Reaction products of ethylene glycol, urea and paraformaldehyde (EUF)

Endpoint summary

Description of key information

Short description of key information on absorption rate:

A dermal absorption study with EUF is technically not feasible.

Additional information

ADME and dermal absorption studies have not been conducted with EUF.

This type of studies usually requires that radio-labelled material is used to allow the sensitive detection and identification of the parent compound and its metabolites in the various matrices. The synthesis of a radiolabelled compound was not possible due the following reasons:

1. the synthesis of this technical product has to be transferred from a large-scale production process to a small-scale (very small) laboratory scale process. This implies that shifts within the product spectrum of this reaction are to be assumed.
2. the supplier for radio-labelled compounds usually is delivering his product with a specific radioactivity (Bq/mol); this is not possible for a mixture like EUF.
3. although some of the reactants can be obtained as radio-labelled a radio-labelled mixture is of restricted value for a metabolism study because proportion of labelled constituents it will remain unclear .

Discussion on absorption rate:

The relevant exposure path of EUF is the dermal route. In aqueous solutions (all biological systems) EUF hydrolyses to formaldehyde, ethylene glycol and urea.

Data on percutaneous absorption of EUF are lacking because of technical/methodological problems due to the reacting compounds and hydrolytic activity in aqueous solution.

Formaldehyde reacts at the site of entry and/or is eliminated rapidly as formic acid in the urine or as CO₂ in the expired air or it enters the carbon pool in the body. The percutaneous absorption rate is 30-40%.

Data on the hydrolysis product ethylene glycol indicate that it is rapidly absorbed (dermal rate is 20 to 30%) and distributed in the body. It is metabolised and excreted via urine as ethylene glycol, glycolic acid, calcium oxalate, and glycine or hippurate and also exhaled as exhaled CO₂. Urea is rapidly absorbed through human skin at a rate of about 10% and rapidly distributed as normal body constituent. Excretion is via urine in unchanged condition.