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Description of key information

Based on the results of the experimental investigations as well as on the molecular weight the test item is considered to be bioavailable via oral and dermal route and potentially also via inhalation. Once systemic available the substance might distribute into the cells and intracellular concentration might be higher than extracellular concentration. 1-(vinyloxy)octadecane might be hydrolysed and metabolites are estimated to enter the mitochondrial β-oxidation pathway followed by the TCA respiration pathway. Therefore, excretion of the presumed metabolites via exhalation is expected. However biliary excretion is expected for the unchanged test substance. Based on the high log Pow value bioaccumulation of the test substance cannot be excluded but is expected to be limited due to the presumed metabolism.

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential

Additional information

1 -(vinyloxy)octadecane is a colourless to yellow solid at room temperature with a melting point of ~31 °C. It has a molecular weight of 296.54 g/mol, a density of 0.821 g/cm3(at 40 °C) and a log Pow value of 9 (25 °C). The substance has a vapour pressure of 0.001 Pa (25 °C) and the solubility in water is low (< 0.1 mg/l at 25°C).

 

The main exposure route at room temperature is dermal as the vapour pressure at 25 °C is considered to be negligible and inhalation exposure is therefore unlikely.

 

In an acute oral toxicity study in rats (BASF, 1988) the LD50was determined to be >5000 mg/kg bw for male and female rats. Neither mortality nor any clinical signs and pathological alterations were observed. Due to the low vapour pressure at room temperature no acute inhalation study was carried out. In an acute dermal toxicity study in rats (BASF SE, 2011) no mortality occurred and the LD50was determined to be >5000 mg/kg bw. Neither any clinical signs nor any macroscopic pathologic abnormalities were observed. No dermal irritation was noted at the site of application. However, in an acute dermal irritation/corrosion study with rabbits (BASF, 1988) the application of 0.5 mL per animal of the liquefied test item revealed slight erythema which were reversible within 7 days. In an acute eye irritation test, slight conjunctiva redness was noted fully reversible within 72 hours (BASF, 1988). Administration of 2.5, 5.0 and 10.0 % of the test item for three consecutive days on the ear of mice revealed a statistically significant and biologically relevant increase of DPM values and lymph node weights compared to control group. Therefore, the substance is considered to be a skin sensitiser.

In a combined repeated dose toxicity study with the reproduction/developmental toxicity screening test with rats, 1 -(vinyloxy)octadecane was administered orally at concentrations of 0, 250, 500 and 1000 mg/kg bw/day (BASF SE, 2012). No clinical signs or changes of general behaviour, body weights and food consumption attributed to the test item were detected in any male or female animal during the whole study. No treatment-related changes among hematological parameters were observed. Cholesterol levels were increased in male and female animals of all dosage groups but were considered to be not adverse. A dose-dependent trend towards increased liver weights was noted in the 500 and 1000 mg/kg bw/day males and females. Treatment-related fatty change of hepatocytes characterized by vacuoles of varying size was noted in many male and female animals of the mid and high dose group correlating partly to light-brown discoloration observed by gross examination. Centrilobular hepatocellular hypertrophy was observed particularly in male animals. No test item-related influence on development of the F1 generation pubs were noted in all dose groups.

In a repeated dose toxicity study (OECD 408), 1 -(vinyloxy)octadecane was administered by gavage to groups of 10 male and 10 female Wistar rats at dose levels of 0 (test group 0), 50 (test group 1), 200 (test group 2) and 800 mg/kg bw/d (test group 3) over a period of 3 months. With regard to clinical examinations, signs of general systemic toxicity were not observed even at a dose level of 800 mg/kg bw/d. Regarding clinical pathology, in rats of both sexes of test group 3 (800 mg/kg bw/d) marginally increased γ-glutamyl transferase (GGT) activities and higher cholesterol levels were observed reflecting an affection of the liver cells. Additionally, in females total protein and globulin levels were increased, most probably due to a greater synthesis of transport globulins by the liver cells. Globulin and cholesterol levels were already increased in females of test group 2 (200 mg/kg bw/d). Regarding pathology, the liver was the target organ. Males and females of test group 3 (800 mg/kg bw/d) revealed a diffuse hepatocellular hypertrophy which correlated with the enlargement observed by gross pathology in females and with the increased liver weight in both sexes. Furthermore, hepatocytes with vacuoles were detected histopathologically, which could be shown to be neutral fat storage within the hepatocytes. This correlated with macroscopic finding of light brown discoloration. For test group 3 (800 mg/kg bw/d) males and females the hypertrophy and fatty change was regarded to be treatment-related and adverse in combination with clinical pathology findings. In test group 2 (200 mg/kg bw/d) only the centrilobular hypertrophy in a single female and the mean liver weight increase were regarded to be treatment-related and adverse, as also clinical pathology parameters were changed in this test group. The fatty change occurred in different animals than the one with hypertrophy. These animals did not reveal other findings than the minimal fatty change, which was regarded to be treatment-related but not adverse.All other findings occurred either individually or were biologically equally distributed over control and treatment groups. They were considered to be incidental or spontaneous in origin and without any relation to treatment.

 

Absorption

Generally, absorption of 1-(vinyloxy)octadecane is limited by its high lipophilicity (log Pow >8) and its low water solubility. However, pathological and histopathological findings in the liver after repeated oral administration indicate that the compound becomes bioavailable to a certain extend. Both, passive diffusion and/or active transport through the cell membrane are considered to be possible mechanisms of absorption from the gastrointestinal tract.

The substance is solidified at room temperature and the vapour pressure of the test item at 25 °C is estimated to be low. Therefore, inhalation of dust or vapour is unlikely. However, if the substance becomes available for inhalation, it might be taken up by micellular solubilisation to a certain extend.

Both, uptake of 1-(vinyloxy)octadecane into the stratum corneum and partition from the stratum corneum into the epidermis is limited by the high log Pow value and the low water solubility, respectively. Thus, absorption across the skin is estimated to be low. However, since the available LLNA revealed a skin sensitising effect, the substance has to penetrate the skin to a certain extend. These results indicate skin penetration after dermal application.

 

Taken together, experimental data indicate bioavailability of the test substance via oral, dermal and possibly also via inhalation route.

Distribution

The substance might distribute into the cells and intracellular concentration might be higher than extracellular concentration particularly in fatty tissues due to the high log Pow value. In the available repeated dose toxicity studies the liver was identified as a target organ.

Based on the high log Pow value bioaccumulation cannot be excluded but is expected to be limited due to the presumed metabolism.

Metabolism

The substance might be hydrolysed by formation of acetaldehyde and octadecanol. Further oxidation could result in acetic acid and octadecanal, subsequently oxidised to octadecanoic acid which in turn may enter the mitochondrial β-oxidation pathway followed by the citric acid cycle (TCA) pathway.

There are no indications of genotoxicity of the substance and its metabolites from the present Ames and cytogenetic test (BASF, 1989, 2012), and several mutation assays in mammalian cells with three different structure analogues (BASF, 1992, 1998, 2010). Thus, 1-(vinyloxy)octadecane and its metabolites are expected not to be genotoxic and metabolic activation is unlikely to occur.

Excretion

Potential metabolites of 1-(vinyloxy)octadecane described above are estimated to be oxidised to carbon dioxide within the TCA pathway and are therefore expected to be excreted via exhalation. In case of the unchanged substance biliary excretion is expected due to the molecular weight (~ 300 g/mol) and the low water solubility.

 

Conclusion

Based on the results of the experimental investigations as well as on the molecular weight the substance is considered to be bioavailable via oral and dermal route and potentially also via inhalation. Once systemic available the substance might distribute into the cells and intracellular concentration might be higher than extracellular concentration.

1-(vinyloxy)octadecane might be hydrolysed and metabolites are estimated to enter the mitochondrial β-oxidation pathway followed by the TCA respiration pathway. Therefore, excretion of the presumed metabolites via exhalation is expected. However, biliary excretion is expected for the unchanged substance.

Based on the high log Pow value bioaccumulation cannot be excluded but is expected to be limited due to the presumed metabolism.