(2-hydroxypropyl)trimethylammonium 2-ethylhexanoate

Endpoint summary

Description of key information

A theoretical toxicokinetic assessment was performed. Based on the physical/chemical properties of the substance, worst-case absorption factors for this substance are derived to be 100% (oral), 100% (inhalation) and 100% (dermal) for risk assessment purposes. The bioaccumulation potential is expected to be low.

Key value for chemical safety assessment

Bioaccumulation potential:

low bioaccumulation potential

Absorption rate - oral (%):

100

Absorption rate - dermal (%):

100

Absorption rate - inhalation (%):

100

Additional information

(2-hydroxypropyl)trimethylammonium 2-ethylhexanoate (CAS  62314-22-1) is the salt of 2-etyhylhexanoic acid and (2 -Hydroxypropyl)trimethylammonium, a Quaternary amine.

 

In general, a compound needs to be dissolved before it can be taken up from the gastrointestinal tract after oral administration. (2-hydroxypropyl)trimethylammonium 2-ethylhexanoate is marketed in a propylene glycol solvent, at up to 75%. It was found to be essentially miscible in water with major components of the test item- 2-Ethylhexanoic acid and the Quaternary amine cation - remaining highly solubilised after dissociation. This high water solubility means that the substance will readily dissolve into the gastrointestinal fluids, favouring passive diffusion.

The partition coefficients of 2-Ethylhexanoic Acid Content (Log Pow 1.20) and Quaternary Amine Cation (Log Pow <-2.00) indicate that penetration through  lipid membranes is likely, and that therefore the ions will have the potential to reach the systemic circulation.

Thus, as soon as it comes in contact with the fluids of the gastro-intestinal tract, a 2-Ethylhexanoic Acid ion and a quaternary ammonium-ion will be formed. It is generally assumed that ionized substances do not readily diffuse across biological membranes, but the varying pH of the GI tract may have influence on the absorption of the ions. Therefore, for risk assessment purposes, a worst-case for oral absorption of (2-hydroxypropyl)trimethylammonium 2-ethylhexanoate is used - 100%. The oral LD50 of Solvent-free Dabco TMR is greater than 2000 mg/kg of body weight in rats (OECD 423).

Once absorbed, wide distribution of the test substance throughout the body is expected based on its high water solubility and molecular weight (261.4).

(2-hydroxypropyl)trimethylammonium 2-ethylhexanoate is marketed in a form that may be applied by spray applications, and that aerosols may be formed. Therefore, it is assumed that (2-hydroxypropyl)trimethylammonium 2-ethylhexanoate can enter the respiratory tract. If (2-hydroxypropyl)trimethylammonium 2-ethylhexanoate reaches the tracheobronchial region, it is likely to be dissolved within the mucus lining of the respiratory tract and to get absorbed due to its high water solubility and low molecular weight.

Furthermore, due its corrosive potential, it may damage the epithelium lining the respiratory tract, which will further promote systemic uptake of the substance. Therefore, for risk assessment purposes the inhalation absorption of (2-hydroxypropyl)trimethylammonium 2-ethylhexanoate is set at 100%.

(2-hydroxypropyl)trimethylammonium 2-ethylhexanoate will dissolve into the surface moisture of the skin. Uptake is facilitated by the relatively low low molecular weight  (261.4) and high water solubility , the ions formed will influence its adsorption. The quaternary ammonium ion may bind to skin components which would limit the uptake. However, due to its corrosive properties, skin integrity will be affected leading to fast uptake of the substance. Once the skin surface is damaged, (2-hydroxypropyl)trimethylammonium 2-ethylhexanoate will be absorbed easily due to its low molecular weight and high water solubility.

 

Therefore, for risk assessment purposes the dermal absorption of (2-hydroxypropyl)trimethylammonium 2-ethylhexanoate is set at 100%. (2-hydroxypropyl)trimethylammonium 2-ethylhexanoate 75% in Ethyleneglycol was tested for acute dermal toxicity on rabbits. The LD50 was > 2 000 mg/kg b.w.