2,4,7,9-tetramethyldec-5-yne-4,7-diol

Endpoint summary

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Absorption rate - oral (%):

50

Absorption rate - dermal (%):

50

Absorption rate - inhalation (%):

100

Additional information

No experimental data are available on toxicokinetics of 2,4,7,9-Tetramethyl-5-decyne-4,7-diol. Thus, the toxicokinetic assessment is mainly based on physicochemical data.

 

Absorption

The log Kow of 2.8, water solubility of 1700 mg/L and the molecular weight of 226 g/mol are suggestive of oral absorption from gastro-intestinal tract, by dermal route or from the lungs.

Some absorption from the gastrointestinal tract is implicit from the effects observed in the repeat dose oral toxicity study. Given its log Kow of 2.8, its moderate water solubility and its molecular weight of 226 Da, absorption might be expected following ingestion or inhalation exposure. Moderate dermal absorption might be expected, and this is likely to be enhanced by its surface-active properties.

 

Oral absorption

For chemical safety assessment an oral absorption rate of 50% is assumed as a worst case default value in the absence of other data in accordance with the Guidance on information requirements and chemical safety assessment.

 

Dermal absorption

For chemical safety assessment a dermal absorption rate of 50% is assumed as a worst case default value (same absorption rate as via the oral route) in accordance with the Guidance on information requirements and chemical safety assessment.

 

Inhalation absorption

For chemical safety assessment an inhalation absorption rate of 100% is assumed as a worst case default value in the absence of other data in accordance with the Guidance on information requirements and chemical safety assessment.

 

Distribution

No evidence of systemic target organ toxicity was seen in repeat dose studies in rats given 2,4,7,9-Tetramethyl-5-decyne-4,7-diol, ethoxylated by the oral route. Toxicity seen in the liver at the highest dose tested is likely the result of compensatory or adaptive response to high doses administered however it is also an indication of some minor distribution of the compounds to highly perfused tissues such as the liver. Based on the relatively high degree of water solubility it is unlikely that the substance will accumulate in body fats and/or breast milk.

 

Metabolism

It is very difficult to predict the metabolic changes a substance may undergo on the basis of physico-chemical information alone. The metabolism simulator included in QSAR toolbox was used to predict possible metabolites. 2,4,7,9-Tetramethyl-5-decyne-4,7-diol, ethoxylated is expected to be oxidised at the terminal methyl-groups, where it could be further functionalised (e.g. by conjugation). In addition, oxidation of the ethylene glycol moieties is possible.

 

Elimination

The major routes of excretion for substances from the systemic circulation are the urine and/or the faeces. Moderate water-solubility and low molecular weight (226 g/mol) are favorable physicochemical properties for urinary excretion. It can be reasonably assumed, that the substances and their metabolites are excreted via the urine.