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Key value for chemical safety assessment

Additional information

Ames test:

The substance N-(2-Hydroxyethyl)-morpholine was tested for its mutagenic potential based on the ability to induce back mutations in selected loci of several bacterial strains in the Ames test and in the Escherichia coli - reverse mutation assay.

Strains: TA 1535, TA 100, TA 1537, TA 98 and E . coli WP2 uvr A

Dose range: 20 µg - 5000 µg/plate (plate incorporation and precincubation test, all strains) 20 µg - 8000 µg/plate (plate incorporation test TA 100)

Test conditions: Standard plate test (SPT) and preincubation test (PIT) both with and without metabolic activation (Aroclor induced rat liver S-9 mix).

Solubility: No precipitation of the test substance was found.

Toxicity: No bacteriotoxic effect was observed.

Mutagenicity: An increase in the number of his+ or trp+ revertants was not observed both in the standard plate test and in the preincubation test either without S-9 mix or after the addition of a metabolizing system. According to the results of the present study, the test substance N-(2-Hydroxyethyl)-morpholine is not mutagenic in the Ames test and in the Escherichia coli - reverse mutation assay under the experimental conditions chosen here (BASF, 1998).

In vivo rat micronucleus test:

The substance N-(2-Hydroxyethyl)morpholine was tested for clastogenicity and for the ability to induce spindle poison effects in rats using the micronucleus test method. For this purpose, the test substance, dissolved in purified water, was administered twice intraperitoneally, with a 24-hour interval between administrations, to male and female animals at dose levels of 500 mg/kg, 1,000 mg/kg and 2000 mg/kg body weight in a volume of 10 mL/kg body weight in each case. As negative controls, both untreated male and female rats and animals which received the vehicle purified water by the same route were used. The positive control chemical cyclophosphamide led to the expected increase in the rate of polychromatic erythrocytes containing small or large micronuclei. Animals which were administered the vehicle or the positive control substance cyclophosphamide did not show any clinical signs of toxicity.

The administration of the test substance led to evident signs of toxicity. The animals were sacrificed and the bone marrow of the femora was prepared 24 hours after the second administration. After staining of the preparations, 2000 polychromatic erythrocytes were evaluated per animal and investigated for micronuclei. The normocytes with and without micronuclei occurring per 2000 polychromatic erythrocytes were also registered. According to the results of the present study, the two intraperitoneal administrations of N-(2-Hydroxyethyl)morpholine did not lead to any increase in the number of polychromatic erythrocytes containing either small or large micronuclei. The rate of micronuclei was nearly the range as that of the concurrent negative control in all dose groups and within the range of the historical control data. A slight inhibition of erythropoiesis, determined from the ratio of polychromatic to normochromatic erythrocytes, was detected at the top dose of 2000 mg/kg body weight.

Thus, under the experimental conditions chosen here, the test substance N-(2-Hydroxyethyl)morpholine does not have any chromosome-damaging (clastogenic) effect, and there were no indications of any impairment of chromosome distribution in the course of mitosis (BASF, 2001).

 

Non-reliable studies:

The studies listed below were non-reliable and thus, disregarded.

Hepatocyte Primary Culture/DNA Repair Assay (NTIS/OTS, 1992 and Conaway et al., 1984)

Balb/3T3 in vitro Transformation Assay(NTIS/OTS, 1992)

In vivo bone marrow cytogenetics test (NTIS/OTS, 1992)


Short description of key information:
In vitro: 2 -morpholinoethanol was shown to be non-mutagenic in a bacterial reverse mutation assay (Ames test). A Hepatocyte Primary Culture/DNA Repair assay and a cell transformation assay (BALB/3T3 cells), both of which suffer from severe methodological and reporting limitations, gave ambigous results. In vivo: A GLP and OECD test guideline (TG 474) conforming in vivo rat micronucleous test in rats clearly shows the lack of mutagenicity in vivo. No clear result was obtained in a less reliable in vivo bone marrow cytogenetic test.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on the results obtained in the Ames test and the in vivo micronucleus test in rats the test substance has not to be classified with respect to mutagenicity according to Regulation (EC) No 1272/2008 (CLP, GHS).