Registration Dossier

Administrative data

Endpoint:
short-term repeated dose toxicity: dermal
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: well documented study
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2011

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Comparison of percutaneous vs. oral (gavage) administration as well as the toxicokinetics of p-Methoxybenzaldehyde was evaluated in a 14 day study in rats.
GLP compliance:
no
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: liquid
Details on test material:
- Name of test material (as cited in study report): p-Methoxybenzaldehyde
- Physical state: clear colorless to slight yellowish liquid
- Lot No.: 00020777L0

Test animals

Species:
rat
Strain:
other: Crl:CD(SD)
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Inc., Portage, MI, USA
- Age at study initiation: approx. 86 days (males), approx. 81 days (females)
- Weight at study initiation: 315 - 427 g (males ), 208 - 254 g (females)
- Housing: During the acclimation and study periods, the rats were individually housed in stainless steel, wire-bottomed cages. During the exposure period (at least 6 hours) of the percutaneous phase, the rats were individually housed in nesting boxes with cage liners and then transferred to clean stainless steel cages after rinsing.
- Diet: Certified Rodent Diet® #5002 meal (PMI® Nutrition International, Inc., St. Louis, MO USA); ad libitum
- Water: local water (processed by passage through a reverse osmosis membrane, add on of chlorine); ad libitum
- Acclimation period: approx. 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 - 25
- Humidity (%): 30 - 70
- Air changes (per hr): minimum of 10
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Type of coverage:
occlusive
Vehicle:
corn oil
Details on exposure:
TEST SITE
- Praparation of test site: The hair on the back of the rats was shaved with a clipper (shaved area of approximately 5 x 7 cm)
- Area of exposure: A total volume of 0.50 mL test substance solution (variable concentration for the prepared formulations) or vehicle was placed in each Hilltop Chamber® with a diameter of 25 mm. Four chambers were attached to the application site of each rat (total of 2 mL).
- Type of wrap if used: Hilltop Chambers® were appropriately secured with gauze and micropore tape at the back of the rat
- Exposure period: at least 6 hours (rats were individually housed in nesting boxes with cage liners and then transferred to clean stainless steel cages after rinsing)
- Time intervals for shavings or clipplings: On an as-needed basis, any hair re-growth was shaved before treatment.

REMOVAL OF TEST SUBSTANCE
- Washing: wrapping and Hilltop Chambers® was removed, the test substance or vehicle was gently wiped from the backs of each rat at least 5 times with fresh gauze pads moistened with 0.9% sodium chloride solution
- Time after start of exposure: at least 6 hours

USE OF RESTRAINERS FOR PREVENTING INGESTION: yes (Elizabethan collar)
Analytical verification of doses or concentrations:
no
Duration of treatment / exposure:
6 hours
Frequency of treatment:
daily for 14 consecutive days
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 100, 250, 500, 1000 mg/kg/day
Basis:
nominal per unit body weight
No. of animals per sex per dose:
5
Control animals:
yes, concurrent vehicle

Examinations

Observations and examinations performed and frequency:
SKIN OBSERVATIONS: Yes
- according to Draize
- Time schedule: before the first daily treatment, approximately one  hour after removal of application materials, on each day of treatment prior to exposure, on the day of scheduled euthanasia

CLINICAL OBSERVATIONS: Yes
- Time schedule: daily before dosage administration, between one and two hours after the start of exposure, and again at the end of the normal working day during the dosage period, on the day of scheduled euthanasia 

OTHER OBSERVATIONS:
see Chapter 7.5.1 "RIFM 2011. Repeated dose toxicity: oral, rat, 14 days"
Sacrifice and pathology:
see Chapter 7.5.1 "RIFM 2011. Repeated dose toxicity: oral, rat, 14 days"

Tissues from male and female rats in vehicle group, 500 ad 1000 mg/kg bw/d dose group were sectioned, mounted on glass slides, and stained with hematoxylin and eosin. 

Results and discussion

Results of examinations

Details on results:
MORTALITY:
All male and female rats survived to scheduled euthanasia on day 15.

CLINICAL SIGNS - SKIN GRADE REACTION:
Males:
Flaking and erythema grade 1 at 500 and 1000 mg/kg bw/d and erythema grade 2 at 1000 mg/kg/day. Observations of flaking grade 1 occurred as early as day 7, while erythema grade 1 and erythema grade 2 were observed as early as day 1 and day 10, respectively.

Females:
Flaking grade 1 was observed in each dosage group, including the vehicle control (observed in the test substance treated groups as early as day 4). However, the incidence and number of rats affected was greatest in the 500 and 1000 mg/kg bw/d dosage groups. Erythema grade 1 occurred in each test substance treated group, and was observed as early as day 4.

No other adverse test substance related clinical signs at any dosage level was observed in males and females.

BODY WEIGHT AND WEIGHT GAIN:
Males:
Net losses in body weight occurred in each test substance treated group the day after the first application of the test substance (day 1 to 2). Thereafter, net losses in body weight or suppressed body weight gains occurred sporadically in each dosage group, including the vehicle control. In the 1000 mg/kg bw/d dose group, a test substance related reduction in body weight gains at DS 1 to 14 by 32% compared to controls was observed. The average body weight on DS 14 was comparable to control animals.

Females:
No test substance related effects observed. Reflecting net losses or suppressed body weight gains that occurred sporadically in the vehicle control group, body weight gains at DS 1 to 14 in the p-Methoxybenzaldehyde-treated groups were increased, i.e. 253%, 172%, 142% and 157% of the vehicle control group for 100, 250, 500 and 1000 mg/kg bw/d, respectively. The average body weight on DS 14 was comparable to control animals.

FOOD CONSUMPTION:
Males:
Absolute and relative feed consumption values were lower in the test substance treated groups than the vehicle control group value during the first three days of the dosage period (day 1 to 3). Thereafter, feed consumption values for male rats were generally comparable among the dosage groups.

Females:
No test substance related effects observed

URINALYSIS:
not analyzed (samples were frozen for possible future analysis)

ORGAN WEIGHTS:
Absolute and relative organ weights of male and female rats were unaffected by dosages of p-Methoxybenzaldehyde as high as 1000 mg/kg bw/d.

GROSS PATHOLOGY:
- Test substance related gross findings were limited to the skin application sites in male and female rats in the 500 and 1000 mg/kg/day dosage groups.
- All other gross findings observed were considered incidental, of the nature commonly observed in this strain and age of Crl:CD (SD), and/or were of similar incidence in vehicle control and treated rats.


HISTOPATHOLOGY:
- Test substance related changes were observed at the skin application sites of the male rats at 500 and 1000 mg/kg/day and females at 1000 mg/kg/day (minimal to mild, focal cellular infiltration of the dermis and focal epithelial hyperplasia).
No additional microscopic findings related to p-Methoxybenzaldehyde were noted.

Effect levels

open allclose all
Dose descriptor:
NOAEL
Remarks:
local
Effect level:
100 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: skin reactions + histopathological finding at skin application side
Dose descriptor:
NOAEL
Remarks:
systemic
Effect level:
500 mg/kg bw/day
Based on:
test mat.
Sex:
male
Basis for effect level:
other: body weights; in females no persistent adverse effect observed up to 1000 mg/kg bw/d.

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion