Dibutyl phthalate

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2000

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: taken from EU RAR

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2004

Report date:

2000

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

not specified

Principles of method if other than guideline:

no data

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Dibutyl phthalate

EC Number:

201-557-4

EC Name:

Dibutyl phthalate

Cas Number:

84-74-2

Molecular formula:

C16H22O4

IUPAC Name:

dibutyl phthalate

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

mean bw males 281.2 g; mean bw females 195.5 g

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose/head only

Vehicle:

not specified

Remarks on MMAD:

MMAD / GSD: 1.5-1.9 μm/ GSD around 2

Details on inhalation exposure:

head-nose exposed 6 hours/day, 5 days/week, for 4 weeks, to measured concentrations of 0, 1.18, 5.57, 49.3 or 509 mg DBP (purity 99.8%)/m3 of air as liquid aerosol [MMAD (=mass median aerodynamic diameter) 1.5-1.9 μm; GSD around 2].

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

5 days/week, for 4 weeks

Frequency of treatment:

6 hours/day

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0
Basis:
other: mg DBP

Doses / concentrations 2

Remarks:

Doses / Concentrations:
1.18
Basis:
other: mg DBP

Doses / concentrations 3

Remarks:

Doses / Concentrations:
5.57
Basis:
other: mg DBP

Doses / concentrations 4

Remarks:

Doses / Concentrations:
49.3
Basis:
other: mg DBP

Doses / concentrations 5

Remarks:

Doses / Concentrations:
509
Basis:
other: mg DBP

No. of animals per sex per dose:

5

Control animals:

not specified

Details on study design:

inhalation experiment according to OECD Guideline No. 412 and (for clinical and neurofunctional examinations and pathology) to OECD No. 407

Examinations

Observations and examinations performed and frequency:

All animals were checked on state of health twice a day on working days and once a day on weekends or public holidays. Clinical examination of all animals was carried out thrice a day on exposure days and once during post-exposure days. Weekly food consumption, water consumption and body weight were recorded and food efficiency was calculated. On days -1, 7, 14 and 21 open field observations were carried out during 2 minutes on all animals after transfer to a standard arena.
Ophthalmoscopy was performed on all animals before exposure and on animals from control and 509 mg/m3 group at day 26.
A functional observation battery (starting with passive observations followed by removal from home cage, open field observations and thereafter sensorimotor tests and reflex tests) was carried out on all animals after the exposure period (day 28). Motor activity of all animals was measured
on the same day as the functional observations were performed.
At the end of the exposure period haematology, clinical chemistry and urinalysis were carried out on all animals, absolute and relative organ weights (10 organs including brain and reproductive organs) of all animals were determined and macroscopy of all animals was performed.

Sacrifice and pathology:

Histopathology was carried out on all gross anomalies and on nasal cavity, larynx, lungs, liver, lymph nodes (mediastinal) and testes + epididymides/ovaries + oviducts of all animals. In addition, histopathology of ca. 20 other tissues (including brain) of all animals in control and 509 mg/m3 group was carried out

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Details on results:

Statistically significant increases of absolute lung weights were seen in males at 5.57 (+18.4%) and 49.3 mg/m3 (+11.1%). At 509 mg/m3 absolute lung weights showed a non-significant increase (+8.1%). Absolute weights of testes showed statistically significant decreases at 1.18 (-11.6%), 5.57 (-10.6%) and 49.3 mg/m3 (-9.3%). A non-significant decrease (-7.3%) of absolute testes weights was observed at 509 mg/m3. Relative organ weights did not reveal statistically significant changes. The observed changes in absolute lung and testes weights were regarded as incidental as these changes did not increase with the dose, and given the lack of changes in relative organ weights and the absence of histopathological findings. Macroscopy did not show treatment-related changes. Histopathology revealed in all treated groups a dose-dependent increased incidence of hyperplasia of mucous cells at some sites of levels II (in 0/2/3/5/5 males and 0/3/5/5/5 females at 0, 1.18, 5.57, 49.3, and 509 mg/m³, respectively), III (in 0/0/2/4/5 males and 0/2/4/5/5 females) and IV (in 0/0/1/2/5 males and 0/2/4/4/5 females) of nasal cavity. The severity increased with dose from grade 1 (minimal) to grade 2 (slight). The epithelium in the respective areas of nasal cavity was regular and infoldings were absent, and signs of
inflammation were missing in the whole nasal cavity. A dose-dependent increased incidence of squamoid metaplasia (of minimal degree) at level I of the larynx was observed (in 0/1/3/4/5 males and 0/1/3/5/4 females at 0, 1.18, 5.57, 49.3 and 509 mg/m³, respectively). Although the effects in
nasal cavity and larynx can be considered as adaptive responses, they are adverse in nature.

Effect levels

Dose descriptor:

NOAEC

Effect level:

ca. 509 mg/m³ air

Based on:

not specified

Sex:

male/female

Basis for effect level:

other: No systemic effects, including neurotoxic effects, were observed up to and including the highest exposure concentration of 509 mg/m3. Therefore, the NOAEC for systemic effects in this study is 509 mg/m³, the highest concentration tested.

Target system / organ toxicity

Critical effects observed:

not specified