2-(2-methoxyethoxy)ethanol

Endpoint summary

Description of key information

Short description of key information on bioaccumulation potential result:

Elimination: 98% eliminated in 24hrs, mainly as 2-(2 -methoxyethoxy)acetic acid in urine

Short description of key information on absorption rate:

Humans: 0.206mg/cm2/hr (damage ratio 3.2+/-1.8; control 1-2)

Rat: 0.051mg/cm2/hr

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

In a study to examine the metabolism 2 -(2 -methoxyethoxy)ethanol, SD rats were given single oral doses of 500, 1000 and 2000mg/kg and the urine collected over two 24 hour periods for analysis for a number of expected metabolites. The dominant metabolite was 2 -(2 -methoxyethoxy)acetic acid, which accounted for 87 -95% of the original dose. Unmetabolised 2 -(2 -methoxyethoxy)ethanol, the glucoronide conjugate and diethylene glycol were also found in small quantities. In addition, the metabolite methoxyacetic acid was found, the amount accounting for ~1 -1.5% of the dose of 2 -(2 -methoxyethoxy)ethanol given. This demonstates that oxidation of the hydroxyl function is the dominant metabolic pathways but small amounts of the substance are metabolised by cleavage of the ether linkage. The study also showed that around 98% of the dose of 2 -(2 -methoxyethoxy)ethanol is eliminated within 24 hours.

Other similar glycol ethers have been found to be metabolised similarly. The absorption and elimination of radio-labelled 2 -(2 -butoxyethoxy)ethanol in rats was followed following 24hr dermal occluded exposure. It was also established that the main route of elimination is overwhelmingly via the urine and the metabolite 2 -(2 -butoxyethoxy)acetic acid. The glucoronidate conjugate was also found at significant levels (5 -8%). Females appeared to absorb and therefore excrete larger quantities than males and the dermal absorption rate was estimated to be 0.73 and 1.46mg/cm2/hr for males and females respectively. Washing studies showed that 90%+ of externally applied substance could be removed after 5 minutes exposure by skin washing.

An in vitro dermal absorption study using human skin showed that 2 -(2 -methoxyethoxy)ethanol is able to pass through the stratum corneum at a rate of 0.206mg/cm2/hr) and causes slight irreversible damage to the skin. There was a lag time of less than 1 hour for the substance to cross the skin and appear in the receptor fluid. An in vitro dermal absorption study was carried out to assess the permeability of rat skin to aviation kerosine. The permeability of the individual components of the kerosine was assessed, including 2 -(2 -methoxyethoxy)ethanol which was present at 8% by weight as an de-icer. This substance was is able to pass through rat stratum corneum at a rate of 0.051mg/cm2/hr, a rate which was 4x that of any of the hydrocarbon components identified. There is a lag time of approximately less than 1 hour for the substance to cross the skin and appear in the receptor fluid and no detectable levels of the glycol ether were found in the skin afterwards. The first result is more reliable as no other substances were present to potentially confound the results and it is based on human skin. This result also provided the higher (more conservative) result.

No formal toxicokinetic studies have been performed on 2 -(2 -methoxyethoxy)ethanol. However, the metabolism study did establish that nearly all of the applied dose is excreted within 24 hours of exposure.