Hexane, 1,6-diisocyanato, homopolymer, N-butyl-1-butanamine-blocked

Endpoint summary

Additional information

in vitro:

Ames-Test:

Hexane, 1,6-diisocyanato, homopolymer, N-butyl-1-butanamine-blocked was tested in a GLP compliant Ames reverse mutation assay according to OECD guideline 471 using Salmonella typhimurium strains TA 1535, TA 1537, TA 98, and TA 100 and Escherichia coli WP2 uvr A at 33 to 5000 µg/plate (two independent experiments (standard plate incorporation test and pre-incubation test) and each concentration was tested in triplicate) with and without metabolic activation (BASF SE, 2012). Precipitation of the test substance was found from 2500 μg/plate onward with and without S9 mix. A bacteriotoxic effect was occasionally observed depending on the strain and test conditions from 2500 μg/plate onward. A relevant increase in the number of his⁺or trp⁺revertants was not observed in the standard plate test or in the preincubation test either without S9 mix or after the addition of a metabolizing system. Thus, under the experimental conditions of this study, the test substance Hexane, 1,6-diisocyanato, homopolymer, N-butyl-1-butanamine-blocked is not mutagenic in the Salmonella typhimurium/Escherichia coli reverse mutation assay in the absence and the presence of metabolic activation.

HPRT-Assay:

A GLP-compliant gene mutation assay, tested according to OECD guideline 476, was performed to investigate the potential of Hexane, 1,6-diisocyanato, homopolymer, N-butyl-1-butanamine-blocked to induce gene mutations at the HPRT locus in V79 cells of the Chinese hamster (Harlan 2012).The assay was performed in two independent experiments, using two parallel cultures each. The first main experiment was performed with and without liver microsomal activation and a treatment period of 4 hours. The second experiment was performed with a treatment time of 4 hours with and 24 hours without metabolic activation.The concentration range of the main experiments was limited by precipitation of the test item.Precipitation of the test item was observed at 20.0μg/mL and above with metabolic activation (4 hours treatment, experiment I and II) and without metabolic activation (4 h treatment, experiment I). In experiment II without metabolic activation (24 h treatment) precipitation was observed at 40μg/mL and above.Cytotoxic effects were observed in the first experiment at 20.0μg/mL and above without metabolic activation.No substantial and reproducible dose dependent increase of the mutation frequency was observed up to the maximum concentration with and without metabolic activation.Therefore, Hexane, 1,6-diisocyanato, homopolymer, N-butyl-1-butanamine-blocked is considered to be non-mutagenic in this HPRT assay.

In vitro Chromosome Aberration:

In a GLP-compliant chromosome aberration test, tested according to OECD guideline 473, the test item Hexane, 1,6-diisocyanato, homopolymer, N-butyl-1-butanamine-blocked, dissolved in ethanol, was assessed for its potential to induce structural chromosome aberrations in V79cells of the Chinese hamster in vitroin the absence and presence of metabolic activation by S9 mix (Harlan 2012). Two independent experiments were performed. In Experiment I the exposure period was 4 hours with and without S9 mix. In Experiment II the exposure period was 4 hours with S9 mix, 18 and 28 hours without S9 mix. The chromosomes were prepared 18 and 28 hours after start of treatment with the test item. In each experimental group two parallel cultures were set up. At least 100 metaphases per culture were evaluated for structural chromosome aberrations, except for the positive control in Experiment II after 28 hours continuous treatment without metabolic activation, where only 50 metaphases were evaluated. The highest treatment concentration in this study, 2600.0 µg/mL was chosen with regard to the solubility properties of the test item and with respect to the OECD Guideline for in vitromammalian cytogenetic tests. In Experiment I and II, visible precipitation of the test item in the culture medium was observed at 26.6 µg/mL and above in the absence and presence of S9 mix after 4 hours treatment time. In addition, precipitation occurred in Experiment II, in the absence of S9 mix, at 166.4 µg/mL and above after 18 hours continuous treatment. After 28 hours continuous treatment precipitation occurred at 166.4, 416.0 and 2600.0 µg/mL. No relevant influence on osmolarity or pH value was observed. In Experiment I in the absence and presence of S9 mix and in Experiment II in the absence of S9 mix no cytotoxicity was observed up to the highest applied concentration. In Experiment II in the presence of S9 mix cytotoxicity, indicated as reduced cell number, was observed at the highest evaluated concentration (46.6 % of control). In both experiments, in the absence and presence of S9 mix, no biologically relevant increase in the number of cells carrying structural chromosome aberrations was observed. The aberration rates of the cells after treatment with the test item (0.0 - 3.5 % aberrant cells, excluding gaps) were slightly above the range of the solvent control values (0.0 - 2.0 % aberrant cells, excluding gaps) and within the range of the laboratory historical solvent control data. Two significant increases were observed in Experiment II after treatment with 10.6 and 26.6 µg/mL. Although these increases of 3.0 and 3.5 % aberrant cells, excluding gaps were statistically significant compared to the low response (0.0 % aberrant cells, excluding gaps) in the solvent control data, the response is within the laboratory historical solvent control data range (0.0 - 4.0 % aberrant cells, excluding gaps). Therefore, the statistical significance has to be regarded as being biologically irrelevant. No evidence of an increase in polyploid metaphases was noticed after treatment with the test item as compared to the control cultures. In both experiments, either EMS (1000.0 or 600.0 µg/mL) or CPA (1.4 or 2.0 µg/mL) were used as positive controls and showed distinct increases in cells with structural chromosome aberrations. In conclusion, it can be stated that under the experimental conditions reported, the test item Hexane, 1,6-diisocyanato, homopolymer, N-butyl-1-butanamine-blocked did not induce structural chromosomal aberrations in V79cells of the Chinese hamster in vitro, when tested up to precipitating and/or cytotoxic concentrations.

Short description of key information:
Ames-test (BASF, 2012): negative
HPRT-Assay (Harlan, 2012): negative
Chr. Abr. (Harland, 2012): negative

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on the available data, the test substance is not classified with regard to genetic toxicity according to Directive 67/548/EEC (DSD) and Regulation (EC) No 1272/2008 (CLP), respectively.