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Absorption

No studies are available that address the absorption of the test substance via the oral, dermal or inhalation route. Nevertheless, some preliminary predictions can be made from its physico-chemical properties.

Oral absorption

Oral absorption can occur along the entire length of the gastro-intestinal tract. For most substances, absorption occurs through passive diffusion. A number of physico-chemical factors determine the extent to which a substance may be absorbed by the oral route. Generally, smaller molecules are more easily absorbed. Furthermore, substances need to be sufficiently water soluble in order to readily dissolve into the gastrointestinal fluids. A moderate log Kow furthermore favors the uptake via passive diffusion. Nevertheless, substances that are more lipophilic might still be absorbed after micellular solubilization.

According to Nielsen et al. (2010), oral absorption is likely for a substance if it has the following properties:

- a molecular weight < 500

- a log Kow between 0 and 4

- water soluble

The test item has a molecular weight of 145 g/mol, a log Kow of 0.62 and a water solubility of 31.6 g/L. Based on these physicochemical properties, it can be concluded that the oral absorption of the substance can be expected to go easily.

Dermal absorption

Like for oral absorption, physico-chemical factors also determine the extent to which a substance may be absorbed by the dermal route. In order for a substance to cross the stratum corneum, the substance should be sufficiently lipophilic (= sufficient solubility in fat). On the other hand, partitioning from the stratum corneum into the epidermis requires sufficient hydrophilicity (= sufficient solubility in water). Hence, the likelihood of dermal absorption is determined by the substance's log Kow and water solubility values.

According to Nielsen et al. (2010), dermal absorption is likely for a substance if it has the following properties:

- a vapour pressure < 100 Pa

- a log Kow between 1 and 4

- a water solubility in the range of 1 - 100 mg/L (moderate absorption), or 100 - 10000 mg/L (high absorption).

The test item has a vapour pressure of 0.0025 Pa, a log Kow of 0.62 and a water solubility of 31.6 g/L. With a vapour pressure of 0.0025 Pa, the substance will not easily evaporate from the skin. However, based on log Kow and water solubility, it can be concluded that the dermal absorption of the substance can be expected to be low. The substance is insufficiently lipophilic to cross the stratum corneum.

Inhalation absorption

The main physicochemical parameters determining the extent to which a liquid substance may be absorbed by the inhalation route are the vapour pressure, the log Kow and the water solubility.

Nielsen et al. (2010) gives the following criteria:

- Highly volatile substances are considered those substances that have a vapour pressure exceeding 25000 Pa (or boiling point < 50°C), whereas a vapour pressure < 500 Pa (or boiling point > 150C°) indicates a low volatility.

- Log Kow > 0 indicates the potential for direct absorption across the respiratory tract epithelum. Substances with a log Kow value between 0 and 4 are sufficiently lipophilic to allow crossing the alveolar and capillary membranes, and hence are likely to be absorbed as well.

- A sufficient water solubility increases the potential for inhalation absorption. Nevertheless, very hydrophilic substances may be retained within the mucus, and transported out of the respiratory tract by clearance mechanisms.

 

Based on the physicochemical properties of the test item (Log Kow 0.62 and water solubility 31.6 g/L), it can be concluded that absorption of the substance following exposure via the inhalation route is likely. However, the very low vapour pressure (0.0025 Pa) will strongly mitigate the likelihood of exposure via the inhalation route.

 

Metabolism and Excretion

No information on the metabolism and excretion of the test item is available.

 

References:

Nielsen E, Ostergaard G, Larsen JC (2010).Toxicological Risk Assessment of Chemicals; A Practical Guide. Published by: Informa Healthcare. ISBN-13: 9780849372650.

 

 

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