Naphthalene-2-sulphonic acid

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2000

Report date:

2000

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Sodium naphthalene-2-sulphonate

EC Number:

208-523-8

EC Name:

Sodium naphthalene-2-sulphonate

Cas Number:

532-02-5

IUPAC Name:

sodium naphthalene-2-sulfonate

Details on test material:

- Name of test material (as cited in study report): BNS-Na
- Physical state: solid powder
- Analytical purity: 97.7% (according to the authors it was considered to be 100% pure for the preparation of dosage formulations)
- Impurities (identity and concentrations):
- Lot/batch No.: 8509
- Stability under test conditions: the test article was considered stable under the storage conditions
- Storage condition of test material: The test article was stored at room temperature with desiccant in plastic bags, protected from light

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Kingston, New York
- Age at study initiation: 84 days (70 days upon receipt)
- Weight at study initiation: 218 - 290 g
- Housing: individually (except during mating)
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 14 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +- 2 °C
- Humidity (%): 30-70 %
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
An appropriate volume of the vehicle, distilled water, was dispensed into a labeled storage container for administration to the control group. A stir bar
was added and the vehicle was stirred continuously throughout the dosing procedures.
An approprial amount of the test article, BNS-Na, was weighed into a tared, calibrated, labeled storage container. A sufficient volume of the
vehicle was added to bring the volume of the preparation to the calibration mark. The formulations were homogenized using an electric homogenizer
until uniform. A stir bar was added and the preparations were stirred continuously throughout the dosing procedures.
Preparations for all dose groups were prepared weekly (November 15, 22, 29 and December 6, 1999) and were dispensed into daily aliquots for
dose administration. The test article formulations were stored refrigerated, protected from light. The preparations were visually inspected by the study
director on Octoter 28, 1999, and were found to be acceptable for use.


VEHICLE
- Concentration in vehicle: 0, 20, 60 and 200 mg/ml (test substance in vehicle)

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Prior to the initiation of dosing, duplicate 10-ml aliquots were collected from the middle of the control group formulation and from the top, middle and bottom of each treated group formulation. One set of these samples was analyzed for homogeneity. The second set of samples was combined and stored for eight-day stability verification under refrigerated conditions to be consistent with the concurrent 28-Day Toxicity Study.
One 10-ml sample of each weekly dosing preparation (November 15, 22 and 29, 1999 and December 6, 1999), including the control, was analyzed for concentration. The dosing formulations were homogeneous, stable for eight days and contained the amounts of the test article specified in the protocol.

Details on mating procedure:

- Impregnation procedure: [cohoused]
- If cohoused:
- M/F ratio per cage: 1/1
- Length of cohabitation: not specified
- no further data
- Verification of same strain and source of both sexes: [yes]
- Proof of pregnancy: [sperm in vaginal smear] referred to as [day 0] of pregnancy

Duration of treatment / exposure:

gestation days 6 through 19

Frequency of treatment:

once daily

Duration of test:

the animals were sacrificed on day 20 of gestation

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 100, 300, 1000 mg/kg bw/day
Basis:
analytical conc.

No. of animals per sex per dose:

25

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dose levels were selected based on a preliminary five-day toxicity study using nonmated females.

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily for moribundity and mortality and one hour after dosing for signs of toxicity


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily, days 0 through 20 of gestation


BODY WEIGHT: Yes
- Time schedule for examinations: Individual maternal body weights for all females were recorded on gestation days 0 and 6-20 (daily).


POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 20
- Organs examined: The thoracic, abdominal and pelvic cavities were opened by a ventral midline incision, and the contents were examined.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes

Fetal examinations:

- External examinations: Yes: [all per litter]
- Soft tissue examinations: Yes: [all per litter]
- Skeletal examinations: Yes: [all per litter]
- Head examinations: Yes: [one half per litter: soft tissue examination, other half: examined by a mid-coronal slice]

Statistics:

All analyses were conducted using two-tailed tests for a minimum significance level of 5%, comparing each treated group to the vehicle control
group. The following statistical tests were performecl using appropriate computing devices or programs: One-way ANOVA with Dunnett's test and Kruskal-Wallis test with Mann-Whitney U-test.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Details on maternal toxic effects:
All animals survived to the scheduled necropsy on gestation day 20. No treatment-related clinical findings were observed in the 100, 300 and 1000 mg/kg/day groups. Clinical findings in these treated groups including hair loss, swelling, staining and matting on various body surfaces at the daily examinations and/or one-hour post-dosing observations occurred infrequently, similarly in the control group, in single animals or in a manner that was not suggestive of a relationship to treatment.
Mean maternal body weights, body weight gains, gravid uterine weights, net body weights and net body weight gains in the 100, 300 and 1000 mg/kg/day groups were unaffected by treatment with the test article. The differences from the control group were slight and not statistically significant.
Food consumption, evaluated as g/animal/day and g/kg/day, in the 100, 300 and 1000 mg/kg/day groups was unaffected by treatment with the test article. Differences from the control group were slight and not statistically significant with the exception of the 300 mg/kg/day group g/kg/day value that was statistically significantly (p<0.05) decreased during gestation days 13-14 and 18-19.
At the scheduled necropsy on gestation day 20, no test article-related internal findings were observed at any dose level. Female no. 33811 in the 100 mg/kg/day group had enlarged placentae (sites 4, 6, 7 and 9). In the 300 mg/kg/day group, female no. 33742 had an enlarged cervical lymph node (left). Female no. 33866 in this same group had a mass on the right inguinal mammary gland. All other animals in the control, 100, 300 and 1000 mg/kg/day groups were internally normal.

Effect levels (maternal animals)

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day

Basis for effect level:

other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Details on embryotoxic / teratogenic effects:
Intrauterine growth and survival were unaffected by treatment in the 100, 300 and 1000 mg/kg/day groups. Parameters evaluated included preimplantation loss, postimplantation loss, viable litter size, fetal body weights, fetal sex ratios and the numbers of corpora lutea and implantation sites.
The numbers of fetuses (litters) available for morphological evaluation were 328(23), 328(22), 359(24) and 338(23) in the control, 100, 300 and 1000 mg/kg/day groups, respectively. Fetal external, soft tissue and skeletal malformations were observed in 2(2) and 1(1) fetuses (litters) in the control and 1000 mg/kg/day groups, respectively, and were considered to be spontaneous in origin. Fetal developmental variations in the treated groups occurred similarly in the control group, occurred at low incidence or occurred in a manner that was not dose-related and were not considered to be related to treatment with the test article. No statistically significant differences in malformations or developmental variations were observed between the control and treated groups.

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day

Basis for effect level:

other: teratogenicity

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Any other information on results incl. tables

All dams survived the treatment to the scheduled necropsy on gestation day 20. From the 25 dams/group 23 (92%), 22 (88%), 24 (96%) and 23 (92%) animals were pregnant in the control, the 100, 300 and 1000 mg/kg bw group, respectively.
No treatment-related clinical findings were noted in the three dose groups when compared to the concurrent control group.
Mean maternal body weighs, body weight gains, gravid uterine weights, net body weights and net body weight gains were unaffected by treatment in all three dose groups.
Food consumption was unaffected by treatment with the test substance. The only statistically significant difference from the control group was seen in the mid dose group (300 mg/kg bw/day) in the form of temporarily decreased food consumption during gestation days 13-14 and 18-19. Due to the temporary appearance and the occurrence only in the mid dose group, this finding is not regarded to be treatment-related.
No test substance-related internal findings were recorded for the dams at any dose level on gestation day 20.
Intrauterine growth and survival (represented by the following parameters: preimplantation and postimplantation loss, viable litter size, fetal body weights, fetal sex ratios and the no. of corpora lutea and implantation sites) were unaffected by treatment in the three dose groups.
With respect to fetal morphological data the numbers of fetuses (litters) available for morphological investigation were 328 (23), 328 (22), 359 (24) and 338 (23) in the control, the 100, 300 and 1000 mg/kg bw/day groups, respectively.
Malformations were observed in 2 (2) and 1 (1) fetuses (litters) in the control and 1000 mg/kg bw/day groups, respectively and were considered to be spontaneous in nature. One fetus each in the control and the high dose group had external malformations. The control fetus had vertebral agenesis and the high dose fetus had localized fetal edema of the neck and thorax. No other external malformations and no external developmental variations were observed in fetuses at any dose level.
No soft tissue malformations were found at any dose level. Soft tissue variations were seen in one control fetus in the form of a major blood vessel variation and in two fetuses of the low dose group, showing distended ureters.
The only skeletal malformation seen was sternoschisis in one control and one high dose group fetus.
Skeletal variations noted (in the form of cervical centrum no. 1 ossified, sternebra(e) nos. 1,2,3,4,5 and/or 6 unossified, 14th rudimentary ribs and unossified hyoid) were seen at similar frequencies in the control and dose group fetuses. Cases of 7th cervical rib(s), reduced ossification of the 13th rib(s), pubis unossified, sternebra(e) malaligned, bent rib(s), were observed in single fetuses or at a similar frequency in the control group and/or a dose-response relationship was missing.
Percentages of skeletal variations per litter were 33.4%, 28.0%, 34.0% and 31.6% for the control, the 100, 300 and 1000 mg/kg bw group, respectively.

According to the authors, no maternal or developmental toxicity was observed at any dose level.
Thus, the NOAEL (no-observed-adverse-effect level) for maternal and prenatal developmental toxicity was considered to be 1000 mg/kg bw/day.