Tetrahydro-1,3-dimethyl-1H-pyrimidin-2-one

Endpoint summary

Description of key information

There are no specific experimental data available concerning toxicokinetics, metabolism and distribution. Based on the physicochemical properties of the substance and available ecotoxicological and toxicological information it is concluded that the substance is systemically bioavailable after oral administration. In contrast, bioavailability via the dermal route is estimated to be very low. Due to the relatively low vapour pressure of the test substance (0.02 hPa at 25°C), the volatility of the substance is rather low and inhalation exposure to vapors is hence considered to be low. The substance has a low potential for bioaccumulation (Log Pow <3).

Key value for chemical safety assessment

Bioaccumulation potential:

low bioaccumulation potential

Additional information

Assessment of the Toxicokinetic Behaviour

Since no toxicokinetic studies are available for N,N'-DIMETHYLPROPYLENE UREA, the following assessment is based on the available physicochemical properties and results from other toxicological studies:

N,N'-DIMETHYLPROPYLENE UREA is a liquid, organic, colourless substance with a small molecular weight of 128.18 g/mol, indicative for a favourable absorbance of the test item.

The test item is miscible with water at room temperature (T = 23°C) and at T = 20.0°C ± 0.5°C in any ratio. Due to this high water solubility, it is predicted that the test item is readily dissolved into the gastrointestinal fluids.

Due to the relatively low calculated vapour pressure of the test substance (0.02 hPa at 20°C), the volatility of the substance is rather low and inhalation exposure to vapors is hence considered to be low.

The partition coefficient of the test substance (Log Pow) is 0.05 at 25°C at pH 7. Based on this rather low partition coefficient the test substance is unlikely to bioaccumulate with the repeated intermittent exposure patterns normally encountered. However, this moderate log Pow value indicates that the substance might be favourable for passive diffusion. In line with this, in an acute oral toxicity study, 4/5 males and females and 1/5 females died after administration of 2000 and 1470 mg/kg bw, respectively, whereas animals receiving 681 mg/kg did not show any signs of mortality (-> LD50 = 1770 mg/kg). Furthermore, animals receiving high and intermediate doses showed clinical signs and symptoms, inlcuding dyspnea, apathy, staggering, twitching, piloerection, cyanosis and a poor general state. These observations are in line with the moderate log Pow value, showing that the substance is systemically bioavailable when administered orally.

In contrast, bioavailability via the dermal route is less likely since the LD50 was estimated to be > 2000 mg/kg. In line with this, a low partition coefficient below 1 predicts low dermal absorbtion. Furthermore, the substance is neither irritating (BASF SE 1989) nor sensitising to the skin (LLNA, Harlan/BASF SE 2012), further supporting the notion that there is a limited bioavailability of the substance via the dermal route.

Studies assessing genotoxicity (Ames-Test; BASF 1989, HPRT test in vitro; BASF 2012, Chromosome aberration in vitro; RCC/BASF 1998, Micronucleus Test in vivo; Sandoz 1985) were negative, i.e. there is no indication of a reactivity of the test substance or its metabolites with macromolecules under the chosen test conditions.