Gas oils (petroleum), straight-run

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study is classified as reliable without restrictions because it was GLP compliant and was conducted generally according to OECD 414 guidelines.

Justification for type of information:

HYPOTHESIS FOR THE CATEGORY APPROACH (ENDPOINT LEVEL)
Petroleum substances of the SRGO 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 a separate document reference); substances within the SRGO 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 SRGO category comprise complex combinations of hydrocarbon constituents. Based on boiling point distribution, the hydrocarbons present will be predominantly in the range of C9-C25 (boiling in the range of 150-471 0C) and can be broadly characterized into distinct hydrocarbon classes, namely aliphatics and aromatics. As described in more detail in the document attached below (“SRGO 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 SRGO 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. Any trend for the developmental toxicity of gas oils would thus be hypothetically described in terms of increasing aromatic content and number of fused aromatic rings. For SRGO specifically, which does not have high levels of 3+-ring PACs, it is hypothesised that there is low potential for adverse effects in developmental reproductive toxicity tests from exposure to VHGOs.
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 (petroleum streams) as shown in the diagram in the attached document. Gas Oils (SRGO, OGO and VHGO) are one of these streams and are consistently distilled between the lighter stream (lower boiling pt) of Kerosine and the heavier stream (higher boiling pt) of Fuel Oil (all gas oils have an approximate carbon range of C9-C30 with SRGO at the lighter- and VHGO at the heavier end). Therefore only the hydrocarbon constituents present in crude oil that come off at this specific boiling point range will be present in SRGO with some overlap between neighbouring streams. They will share some common molecule types, which can give us some indication to the (reproductive) toxicity potential of SRGO substances when this information is available for these related streams.
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 SRGO specifically, this means that the 4 SRGO CAS numbers are produced by slightly different refining processes but still leading to the same petroleum product to meet performance specifications for SRGO, 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 SRGO, 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).
SRGO substances are used to manufacture distillate fuels (automotive diesel fuels, home heating oils, marine gas oils), as petrochemical intermediates or as components of formulated lubricants and additives (see Concawe identified uses of petroleum substances document: https://www.concawe.eu/wp-content/uploads/2017/05/Uses_Map_for_Website-21_December_2016.pdf). The only relevant routes of exposure for SRGO, as with most petroleum products especially those which are mainly used as fuels, are dermal and inhalation.
See Category Justification Document for more detailed information.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

64741-43-1

Cas Number:

64741-43-1

IUPAC Name:

64741-43-1

Constituent 2

Reference substance name:

Straight-run petroleum gas oil, F-193

IUPAC Name:

Straight-run petroleum gas oil, F-193

Test material form:

other: liquid

Details on test material:

Sample F193
Straight Run Gas Oil
CAS 64741-43-1
Appearance: brown to black-coloured liquid; slightly cracked or burnt to asphaltic odour
Details of this material from MSDS:
Flash point: 150 °F
Boiling range: 320 - 800 °F
Autoignition T: 505 °F
Flammable limits: 0.7-6 % volume in air
Specific gravity: 0.89 - 0.95
Viscosity at 100°F: 200-2000 SUS
Reid Vapour pressure at 100°F: 0.1 psia
Vapour specific gravity: 10.0

Test animals

Species:

rat

Strain:

other: Crl:CD BR VAF/Plus

Administration / exposure

Route of administration:

dermal

Vehicle:

acetone

Duration of treatment / exposure:

Days 0 through 19 of gestation

Frequency of treatment:

Daily

Duration of test:

Days 0 through 20 of gestation

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 50, 250, or 500 mg/kg bw/day
Basis:
nominal conc.

No. of animals per sex per dose:

25 dams per dose

Control animals:

yes

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes

Effect levels (maternal animals)

1

Dose descriptor:

LOAEL

Effect level:

50 mg/kg bw/day

Basis for effect level:

other: maternal toxicity

2

Dose descriptor:

NOAEL

Effect level:

50 mg/kg bw/day

Basis for effect level:

other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:yes

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

Applicant's summary and conclusion

Conclusions:

The maternal toxicity LOAEL was 50 mg/kg/day, based on dermal effects. There was no maternal NOAEL. The developmental LOAEL was 250 mg/kg/day, based on pup body weight and malformations. The developmental NOAEL was 50 mg/kg/day.

Executive summary:

In a developmental toxicity study, straight-run petroleum gas oil (F-193) in acetone was dermally administered to 25 presumed pregnant rats/dose at dose levels of 0, 50, 250, or 500 mg/kg bw/day from days 0 through 19 of gestation.

 

Skin reactions (erythmea, oedema, atonia, and desquamation) occurred in all treatment groups. There was a significant reduction in body weight and food consumption in the 250 and 500 mg/kg/day groups.  There was also a significant reduction in average litter size and live foetuses and an increase in resorptions in these groups.  The maternal toxicity LOAEL was 50 mg/kg/day, based on dermal effects. There was no maternal NOAEL. 

There was a significant decrease in pup body weight and increase in external, visceral, and skeletal malformations in the mid- and high-dose groups. The developmental LOAEL was 250 mg/kg/day, based on pup body weight and malformations The developmental NOAEL was 50 mg/kg/day.

 

This study received a Klimisch score of one and is classified as reliable without restrictions because it was GLP compliant and was generally conducted according to OECD 414 guidelines.