Pitch, coal tar, high-temp., < 1% 4- to 5-membered condensed ring aromatic hydrocarbons

Endpoint summary

Description of key information

No experimental repeated-dose toxicity data is available on Pitch, coal tar, high-temp., < 1% 4- to 5-membered condensed ring aromatic hydrocarbons [EC no. 701-305-8] (CTPhtht) itself. A related coal-tar material containing also constituents present in CTPhtht produced no particular, treatment-related toxicity in male and female mice receiving the test material in the feed for up to 6 months. The NOAEL, 0.5 % in the diet, is estimated to correspond to approximately 400 mg/kg bw/d.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study, acceptable for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Deviations:

yes

Remarks:

no full examination protocol: hematology, urinalysis are lacking

GLP compliance:

not specified

Limit test:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): manufactured gas plant residue, MGP (= Coal-tar sample C in Weyand et al. 1991)
- Physical state: viscous liquid at room temperature
- Source: Electric Power Research Institute, Palo Alto
- Production: by-product from coal gasification of East Coast coal feedstock

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Wilmington/Mass
- Age at study initiation: 49 - 56 d
- Weight at study initiation: 23 - 24 g (m); 17 - 18 g (f) (estimated from Report, Fig. 1
- Fasting period before study: none
- Housing:
- Diet: ad libitum
- Water: ad libitum

ENVIRONMENTAL CONDITIONS
- controlled conditions: no details
- Photoperiod (hrs dark / hrs light): 12 / 12

Route of administration:

oral: feed

Vehicle:

other: water and gelling agent

Details on oral exposure:

DIET PREPARATION
- Rate of preparation of diet (frequency): 1x
- Preparation of the diet (basal gel diet): 3020 mL of boiling water was blended with 100 g of a gelling agent (not specified) for 1 min,
then 1948 g dry food added and blending continued for additionakl 2-3 min.
- Mixing appropriate amounts: Aliquots of MPG was added, followed by homogenisation (2-3 min).
The food blends were cooled down in bar molds.
- Storage temperature of food: packaged into plastic bags and stored at -20 °C

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

94 d and 185 d

Frequency of treatment:

continuous

Dose / conc.:

0.05 other: % (w/w) in diet (nominal)

Remarks:

51 / 42 mg/kg bw/day (males / females) actual dose ingested

Dose / conc.:

0.25 other: % (w/w) in diet (nominal)

Remarks:

251 / 196 mg/kg bw/day (males / females) actual dose ingested

Dose / conc.:

0.5 other: % (w/w) in diet (nominal)

Remarks:

462 / 344 mg/kg bw/day (males / females) actual dose ingested

No. of animals per sex per dose:

12 (94 d)
12 (185 d)

Control animals:

yes, plain diet

Details on study design:

- Dose selection rationale: previous range finding and acceptance (palatability) testing

Positive control:

Benzo[a]pyrene (BaP): 0.005 % in diet

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes, no details

DETAILED CLINICAL OBSERVATIONS: Yes, no details

BODY WEIGHT: Yes
- Time schedule for examinations: throughout (see Report, Fig. 1)

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/mouse/day: Yes, per mouse

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

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: No (bone marrow was examined, 94 d and 185 d)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: 94 d or 185 d
- How many animals: 12 per group
- Parameters: glucose, creatine, BUN, protein, Asp-aminotransferase, ala-aminotransferase, alk. phosphatase

URINALYSIS: No data on standard parameters /
Chemical analysis of PAH metabolites in male mice over time (1-OH-pyrene + 3-OH-BaP)

Sacrifice and pathology:

GROSS PATHOLOGY: Yes, all organs after 94 d and 185 d
HISTOPATHOLOGY: Yes, in in 10 animals per sex of the 0.5% group, BaP and control group (after 94 d and 185 d)

Other examinations:

DNA adducts in lung and forestomach

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not specified

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

no effects observed

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
no mortality

BODY WEIGHT AND WEIGHT GAIN (estimated from Report, Fig. 1)
Dose-related decrease, exception 0.05% (females):
0.25% (males): significant decrease in body weight of 10 - 12 % at 94 d and 185 d, respectively, as compared to the control
0.50 % (males): significant decrease in body weight of ~22 and ~15 % at 94 d and 185 d, respectively, as compared to the control
0.05% (female): significant increase in body weight of ~16 % at 94 d and 185 d, respectively, as compared to the control
0.50 % (female): significant decrease in body weight of ~20 % at 94 d and 185 d, respectively, as compared to the control


FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study) [Report, Tab. 1]
Dose-related decrease as compared to the untreated control / increase for the 0.05 % female group

Changes in body-weight development may be partly explained by the differences in food consumption.


HISTOPATHOLOGY: NON-NEOPLASTIC
After 94 d. lesions observed included minimally to moderate vacuolisation of hepatocytes, increased hematopoietic cell proliferation
in spleens, modest hyperplasia of granulocytic cells in the bone marrow of the femur, and cytoplasmic alteration of the olfactory epithelial cells.

After 185 d, microscopic lesions observed included irregular cytoplasmic vacuoles in hepatocytes, infiltration of lymphoid cells in various tissues, and changes in the olfactory epithelial cells of the nose.

HISTOPATHOLOGY: NEOPLASTIC (if applicable)
After 185 d, a squamous cell carcinoma was present in the forestomach of one male (0.5 %),
one squamous papilloma was found in the forestomach of a female.

The effects were sporadic and not considered treatment-related.

Key result

Dose descriptor:

NOAEL

Remarks:

(highest tested dose)

Effect level:

0.5 other: % in diet (nominal), 462/344 mg/kg bw/day (males/females) actual dose ingested;

Based on:

test mat.

Basis for effect level:

other: no effects observed related to specific systemic toxicity

Key result

Dose descriptor:

NOAEL

Effect level:

0.25 other: % in diet (nominal), 251/196 mg/kg bw/day (males/females) actual dose ingested;

Based on:

test mat.

Basis for effect level:

other: body weight

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

400 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

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

No repeated-dose toxicity studies with Pitch, coal tar, high-temp., < 1% 4- to 5-membered condensed ring aromatic hydrocarbons [EC no. 701-305-8] (CTPhtht), itself or its precursor, Coal-tar pitch, high temp. [CAS no. 65996-93-2], have been located. The subchronic feeding study in mice with coal-tar material (compared to pitches a worst case) indicates that more marked toxicity following long-term exposure to CTPhtht is very unlikely to occur.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint: No adverse effects observed that were assessed treatment-related at the highest dose tested (400 mg/kg bw/day).

Justification for classification or non-classification

Pitch is not classifiable, as there was no evidence for specific target-organ effects at doses lower than 100 mg/kg bw/d (test material: coal tar).