1,1'-(methylimino)dipropan-2-ol

Endpoint summary

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

1. Physical-chemical properties

1,1’-(methylimino)-dipropane-2-ol (MW 147.2 g/mol) is at RT a liquid with a measured boiling point of 225°C at 1013 hPa, a measured vapour pressure of 0.015 hPa at 20 °C, and a dissociation constant (pKa) of 7.86 at 25 °C. The octanol-water partition coefficient (log Pow) is -0.015 at 23 °C, and it is miscible with water in any ratio.

 

2. Data from acute and repeated dose toxicity studies

Acute toxicity data indicate low toxicity: in rats the oral LD50 was 2150 mg/kg bw (BASF AG, 1987). At this dose and above various clinical signs (dyspnea, apathy, staggering, piloerection, salivation, poor general state), general congestion and severe redness of forestomach, glandular stomach and small intestines were noted. At the highest dose group pink colouration of the urine (5000 mg/kg bw) was also detected. No reliable acute inhalation toxicity data are available for 1,1’-(methylimino)-dipropane-2-ol. However, due to its low vapour pressure, exposure to 1,1’-(methylimino)-dipropane-2-ol vapour is very unlikely. There is no repeated dose toxicity study with 1,1’-(methylimino)-dipropane-2-ol available. Nevertheless, a subacute as well as a subchronic study via the dermal (OECD TG 410) and oral route of exposure (performed according to FDA guidelines) were carried out with tris-(2-hydroxypropyl)-amine (CAS 122-20-3) and were used for cross reading.

In the oral repeated dose study, beagle dogs were administered 0, 500, 2000 or 7500 ppm tris-(2-hydroxypropyl)-amine in their diet for 102-104 days (Dupont, 1987). Ophthalmology, hematology, serum chemistry, urinalysis, blood methaemoglobin, macroscopic and microscopic examinations, and organ weight evaluations showed no treatment-related effects, resulting in a NOAEL of 272-288 mg/kg bw/day (the highest dose tested). In a dermal repeated dose study, rats were exposed to 0, 300, 1000 or 3000 mg/kg bw, 5 days/week for 28 days. Besides irritative effects at the site of application at the higher doses, no systemic toxicity was observed. A NOAEL for systemic effects of 3000 mg/kg bw/day was established (Dow, 1994).

 

3. Absorption, distribution, metabolism, excretion (ADME)

Concerning ADME, no studies are available with1,1’-(methylimino)-dipropane-2-ol. However, there are data on metabolism and excretion of 2,4-dichlorophenoxyacetate, 1,1’,1’’-nitrilotripropan-2-ol salt (2,4-D-TIPA), which were assessed in an OECD guideline 417 oral study in male Fischer 344 rats. A single oral dose, equivalent to 11.2 mg¹⁴C-TIPA/kg bw, was administered, followed by blood sampling at intervals up to 72 hours post-dose. Radioactivity peaked in the plasma at 0.25 hrs post-dosing and declined triexponentially. The kidney was the major route of excretion with about 80% of the dose excreted in 24 hours and 81 to 85% of the dose excreted in 72 hours, primarily unmetabolised. The feces and expired air accounted for only 4% to 7% and 3% to 5%, respectively. After 72 hours, 94% to 96% was recovered with only less than 1% remaining in the tissues or carcass (Dow, 1992). Since 2,4-D-TIPA is rapidly absorbed and eliminated in the rat, bioaccumulation is considered unlikely, which counts also for1,1’-(methylimino)-dipropane-2-ol.

Since no data regarding absorption, distribution, metabolism, excretion of 1,1’-(methylimino)-dipropane-2-ol are available, a complete bioavailability (100%) is assumed for the oral and dermal routes of exposure, which will result in a most conservative risk assessment.