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Toxicological information

Repeated dose toxicity: inhalation

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Administrative data

Endpoint:
sub-chronic toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Comparable to guideline study with minor deviations. The following summary of the data contained in the study named above has been created by the Lead Registrant for the purpose of this filings. The study is publicly available at the National Technical Information Service of the United States. The study was filed by the owner companies to the US Environmental Protection Agency in 1990 in accordance with the requirements of Sec. 8e of the TSCA and no confidentiality protection was claimed for the study under the procedures provided therefore by the US Environmental Protection Agency. The following summary has only been created for the purpose of this filing procedure based on the data produced in the study and has not been used before.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1990
Report Date:
1990

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)
Deviations:
yes
Remarks:
No measurements of food consumption, MCH, MCHC, percentage reticulocytes, clotting potential; no ophthalmoscopy at end; no weighing of ovaries, thyroid, uterus.
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): 1,3-dioxolane
- Physical state: liquid
- Analytical purity: 99.78-99.95%
- Lot/batch No.: lot #8313
Specific details on test material used for the study:
1,3-dioxolane was obtained from Grant Chemical Co., Baton Rouge, LA and submitted to the Analytical Laboratory, Dow Chemical Co., Michigan, MI. Test material Lot # 8313, drum 1), 99.95% purity.

Test animals

Species:
rat
Strain:
Fischer 344
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratories, Kingston, New York, USA
- Age at study initiation: 7 weeks
- Weight at study initiation: mean weights per test group 147-150 g (males) and 106-109 g (females)
- Fasting period before study: no
- Housing: group-housed (exposure took place in 4-m3 stainless steel and glass chamber under dynamic air flow conditions (800 L/min))
- Diet (e.g. ad libitum): ad libitum rodent chow except during exposure
- Water (e.g. ad libitum): ad libitum except during exposure
- Acclimation period: 3 weeks
ENVIRONMENTAL CONDITIONS
- Temperature (°C): no data (room was designed to maintain adequate temperature)
- Humidity (%): no data (room was designed to maintain adequate humidity)
- Air changes (per hr): about 12 changes per hour during exposure (no data for non-exposure)
- Photoperiod (hrs dark / hrs light): no data (room was designed to maintain adequate photocycle)
IN-LIFE DATES: Not reported in detail (study year was 1989)

Administration / exposure

Route of administration:
inhalation: vapour
Type of inhalation exposure:
whole body
Vehicle:
other: unchanged (no vehicle)
Remarks on MMAD:
MMAD / GSD: not relevant
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: 4-m3 stainless steel and glass inhalation chambers
- Method of holding animals in test chamber: group-wise, whole body exposure
- Source and rate of air: Dynamic air flow conditions.
- Method of conditioning air: no data
- System of generating particulates/aerosols: nitrogen was heated to a minimum extent necessary to volatilize the test material. Nitrogen gas was introduced into the control test chambers at a rate equal to that of the treated chambers
- Temperature, humidity, pressure in air chamber: Temperature 20-23°C, humidity 52-56%, oxygen conc. 20.1-20.6%, pressure no data.
- Air flow rate: 190 L/min
- Air change rate: about 12 times per hour
- Method of particle size determination: not relevant (exposure to gas)
- Treatment of exhaust air: no data
TEST ATMOSPHERE
- Brief description of analytical method used: daily nominal exposure concentrations were calculated based on the amount of test material used (by weighing) and the total air passed through each chamber. The analytical concentration of 1,3-dioxolane in each chamber was determined by infrared spectrometry (IR) ( 10 times or more per exposure period)
- Samples taken from breathing zone: not relevant
VEHICLE: not applicable
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Daily nominal exposure concentrations were calculated based on the amount of test material used (by weighing) and the total air passed through each chamber. The analytical concentration of 1,3-dioxolane in each chamber was determined by IR (10 times or more per exposure period)
Duration of treatment / exposure:
6 hours/day, 5 days/week, for 13 weeks
Frequency of treatment:
6 hours/day, 5 days/week, for 13 weeks
No. of animals per sex per dose:
10 males and 10 females per treatment group and the control
Details on study design:
Groups of 10 rats were exposed to targeted concentrations of 0, 300, 1000 and 3000 ppm 6 hours/day, 5 days/week, for 13 weeks. Satellite groups of 10 animals/sex/concentration were exposed at the above concentrations for 13 weeks and then allowed to recover for 8 weeks.
Positive control:
Not applicable

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily for exposure related changes
- Cage side observations checked in table were included.
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: weekly individual examination.
BODY WEIGHT: Yes
- Time schedule for examinations: prior to exposure and weekly thereafter
FOOD CONSUMPTION: no
FOOD EFFICIENCY: no
WATER CONSUMPTION: No
OPHTHALMOSCOPIC EXAMINATION: No
HAEMATOLOGY: Yes
- Time schedule for collection of blood: for the main group, during the week prior to necropsy using orbital sinus puncture; for the satellite group, during weeks 4 and 13 of exposure and weeks 4 and 8 of post-exposure; animals were not exposed on the day blood samples were collected.
- Anaesthetic used for blood collection: methoxyflurane
- Animals fasted: yes
- How many animals: all animals of each group.
- Parameters checked in table were examined: PCV, RBC, HGB, WBC, platelets, differential WBC and RBC morphology.
CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: for the main group, during the week prior to necropsy using orbital sinus puncture; for the satellite group, during weeks 4 and 13 of exposure and weeks 4 and 8 of post-exposure; animals were not exposed on the day blood samples were collected.
- Anaesthetic used for blood collection: methoxyflurane
- Animals fasted: yes
- How many animals: all animals of each group.
- Parameters checked in table were examined: BUN, creatinine, ALT, AST, AP, glucose, total protein, albumin, globulin, total bilirubin, cholesterol, triglycerides, phosphorous, calcium, sodium, potassium, chloride.
URINALYSIS: Yes
- Time schedule for collection of urine: for the main group, during the final week of exposure, and repeated prior to necropsy; for the satellite group, during weeks 4 and 8 of post-exposure.
- Metabolism cages used for collection of urine: No data
- Animals fasted: No data
- Parameters checked in table were examined: colour, appearance, bilirubin, glucose, ketone, blood, pH, protein, urobilinogen, specific gravity, microscopic examination of urine sediment.
NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: during the sixth and the last week of the study.
- Dose groups that were examined: All main study group rats
- Battery of functions tested: Functional Observational Battery consisting of pupil size, respiration, movement, skin and hair coat, salivation, lacrimation, urine staining, fecal staining, locomotor behaviour and responsiveness to touch, noise and tail pinch
Sacrifice and pathology:
GROSS PATHOLOGY: Yes; main group following the last exposure and satellite groups at the end of the 8-weeks post-exposure; weighing of liver, kidneys, adrenals, thymus, spleen, heart, lungs, testes.
HISTOPATHOLOGY: Yes; all organs and tissues of the control and high dose group; In the other dose groups liver, brain, kidney, lungs, spleen, bone were examined. From all animals bone marrow smears were obtained for counting of myeloid and erythroid cells. Morphologic evaluation of haemopoietic cells and their micro-environment in bone marrow was confined to main group rats.
Statistics:
Bartlett’s test of homogeneity (1% level) was used for evaluation of weights of body and organs, organ/body weight ratio data, clinical chemistry, bone marrow myeloid/erythroid ratio, haematology data, absolute lymphocyte and neutrophil numbers. Data were statistically compared against the control using the following statistical tests: Bartlett’s test of homogeneity (1% level); one-way analysis of variance (10% risk level), followed by a Dunnett’s test or the Wilcoxon Rank-Sum test with a Bonferroni correction for multiple comparisons (5% risk level, 2-sided).

Results and discussion

Results of examinations

Clinical signs:
effects observed, non-treatment-related
Description (incidence and severity):
red swollen eyes, perineal soiling, diarrhe and darkened crusty material around the yes and/or nares.
Mortality:
mortality observed, treatment-related
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Body weights were slightly reduced relative to controls in females exposed to 3000 ppm.
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
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
The primary effect of exposure to l,3-dioxolane was a reduction in white blood cell (WBC) counts, primarily due to decreased numbers of lymphocytes; the reductions in WBC counts were apparent in animals exposed to 1000 ppm or 3000 ppm l,3-dioxolane. There was recovery of WBC values during the 8 week post-exposure period to normal values. The reduced WBC counts were also accompanied by a slight reduction in myeloid cells of the bone marrow in 3000 ppm exposed rats, but there was no histologic indication of myeloid cytotoxicity.
Urinalysis findings:
effects observed, treatment-related
Description (incidence and severity):
Not considered biologically or toxicologically sigsnificant.
Behaviour (functional findings):
effects observed, non-treatment-related
Description (incidence and severity):
low incidence and lack of a dose-response.
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
Mean relative spleen weights were reduced in 1000 ppm (females only) and 3000 ppm exposed rats. Mean liver weights were slightly increased in 3000 ppm exposed rats.
Gross pathological findings:
no effects observed
Description (incidence and severity):
Exposure-related pathologic effects were limited to slight enlargement of centrilobular hepatocytes in 3000 ppm l,3-dioxolane exposed males at 13 weeks only. Urinary specific gravity was reduced in 3000 ppm l,3-dioxolane exposed rats, although there were no morphologic indications of nephrotoxicity.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Histopathological findings: neoplastic:
not examined
Details on results:
The targeted concentrations were 300, 1000 and 3000 ppm. The mean measured nominal concentrations were 315, 1031 and 3119 ppm, equivalent to 0.95, 3.12 and 9.45 mg/L. The analytically determined mean measured concentrations were 298, 1000 and 3010 ppm, equivalent to 0.90, 3.03 and 9.12 mg/L.
Other results are summarised in Tables 1a and 1b under “Remarks on results including tables and figures” and in Table 1c under "Overall remarks, attachments" (note: the reason for splitting the table was limitations of software of IUCLID). The changes are represented either as percentage change relative to the control (e..g -35 = 35% reduction, +10 = 10% increase) or as incidence (e.g. 3/10 represents 3 out of 10 rats). Where a dose relationship was observed, this is indicated in the last column.
Below Table 1c, a discussion of the study results is provided and the NOAEL is derived.

Effect levels

Dose descriptor:
NOAEC
Effect level:
298 ppm (analytical)
Sex:
male/female
Basis for effect level:
other: The NOAEC was based on reduced WBC and lymphocyte count and increased platelet count in males and females, and reduced spleen weights in females, all at 1000 ppm.

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

Table 1a. Results from 13-week vapour inhalation study with 1,3-dioxolane

target concentration (ppm)

0

0

300

300

1000

1000

3000

3000

DR

 

Sex

m

f

m

f

m

f

m

f

 

Mortality

none

 

Clinical signs

 

 

 

 

 

 

 

 

 

   cage side observations(A)

 

 

 

 

 

 

+

+

 

   FOB

no treatment related findings

 

Body weight

 

 

 

 

-4*(B)

 

 

-5*(C)

 

Haematology

 

 

 

 

 

 

 

 

 

   week 4 (satellite)

 

 

 

 

 

 

 

 

 

   platelets

 

 

 

+6*

+6*

+8*

+14*

+9*

M&F

   WBC

 

 

 

+19*

-23*

-15

-49*

-33*

M&F

   no. of lymphocytes

 

 

 

+20*

-25*

-17*

-55*

-39*

M&F

   week 13 (main)

 

 

 

 

 

 

 

 

 

   platelets

 

 

 

 

+10*

+9*

+34*

+24*

M&F

   WBC

 

 

 

 

 

-15*

-34*

-45*

F

   no. of lymphocytes

 

 

 

 

 

-17*

-43*

-46*

F

   no. of neutrophils

 

 

 

 

 

 

 

-42*

 

   bone marrow myeloid

 

 

 

 

 

 

-16*

-17*

 

   RBC

 

 

 

 

 

+3*

 

+4*

 

   % eosinophils(D)

 

 

 

 

 

 

+200

+100

 

   week 13 (satellite)

 

 

 

 

 

 

 

 

 

   platelets

 

 

 

 

+5*

+8*

+29*

+19*

M&F

   WBC

 

 

 

 

 

-23*

-30*

-41*

F

   no. of lymphocytes

 

 

 

 

-15*

-23*

-36*

-47*

M&F

   no. of neutrophils

 

 

 

 

 

-24*

 

-30*

F

   RBC

 

 

 

 

 

 

 

+5*

 

   % eosinophils(D)

 

 

 

 

 

 

+100

+100

 

   4-week recovery   (satellite)

 

 

 

 

 

 

 

 

 

   platelets

 

 

 

 

 

 

+9*

 

 

   WBC

 

 

-20*

 

-15*

-15*

-13*

-17*

 

   no. of lymphocytes

 

 

-20*

 

-18*

-15

-16*

-22*

 

   HGB

 

 

 

 

 

 

-3*

 

 

   HCT

 

 

 

 

 

 

-3*

 

 

   8-week recovery   (satellite)

 

 

 

 

 

 

 

 

 

   platelets

 

 

 

 

-8*

 

 

 

 

   WBC

 

 

 

 

-16*

 

-14*

 

 

   no. of lymphocytes

 

 

 

 

-16*

 

-10

 

 

   RBC

 

 

 

 

 

 

-3*

 

 

   HCT

 

 

 

 

 

 

-3*

 

 

   bone marrow myeloid

no treatment related findings

 

DR          dose related

FOB       Functional Obsevational Battery

*              Statistically significant difference from control at 5% level or below

+             Clinical signs were observed

(A)          Clinical signs observed were decreased alertness and responsiveness at the end of each exposure. Animals appeared to be fully recovered about 30 minutes after cessation of exposure.

(B)          On day 31 only, considered unrelated to treatment (no time and dose relationship).

(C)          Statistically significant reduction of 4-5% on days 5-31 and day 67.

(D)          The percentage change (100-200%) represented absolute values of 2-3%, relative to a control value of 1%.

 

Table 1b. Results from 13 -week vapour inhalation study with 1,3 -dioxolane (ctd.)

target concentration (ppm)

0

0

300

300

1000

1000

3000

3000

DR

 

Sex

m

f

m

f

m

f

m

f

 

Clinical chemistry

 

 

 

 

 

 

 

 

 

   week 4 (satellite)

 

 

 

 

 

 

 

 

 

   ALT

 

 

 

 

 

 

+12*

+26*

 

   AP

 

 

 

 

 

 

-10*

-13*

 

   AST

 

 

-13*

 

 

 

 

 

 

   triglycerides

 

 

 

 

 

 

-37*

-22*

 

   glucose

 

 

+10*

 

 

 

 

 

 

   week 13 (main)

 

 

 

 

 

 

 

 

 

   BUN

 

 

 

 

 

 

+21*

 

 

   ALT

 

 

 

 

 

 

+11*

+64*

 

   AP

 

 

 

 

 

 

-9*

 

 

   glucose

 

 

 

+14*

 

+16*

 

+18*

 

   total protein

 

 

 

 

 

+6*

+4*

+6*

 

   albumin

 

 

 

 

 

+5*

 

+5*

 

   cholesterol

 

 

 

 

 

 

+15*

 

 

   triglycerides

 

 

 

 

-24*

 

-23*

 

 

   calcium

 

 

 

+4*

 

+5*

 

+5*

 

   phosphate

 

 

 

-9*

+9*

 

+12*

 

 

   sodium

 

 

 

 

+2*

+3*

+3*

+3*

 

   potassium

 

 

 

 

 

 

 

+11*

 

   chloride

 

 

 

+2*

 

+3*

 

 

 

   4-week recovery   (satellite)

 

 

 

 

 

 

 

 

 

   AST

 

 

-22*

 

 

 

 

 

 

   cholesterol

 

 

 

 

 

 

+10*

 

 

   8-week recovery   (satellite)

no treatment related findings

 

DR          dose related

*              Statistically significant difference from control at 5% level or below

Applicant's summary and conclusion

Conclusions:
Based on reduced WBC and lymphocyte count and increased platelet count in males and females, and reduced spleen weights in females, all at 1000 ppm, the NOAEC is 300 ppm target concentration equivalent to 298 ppm mean measured concentration, equivalent to 0.90 mg/L. Based on a respiration rate of 6 L/h and a 6-h exposure time, 0.90 mg/L corresponds with an inhalation exposure of 32 mg/day. The mean body weight of males at 298 ppm (main group) was 239 g, and that of females 157 g. For males and females, respectively, the concentration of 0.90 mg/L is equivalent to an inhaled dose of 135 and 205 mg/kg bw/day.
Executive summary:

A 13-week repeated dose inhalation toxicity study on 1,3-dioxolane was performed essentially according to OECD 413 (2009) in Fischer 344 rats at targeted concentrations of 300, 1000 and 3000 ppm (10 males and 10 females per dose, exposure for 6 hours per day, 5 days per week, for a total of 13 weeks). A satellite group of 10 animals/sex/concentration was exposed at the above concentrations for 13 weeks and then allowed to recover for 8 weeks. The nominal exposure concentrations were determined by dividing the amount of test material delivered (determined by weighing before and after exposure) by the total air flow though the chamber during exposure. In addition, the concentrations of 1,3-dioxolane were determined at least 10 daily samples by IR spectroscopy. The mean measured nominal concentrations were 315, 1031 and 3119 ppm, equivalent to 0.95, 3.12 and 9.45 mg/L. The analytically determined mean measured concentrations were 298, 1000 and 3010 ppm, equivalent to 0.90, 3.03 and 9.12 mg/L. Observations on toxicological signs were made daily and a detailed physical assessment once weekly. A neurobehavioural examination was made during the sixth and the last week of the study. Body weights were measured pretest and weekly thereafter. Haematology and clinical chemistry was performed on blood collected from the main group animals during the week prior to necropsy, and from the satellite group animals during weeks 4 and 13 of exposure and weeks 4 and 8 of post-exposure. Urinalysis was performed on samples collected from the main group during the final week of exposure and prior to necropsy, and from the satellite group during weeks 4 and 8 of post-exposure. Necropsy was performed on all animals at termination . Organ weights of liver, kidneys, adrenals, thymus, spleen, heart, lungs and testes were measured at sacrifice. Histopathology was performed on all organs and tissues of the control and high dose group, and on liver, brain, kidney, lungs, spleen, bone marrow and gross lesions of the lower exposure groups. Bone marrow smears from all animals were prepared for counting of myeloid and erythroid cells, and morphologic evaluation of haemopoietic cells and their micro-environment was perfomed on bone marrow from main group rats.

All animals survived the treatment. The primary effect obseved was reduced WBC count in males and females at 1000 and 3000 ppm, primarily due to reduced numbers of lymphocytes, and in females also accompanied by reduced numbers of neutrophils. At the highest dose, this finding was accompanied by a slight reduction of the number of myeloid cells in the bone marrow, but there was no microscopic evidence of bone marrow pathology or pathology of the lymphoid organs. Full recovery of WBC counts at 8 weeks after the end of exposure occurred in females but not in males. Slight liver toxicity (slight enlargement of centrilobular hepatocytes) was observed in males at 3000 ppm, and accompanied by clinical chemistry findings (increased ALT, reduced AP). Increased ALT and reduced AP values were also found in females at 3000 ppm, but they were not accompanied by microscopic evidence of pathology. However, absolute and relative liver weights of both males and females were increased at 3000 ppm. Slightly elevated cholesterol levels in males at 3000 ppm after 13 weeks and after 4 weeks of recovery, and reduced triglyceride levels in males and females after 4 weeks and in males after 13 weeks may also be indicators of slight liver toxicity. The following findings were also considered to be treatment related: increased eosinophils in males and females at 3000 ppm after 13 weeks; slightly reduced body weights in females at 3000 ppm; decreased alertness and responsiveness in males and females at 3000 ppm at the end of each exposure; increased platelet counts in males and females at 1000 and 3000 ppm (platelet counts had returned to normal after 8 weeks of recovery); reduced absolute and relative spleen weights of females at 1000 and 3000 ppm and reduced relative spleen weights of males at 3000 ppm. This finding may be associated with reduced WBC counts, although there was no morphologic evidence of toxicity to the spleen.

Based on reduced WBC and lymphocyte count and increased platelet count in males and females, and reduced spleen weights in females, all at 1000 ppm, the NOAEC is 300 ppm target concentration equivalent to 298 ppm mean measured concentration, equivalent to 0.90 mg/L. Based on a respiration rate of 6 L/h and a 6-h exposure time, 0.90 mg/L corresponds with an inhalation exposure of 32 mg/day. The mean body weight of males at 298 ppm (main group) was 239 g, and that of females 157 g. For males and females, respectively, the concentration of 0.90 mg/L is equivalent to an inhaled dose of 135 and 205 mg/kg bw/day.