N-[(1,1,3,3-tetramethylbutyl)phenyl]naphthalen-1-amine

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

30 May 2012 - 27 July 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Report date:

2013

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: The United States Environmental Protection Agency (EPA) Health Effects Test Guidelines, OPPTS 870.3650, Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test, July 2000.

GLP compliance:

yes (incl. QA statement)

Remarks:

WIL Research Europe B.V., Hambakenwetering 7, 5231 DD 's-Hertogenbosch, The Netherlands

Test material

Test material information

Constituent 1

Reference substance name:

N-[(1,1,3,3-tetramethylbutyl)phenyl]naphthalen-1-amine

EC Number:

257-406-8

EC Name:

N-[(1,1,3,3-tetramethylbutyl)phenyl]naphthalen-1-amine

Cas Number:

51772-35-1

Molecular formula:

C24H29N

IUPAC Name:

N-[(1,1,3,3-tetramethylbutyl)phenyl]naphthalen-1-amine

Details on test material:

- Physical state: solid/white
- Analytical purity: 99.0 g/100 g determined by 1H-MR spectroscopy
- Expiration date of the lot/batch: July 15, 2015
- Storage condition of test material: Room temperature; avoid temperatures > 35°C

Test animals

Species:

rat

Strain:

other: Crl:WI(Han)

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany.
- Age at study initiation: 11 weeks
- Weight at study initiation: about 200 g (fermales) and 300 g( males)
- Housing:
Pre-mating: Animals were housed in groups of 5 animals/sex/cage in Macrolon plastic cages (MIV type, height 18 cm).
Mating: Females were caged together with males on a one-to-one-basis in Macrolon plastic cages (MIII type, height 18 cm).
Post-mating: Males were housed in their home cage (Macrolon plastic cages, MIV type, height 18 cm) with a maximum of 5 animals/cage. Females wwere individually housed in Macrolon plastic cages (MIII type, height 18 cm).
Lactation: Pups were kept with the dam until termination in Macrolon plastic cages (MIII type, height 18 cm). During locomotor activity monitoring of the dams the pups were kept warm in their home cage using bottles filled with warm water. In order to avoid hypothermia of pups, pups were not left without their dam or a bottle filled with warm water for longer than 30-40 minutes.
- Diet: Free access to pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest, Germany).
- Water: ad libitum, tap water
- Acclimation period: at least five days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 to 24°C
- Humidity (%): 40 - 70 %
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

propylene glycol

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Formulations (w/w) were prepared daily within 6 hours prior to dosing and were homogenized to a visually acceptable level. Adjustment was made for specific gravity of the vehicle. No correction was made for the purity of the test substance.

VEHICLE
- Justification for use and choice of vehicle (if other than water): Based on trial formulations performed at WIL Research Europe.
- Amount of vehicle (if gavage): 5 ml/kg

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses were conducted on a single occasion during the treatment phase (05 June 2012), according to a validated method (Project 499646, BASF Project 05Y0630/11X472). Samples of formulations were analyzed for homogeneity (highest and lowest concentration) and accuracy of preparation (all concentrations). Stability in vehicle over 6 hours at room temperature was also determined (highest and lowest concentration).
The accuracy of preparation was considered acceptable if the mean measured concentrations were 85-115% of the target concentration. Homogeneity was demonstrated if the coefficient of variation was ≤ 10%. Formulations were considered stable if the relative difference before and after storage was maximally 10%.

Details on mating procedure:

Following a minimum of 14 days of exposure for the males and females, one female was cohabitated with one male of the same treatment group, avoiding sibling mating. Detection of mating was confirmed by evidence of sperm in the vaginal lavage or by the appearance of an intravaginal copulatory plug. This day was designated Day 0 post-coitum. Once mating occurred, the males and females were separated. A maximum of 14 days was allowed for mating, after which females who had not shown evidence of mating were separated from their males. Detection of mating was not confirmed for animal nos. 50, 63 and 76 which did deliver live offspring. The mating date for these animals was estimated at 21 days prior to the actual delivery date. This day was designated Day 0 postcoitum

Duration of treatment / exposure:

Males were exposed for 29 days, i.e. 2 weeks prior to mating, during mating, and up to the day prior to scheduled necropsy. Females were exposed for 40-54 days, i.e. during 2 weeks prior to mating, during mating, during post-coitum, and during at least 4 days of lactation (up to the day prior to scheduled necropsy). Female nos. 49 and 50 (Group 1), 53 (Group 2), 65 and 66 (Group 3) were not dosed during littering.

Frequency of treatment:

Once daily for 7 days per week, approximately the same time each day with a maximum of 6 hours difference between the earliest and latest dose. Animals were dosed up to the day prior to scheduled necropsy.

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

62.5 mg/kg bw/day (actual dose received)

Doses / concentrations 2

Dose / conc.:

250 mg/kg bw/day (actual dose received)

Doses / concentrations 3

Dose / conc.:

1 000 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dose levels were based on results of a 14-day dose range finding study (Project 499643; BASF Project 01R0630/11X470).

Examinations

Maternal examinations:

At dose level allocation, 5 animals/sex/group were randomly selected for functional observations, locomotor activity, clinical pathology, organ weights (full list) and histopathology.

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily, detailed clinical observations were conducted for all animals after dosing at no specific time point, but within a similar time period after dosing for the respective animals. Once prior to start of treatment and at weekly intervals during the treatment period this was also performed
outside the home cage in a standard arena.

BODY WEIGHT: Yes
- Time schedule for examinations: Males and females were weighed on the first day of exposure and weekly thereafter. Mated females were weighed on Days 0, 4, 7, 11, 14, 17 and 20 post-coitum and during lactation on Days 1 and 4.

FOOD CONSUMPTION:
Weekly, except for males and females which were housed together for mating and for females without evidence of mating. Food consumption of
mated females was measured on Days 0, 4, 7, 11, 14, 17 and 20 postcoitum and on Days 1 and 4 of lactation.

WATER CONSUMPTION:
Subjective appraisal was maintained during the study, but no quantitative investigation was introduced as no treatment related effect was suspected.

OPHTHALMOSCOPIC EXAMINATION: Yes / No / No data
- Time schedule for examinations:
- Dose groups that were examined:

HAEMATOLOGY: Yes
- Time schedule for collection of blood: on the day of scheduled post mortem examination between 7.00 and 10.30 a.m.
- Anaesthetic used for blood collection: Yes, isoflurane
- Animals fasted: Yes
- How many animals: the selected 5 animals/sex/group
- Parameters checked: White blood cells, Differential leucocyte count, Red blood cells, Reticulocytes, Red blood cell distribution width, Haemoglobin, Haematocrit, Mean corpuscular volume, Mean corpuscular haemoglobin, Mean corpuscular haemoglobin concentration MCHC, Platelets, Prothrombin time, Activated Partial thromboplastin time

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: on the day of scheduled post mortem examination between 7.00 and 10.30 a.m.
- Animals fasted: Yes
- How many animals: the selected 5 animals/sex/group
- Parameters checked: Alanine aminotransferase, Aspartate aminotransferase, Alkaline phosphatase, Total Protein, Albumin, Total Bilirubin, Urea, Creatinine, Glucose, Cholesterol, Sodium, Potassium, Chloride, Calcium, Inorganic Phosphate, Bile acids

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: The selected males were tested during Week 4 of treatment and the selected females were tested towards the end of the scheduled lactation period after clinical signs observations (incl. arena observations, if applicable) and before blood sampling.
- Dose groups that were examined: the selected 5 animals/sex/group.
- Battery of functions tested: hearing ability, pupillary reflex, static righting reflex, grip strength, locomotor activity

REPRODUCTION DATA
Male number paired with, mating date, confirmation of pregnancy, and delivery day were recorded. Pregnant females were examined to detect signs of difficult or prolonged parturition, and cage debris of pregnant females was examined to detect signs of abortion or premature birth. Any deficiencies in maternal care (such as inadequate construction or cleaning of the nest, pups left scattered and cold, physical abuse of pups or apparently inadequate lactation or feeding) were examined (see section 7.8.1 and 7.8.2 for details).

Fetal examinations:

PARAMETERS EXAMINED
The following parameters were examined in F1 offspring:
Mortality / Viability, clinical signs, body weights, sex

GROSS EXAMINATION OF DEAD PUPS:
yes, for external abnormalities; if possible, defects or cause of death were evaluated.

NECROPSY
Pups surviving to planned termination were killed by decapitation on Days 5 and 7 of lactation. All pups were sexed and descriptions
of all external abnormalities were recorded. The stomach was examined for the presence of milk. If possible, defects or cause of death were evaluated.

Statistics:

The following statistical methods were used to analyze the data:
- If the variables could be assumed to follow a normal distribution, the Dunnett-test based on a pooled variance estimate was applied for the comparison of the treated groups and the control groups for each sex.
- The Steel-test was applied if the data could not be assumed to follow a normal distribution.
- The Fisher Exact-test was applied to frequency data.
The following additional methods of statistical analysis were used:
Motor activity data was subjected to the Kruskal-Wallis nonparametric ANOVA test to determine intergroup differences followed by the Wilcoxon test to compare the treated groups to the control group.
All tests were two-sided and in all cases p < 0.05 was accepted as the lowest level of significance.
Group means were calculated for continuous data and medians were calculated for discrete data (scores) in the summary tables. Test statistics were calculated on the basis of exact values for means and pooled variances. Individual values, means and standard deviations may have been rounded off before printing. Therefore, two groups may display the same printed means for a given parameter, yet display different test statistics values.

Indices:

Mating index, Fertility index, Conception index, Gestation index, Duration of gestation, Percentage live males at First Litter Check, Percentage live females at First Litter Check, Percentage of postnatal loss Days 0-4 of lactation, Viability index

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Details on maternal toxic effects:
No substance-related effects were observed for maternal rats.

Effect levels (maternal animals)

1

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

2

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Maternal abnormalities

Abnormalities:

no effects observed

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Details on embryotoxic / teratogenic effects:
No toxicologically relevant effects on the gestation index and duration, parturition, maternal care and early postnatal pup development (mortality, clinical signs, body weight and macroscopy) were observed.

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no effects observed

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Based on these results, a parental, reproduction and developmental No Observed Adverse Effect Level (NOAEL) of at least 1000 mg/kg bw/day was derived.

Executive summary:

A GLP compliant combined 28-day repeated dose toxicity study with the reproduction/developmental toxicity screening test was performed in male and female Wistar Han rats at dose levels of 62.5, 250 and 1000 mg/kg bw/day. Animals of the control group received the vehicle, propylene glycol, alone.Males were exposed for 29 days, i.e. 2 weeks prior to mating, during mating, and up to termination. Females were exposed for 40-54 days, i.e. during 2 weeks prior to mating, during mating, during postcoitum, and during at least 4 days of lactation. The following observations and examinations were evaluated: mortality / viability, clinical signs (daily), functional observations and locomotor activity (Males: Week 4; females: end of lactation), body weightand food consumption (at least at weekly intervals), clinical pathology (Males: Week 4; females: end of lactation), macroscopy at termination, organ weights and histopathology on a selection of tissues, and reproduction/developmental parameters, consisting of mating, fertility and conception indices, precoital time, number of corpora lutea and implantation sites, gestation index and duration, parturition, maternal care, sex ratio and early postnatal pup development (mortality, clinical signs, body weights and macroscopy). Accuracy, homogeneity and stability of formulations were demonstrated by analyses.

At 1000 mg/kg bw/day, there was an increased severity of multifocal hypertrophy in the adenohypophysis of the pituitary gland in males. The severity (moderate) was higher than background for a single male. No toxicologically relevant changes were noted in any of the remaining parental parameters investigated in this study (i.e. clinical appearance, functional observations, body weight, food consumption, clinical laboratory investigations, macroscopic examination and organ weights). No developmental toxicity was observed up to the highest dose level tested (1000 mg/kg bw/day).

In conclusion, treatment with the test article by oral gavage in male and female Wistar Han rats at dose levels of 62.5, 250 and 1000 mg/kg body weight/day revealed histological findings at 1000 mg/kg body weight/day characterized by an increased severity of multifocal hypertrophy in the adenohypophysis of the pituitary gland in males only. As this was higher thanbackground in only a single male, when taken together in the absence of any other toxicologically relevant effects, the NOAEL was considered to be 1000 mg/kg bw/day for parental animals. No reproduction and developmental toxicity was observed for treatment up to 1000 mg/kg body weight/day. Based on these results, a parental, reproduction and developmental No Observed Adverse Effect Level (NOAEL) of at least 1000 mg/kg bw/day was derived.