Registration Dossier

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

Constituent 1
Chemical structure
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 / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
0
Basis:
other: mg DBP
Remarks:
Doses / Concentrations:
1.18
Basis:
other: mg DBP
Remarks:
Doses / Concentrations:
5.57
Basis:
other: mg DBP
Remarks:
Doses / Concentrations:
49.3
Basis:
other: mg DBP
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

Applicant's summary and conclusion