfactory epithelium degeneration. No other lesions related to the treatment by inhalation with the test substance at the doses defined above, were observed in the other parts of the respiratory tract (larynx, trachea, lung) or in the other organs microscopically examined.

Histopathological findings: neoplastic:

effects observed, treatment-related

Description (incidence and severity):

The hyperplastic and metaplastic changes of the ciliated respiratory epithelium lining the nasal septum and the antero-turbinates were also dose-dependent and mostly restricted to the high dose and medium dose animals. After the reversibility period these changes were no longer observed in the high dose group. It should be noted that the olfactory epithelial degeneration is more marked than the hyperplastic changes of the respiratory epithelium. This suggests that the olfactory epithelium is a more specific target organ than the respiratory epithelium for the test substance when administered by inhalation.
No other lesions related to the treatment by inhalation with the test substance at the doses defined above, were observed in the other parts of the respiratory tract (larynx, trachea, lung) or in the other organs microscopically examined.

Other effects:

not specified

Key result

Dose descriptor:

NOAEC

Effect level:

0.1 mg/L air (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

histopathology: neoplastic

histopathology: non-neoplastic

Critical effects observed:

yes

Lowest effective dose / conc.:

0.5 mg/L air (nominal)

System:

respiratory system: upper respiratory tract

Organ:

nasal cavity

other: olfactory mucosa and ciliated respiratory epithelium

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

yes

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

100 mg/m³

Study duration:

subacute

Species:

rat

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Repeated dose inhalation:
To evaluate the inhalation repeated dose toxicity of the test substance male rats were exposed (whole body) to fifty 7-hour exposures to 4 different vapor concentrations (38, 75, 150, or 300 ppm) (US EPA, 1957). The vapor concentrations were monitored at intervals ranging from twice daily to once weekly, by analysis of air drawn from the sampling port of each chamber. The vapor was absorbed from the air in pyridine, and reacted with pyridinium chloride; the amount of acid consumed was then measured. At 300 ppm, there were 5 deaths, all occurring between the twentieth and thirty-fifth exposures. At the level of 150 ppm, there was one death after 20 exposures. At 38 and 27 ppm, there were no deaths. A decrease in bodyweight gain was significant (p=0.05) in the 300 ppm group as well as in the 150 ppm groups. At lower doses there was no significant effect on bodyweight (gain) observed. At 150 ppm, surviving animals were without further signs of toxicity except that weight gain was retarded. The only significant difference in organ/body weight ratios occurred in the kidneys and lungs of rats in the 300 ppm group, which were heavier than those of the control group (p=0.05). The record of the organ weights for the 75 ppm group was lost in a laboratory accident, but it may be assumed that there were no differences, since there were none at 150 ppm. There were few gross pathological findings at necropsy, other than general decrease in body fat. One rat exposed to 150 ppm had tan discoloration of the thymus, and 2 others had small areas of atelectasis in the lung. One rat exposed to 300 ppm had a consolidated lobe in the lung.; one had atelectasis of a lobe; another had very small testes; and another a brown discoloration of the thymus. No abnormalities were seen in the other exposure groups. Atelectasis was the most common histopathological finding, appearing in the lungs of 4 controls and 18 of 35 experimental animals. Lung congestion was noted in 2 controls and 4 experimental animals. These lesions would not appear to be related to the treatment. There were no other findings among controls or animals exposed to 39 ppm. One animal exposed to 75 ppm had severe pneumonia and slight patchy atrophy of the testis. Five animals exposed to 150 ppm had bronchopneumonia. Three of the five survivors in the 300 ppm group had pneumonia; two of these had atrophic testes, and one had also focal liver necrosis. Both the other animals had atrophic testes and atelectasis of the lungs, and one had fecal liver necrosis. Based on the effects seen in the rat exposed to 75 ppm showing severe pneumonia and slight patchy atrophy of the testis the NOAEC was determined to be 38 ppm (0.20 mg/L).

In a study (US EPA, 1985) performed similar to OECD guideline 412, 10 rats per sex per dose were exposed (vapor, nose only) to three concentrations of the test substance. A small number of animals were used to estimate the LC50 in rats following a 4-hour exposure. This concentration was found to be 14 mg/L air with the 95% confidence limits of 10-20 mg/L air. Using the results of this experiment, 1 mg/L, 0.5 mg/L and 0.1 mg/L were chosen as the high, medium and low doses, respectively, for the 28-day exposure of 6 hours per day, 5 days per week. A reversibility group of 5 animals per sex in the control group and 5 in the high dose group was also included. The exposure concentrations were measured using a gas chromatographic calibrated weight differential method. The actual mean exposure concentrations for the experiment were: high dose = 1.013± 0.158 mg/L; medium dose = 0.470±0.040 mg/L; low dose = 0.084 ± 0.016 mg/L. The exposures resulted in decreased body weights in the high dose groups, changes in fasting glucose in the high dose reversibility group, elevated aspartate transferase levels in serum of high dose males and slightly increased haemoglobin in high dose male animals which was reversible. Some changes were also seen in the blood lymphocytes. Histopathological examination revealed a degeneration of the olfactory mucosa and hyperplastic/metaplastic changes of the ciliated respiratory epithelium, both changes were more apparent in males than in females. These changes were present in the high and medium dose groups but not in the low dose group. Based on the later effects observed, the NOAEC was determined to be 0.1 mg/L.

Justification for classification or non-classification

Based on the results obtained from the repeated dose inhalation studies, the test substance does not fulfil the criteria for classification as STOT RE in accordance with EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.