Fatty acids, C18-unsatd., dimers, polymers with 2-ethylhexanol and neopentyl glycol

Endpoint summary

Description of key information

RDT oral (OECD 408), rat NOAEL = 741 and 855 mg/kg bw/day for males and females (RA CAS 61788-89-4)

The NOAEL is corrected for differences in molecular weight between the source and target substance thus, the mass corrected NOAEL is 481.65 - 1820 mg/kg bw/day (males) and 555.75 - 2094.75 mg/kg bw/day (females) for Fatty acids, C18-unsatd., dimers, polymers with 2-ethylhexanol and neopentyl glycol

RDT oral (OECD 408), rat NOAEL = 125 (m/f) mg/kg bw/day (RA CAS 104-76-7)

The NOAEL is corrected for differences in molecular weight between the source and target substance thus, the mass corrected NOAEL is 353.22 - 1330.34 mg/kg bw/day for Fatty acids, C18-unsatd., dimers, polymers with 2-ethylhexanol and neopentyl glycol

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

353.22 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

The available information comprises an adequate and reliable studies from reference substances with similar structure and intrinsic properties. Read-across is justified based on theoretical hydrolysis of the parent substance. The selected studies are thus sufficient to fulfil the standard information requirements set out in Annex VIII-IX, 8.6, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006.

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Justification for read-across

There are no available data assessing the repeated dose toxicity potential of Fatty acids, C18-unsatd., dimers, polymers with 2-ethylhexanol and neopentyl glycol (CAS 68552-19-2). The assessment of repeated dose toxicity was therefore based on studies conducted with the source substances Fatty acids, C18-unsatd., dimers (CAS 61788-89-4) and 2-ethylhexylhexanol (CAS 104-76-7) as part of a read across approach, which is in accordance with Regulation (EC) No 1907/2006, Annex XI, 1.5. in order to fulfil the standard data requirements defined in Regulation (EC) No 1907/2006, Annex VIII, 8.6. Read-across is justified based on theoretical hydrolysis of the test substance. A detailed justification for the analogue read-across approach is provided in the technical dossier (see IUCLID Section 13).

Repeated dose toxicity: oral

CAS 61788-89-4

A reliable repeated dose toxicity (90-day) study with Fatty acids, C18-unsaturated, dimers (CAS 61788-89-4) is available and was performed equivalent or similar to OECD TG 408 and in compliance with GLP (Environmental Safety Laboratory, 1993). Three groups of 20 Sprague-Dawley rats of each sex were fed the test material at 0, 0.1, 1 and 5% (w/w) corresponding to 74.1, 740.9, 3591.2 mg/kg bw/day (males) and 90.5, 854.9, 4085.5 mg/kg bw/day (females) in purified diet for 90 consecutive days. The animals were observed for clinical signs up to two times per day. Food and water consumption was determined twice weekly. Body weights were determined weekly. Ophthalmoscopy was carried out before the start of the study and during the last week of the feeding period. Before necropsy, blood samples were taken for clinical pathology determinations. At necropsy, a full range of tissues were taken for histological examination. All tissues from the control and 5% groups were examined. Liver, adrenals, eyes, mesenteric lymph nodes, spleen and thyroids (females) from all groups were also examined. There were no decedents and no treatment-related clinical signs in rats fed the test substance for thirteen weeks. The lower food intake during the first four weeks of the study in rats fed the test material at 5% in diet may reflect an initial reluctance of the rats to eat the diet. Decreases in organ weight and/or relative organ weight of spleen, kidney and liver were observed, mainly after feeding the test material at 1% and 5%, but there was no relation to any effect which might have been expected on the basis of the histopathology findings. Plasma alkaline phosphatase activity (ALP) was increased in males and females fed the test material at 1% or 5%. An increase in plasma ALP activity may reflect induction (increased synthesis) in liver cells rather than increased release from damaged cells. Another plasma enzyme derived from the liver in the rat, alanine aminotransferase (ALT) was also increased in male and female rats fed at 5%. In addition to increases in plasma ALP level derived from the liver, treatment-related effects were observed on microscopic examination of that organ. Histological examination of liver from animals in the 5% treatment group revealed an increase in biliary hyperplasia. Interference in bile flow could be related to the observed increase in ALP, which is a sensitive indicator of cholestasis. Changes in ALP develop before there are any detectable increases in plasma bilirubin levels. It should be noted that while a very small increase in plasma bilirubin was observed in male rats fed the test material at 5% or 1%, the levels measured were below the sensitivity of the method and must be viewed with caution. Although the bile duct proliferation and sclerosis recorded in the liver may correlate with the increase in ALP, it should be noted only very minor biliary changes were seen in a few female rats. A small reduction in plasma calcium was observed in male and female rats fed the test material at 5%. Small reductions in both total serum protein and albumin were also observed in male and female rats in the 5% group. It is possible the calcium and serum protein changes may be connected. However, reduction in plasma calcium was not always accompanied by a parallel reduction in plasma albumin. The changes in plasma calcium and serum proteins are small, probably representing a physiological rather than a pathological response to treatment with the test material. The plasma lipids cholesterol and triglyceride were reduced in male and female rats in the 5% and 1% treatment groups. It is possible that the test material blocks the absorption of lipid and other nutrients from the gut. Such activity could also explain changes in plasma electrolytes and intermediate metabolites. The reduction in periportal hepatocyte vacuolation seen on histological examination of the liver could correlate with the reduced plasma lipids, indicating some alteration in lipid metabolism, another possible explanation for the plasma lipid, serum protein and calcium changes. The pigment present in the macrophages in the mesenteric lymph nodes and spleen did not stain with Perls' stain for haemosiderin or aldehyde fuchsin for lipofuscin, but did stain with Schmorl's stain for lipofuscin. Lipofuscin is derived from oxidation of unsaturated lipids or lipoproteins. The test material is composed of a mixture of monomers, dimers and trimers of various fatty acids. It is likely that the pigment represents either lipofuscin produced by oxidation of some component of the test material, or that the test material itself stains positively. There was no evidence of any degenerative effect associated with pigmented macrophages. It is probable that they represent a physiological response to dietary administration of lipid materials such as the test material. Accumulations of macrophages in the mesenteric lymph nodes commonly occur as a result of ageing, or following administration of pigmented or lipid substances in the diet. Although the pigment appeared darker in the spleen than in the mesenteric lymph node, this may reflect a difference in density. The pigment was present alongside normal levels of haemosiderin which appeared tinctorially distinct. The coloured nature of the compound is also likely to have been responsible for the alteration in the colour of the caecal contents that was observed at necropsy. Increased cortical vacuolation in the adrenals, coupled with decreased cytoplasmic rarefaction probably indicates altered steroidogenesis. This was not accompanied by any evidence of degenerative change. The significance of the reduced extramedullar haemopoiesis in the adrenals is uncertain, but may possibly correlate with the reduction in neutrophil count in females fed the test material at 5% and 1%. All of the changes in the adrenal are minor in nature and of limited importance.

In summary, based on clinical chemistry parameters and histopathological findings a NOAEL for 1% (w/w) test material in diet can be derived, corresponding to a dose of 741 and 855 mg/kg bw/day for males and females, respectively. The molecular weight ratio of Fatty acids, C18-unsaturated, dimers (MW 564.93 g/mol) and Fatty acids, C18-unsatd., dimers, polymers with 2-ethylhexanol and neopentyl glycol (CAS 68552-19-2) (MW range: 368 - 1386 g/mol) is 0.65 (368/564.3) and 2.45 (1386/564.3). Thus, based on this molecular ratio factor the NOAEL for Fatty acids, C18-unsatd., dimers, polymers with 2-ethylhexanol and neopentyl glycol (CAS 68552-19-2) was calculated to be 481.65 - 1820 mg/kg bw/day ((368/564.3)*741) - ((1386/564.3)*741) for males and 555.75 – 2094.75 mg/kg bw/day ((368/564.3)*855) - ((1386/564.3)*855) for females, respectively.

CAS 104-76-7

The subchronic oral toxicity of 2-ethylhexanol (CAS 104-76-7) was investigated in Fischer 344 rats in a study performed similar to OECD guideline 408 (Astill et al., 1996). Groups of 10 male and 10 female rats received the test substance diluted in Cremophor EL once daily on 5 days/week at dose levels of 25, 125, 250, and 500 mg/kg bw/day for a period of 90 days. A similar constituted group of animals was administered the vehicle alone and served as controls. The animals were observed for clinical signs up to two times per day. Food consumption and body weights were determined weekly. On days 29 and 84, blood samples were taken for clinical chemistry and haematology. A gross pathology was performed and adrenals, brains, kidneys, livers, stomachs, testes, and ovaries from all animals were weighed. At histopathological examination, all tissues from high dose and control animals were stained with hematoxylin—eosin and examined microscopically. During the study period, no mortalities and no clinical signs of toxicity were observed in rats at any treatment level. At study termination, body weight gain was decreased in male (-6%) and female (-7%) rats compared to controls. No differences in food consumption were noted between treated animals and controls. Clinical chemistry revealed a 30 and 36% decrease in serum ALT activities in females treated with 250 and 500 mg/kg bw/day, respectively. At 500 mg/kg bw/day, a 16% decrease in serum cholesterol concentration in females and 13% decreases in total protein and albumin concentrations in males were observed. Furthermore, the reticulocyte numbers in male and female rats was increased (+25%) at 500 mg/kg bw/day. Moderate, but statistically significant increases in relative organ weights compared to controls were noted in the brain, kidneys, liver, stomach, and testes of male and female rats at 250 and 500 mg/kg bw/day. At necropsy, 2/10 males and 4/10 females exhibited single or multiple slightly elevated foci in the forestomach at 500 mg/kg bw/day. No other gross pathological findings were observed in any of the animals. Histopathological examination revealed dose-related findings in rats, which were limited to the forestomach and liver at 500 mg/kg bw/day. In the forestomach, generalised acanthosis of the mucosa in 1/10 males with ballooning degeneration of the epithelial wall and acanthosis of the forestomach mucosa in 2/10 males and 5/10 females was observed. However, the effects on forestomach were likely to be attributed to gavage administration of the test substance. In the liver, hepatic peripheral lobular fatty infiltration in 4/10 males and 2/10 females and adrenal beta-cell hyperplasia in 3/10 female rats were noted.

Based on the results of this study, the NOAEL for 2-ethylhexanol in male and female Fischer 344 rats was established at 125 mg/kg bw/day. The molecular weight ratio of 2-ethylhexanol (MW 130.23 g/mol) and Fatty acids, C18-unsatd., dimers, polymers with 2-ethylhexanol and neopentyl glycol (CAS 68552-19-2) (MW range: 368 - 1386 g/mol) is 2.85 (368/130.23) and 10.64 (1386/130.23). Thus, based on this molecular ratio factor the NOAEL for Fatty acids, C18-unsatd., dimers, polymers with 2-ethylhexanol and neopentyl glycol (CAS 68552-19-2) was calculated to be 353.22– 1330.34 mg/kg bw/day ((368/130.23)*125) – ((1386/130.23)*125).

Conclusion

Based on a worst case approach, the lowest NOAEL of 125 mg/kg bw/day (corresponding to the mass corrected NOAEL = 353.22– 1330.34 (m/f) mg/kg bw/day for Fatty acids, C18-unsatd., dimers, polymers with 2-ethylhexanol and neopentyl glycol) determined in the subchronic oral toxicity study with 2-ethylhexanol was chosen.

Justification for classification or non-classification

Based on the analogue read-across approach, the available data on repeated dose toxicity do not meet the classification criteria according to Regulation (EC) 1272/2008, and are therefore conclusive but not sufficient for classification.