Octadecylnaphthalene

Repeated dose toxicity: oral

Administrative data

Endpoint:

repeated dose toxicity: oral, other

Remarks:

28 day repeat dose study

Type of information:

experimental study

Adequacy of study:

key study

Study period:

19 September 2012 to 07 December 2012 (end of in-life phase)

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study without significant deficiencies

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Reference

Name:

Unnamed

Type:

Constituent

Test material form:

liquid: viscous

Details on test material:

Identification: Alkylated Naphthalene
Description: Clear amber slightly viscous liquid
Batch: 18515
Purity/Composition: UVCB 100%

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

Environmental controls for the animal room were set to maintain 18 to 24°C, a relative humidity of 40 to 70%, approximately 15 room air changes/hour, and a 12-hour light/12-hour dark cycle. Any variations to these conditions were maintained in the raw data and had no effect on the outcome of the study.

Rat: Crl:WI(Han) (outbred, SPF-Quality). Nulliparous and non-pregnant females and untreated animals were used at initiation of the study.

Source F0: Charles River Deutschland, Sulzfeld, Germany.

Age at start F0-treatment: Approximately 11 weeks.

Number of F0-animals: 40 females and 40 males.

Acclimatization F0: At least 5 days prior to start of treatment.

Health inspection F0: Upon receipt of the animals.

Randomization F0 Prior to commencement of treatment, by computer-generated random algorithm according to body weight, with all animals within ± 20% of the sex mean.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

Oral gavage, using a plastic feeding tube. Formulations were placed on a magnetic stirrer during dosing.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analytical testing of doses showed they were comparable to nominal target doses.

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. 66 (Group 4) and 75 (Group 4) were not dosed during littering.

Frequency of treatment:

once daily

No. of animals per sex per dose:

10

Control animals:

yes, concurrent no treatment

Details on study design:

The purpose of this study was to evaluate the potential toxic effects of the test substance when administered to rats for a minimum of 28 days and to evaluate the potential of the test substance to affect male and female reproductive performance such as gonadal function, mating behaviour, conception, parturition and early postnatal development.
Parental, reproduction (up to and including implantation) and developmental (from implantation onwards) No Observed Adverse Effect Levels (NOAELs) were evaluated.

Positive control:

No

Examinations

Observations and examinations performed and frequency:

The following observations and examinations were evaluated: mortality / viability, clinical signs (daily), functional observations and locomotor activity (end of treatment), body weight and food consumption (at least at weekly intervals), clinical pathology (end of treatment), 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).

Sacrifice and pathology:

All males and the selected 5 females/group were deprived of food overnight (with a maximum of 24 hours) prior to planned necropsy, but water was provided. Non-selected females were not deprived of food. Animals were deeply anaesthetized using isoflurane (Abbott B.V., Hoofddorp, The Netherlands) and subsequently exsanguinated.

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 (many-to-one t-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 (many-to-one rank 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 Kruskal-Wallis nonparametric ANOVA test was applied to motor activity data to determine intergroup differences

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.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Behaviour (functional findings):

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

Mortality
No mortality occurred during the study period that was considered to be related to treatment with the test substance.

One female at 300 mg/kg (no. 66) was sacrificed after having a total litter loss (her two pups went missing on Day 2 of lactation).

Clinical signs
No clinical signs of toxicity were noted during the observation period.

Incidental findings that were noted for control and/or treated animals included scabbing on both cheeks, scales and scabs on the neck and alopecia. These findings occurred within the range of background findings to be expected for rats of this age and strain which are housed and treated under the conditions in this study. At the incidence observed, these were considered not to be toxicologically relevant.

Functional observations
Hearing ability, pupillary reflex, static righting reflex and grip strength were normal in all selected animals.

The variation in motor activity did not indicate a relation with treatment. All groups showed a similar habituation profile with high activity in the first interval that decreased over the duration of the test period.

Body weights
Body weights and body weight gain of treated animals remained in the same range as controls over the treatment period.

Food consumption
Food consumption before or after allowance for body weight was similar between treated and control animals.

Haematology
No toxicologically relevant changes occurred in haematological parameters of treated rats.

Any statistically significant changes in haematology parameters occurred in the absence of a dose-related trend and means remained within the range considered normal for rats of this age and strain. These changes consisted of a lower haemoglobin and prothrombin time (PT) in males at 300 mg/kg and higher relative monocyte counts in males at 100 mg/kg.

Clinical biochemistry
No toxicologically relevant changes occurred in clinical biochemistry parameters of treated rats.

The higher bilirubin level of females at 1000 mg/kg remained within the range considered normal for rats of this age and strain and occurred in the absence of any supportive morphological or clinical biochemistry changes. No toxicological relevance was therefore ascribed to this change.

Macroscopic examination
Macroscopic observations at necropsy did not reveal any alterations that were attributable to treatment.

Incidental necropsy findings noted for control and treated animals remained within the range of findings considered normal for rats of this age and strain, did not show a dose-related incidence trend, or supportive treatment-related histopathological lesions. Therefore, all observed macroscopic findings were not considered to be toxicologically relevant.

Organ weights
No toxicologically relevant changes were noted in organ weights and organ to body weight ratios.

The statistically significantly lower absolute seminal vesicle weight of males at 100 and 300 mg/kg occurred in the absence of a dose-related trend and means remained within the range considered normal for rats of this age and strain. These changes were therefore considered to be of no toxicological relevance.

Microscopic examination
There were no treatment-related microscopic findings.

There were no microscopic findings in any of the animals suspected of infertility which could explain their lack of reproductive performance.

The spermatogenic staging profiles were normal for all animals assessed.

The recorded microscopic findings were within the range of background lesions encountered in Wistar (Han) rats of this age in this type of study and occurred at similar incidences and severity in both control and treated rats.

Effect levels

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 adverse effects were seen any in either sex in any of the treatment groups.

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

The repeat dose No Observed Adverse Effect Level (NOAEL) is equal to or greater than the high dose of 1000 mg/kg per day.

Executive summary:

A combined 28-day repeated dose toxicity study with the reproduction/developmental toxicity screening test was conducted with Alkylated Naphthalene in rats by oral gavage.

The study was based on  OECD 422, Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test, March 1996.

Rationale for dose levels

Based on the results of a 10-day dose range finding study, the dose levels for this combined 28-day oral gavage study with reproduction/developmental toxicity screening test were selected to be 100, 300 and 1000 mg/kg.

 

Study outline

After acclimatization, four groups of ten male and ten female Wistar Han rats were exposed by oral gavage to the test substance at 0, 100, 300 and 1000 mg/kg.

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, duringpost-coitum, and during at least 4 days of lactation.

 

Evaluated parameters

The following observations and examinations were evaluated: mortality / viability, clinical signs (daily), functional observations and locomotor activity (end of treatment), body weight and food consumption (at least at weekly intervals), clinical pathology (end of treatment), 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).

Results/discussion

 

Parental results:

No parental toxicity was observed up to the highest dose level tested (1000 mg/kg).

 (reproduction and development results are reported in separate endpoint study records)

Treatment with Alkylated Naphthalene by oral gavage in male and female Wistar Han rats at dose levels of 100, 300 and 1000 mg/kg revealed no parental toxicity up to 1000 mg/kg.

 

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