Registration Dossier

Administrative data

Description of key information

Oral route:
The NOEL for NDC is >50,000 ppm (>3000 mg/kg b.w./day) NDC in the diet (IIT Research Institute, 1990).
Inhalation route:
The NOAEC for NDC is >10.02 mg/m3 (IIT Research Institute, 1988).
Dermal route:
Based upon low human exposure potential and available study data, this endpoint is being waived.

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:
key study
Study period:
April to July 1989
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study run to a method comparable with current guidelines and to GLP
Qualifier:
according to guideline
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)
Deviations:
no
GLP compliance:
yes
Limit test:
no
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Portage, M
- Age at study initiation: approximately 4 weeks of age
- Housing: The rats were individually housed in stainless steel cages measuring 24.0 x 17.8 x 17.6 cm during the quarantine, feeding and recovery periods. The cages were suspended over excrement pans fitted with deotized cage boards.
- Diet (e.g. ad libitum): Certified Ground Purina Rodent Chow 5002 was provided ad libitum.
- Water (e.g. ad libitum): Water supplied from a reverse-osmosis (RO) purifier by an automatic watering system was provided ad libitum.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): approximately 22°C
- Humidity (%): 40-70%
- Photoperiod (hrs dark / hrs light): Fluorescent lighting was provided for 12 hours followed by 12 hours of darkness.

No additional data
Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on oral exposure:
DIET PREPARATION
- Mixing appropriate amounts with (Type of food): All three levels of test diet were obtained by first preparing a premix (100,000 ppm) and then diluting aliquots of the premix with control feed to achieve the desired concentration of test diet. The premix and all diets were mixed using a 16-quart (11 kg) capacity Patterson-Kelly V-blender containing a high speed intensifier bar.
- Storage temperature of food: Diets were stored in sealed plastic bags inside plastic bins at room temperature prior to and during use.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The samples were analyzed using a Varian 5560 High Performance Liquid Chromatograph (HPLC) with a UV200 detector and a Varian 402 Data Station, which was calibrated against a standard calibration curve covering the range of concentrations expected in the sample analyses. The HPLC conditions were as follows:
Column: Vydac, C18, 201TP, 4.6 mm diameter x 250 mm length, 5 μm particle size
Mobile Phase: Methanol:Water (75:25)
Injection Volume: 10 μL sample loop, filled with 2.5 times volume (i.e., 25 μL injection)
Flow: 1.5 mL/min
Retention Time: approximately 4.5 minutes
Zero Offset: 5%
Chart Speed: 0.5 cm/mm
Stop Time: 8.0 minutes
Plot Attenuation: 32
Detector: Varian UV 200 at 348 nm
Time Constant: 0.5 seconds
Absorbance Range: 0.05 au/mv
Duration of treatment / exposure:
13 weeks
Remarks:
Doses / Concentrations:
120 mg/kg (2,000 ppm), 600 mg/kg (10,000 ppm) and 3,000 mg/kg (50,000 ppm)
Basis:
nominal in diet
No. of animals per sex per dose:
20/sex/group
Control animals:
yes, plain diet
Details on study design:
- Dose selection rationale: The dose levels used in this study were selected on the basis of results obtained from a two-week dose range-finding/palatability study in which two rats of each sex were fed diets containing DM-2,6-NDC at levels of 0, 100, 1000, 2500, 5000, 10,000, 25,000 and 50,000 ppm (the maximum allowable concentration of DM-2,6-NDC for a feeding study) for two weeks. No change in body weight or food consumption was seen in any animal at the 50,000 ppm (5%) level, thus 50,000 ppm was selected as the highest feeding level for the 90-day study.
Positive control:
None stated
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Rats were observed once daily for morbidity and mortality during the 3-week quarantine period. Following initiation of feeding, all rats were observed twice daily on weekdays and once daily on weekends and holidays.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Physical examinations for adverse clinical symptoms were performed on each animal once prior to study initiation to ensure suitability for use as a test animal and daily during the 13-week feeding period. Recovery rats were examined daily during the recovery period.

BODY WEIGHT: Yes
- Time schedule for examinations: Body weights were measured prior to initiation of the study, weekly during the feeding period and at the termination of the study immediately prior to sacrifice (fasted weight).

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No data

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No data

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No data

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: prior to initiation of the study and after 13 weeks of feeding
- Dose groups that were examined: 2000, 10000 and 50000 ppm

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at their scheduled time of sacrifice
- Anaesthetic used for blood collection: Yes (sodium pentobarbital)
- Animals fasted: Yes
- How many animals: 160

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at their scheduled time of sacrifice
- Animals fasted: Yes
- How many animals: 160

URINALYSIS: Yes
- Time schedule for collection of urine: at the end of the 13-week feeding period
- Metabolism cages used for collection of urine: No data
- Animals fasted: Yes

NEUROBEHAVIOURAL EXAMINATION: No data
Sacrifice and pathology:
GROSS PATHOLOGY: Yes. Necropsies were performed on all rats and the following tissues were collected and fixed in 10% neutral buffered formalin: adrenals, brain, epididymides, eyes, esophagus, femur and bone marrow (smear), gonads, heart, duodenum, jejunum, ileum, cecum, colon, rectum, kidneys, liver, lungs, lymph nodes (mandibular, mediastinal and mesenteric), mammary gland, nasal turbinates, exorbital lachrymal glands, Harderian glands, pancreas, parathyroids, aorta, pituitary, prostate and seminal vesicles, salivary glands, sciatic nerve, skeletal muscle, skin, spinal cord, spleen, sternum (bone marrow), stomach, thymus, thyroid, tongue, trachea, urinary bladder, uterus, vagina, gross lesions and ear with attached tag. The adrenal glands, brain, gonads, heart, kidneys, liver and spleen were weighed at necropsy and the organ weights relative to body weights were calculated.

HISTOPATHOLOGY: Yes. Microscopic examination was performed on the complete set of collected tissues (with the exception of the femur, ear, nasal turbinates, exorbital lachyrmal glands and Harderian glands) from the control and high dose (50,000 ppm) animals sacrificed at the end of the 13-week feeding period. In addition, the lungs, liver, kidneys and gross lesions from the low and medium dose animals sacrificed after 13 weeks were also examined microscopically.
Other examinations:
None stated
Statistics:
None stated
Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
not specified
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 specified
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:
not specified
Details on results:
CLINICAL SIGNS AND MORTALITY
No signs of DM-2,6-NDC-related toxicity were seen in any animal during the 13-week feeding period. None of the rats died during the 13-week feeding or 4-week recovery periods.

BODY WEIGHT AND WEIGHT GAIN
No statistically significant differences in mean body weight, cumulative body weight gain or food consumption were noted among the treated and control groups during the 13-week feeding period.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)
Food consumption data for all males and 6 of 10 females in the 2,000 ppm group was not available during the first week of the recovery period due to a technician error.
No statistically significant differences in food consumption were noted among the treated and control groups during the 13-week feeding period.

OPHTHALMOSCOPIC EXAMINATION
No ocular manifestations of a toxic nature could be attributed to feeding of DM-2,6-NDC.

HAEMATOLOGY
No statistically significant differences were noted between any DM-2,6-NDC-treated group and the respective control group for any of the hematology or differential white blood cell parameters examined after 13 weeks of feeding and/or 4 weeks of recovery.

CLINICAL CHEMISTRY
No statistically significant differences were noted between any treatment group and the respective control group for any of the parameters examined after 13 weeks of feeding, with the exception of significantly decreased BUN in the 50,000 ppm females. Since the BUN level was decreased rather than increased, as would be expected in cases of renal toxicity, the decrease in these animals was not considered toxicologically significant. Creatine kinase activity was significantly decreased in the low and high dose recovery females, however, decreased enzyme activity has no toxicologic significance.

URINALYSIS
No effects related to administration of DM-2,6-NDC were noted on any of the parameters examined after 13 weeks of feeding.

ORGAN WEIGHTS
No statistically significant differences in either the absolute or relative weight of any organ were noted between the groups fed DM-2,6-NDC and the respective control group after 13 weeks of feeding

GROSS PATHOLOGY
The most common gross lesions seen in animals sacrificed after the 13-week feeding and/or 4-week recovery periods included red and/or enlarged mandibular lymph nodes, lung foci and urinary bladder calculi (males only). Since there was no significant differences in the incidence of these observations between the treated and control groups, they were not considered to be treatment-related. Other gross observations were of a minor, incidental nature.

HISTOPATHOLOGY: NON-NEOPLASTIC
No DM-2,6-NDC-related microscopic abnormalities were seen in any organ or tissue from any animal examined at the end of the feeding period. Due to the lack of DM-2,6-NDC-related abnormalities in the high dose animals after 13 weeks of feeding, the tissues collected from the recovery rats were not processed or examined.
Dose descriptor:
NOEL
Effect level:
3 000 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: (50,000 ppm) No statistically significant differences in either the absolute or relative weight of any organ were noted between the groups fed DM-2,6-NDC and the respective control group after thirteen weeks of feeding.
Critical effects observed:
not specified
Conclusions:
In an OECD 408 90-day repeated dose oral toxicity study, conducted according to GLP, dietary administration of DM-2,6-NDC to Sprague-Dawley rats for 13 consecutive weeks at levels of 2,000, 10,000 and 50,000 ppm resulted in no toxicological or pathological effects related to DM-2,6-NDC, therefore, the no-observed-effect level (NOEL) is 50,000 ppm.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
3 000 mg/kg bw/day
Study duration:
subchronic
Species:
rat
Quality of whole database:
2

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records
Reference
Endpoint:
short-term repeated dose toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1988
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)
Deviations:
no
Principles of method if other than guideline:
NDC was administered as a particulate aerosol by inhalation at target concentrations of 0, 1.0, 5.0, and 10.0 mg/m3 to four groups of 10 male and 10 female Sprague-Dawley rats each. The rats were exposed 6 hours per day, 5 days per week for four weeks.
GLP compliance:
not specified
Limit test:
no
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Portage, MI
- Age at study initiation: approximately 6 weeks of age
- Housing: The rats were individually housed in stainless steel cages measuring 15.5 x 17.0 x 15.8 cm during the 4-week quarantine period. The rats were confined in inhalation cages measuring 13.0 x 20.0 x 27.5 cm during the exposure phase. The cages were suspended over excrement pans. The pans were fitted with deotized cage boards, except during the exposure.
- Diet (e.g. ad libitum): Purina Rodent Chow 5001 supplied from a reverse-osmosis (RO) purifier by an automatic watering system was provided ad Iibitum, except during the inhalation exposures.
- Water (e.g. ad libitum): Water supplied from a reverse-osmosis (RO) purifier by an automatic watering system was provided ad Iibitum, except during the inhalation exposures.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): approximately 22°C
- Humidity (%): 40%
- Photoperiod (hrs dark / hrs light): Fluorescent lighting was provided for 12 hours followed by 12 hours of darkness.

IN-LIFE DATES: From: 24 May 1988 To: 22 June 1988
Route of administration:
inhalation: aerosol
Type of inhalation exposure:
not specified
Vehicle:
air
Remarks on MMAD:
MMAD / GSD: MMAD (mean of 4 samples): Low Exposure: 5.54 ± 0.174; Medium Exposure: 5.05 ± 0.488; High Exposure: 5.56 ± 0.495
Min/Max: Low Exposure (5.28/5.66) ; Medium Exposure (4.57/5.73); High Exposure (5.11/6.19)
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- System of generating particulates/aerosols: The generator was a dry materials feeder (Model 310, AccuRate, Whitewater, WI).
- Air flow rate: Chamber airflow in the 2-m3 chambers varied between 300 and 370 L/min, depending on the designated exposure concentration.
- Method of particle size determination: The particle size of the aerosols in each exposure chamber was determined weekly using an Andersen Cascade Impactor.
- Treatment of exhaust air: The chamber exhaust air was drawn through a filtering system before being discharged to the outside environment.

TEST ATMOSPHERE
- Brief description of analytical method used: Test article aerosol concentrations were determined both gravimetrically and spectrophotometrically.
Test article exposure concentrations were also monitored weekly using a Perkin-Elmer Lambda 5 UVIVIS Spectrophotometer operated at 334.0 nm. Sampling filters were extracted with 6 ml of HPLC/Spectro Grade Methanol and the optical density of the extract determined.
- Samples taken from breathing zone: yes

VEHICLE (if applicable)
- Concentration of test material in vehicle: 1.0, 5.0 and 10.0 mg/m3

No additional data
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Dimethyl-2,6-Naphthalene Dicarboxylate aerosol concentrations were determined both gravimetrically and spectrophotometrically. Samples were collected by drawing a given volume of test atmosphere (i.e. approximately 100-200, 250-350 and 800-1000 liters for the high, medium, and low concentration chambers, respectively, and 800-1000 liters for the filtered air control chamber) across an open-faced filter.
Dimethyl-2,6-Naphthalene Dicarboxylate exposure concentrations were also monitored weekly using a Perkin-Elmer Lambda 5 UVIVIS Spectrophotometer operated at 334.0 nm. Sampling filters were extracted with 6 mL of HPLC/Spectro Grade Methanol and the optical density of the extract determined.
Duration of treatment / exposure:
The duration of the exposures was 6 hours per day, 5 days per week, for a total of 20 exposures within a 28-day period.
Frequency of treatment:
6 hours per day, 5 days per week
Remarks:
Doses / Concentrations:
1.0, 5.0 and 10.0 mg/m3
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
099, 4.65 and 10.02 mg/m3
Basis:
analytical conc.
No. of animals per sex per dose:
10 rat/sex/group
Control animals:
yes, concurrent vehicle
Details on study design:
None stated
Positive control:
None stated
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: The rats were observed once daily for morbidity and mortality during the quarantine period. Following treatment initiation, all rats were observed at least once daily, 7 days/week.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: A complete physical examination was performed once prior to study initiation. Clinical observations were performed daily on weekdays during the exposure phase of the study.

BODY WEIGHT: Yes
- Time schedule for examinations: Body weights were measured at the initiation of the study, weekly during the exposure phase of the study, and at the termination of the study immediately prior to sacrifice.

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No data

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No data

WATER CONSUMPTION: No data

OPHTHALMOSCOPIC EXAMINATION: No data

HAEMATOLOGY: Yes
- Anaesthetic used for blood collection: No data
- Animals fasted: No data

CLINICAL CHEMISTRY: Yes
- Animals fasted: No data

URINALYSIS: No data

NEUROBEHAVIOURAL EXAMINATION: No data

No additional data
Sacrifice and pathology:
GROSS PATHOLOGY: Yes. Necropsies were performed on all rats and the following tissues were collected and fixed in 10% neutral buffered formalin: adrenals, brain, epididymides, eyes, esophagus, femur and bone marrow (smear), gonads, heart, duodenum, Jejunum, Ileum, cecum, colon, kidneys, liver, lungs, lymph nodes (mandibular, respiratory, and mesenteric), mammary gland, nasal turbinates, pancreas, parathyroids, pituitary, prostate and seminal vesicles, salivary glands, sciatic nerve, skeletal muscle, skin, spinal cord, spleen, stomach, thymus, thyroids, tongue, trachea, urinary bladder, uterus, ear with attached tag
HISTOPATHOLOGY: Yes. Any tissue masses or suspect lesions and the lymph nodes which drain the region of the mass or lesion.
Other examinations:
None stated
Statistics:
Means and standard deviations (SD) were calculated for all quantitative parameters.
Clinical signs:
effects observed, treatment-related
Mortality:
mortality observed, treatment-related
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
not specified
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not specified
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
not specified
Behaviour (functional findings):
not specified
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:
not specified
Details on results:
CLINICAL SIGNS AND MORTALITY
The Incidences of salivation and redness around the nose were slightly increased in the Dimethyl-2,6-Naphthalene Dicarboxylate-exposed groups compared to the controls. No rats died during the study.

BODY WEIGHT AND WEIGHT GAIN
There were no statistically significant effects of treatment on body weight or body weight gain during the study.

HAEMATOLOGY
There were no statistically significant effects of treatment on hematology.

CLINICAL CHEMISTRY
There were no statistically significant effects of treatment on the clinical chemistry.

ORGAN WEIGHTS
There were no statistically significant effects of treatment on absolute or relative organ weights or lung volumes.

GROSS PATHOLOGY
Prominent signs observed at necropsy Included lung foci and enlarged, focally reddened mandibular lymph nodes. However, there was no difference in Incidence of these observations between the exposed and the control groups so they were not considered to be treatment-related. Other observations were of a minor, incidental nature.

HISTOPATHOLOGY: NON-NEOPLASTIC
No treatment-related microscopic lesions was observed in the nasal turbinates, trachea or lungs of any of the rats exposed to Dimethyl-2,6-Naphthalene Dicarboxylate. The most common microscopic lesions seen included lymphoid and plasma cell hyperplasla in the mandibular lymph nodes, but these were of similar incidence among the exposed and control rats, so that the lesions were not considered to be treatment-related. Other lesions in the exposed rats were minor and of an Incidental nature, unrelated to treatment.

No additional data
Dose descriptor:
NOAEC
Effect level:
10.02 mg/m³ air (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
clinical signs
Critical effects observed:
not specified
Conclusions:
In an OECD 412 28-day repeated dose inhalation toxicity study in Sprague-Dawley male and female rats, conducted according to GLP, the NOAEC of NDC is 10.02 mg/m3.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEC
10.2 mg/m³
Study duration:
subacute
Species:
rat
Quality of whole database:
1

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:
key study
Study period:
1988
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)
Deviations:
no
Principles of method if other than guideline:
NDC was administered as a particulate aerosol by inhalation at target concentrations of 0, 1.0, 5.0, and 10.0 mg/m3 to four groups of 10 male and 10 female Sprague-Dawley rats each. The rats were exposed 6 hours per day, 5 days per week for four weeks.
GLP compliance:
not specified
Limit test:
no
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Portage, MI
- Age at study initiation: approximately 6 weeks of age
- Housing: The rats were individually housed in stainless steel cages measuring 15.5 x 17.0 x 15.8 cm during the 4-week quarantine period. The rats were confined in inhalation cages measuring 13.0 x 20.0 x 27.5 cm during the exposure phase. The cages were suspended over excrement pans. The pans were fitted with deotized cage boards, except during the exposure.
- Diet (e.g. ad libitum): Purina Rodent Chow 5001 supplied from a reverse-osmosis (RO) purifier by an automatic watering system was provided ad Iibitum, except during the inhalation exposures.
- Water (e.g. ad libitum): Water supplied from a reverse-osmosis (RO) purifier by an automatic watering system was provided ad Iibitum, except during the inhalation exposures.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): approximately 22°C
- Humidity (%): 40%
- Photoperiod (hrs dark / hrs light): Fluorescent lighting was provided for 12 hours followed by 12 hours of darkness.

IN-LIFE DATES: From: 24 May 1988 To: 22 June 1988
Route of administration:
inhalation: aerosol
Type of inhalation exposure:
not specified
Vehicle:
air
Remarks on MMAD:
MMAD / GSD: MMAD (mean of 4 samples): Low Exposure: 5.54 ± 0.174; Medium Exposure: 5.05 ± 0.488; High Exposure: 5.56 ± 0.495
Min/Max: Low Exposure (5.28/5.66) ; Medium Exposure (4.57/5.73); High Exposure (5.11/6.19)
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- System of generating particulates/aerosols: The generator was a dry materials feeder (Model 310, AccuRate, Whitewater, WI).
- Air flow rate: Chamber airflow in the 2-m3 chambers varied between 300 and 370 L/min, depending on the designated exposure concentration.
- Method of particle size determination: The particle size of the aerosols in each exposure chamber was determined weekly using an Andersen Cascade Impactor.
- Treatment of exhaust air: The chamber exhaust air was drawn through a filtering system before being discharged to the outside environment.

TEST ATMOSPHERE
- Brief description of analytical method used: Test article aerosol concentrations were determined both gravimetrically and spectrophotometrically.
Test article exposure concentrations were also monitored weekly using a Perkin-Elmer Lambda 5 UVIVIS Spectrophotometer operated at 334.0 nm. Sampling filters were extracted with 6 ml of HPLC/Spectro Grade Methanol and the optical density of the extract determined.
- Samples taken from breathing zone: yes

VEHICLE (if applicable)
- Concentration of test material in vehicle: 1.0, 5.0 and 10.0 mg/m3

No additional data
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Dimethyl-2,6-Naphthalene Dicarboxylate aerosol concentrations were determined both gravimetrically and spectrophotometrically. Samples were collected by drawing a given volume of test atmosphere (i.e. approximately 100-200, 250-350 and 800-1000 liters for the high, medium, and low concentration chambers, respectively, and 800-1000 liters for the filtered air control chamber) across an open-faced filter.
Dimethyl-2,6-Naphthalene Dicarboxylate exposure concentrations were also monitored weekly using a Perkin-Elmer Lambda 5 UVIVIS Spectrophotometer operated at 334.0 nm. Sampling filters were extracted with 6 mL of HPLC/Spectro Grade Methanol and the optical density of the extract determined.
Duration of treatment / exposure:
The duration of the exposures was 6 hours per day, 5 days per week, for a total of 20 exposures within a 28-day period.
Frequency of treatment:
6 hours per day, 5 days per week
Remarks:
Doses / Concentrations:
1.0, 5.0 and 10.0 mg/m3
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
099, 4.65 and 10.02 mg/m3
Basis:
analytical conc.
No. of animals per sex per dose:
10 rat/sex/group
Control animals:
yes, concurrent vehicle
Details on study design:
None stated
Positive control:
None stated
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: The rats were observed once daily for morbidity and mortality during the quarantine period. Following treatment initiation, all rats were observed at least once daily, 7 days/week.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: A complete physical examination was performed once prior to study initiation. Clinical observations were performed daily on weekdays during the exposure phase of the study.

BODY WEIGHT: Yes
- Time schedule for examinations: Body weights were measured at the initiation of the study, weekly during the exposure phase of the study, and at the termination of the study immediately prior to sacrifice.

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No data

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No data

WATER CONSUMPTION: No data

OPHTHALMOSCOPIC EXAMINATION: No data

HAEMATOLOGY: Yes
- Anaesthetic used for blood collection: No data
- Animals fasted: No data

CLINICAL CHEMISTRY: Yes
- Animals fasted: No data

URINALYSIS: No data

NEUROBEHAVIOURAL EXAMINATION: No data

No additional data
Sacrifice and pathology:
GROSS PATHOLOGY: Yes. Necropsies were performed on all rats and the following tissues were collected and fixed in 10% neutral buffered formalin: adrenals, brain, epididymides, eyes, esophagus, femur and bone marrow (smear), gonads, heart, duodenum, Jejunum, Ileum, cecum, colon, kidneys, liver, lungs, lymph nodes (mandibular, respiratory, and mesenteric), mammary gland, nasal turbinates, pancreas, parathyroids, pituitary, prostate and seminal vesicles, salivary glands, sciatic nerve, skeletal muscle, skin, spinal cord, spleen, stomach, thymus, thyroids, tongue, trachea, urinary bladder, uterus, ear with attached tag
HISTOPATHOLOGY: Yes. Any tissue masses or suspect lesions and the lymph nodes which drain the region of the mass or lesion.
Other examinations:
None stated
Statistics:
Means and standard deviations (SD) were calculated for all quantitative parameters.
Clinical signs:
effects observed, treatment-related
Mortality:
mortality observed, treatment-related
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
not specified
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not specified
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
not specified
Behaviour (functional findings):
not specified
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:
not specified
Details on results:
CLINICAL SIGNS AND MORTALITY
The Incidences of salivation and redness around the nose were slightly increased in the Dimethyl-2,6-Naphthalene Dicarboxylate-exposed groups compared to the controls. No rats died during the study.

BODY WEIGHT AND WEIGHT GAIN
There were no statistically significant effects of treatment on body weight or body weight gain during the study.

HAEMATOLOGY
There were no statistically significant effects of treatment on hematology.

CLINICAL CHEMISTRY
There were no statistically significant effects of treatment on the clinical chemistry.

ORGAN WEIGHTS
There were no statistically significant effects of treatment on absolute or relative organ weights or lung volumes.

GROSS PATHOLOGY
Prominent signs observed at necropsy Included lung foci and enlarged, focally reddened mandibular lymph nodes. However, there was no difference in Incidence of these observations between the exposed and the control groups so they were not considered to be treatment-related. Other observations were of a minor, incidental nature.

HISTOPATHOLOGY: NON-NEOPLASTIC
No treatment-related microscopic lesions was observed in the nasal turbinates, trachea or lungs of any of the rats exposed to Dimethyl-2,6-Naphthalene Dicarboxylate. The most common microscopic lesions seen included lymphoid and plasma cell hyperplasla in the mandibular lymph nodes, but these were of similar incidence among the exposed and control rats, so that the lesions were not considered to be treatment-related. Other lesions in the exposed rats were minor and of an Incidental nature, unrelated to treatment.

No additional data
Dose descriptor:
NOAEC
Effect level:
10.02 mg/m³ air (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
clinical signs
Critical effects observed:
not specified
Conclusions:
In an OECD 412 28-day repeated dose inhalation toxicity study in Sprague-Dawley male and female rats, conducted according to GLP, the NOAEC of NDC is 10.02 mg/m3.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEC
10.02 mg/m³
Study duration:
subacute
Species:
rabbit
Quality of whole database:
1

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

Oral route

Key study:

In the key oral repeated dose toxicity study, conducted equivalent to OECD 408 according to GLP, male and female rats were administered NDC via diet for 13 weeks. The NOEL for NDC is >50,000 ppm (>3,000 mg/kg b.w./day) (highest dose tested). No statistically significant differences in either the absolute or relative weight of any organ were noted between the experimental and control groups (IIT Research Institute, 1990).

 

Supporting studies:

In an OECD 422 study, conducted according to GLP, male and female rats were administered NDC via gavage over a 50 day period. The NOAEL for NDC is >1,000 mg/kg b.w./day (highest dose tested). No toxicological effects were observed. (Ministry of Health and Welfare (MHW), 1996).

Inhalation route:

Key study:

In the key inhalation repeated dose toxicity study conducted similar to OECD 412 (not conducted according to GLP), male and female rats were administered NDC via inhalation over a 4 week period. The NOAEC for NDC is >10.02 mg/m3 (highest dose tested). No toxicological effects were observed. (IIT Research Institute, 1988).

 

Dermal route:

According to Column 2 of Annex VIII of the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) legislation, repeated dose toxicity via the dermal route does not need to be conducted if exposure of humans is unlikely, taking into account any skin contact during production and the rate of absorption through the skin. Exposure of NDC to humans via skin contact is considered minimal due to appropriate Risk Management Measures (RMM) identified in the Chemical Safety Report.

 

In addition, repeated dose toxicity studies are available via the oral and inhalation routes ( oral (diet) study (conducted to OECD TG 408) and inhalation study (conducted similar to OECD TG 412)with a NOAEL of 3,000 mg/kg diet in female and male rats and NOAEC of 10.02 mg/m3 in female and male rats respectively.

Based upon low human exposure potential and available study data, this endpoint is being waived.


Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
13 week study conducted according to OECD 408 and to GLP.

Justification for selection of repeated dose toxicity inhalation - systemic effects endpoint:
Conducted similar to OECD 412 study (not conducted according to GLP).

Justification for selection of repeated dose toxicity inhalation - local effects endpoint:
Conducted similar to OECD 412 study (not conducted according to GLP)

Justification for classification or non-classification

Repeated dose (Oral):

In accordance with Regulation No 1272/2008 Table 3.9.3 NDC is not classified for repeated dose toxicity (oral), based on the NOEL (male and female rats) of >50,000ppm (>3,000 mg/kg b.w./day).

Repeated dose (Inhalation):

In accordance with Regulation No 1272/2008 Table 3.9.3 NDC is not classified for repeated dose toxicity (inhalation), based on the NOAEC (male and female rats) >10.02 mg/m3.