Registration Dossier

Toxicological information

Developmental toxicity / teratogenicity

Currently viewing:

Administrative data

Endpoint:
developmental toxicity
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
1988-04-18 to 1988-05-24
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study is classified as reliable without restrictions because it closely followed OECD Guideline 414 and appears to be GLP compliant
Justification for type of information:
HYPOTHESIS FOR THE CATEGORY APPROACH (ENDPOINT LEVEL)
Petroleum substances of the RAE category are UVCB substances grouped within established production boundaries based on phys-chem properties and hydrocarbon type (a full justification for this grouping is given in the category justification document attached to the category object and to Section 13 of this dossier); substances within the RAE category have qualitatively similar properties. The prediction for read-across of hazard information on relevant human health endpoints in the category will be based on what is considered to be the worst-case substance.

The registered substances of the RAE category comprise complex combinations of hydrocarbon constituents. Based on the boiling point, the hydrocarbons present will be predominantly > C25 (boiling > 380 0C) and can be broadly characterized into distinct hydrocarbon classes, namely mostly cyclo-alkanes and aromatics. As described in more detail in the document attached below (“RAE PNDT Read-across Hypothesis”), there are sufficient data showing that the aliphatic constituents of petroleum substances are not developmental toxicants, do not affect fertility, and do not produce reproductive organ toxicity (references to these data are included in Section 2 of the attached document). For aromatic molecules, data indicate that mainly 3-7 ring polycyclic aromatic compounds (PACs) may be associated with reproductive toxicity. These data include high boiling petroleum products with a relatively high level of PACs which do show potential for reproductive toxicity, whereas effects are absent in similar products without PACs.

It is therefore hypothesised that the reproductive toxicity of RAE will be related to the types and levels of aromatics present, and will generally follow a pattern of increasing severity with increased percentage of 3 – 7 ring PACs. In general, any trend for the developmental toxicity of petroleum products would thus be hypothetically described in terms of increasing aromatic content and number of fused aromatic rings. For RAE specifically, based on the petroleum process by which these are produced they can have relatively high or low 3+-ring PACs.

In conclusion, there is a hypothetical case to suggest that any developmental reproductive effects observed in petroleum substances are associated with 3 – 7 ring PACs, and there is in-vitro and in-vivo toxicity data to support this hypothesis. However, there is no comprehensive investigation of fertility and the implications of interaction with the AhR receptor, which is thought to be a critical step in the underlying mechanism of action for these effects. Currently, Concawe has several research efforts ongoing to further support these hypotheses for reproductive toxicity; results will be published in peer reviewed scientific journals and will be submitted in future dossier updates as they come available.

CATEGORY APPROACH JUSTIFICATION (ENDPOINT LEVEL)
Crude oil (Petroleum, CAS 8002-05-9) is a complex combination of hydrocarbons, a so called UVCB (unknown variable composition, complex reaction products, biological materials) extracted in its natural state from the ground. It consists predominantly of aliphatic, alicyclic and aromatic hydrocarbons. It is used as a feedstock for petroleum refining operations, which separate and convert it into UVCB fractions. RAEs are one of these fractions and produced by extraction of mainly aromatic molecules from heavier petroleum streams such as lubricating base oils.

It is important to note that petroleum UVCBs are not intentional mixtures of chemicals but are substances comprising of complex combinations of hydrocarbon species, produced to meet physical-chemical and technical performance specifications. Refining processes leading to these substances can vary slightly between manufacturers, which is reflected in the CAS number. For RAE specifically, this means that the 2 RAE CAS numbers are produced by slightly different refining processes but still leading to the same petroleum product to meet performance specifications for RAEs, and are thus expected to have similar compositional – and therefore toxicological- properties. Although the domain of this category of UVCB substances can be described by these broader parameters like boiling point / carbon number ranges corresponding to the refining processes by which the category members are produced, the characterization of the toxicity of hydrocarbon UVCBs, including RAE, by assessing or summing the contributions of the individual constituents is not feasible because of the very large number of individual hydrocarbons and their isomers present (thousands to millions).

For this end point (rodent developmental toxicity there is a rat dermal embryo-foetal development study with CAS number 64742-10-5. This study will be supported with information on rodent developmental toxicity from within the RAE category, including the following:
• Rat OECD 422 (screening studies for reproductive and repeat dose toxicity) with both category members
• The embryonic stem cell test (EST) and a number of other in-vitro tests to assess the prenatal developmental toxicity hazard (such as the zebra fish embryo test and various receptor binding assays) will be conducted for all CAS numbers. The EST test has been validated by ESAC (2002) [1] and is recommended as part of an integrated strategy [2] to address developmental toxicity. The test can be used as a predictive test and/or part of the ‘weight of evidence’ for addressing the endpoint of developmental toxicity in REACH [3].
• A Rat OECD 443 (Extended One Generation Reproductive Study) with CAS number 91995-70-9

Information for read-across to CAS number 91995-70-9 will be supported with the following information:
• OECD 422 (screening studies for reproductive and repeat dose toxicity) for both RAE category members. This will allow comparison of toxicity endpoints between the substances.
• The EST as mentioned above will again allow a comparison within the categories.
• CatApp data which is aiming to develop a framework to support chemical-biological grouping and read-across of PS. In addition, initial data coming out of Cat-App provide further support that grouping of substances may indeed be dependent on their refining history and the percentage of PAH.
• Analytical data, for comparison within categories.

It should be noted that the in vivo work mentioned above is part of Concawe’s overall Human Health strategy, and is still to be initiated. In the first instance Concawe would like to explore building a robust argument for read-across using this data (when it is available), before initiating additional animal studies. However, Concawe accept that if this is not possible then a testing proposal for a rodent developmental toxicity study will be required.
See Category Justification Document for more detailed information.

[1] https://eurl-ecvam.jrc.ec.europa.eu/about-ecvam/archive-publications/publication//Embryotoxicity_statements.PDF
[2] Document of the subgroup ‘reproductive and developmental toxicity’ ECVAM-JRC
[3] https://echa.europa.eu/documents/10162/23047722/ir_csa_r7a_r76_reprotox_draft_en.pdf/e4ab36a5-e3d4-456c-b1d3-d9efcba31001

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1989
Report Date:
1989

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
GLP compliance:
not specified
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Mobilsol 40
- Substance type: Residual Aromatic Extract
- Density 0.95 g/ml

Test animals

Species:
rat
Strain:
Sprague-Dawley
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratories, Kingston, New York
- Age at study initiation: 9 weeks
- Weight at study initiation: No data
- Fasting period before study: No data
- Housing: No data
- Diet (e.g. ad libitum): Purina Certified Rodent Chow # 5002; ad libitum
- Water (e.g. ad libitum):Tap water; ad libitum
- Acclimation period: 2 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 to 22
- Humidity (%): 40 to 60
- Air changes (per hr): No data
- Photoperiod (hrs dark / hrs light): 12 hrs dark/12 hrs light


Administration / exposure

Route of administration:
dermal
Vehicle:
unchanged (no vehicle)
Details on exposure:
TEST SITE
- Area of exposure: Dorsal surface
- % coverage: No data
- Type of wrap if used: No wrap used
- Time intervals for shavings or clipplings: Once a week


REMOVAL OF TEST SUBSTANCE
- Washing (if done): No data
- Time after start of exposure: No data


TEST MATERIAL
- Amount(s) applied (volume or weight with unit): Volume not specified; however volume applied was adjusted based on the most recent body weight data
- Constant volume or concentration used: No; volume was adjusted based on the most recent body weight data

USE OF RESTRAINERS FOR PREVENTING INGESTION: No data
Analytical verification of doses or concentrations:
not specified
Details on mating procedure:
- Impregnation procedure: Cohoused
- If cohoused:
- M/F ratio per cage: 1/1
- Length of cohabitation: No data
- Proof of pregnancy: Vaginal plug referred to as day 0 of pregnancy
- Any other deviations from standard protocol: Based on the data provided, no deviations are apparent
Duration of treatment / exposure:
19 days; pre-natal
Frequency of treatment:
Once a day
Duration of test:
19 days
Doses / concentrations
Remarks:
Doses / Concentrations:
500 or 2000 mg/kg/day
Basis:
nominal conc.
No. of animals per sex per dose:
15 animals/dose
Control animals:
yes
Details on study design:
- Dose selection rationale: No data
- Rationale for animal assignment (if not random): Radom; Computer-aided table of random numbers used for a stratified sample of three

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: No data

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Dams were observed at least once a day through the gestation period until sacrifice

BODY WEIGHT: Yes
- Time schedule for examinations: Body weights were taken on days 0, 3, 6, 10, 13, 16 and 20 of the gestation period

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No data
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No data

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

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 20
- Organs examined: Ovaries and uterus of each rat were examined following sacrifice. Number of corpora- lutea per ovary of each pregnant rat was also counted and recorded


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: Number of live and dead foetuses were also noted
Fetal examinations:
- External examinations: Yes: No data regarding number o foetuses examined per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: No data
- Head examinations: No data
Statistics:
Maternal biophase data, caesarean section data, and fetal data were statistically evaluated using analysis of variance (ANOVA) followed by group comparisons using Fisher’s Exact or Dunnett’s test. Fetal skeletal and visceral data were recorded manually and the data were evaluated using ANOVA followed by group comparison using Fisher’s Exact Test.
Indices:
No data
Historical control data:
No Data

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:no effects

Details on maternal toxic effects:
No maternal toxicity effects were noted in any of the treated animals.

Effect levels (maternal animals)

Dose descriptor:
NOAEL
Effect level:
2 000 mg/kg bw/day (nominal)
Basis for effect level:
other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
No developmental toxicity effects were noted in of the litters.

Effect levels (fetuses)

Remarks on result:
other: see Details on embyotoxic/teratogenic effects

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

Pregnant rats treated with Mobilsol 40 exhibited slight skin irritation at the site of application at 500 and 2000 mg/kg-day dose levels. The study authors reported a significant lack in weight gain in animals dosed with 2000 mg/kg-day. However, they concluded that lack in weight gain was not treatment related since a similar lack in weight gain was also noted in a separate postpartum group treated with the same dose of Mobilsol 40. No evidence of developmental effects were observed during external, skeletal and visceral evaluation of rat fetuses from pregnant rats exposed to the test material. Mean fetal body weights were similar for the two dosed groups and the control group. Maternal serum chemistry of pregnant dams were marginally affected in the 200 mg/kg-day dose. However, the study authors reported that since other indications of maternal toxicity were not present, the biological significance of serum chemistry findings were uncertain.

 

Based on these results, a NOAEL of 2000 mg/kg-day was identified for developmental toxicity.

Applicant's summary and conclusion

Conclusions:
The study authors conlcuded that the NOAEL for Mobilsol 40 for developmental toxicity is 2000 mg/kg-day.
Executive summary:

In a developmental toxicity study via dermal application, groups of 15 pregnant Sprague-Dawley rats were clipped free of hair and collared on gestation day 0 prior to treatment with Mobilsol 40. Mobilsol 40 was applied once daily to the clipped and intact dorsal surface of the dams using a spatula at doses of 0, 500 or 2000 mg /kg-day until gestation day 19. The application sites were left uncovered. Animals were clipped once a week and collars were replaced as necessary. Dams were observed once daily for signs of pathosis, abortion, premature delivery, dystocia and or death throughout the gestation period until sacrifice on gestation day 20. On postpartum day 0, pups were examined for external malformations and variations and for the presence or absence of milk in their stomachs.

 

Pregnant rats treated with Mobilsol 40 exhibited slight skin irritation at the site of application at 500 and 2000 mg/kg-day dose levels. The study authors reported a significant lack in weight gain in animals dosed with 2000 mg/kg-day. However, they concluded that lack in weight gain was not treatment related since a similar lack in weight gain was also noted in a separate postpartum group treated with the same dose of Mobilsol 40. No evidence of developmental effects were observed during external, skeletal and visceral evaluation of rat fetuses from pregnant rats exposed to the test material. Mean fetal body weights were similar for the two dosed groups and the control group. Maternal serum chemistry of pregnant dams were marginally affected in the 2000 mg/kg-day dose. However, the study authors reported that since other indications of maternal toxicity were not present, the biological significance of serum chemistry findings were uncertain.

 

Based on these results, a NOAEL of 2000 mg/kg-day was identified for developmental toxicity.

 

This study received a Klimisch score of 1 and is classified as “reliable without restrictions” because it closely followed OECD Guideline 414 and appears to be GLP compliant.