Tar bases, coal, lutidine fraction

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1989

Report date:

1989

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

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

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Tar bases, coal, lutidine fraction

EC Number:

293-766-2

EC Name:

Tar bases, coal, lutidine fraction

Cas Number:

91082-52-9

IUPAC Name:

Tar bases, coal, lutidine fraction

Test material form:

liquid

Test animals

Species:

rat

Strain:

Wistar

Remarks:

Alpk:APfSD, albino

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: colony maintained at Alderley Park, Cheshire, UK
- Age at study initiation: approximately 8 weeks
- Weight at study initiation: bodyweight range 215-256 g in females and 288-328 g in males
- Housing: animals were house 5 per cage (sexes separately) in long-term exposure chambers, cages were made of wire mesh (45 x 41 x 20 cm) and each was divided into two by a wire mesh partition
- Diet: pelleted Porton Combined diet, supplied by Special Diets Services Ltd, Witham, Essex, United Kingdom was available ad libitum, served from a central food hopper
- Water (e.g. ad libitum): potable water was available ad libitum
- Acclimation period: 9 days

DETAILS OF FOOD AND WATER QUALITY:

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 to 26
- Humidity (%): 50-80
- Air changes (per hr): not reported
- Photoperiod (hrs dark / hrs light): 12 hours:12 hours

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

whole body

Vehicle:

clean air

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: animals were exposed whole-body in stainless steel exposure chambers with an internal volume of 3.4 m3
- Source and rate of air: laboratory air
- Method of conditioning air: dried and filtered using equipment supplied by Atlas-Copco (Sweden)
- System of generating particulates/aerosols: initial aerosolisation using concentric jet atomisers, which were supplied with the test substance using Hamilton Minpuls II dispensers; the aerolsols were generated into round-bottomed flasks, heated to 75 °C using a water bath, where they volatilised; clean dry air was introduced into the mixing flasks, and carried the test atmospheres into the exposure chambers
- Temperature, humidity, pressure in air chamber: 23 ± 3 °C, 40-60%
- Air flow rate: 700 L/minutes
- Air change rate: 12.4 per hour
- Method of particle size determination: particulate concentrations of the 200 μg/L test atmosphere was measured gravimetrically once a week, the test atmosphere was drawn at a flow rate of 2 L/min over a 330 minute period, through a 25 mm diameter Vinyl Metricel (VM-1) filter housed in a Delrin open-faced filter holder; the filter was weighed before and after sampling and the concentration was then calculated from post and pre-weight, time and airflow.
- Treatment of exhaust air: not reported

TEST ATMOSPHERE
- Brief description of analytical method used: the concentration of the test substance in the test atmospheres was measured by drawing samples of the atmospheres through adsorption tubes, followed by thermal desorption into a gas chromatograph equipped with a flame ionisation detector
- Samples taken from breathing zone: test atmospheres were measured close to the animals' breathing zone

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

6 hours

Frequency of treatment:

5 days per week over four weeks

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

5.2 mg/m³ air (analytical)

Doses / concentrations 2

Dose / conc.:

50 mg/m³ air (analytical)

Doses / concentrations 3

Dose / conc.:

207 mg/m³ air (analytical)

No. of animals per sex per dose:

Five

Control animals:

yes, concurrent no treatment

Details on study design:

- Dose selection rationale: the exposure levels in the main study were selected on the basis of a 3-day preliminary study
- Rationale for animal assignment: rats were assigned to five weight ranges per sex; the animals were then allocated to four groups, using a Latin square method until there were two groups containing ten animals of each sex and two groups containing five of each sex; the allocation process started with the middle weight range and then went on to those on either side
- Rationale for selecting satellite groups: five animals of each sex in the control group and the top dose group were used for maintained during a recovery period
- Post-exposure recovery period in satellite groups: 14 days

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: prior to, during (every 30 minutes) and following exposure, and daily during recovery period

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: on days 1, 2, 3, 4, 11, 18, 25 and 29; animals maintained for the 14-day recovery period were also examined on days 36 and 43

BODY WEIGHT: Yes
- Time schedule for examinations: individual bodyweights were recorded one day before start of exposure, on days 1, 2, 3, 4, 11, 18, 25 and 29; animals maintained for the 14-day recovery period were also examined on days 36 and 43

OPHTHALMOSCOPIC EXAMINATION: Yes, following the use of a mydriate (MYDRIACYL, Alcon Laboratories, Watford, Herts, UK)
- Time schedule for examinations: one day before start of exposure, day 28, day 42 for animals maintained for a 14-day recovere period
- Dose groups that were examined: control and top-dose groups

HAEMATOLOGY: Yes
- Time schedule for collection of blood: cardiac blood samples were taken at post mortem examination
- Anaesthetic used for blood collection: not applicable
- Animals fasted: not applicable
- How many animals: all animals

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: cardiac blood samples were taken at post-mortem examination
- How many animals: all animals

URINALYSIS: Yes
- Time schedule for collection of urine: following exposure on day 27
- Metabolism cages used for collection of urine: Yes
- Animals fasted: provided with food and water for at least 2 hours priort to being placed in the metabolism cages, then deprived of food and water for 16 hours

NEUROBEHAVIOURAL EXAMINATION: No

IMMUNOLOGY: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
On day 29 or 43, designated animals were deeply anaesthetised by exposure to halothane BP vapour (FLUOTHANE, ICI Pharmaceuticals, Macclesfield, Cheshire, UK) and killed by exsanguination using cardiac puncture. Animals were subjected to a full post mortem examination.
All tissues from the controll and top dose groups at the two time periods were processed to paraffin blocks. 5 μm sections were cut and stained with haematoxylin and eosin for microscopic examination.

Statistics:

Where appropriate, test and control data were compared statistically using a two-sided Student's t-test.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Hunched posture and a reduced response to sound were apparent daily in most animals in the 50 and 207 mg/m3 groups. Abnormal respiratory noise was heard in some animals in the 207 mg/m3 group. One animal in the group exposed to 50 mg/m3, during the 28-day exposure period, demonstrated similar symptoms. The abnormal respiratory noise persisted throughout the 14-day recovery period in some animals of the top-dose group.

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

There were reductions in bodyweight gain during the exposure period, in males and females exposed to 207 mg/m3, which were considered to indicate a mild non-specific response to exposure.

Ophthalmological findings:

effects observed, non-treatment-related

Description (incidence and severity):

A variety of ophthalmological findings was recorded in the eyes of treated and control animals at all time-points. None was attributable to treatment and the changes present are commonly seen in the eyes of rats of this age and strain.

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

Platelet counts were slightly increased at day 29 in the male rats in the 50 and 207 mg/m3 groups. These changes were small and of little toxicological significance. By day 43 the platelet counts in the males in the 207 mg/m3 group were similar to the male control value. All other changes seen were minor and are considered to be incidental to treatment with the test substance.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

Slightly increased plasma ALP activitieds were seen in females in the 50 and 207 mg/m3 groups killed on day 29. Plasma total protein and calcium levels were slightly decreased in females in the 207 mg/m3 group killed on day 43. These changes are considered to be of no toxicological significance.

Urinalysis findings:

effects observed, non-treatment-related

Description (incidence and severity):

The urinary pH value of the male 50 mg/m3 group was raised slightly in week 4. This change is considered to be of no toxicological significance.

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

There were no statistically significant differences in absolute organ weights or organ:bodyweight ratios in any of the groups killed on day 29 or in females killed on day 43. There were statistically significant reductions in absolute heart, kidney, liver and testes weights and an increased brain:bodyweight ratio in males in the 207 mg/m3 group killed on day 43, when compared to controls. These are considered to reflect the differences in group mean bodyweight of these animals at termination.

Gross pathological findings:

no effects observed

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Effect levels

Dose descriptor:

NOAEC

Effect level:

207 mg/m³ air (analytical)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No dose related toxic effects were observed.

Target system / organ toxicity

Critical effects observed:

no

Applicant's summary and conclusion

Conclusions:

Repeated inhalation exposure over a period of 28 days to concentrations of the test substance up to 207 mg/m3 produced no appreciable toxicity. A concentration of 207 mg/m3 can be considered to be a toxicological no-effect level.

Executive summary:

The sub-acute toxicity of the test substance was investigated under GLP in a 28-day repeated dose inhalation toxicity study following the principles of OECD TG 412. The experiment is considered relevant, adequate and conclusive.

Groups of five male and five female rats, aged approximately 8 weeks at the study start, were exposed whole-body to target concentrations of 5 and 50 mg/m3, and a group of ten male and ten female rats was exposed to a target concentration of 200 mg/m3, for 6 hours per day, 5 days per week over a 28-day period. A concurrent control group of ten male and ten female rats was similarly treated and exposed to air only.

All the animals in the 5 and 50 mg/m3 groups, and five of each sex in the control and 200 mg/m3 groups were killed on the day following final exposure (day 29). Remaining animals in the control and 200 mg/m3 groups were retained for a further 14 days following the end of the exposure period to assess recovery. During the study all animals were clinically observed each day and were examined and weighed each week. Ophthalmoscopy was conducted pre-study, and at the end of the exposure and recovery phases for the control and 200 mg/m3 groups. Urine samples were collected overnight in week 4 for analysis from five males and five females in each group. At termination, cardiac blood samples were taken for clinical chemistry and haematological evaluation. A range of organs was taken from all animals at necropsy, those from 200 mg/m3 and control groups were examined histologically.

The mean atmospheric concentrations of the test substance throughout the study were 5.2, 50.0 and 207 mg/m3. No appreciable toxicity was observed in any of the groups and the majority of effects that were seen were confined to the top dose group. Respiratory tract irritation was present in a few animals in this group during exposue and there were clinical signs indicative of a mild non-specific response to exposure in this group. There was a slight decrease in bodyweight gain seen in this group during the exposure period, which persisted in the males during the recovery period. This is considered to reflect a mild non-specific response to exposure which is of questionable toxicological significance. There were no toxicologically signficant ophthalmological, haematological or clinical chemical abnormalities and no macroscopic or microscopic changes. There were no effects on the organ weights of animals killed on day 29, and the reductions seen on day 43 in the test animals are considered to be a reflection of the bodyweight effects seen in these animals.

A concentration of 207 mg/m3 is considered to be a toxicological no-effect level in this sub-acute repeated dose inhalation toxicity study.