Paraffin waxes and Hydrocarbon waxes, microcryst., hydrotreated

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

Study period:

1987-10-28

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study is classified as reliable without restriction because it was performed in compliance with OECD guideline 414.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1987

Report date:

1987

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

yes

Remarks:

Insufficient number of dams per group

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

most likely 64741-88-4

IUPAC Name:

most likely 64741-88-4

Constituent 2

Reference substance name:

Solvent refined base oil, sufficiently refined, IP 346 < 3%

IUPAC Name:

Solvent refined base oil, sufficiently refined, IP 346 < 3%

Test material form:

liquid: viscous

Details on test material:

Read Across to Other Lubricant Base Oils
This substance is similar to the feed to most of current dewaxing operations.

- Name of test material (as cited in study report): 100 SUS solvent refined base oil
- Substance type: lubricant base oil (IP 346 <3%)
- Lot/batch No.: CRU #84120
- Radiochemical purity (if radiolabelling): [1-14C]Octacosane
- Specific activity (if radiolabelling): 6.15 mCi/mmol
- Other: Density = 0.86 g/mL

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories (Kingston, NY)
- Age at study initiation: 10 and 8 weeks old
- Fasting period before study: No
- Housing: Dams were individually housed after mating.
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: December 17, 1985 to January 2, 1986

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 to 22
- Humidity (%): 40 to 60%
- Photoperiod (hrs dark / hrs light): 12 hours dark/12 hours light

Administration / exposure

Route of administration:

dermal

Vehicle:

unchanged (no vehicle)

Details on exposure:

TEST SITE
- Area of exposure: Intact dorsal surface
- Type of wrap if used: No wrap was used
- Time intervals for shavings or clippings: Animals were clipped on gestation day 0 and once weekly thereafter

REMOVAL OF TEST SUBSTANCE
- Washing (if done): No washing was performed
- Time after start of exposure: Test material was not removed after exposure.

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 1 cc of 125, 500, or 2000 mg/kg/day

USE OF RESTRAINERS FOR PREVENTING INGESTION: Yes, Elizabethan-style collars

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

No data reported.

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1:1
- Length of cohabitation: Cohabitation period lasted until 55 presumed pregnant rats were obtained.
- Verification of same strain and source of both sexes: No
- Proof of pregnancy: Females were examined every morning during mating for vaginal sperm plugs. The drop-pans under the animals cages also were checked for expelled vaginal plugs daily. Vaginal lavage fluid was examined for the presence of spermatozoa in those dams that exhibited a vaginal plug either in situ or in the drop-pan. Females with the presence of spermatozoa and a vaginal plug were considered to be at day 0 gestation and placed in individual housing units.

Duration of treatment / exposure:

The test material was applied on dose groups 2 through 4 on gestation days 0 through 19; a fifth dose group was used, in which dams were applied the base oil on gestation day 0-17. A base oil fortified with [1-14C]octacosane was administered on gestation day 18.

Frequency of treatment:

Daily

Duration of test:

The acclimation period started on 17 December, 1985. Visceral evaluations ended on August 27, 1987.

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 125, 500, and 2000 mg/kg/day
Basis:
other: dermal exposure

No. of animals per sex per dose:

Control group (0 mg/kg/day): 15 animals
Group 2 (125 mg/kg/day): 10 animals
Group 3 (500 mg/kg/day): 10 animals
Group 4 (2000 mg/kg/day): 15 animals
Group 5 (2000 mg/kg/day plus [1-14C]octacosene: 5 animals

Control animals:

yes, sham-exposed

Details on study design:

Groups 2 through 4 were administered 125, 500, 2000 mg/kg/day using a 1 cc syringe (calibrated in 0.01 cc). Dams were clipped on the dorsal surface, and the test material was dispensed evenly over the test site. Animals were fitted with Elizabethan-style collars. The control group was clipped and collared in a similar fashion. The dorsal skin of each rat was stroked with the tip of a 1 cc syringe, but no test material was applied. A fifth dose group was used, in which dams were applied the base oil on gestation day 0-17 at a dose level of 2000 mg/kg/day. A base oil fortified with [1-14C]octacosane was administered on gestation day 18.

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: At least once daily
- Cage side observations included pathosis, abortion, premature delivery, and/or death.

DETAILED CLINICAL OBSERVATIONS: No data

BODY WEIGHT: Yes
- Time schedule for examinations: Gestation days 0, 3, 6, 10, 13, 16, and 20

FOOD CONSUMPTION: Yes
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes; gestation days 0-3, 3-6, 6-10, 10-13, 13-16, and 16-20
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20
- Organs examined: Thoracic and abdominal cavities of animals in groups 1 through 4 were exposed and all organs were grossly examined.

OTHER: Clinical chemistry endpoints were also evaluated. Blood samples were collected at the time of sacrifice from the aorta of each rat. Clinical chemistry endpoints measured are presented in Table 1 below.

Dose group 5 was sacrificed by over-exposure to ether on gestation day 20. Blood placentae, and foetuses were collected. Placental and foetal samples were homogenized prior to combustion, while blood samples were combusted directly. 14C Radioactivity was determined in combusted samples via a liquid scintillation counter.

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
- Other: Live and dead foetuses

Fetal examinations:

- External examinations (anomalies, malformations, and variations): Yes: all per litter
- Soft tissue examinations (anomalies, malformations, and variations): Yes: half per litter
- Skeletal examinations (anomalies, malformations, and variations): Yes: half per litter
- Head examinations: No data

Statistics:

An ANOVA followed by Fisher's Exact or Dunnett's test was used to evaluated maternal biophase and caesarean section data. Foetal skeletal and visceral data were evaluated using Fisher's Exact test. Residue data was evaluated through a Student's t-test. Clinical chemistry data was evaluated using the F-test, which was employed to do an ANOVA on the serum data. The Student-Newman-Keul's multiple comparison test was then used. Differences between the control and treated animals were considered statistically significant if the probability of the differences being due to chance was less than 5%.

Indices:

Female mortality; viable female foetuses; viable male foetuses; and preimplantation loss

Historical control data:

No data reported.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
Dermal application of the lubricant base oil to pregnant rats during gestation produced slight dermal irritation at all dose levels. At these dosages, the lubricant base oil produced erythema and flaking of the skin at the site of application in a dose-dependent manner. One animal in the 500 mg/kg/day dose group had dermal oedema. However, no other signs of test material-related toxicity were observed.

Effect levels (maternal animals)

Dose descriptor:

LOAEL

Remarks:

Inferred LOAEL

Effect level:

125 mg/kg bw/day

Basis for effect level:

other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
There was no evidence of teratogenicity. There were no treatment-related changes observed during external, skeletal, or visceral evaluations.

Effect levels (fetuses)

Dose descriptor:

NOAEL

Remarks:

Inferred NOAEL

Effect level:

>= 2 000 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

Skin Irritation (number affected/number examined)
Observation	Dose Groups (mg/kg/day)
	0	125	500	2000
Erythema	0/15	1/10	4/10	9/15
Flaking of Skin	0/15	2/10	2/10	4/15
Oedema	0/15	0/15	1/15	0/15

Applicant's summary and conclusion

Conclusions:

Dermal administration of the base oil did not adversely affect maternal reproductive performance, nor did it affect offspring survival or development.

Executive summary:

Justification for Read Across

This substance is similar to the feedstocks for most of current dewaxing operations that produce the finished paraffin and microcrystalline waxes. These lubricant base oil data may serve as the basis for a worst case assessment of the reproductive potential of paraffin and microcrystalline waxes and are summarised in this section.

In a developmental toxicity study, 100 SUS solvent refined base oil was administered to female Sprague Dawley rats dermally. There were five dose group. Groups 2 through 4 (10 dams/group in Groups 2 and 3; 15 dams/group in Group 4) were administered 125, 500, 2000 mg/kg/day using a 1 cc syringe (calibrated in 0.01 cc). Dams were clipped on the dorsal surface, and the test material was dispensed evenly over the test site. Animals were fitted with Elizabethan-style collars. The control group (Group 1; 15 dams/group) was clipped and collared in a similar fashion. For the control group, the dorsal skin of each rat was stroked with the tip of a 1 cc syringe, but no test material was applied. A fifth dose group (5 dams/group) was used, in which dams were applied the base oil on gestation day 0-17 at a dose level of 2000 mg/kg/day. A base oil fortified with [1-14C]octacosane was administered on gestation day 18.

Dermal application of the lubricant base oil to pregnant rats during gestation produced slight dermal irritation at all dose levels. At these dosages, the lubricant base oil produced erythema and flaking of the skin at the site of application in a dose-dependent manner. One animal in the 500 mg/kg/day dose group had dermal oedema.

There were no other signs of maternal toxicity. Serum components were not adversely affected by the test material. According to the Group 5 results, the test material metabolites were able to pass across the placenta, but did not bioacculmulate in the foetuses. A maternal LOAEL was not reported but can be inferred to be 125 mg/kg/day based on skin irritation.

There was no evidence of teratogenicity. There were no treatment-related changes observed during the external, skeletal, or visceral evaluations. Mean foetal weight and crown-rump lengths were comparable across all dose groups. A developmental/teratogenic NOAEL was not reported; however, it can be inferred that this value is ≥2000 mg/kg/day.

 

This study received a Klimisch score of 1 and is classified as reliable without restriction because this study is compliant with OECD Guideline 414.