Distillates (petroleum), light paraffinic

Additional toxicological data

Administrative data

Endpoint:

additional toxicological information

Adequacy of study:

other information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The report evaluated was incomplete but nevertheless was sufficient to identify the relevant effects of exposure to the test material.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Materials and methods

Type of study / information:

Type: other: Developmental toxicity screen on Heavy vacuum gas oil

Test material

Test material information

Constituent 1

Reference substance name:

Automatically generated during migration to IUCLID 6, no data available

IUPAC Name:

Automatically generated during migration to IUCLID 6, no data available

Details on test material:

The sample of Heavy vacuum gas oil (CAS 64741-57-7) was produced by the vacuum distillation of crude oil. It was a dark amber liquid with a boiling range of approximately 657 to 1038 °F and density 0.93 g/ml. The sample (CRU #85244) originated from the Beaumont crude
unit B and contained:
54% paraffins
35% polycyclic aromatic hydrocarbons
2% nitrogen-containing polycyclic aromatic hydrocarbons
9% residuals

Results and discussion

Any other information on results incl. tables

Parental animals.

There were no clinical signs attributable to exposure to HVGO other than in the highest dose group in which 2 rats had a red vaginal discharge, one animal was pale in color and six had decreased stool. The latter observation was probably associated with smaller food consumption in this group. Although food consumption was generally also less than controls in the 500 mg/kg/day group there was no associated body weight decrease.

At doses in excess of 125 mg/kg/day there was a decrease in mean body weights which reflected the decreased litter sizes for this group.

The only dose-related finding at gross necropsy was a pale appearance of lungs in a few animals. 4 animals were affected at the highest dose and only one in the 500 mg/kg/day group.

Mean thymus weights of animals in the highest dose group were approximately half those of the control groups. Although absolute liver weights were unaffected by exposure to HVGO, mean relative liver weights were increased (approximately 15%) in groups exposed to doses greater than 125 mg/kg/day.

Observations of Dams at Caesarean section.

Parameters with treatment-related effects are shown below

0(R) 0(P) 30 125 500 1000	0(R)	0(P)	30	125	500	1000
Pregnant females	9	10	10	8	10	9
Dams with viable fetuses	9	10	10	8	10	6
Dams with all resorptions	0	0	0	0	0	3
Mean litter size of viable fetuses	13.9	14	13.8	14.4	10	5.8
Resorptions	1.1	0.6	1.1	1.1	5.6	9.9
Mean  % Dams with resorptions	56	50	70	63	100	100

    

Parameters unaffected were:
        No. premature births
        Female mortality
        No. corporea lutea
        No. implantation sites
        Pre-implantation losses
        Viable male fetuses
        Viable female fetuses
        No. dead fetuses
         
Fetal evaluations

fetal body weights were significantly reduced in fetuses exposed in utero to HVGO at doses in excess of 125 mg/kg/day.

Although there were differences between control and treated crown-rump lengths they were not statistically significant. At the time of external examination, malformations were observed in one fetus in the 1000 mg/kg/day group.  The fetus was edematous and pale in color. Both hindpaws were malformed; the digits were reduced in size with a subcutaneous hematoma located at the distal most aspect of each of the digits.

Malformations of the vertebral column were restricted to the 500 mg/kg/day group.

Although a variety of skeletal malformations were observed in treated and control groups the degree of aberant development in control fetuses was not as severe as in the HVGO-exposed groups.

Visceral malformations were restricted to two fetuses in the 500 mg/kg/day group.  One fetus had microphthalmia and the other fetus had a diaphragmatic hernia which displaced the heart from the left to right hand side.

The authors concluded that the maternal NOAEL was 125
mg/kg/day and that the fetal NOAEL was also 125 mg/kg/day