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Administrative data

Link to relevant study record(s)

Description of key information

Gastro-intestinaI-, respiratory- and dermal absorption of Ocadecyl acrylate to a major extent is not expected due to their physico-chemical properties (log Pow: > 9; water solubility: < 0.1 mg/L, molecular weight: > 320 g/mol). 
In addition, bioaccumulation is unlikely due to a very limited absorption of the substance.

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential
Absorption rate - dermal (%):

Additional information

Read across has been done to a dataset of suitable congeners of the family of acrylate esters, mainly to a mixture of C16-C18 acrylates. The substance to be registered (Octadecyl acrylate, C18) was part of this mixture.

Octadecyl acrylate is yellow and liquid or solid at room temperature with a molecular weight of > 320 g/mol and an absolute density of 0.87 g/cm³ at 25°C. The substance has a melting point of 30 °C. Water solubility for Octadecyl acrylate of < 0.1 mg/L (25 °C) and a log Pow of > 6.5 (23 °C) were determined. The vapour pressure was estimated to be < 0.000006 mbar (20 °C).


Based on the molecular weight, the high log Pow and a low water solubility, Octadecyl acrylate is not very likely to be absorbed in the GI tract. The log Pow of > 6.5 indicates that it will not diffuse well across plasma membranes. In addition, gastro-intestinal absorption of Octadecyl acrylate will not be triggered by passage via passive diffusion through aqueous pores or carriage with the bulk passage of water, which is favoured for small (molecular weight < 200 g/mol), water soluble substances.

The substance may be taken up by micellular solubilisation since this mechanism may be of particular importance for highly lipophilic compounds (log Pow > 4), particularly those that are poorly soluble in water. Overall, limited gastrointestinal absorption is expected for Octadecyl acrylate based on its physicochemical properties. Moreover, almost no systemic effects were seen in acute and repeated dose toxicity studies after oral administration of structural related substances (mixture of C12/C14 acrylates or mixture of C18-C22 acrylates) demonstrating and supporting that Octadecyl acrylate is not very well absorbed in the gastrointestinal tract, and if absorbed reveal a low systemic toxicity.

As Octadecyl acrylate is liquid or solid with very low water solubility (< 0.1 mg/L), a molecular weight of > 320 g/mol and a log Pow of > 6.5, dermal absorption is expected to be low. In addition, Octadecyl acrylate showed no effects when tested for acute dermal toxicity or skin irritation.

These characteristics are in line with information obtained with a structural related substance Lauryl methacrylate: Experiments on the structural related substance Dodecyl methacrylate (Lauryl methacrylate) with rat skin have demonstrated that the long-chain methacrylate esters in principle are dermally absorbed at very low amounts (0.26 % over 26 h). As a tendency confirmed with experiments on esters up to a chain length of C8, absorption decreased with increasing ester chain length. Due to the slow diffusion and the metabolic competency of the skin, the ester underwent complete hydrolysis to methacrylic acid and the long-chain alkyl alcohol, even if the kinetics might be influenced by the water solubility and in addition, it cannot be excluded that the long C-chain might hinder the enzyme to access the ester bound.

Octadecyl acrylate exhibits a low volatility (vapour pressure of < 0.000006 mbar). Therefore, only a very minimal amount of the substance is available for inhalation and thus, absorption by inhalation can be almost excluded. In addition, fine dust is not formed by this compound. Consequently, inhalation exposure due to fine dust or particles is also unlikely.

Distribution and metabolism:

Based on the physicochemical properties (molecular weight: > 320 g/mol, log Pow: > 6.5, water solubility: < 0.1 mg/L) Octadecyl acrylate is unlikely to be widely distributed systemically throughout the extracellular compartments of the body after absorption. Particularly due to the low water solubility and the high log Pow value above 7, a long biological half-life in tissues could be expected, but is almost excluded due to the poor absorption. Thus, Octadecyl acrylate has no bioaccumulation potential.

The metabolism is determined by physicochemical factors like electronic and steric effects within the molecule and/or by the presence of functional groups. Phase II conjugation reactions like glucuronidation or sulfatation might occur subsequent to Phase I reaction, e.g. after introduction of a OH-group via Cytochrome P450 mediated oxidation.

Esters are supposed to be rapidly hydrolysed in local tissues as well as in blood by carboxyl esterases (high activity within many tissues and organs like liver, GI tract, nasal epithelium and skin) forming acrylic acid and the respective alcohol. However, the kinetic strongly depends on water solubility. In addition, it cannot be excluded that the long C-chain might hinder the enzyme access to the ester bound.

There is a trend towards increasing half-life of the esters in blood with increasing alcohol chain length. But systemically absorbed parent esters will be effectively removed during first pass through the liver resulting in their relatively rapid elimination from the body. The primary metabolite acrylic acid is subsequently cleared rapidly from blood and this metabolism occurs by standard physiological pathways with the majority being exhaled as CO2. The respective alcohol is also predominantly cleared via the liver. In the organism, the acid is further metabolised via the valine pathway of the citric acid cycle. The alcohol will be further metabolised by the two standard metabolic pathways for fatty alcohols.

Consequently, effects observed are linked to the hydrolysis products: alcohols and acrylic acid. The alcohols are considered of low toxicity especially the unbranched long-chain ones, as those follow the metabolic pathways of fatty nutritional substrates (e.g. fatty acids). The other metabolite acrylic acid is identical for all esters.

Generally, metabolism will render the molecule more polar and harmless, leading to faster excretion. No conversion into a metabolite that is more toxic than the parent is expected as no increases in toxicity were noted in the presence of metabolic activation during the in vitro tests.


The relatively low water solubility and the molecular weight (> 320 g/mol) indicate that renal excretion is not a relevant route of systemically available Octadecyl acrylate. Excretion might occur predominantly via the faecal route.


The above TK information derived by taking into account a basic data set which includes mainly physico-chemical data, and data like skin irritation/corrosion, eye irritation, in vitro mutagenicity, acute oral toxicity, short-term and repeated dose toxicity enable qualitative judgments of the TK behavior of Octadecyl acrylate.

It can be concluded that gastro-intestinaI-, respiratory- and dermal absorption of Octadecyl acrylate to a major extent is not expected due to its physico-chemical properties (log Pow: > 9; water solubility: < 0.1 mg/L, molecular weight: > 320 g/mol).

In addition, bioaccumulation is unlikely due to a very limited absorption of the substance.