Extracts (petroleum), solvent-refined heavy paraffinic distillate solvent

Endpoint summary

Description of key information

TDAEs: IP 346 > 3%:

Dermal application of radio labelled distillate aromatic extract in the pregnant rat resulted in low levels of uptake of key constituents in maternal tissues.  Very low levels of radioactivity were detected in the foetus.

TDAEs: IP 346 < 3%

In key animal toxicity studies that investigated the toxicokinetic activity of highly refined base oils, no mortalities were observed. Highly refined base oils were not well absorbed overall, with <5% absorbed and the rest excreted in the faeces.  Orally administered, sufficiently refined hydrocarbons (hydrotreated highly refined base oils) were observed to have metabolized to the corresponding fatty acids of the same carbon chain length as the parent carbons, suggesting omega oxidation (in male and female rats). Simple mixtures of aliphatic hydrocarbons (IP 346 < 3%) when orally administered to CD male rats demonstrated that percentage retention was inversely proportional to the number of carbon atoms and ranged from 60% for C14 to 5% for C28 compounds, the small intestine being the major site of absorption. Both oral and i.p. routes of administration exhibited the same characteristics of absorption in studies conducted in rats.  

Key value for chemical safety assessment

Bioaccumulation potential:

low bioaccumulation potential

Additional information

Treated distillate aromatic extracts (TDAEs) are a further processing of untreated distillate aromatic extracts (UDAEs) in an attempt to reduce the amount of 3-7 ring PAC that is present. Since the treatment is mostly a selective reduction of PACs, the data from UDAEs can serve as read across where treatment was insufficient and a significant amount of PACs still remain (≥ 3 wt% DMSO extractables as measured by IP-346). Where treatment was sufficient to reduce the 3-7 ring PACs (<3 wt% DMSO extractables as measured by IP-346), the material is most similar to refined lubricating base oils and these data can be used for read across. 

TDAEs (IP 346 ≥ 3 wt%)

In a key read across bioavailability toxicokinetics study in pregnant rats, 1000 mg/kg of radiolabelled 318 isthmus furfural extract (an untreated distillate aromatic extract) was dermally applied on gestation days 10, 11, and 12 (Mobil 1989; Klimisch score = 2). Maternal tissues, blood, placentas, uteri, embryos, and yolk sacs were collected and analyzed for radioactivity on gestation day 13 following sacrifice. Urine, faeces, and cage wash was collected every 24 hours and also analyzed for radioactivity.

Dermal absorption of 14C-carbazole occurred more extensively than did 3H-benzo(a)pyrene over a 72 hour period. About 19.9% and 4.1% of the total applied of 14C-carbazole and 3H-benzo(a)pyrene, respectively, was dermally absorbed. Of the total absorbed dose of 14-C-carbazole, 2.1% was found in the maternal tissues and less than 0.01% was detected in the embryo. Of the total absorbed dose of 3H-benzo(a)pyrene 1.8% was detected in the maternal tissue and less than 0.01% was found in the embryo. 17.7% of 14C-carbazole was excreted in the urine and faeces over 72 hours. 2.3% of 3Hbenzo(a)pyrene was excreted in the urine and faeces over 72 hours.

Based on the bioavailability results, neither of the radiolabelled components of 318 isthmus furfural extract were found to selectively accumulate in the embryo.

Mutagenicity and carcinogenicity of a series of 39 petroleum oils, including several DAEs, were correlated with the content of 3-7 ring PACs. Further, the steady-state dermal penetration of PAC in long-term testing was also determined predominantly by PAC concentration. Although aromaticity and viscosity had a minimal effect on dermal penetration, neither was an important determinant of the carcinogenic potency.

Substances in this category are UVCBs; hence it is not possible to apply standard methodology for assessing absorption, distribution and metabolism. Relevant data for use in risk assessment are available for constituent compounds.

TDAEs (IP 346 < 3 wt%)

In a basic key read across toxicokinetics study (Baldwin et al., 1992; Klimisch score = 2), a group of male and female rats were fed oleum-treated highly refined base oil and hydrotreated highly refined base oil in concentrations of 5000, 10000, 20000 ppm and a group of female rats were fed OTWO and HTWO in concentrations of 10, 100, 500, 1000, 10000, 20000 ppm for a period of 13 weeks. Animals were euthanized at the conclusions of the study, after which haematological, clinical chemistry, gross necropsy, tissue residue, and histopathological examination were performed. 

Pathological findings in the test animals were quantitatively similar to those previously associated with the ingestion of mineral hydrocarbons by a range of species, but the effects occurred at much lower levels of dietary intake than previously reported. No pathological changes were observed after 25 days of feeding, but after 90 days there were very slight to moderate multifocal granulomatous changes in mesenteric lymph nodes and liver. Although rats fed the oleum-treated highly refined base oil were more affected than those fed the hydrotreated highly refined base oil differences in the specification of each oil rather than processing method were more likely to have accounted for the variation. The insufficiently refined hydrocarbons oleum-treated highly refined base oils are suggested to undergo a process of omega oxidation. The sufficiently refined hydrocarbons (hydrotreated highly refined bas oils; IP 346 <3%) are metabolized to the corresponding fatty acids of the same carbon chain length as the parent carbons, suggesting omega oxidation.

A supporting read across toxicokinetics study performed by Albro et al. (1970; Klimisch score = 2) evaluated absorption of hydrocarbon mixtures (IP 346 <3%). Simple mixtures of aliphatic hydrocarbons were administered to CD male rats by gastric intubation at dose levels of up to 500 mg/kg b.w. The percentage retention of the aliphatic hydrocarbons was inversely proportional to the number of carbon atoms and ranged from 60% for C14 to 5% for C28 compounds. The major site of absorption was found to be the small intestine.

A supporting read across toxicokinetic study performed by Ebert et al. (1966; Klimisch score = 2) evaluated the distribution of mineral oil (IP 346 < 3%) administered orally and via i.p. injection. Male and female Sprague-Dawley and Holtzman rats were treated orally and via i.p. injection with 0.66 mg/kg bw of non-labelled mineral oil for 31 consecutive days. Tritiated mineral oil was given on the thirty-second day,as at final dose. Both oral and i.p. routes of administration exhibited the same characteristics of absorption. Results indicated that radioactivity was found in liver, fat, kidney, brain, and spleen. After oral administration, the concentration of tritiated mineral oil decreased rapidly to 0.3% within 2 days post treatment and very slowly by day 21 indicating a very low absorption. After i.p administration the extraction was very slow: 11% was found in faeces within 8 days post treatment and negligible traces were found in urine.