Prop-2-yn-1-ol

Endpoint summary

Additional information

1. Genetic toxicity in vitro

In a reverse gene mutation assay in bacteria (BASF SE, 2015), strains TA 98, TA 100, TA 1535, TA 1537 of S. typhimurium and E. coli WP2 uvrA were exposed to Propargyl alcohol (> 99%) at concentrations of 3.3 µg - 5000 µg/plate in the presence and absence of mammalian metabolic activation. A relevant increase in the number of his+ or trp+ revertants was not observed in the standard plate test or in the preincubation test (SPT, PIT) either without S9 mix or after the addition of a metabolizing system. This study is classified as acceptable and satisfies the requirement for Test Guideline OECD 471 for in vitro mutagenicity (bacterial reverse gene mutation).

These results are supported by further reverse gene mutation assays:

In a reverse gene mutation assay in bacteria, strains TA 98, TA 100, TA 1535, TA 1537, TA 1538 of S. typhimurium were exposed to Propargyl alcohol (ca. 99 % a.i.) at concentrations of 0, 4, 20, 100, 250, 500, 2000 or 2500 µg/plate (vehicle: aqua dest.) in the presence and absence of mammalian metabolic activation (S9 -mix) in the standard plate test (plate co-incubation). Propargyl alcohol was tested up to slight cytotoxic concentrations (without S9-mix: 2500 µg/plate; with S9-mix:500 µg/plate ). The positive controls induced the appropriate responses in the corresponding strains. There was no evidence of a concentration related positive response of induced mutant colonies over background. (BASF, 1979)

Furthermore, a test reported by Blakey et al. (1994), where Propyrgyl alcohol did not increase the number of revertants in the strains TA 97, TA 98, TA 100 and TA 102 of S. typhimurium when tested at five concentrations ranging from 7.3 to 730 µg/plate in the presence and absence of mammalian metabolic activation.

In a reverse gene mutation assay in bacteria (NTP, 2008), strains TA 98, TA 100 or TA 1535 of S. typhimurium were exposed to Propargyl alcohol (> 99 % a.i.) at concentrations of 0, 3, 10, 33, 100, 333, 666, 1000, 1666, 3333, 6666, or 10000 µg/plate in the presence and absence of mammalian metabolic activation (S9 -mix) in the standard pre-imcubation plate test. Each concentration was tested in triplicate. The included positive controls induced the appropriate responses in the corresponding strains. The authors concluded that Propargyl alcohol was mutagenic in strain TA 100 without S9 based on a dose related increase in revertants. However, this dose response was only seen in 2 of 3 trials and the increase was only in the first trial more than two-fold (2.2 x) above the control revertant number. Therefore, it is concluded that the result in TA 100 without S9 is equivocal. No mutagenicity was observed in TA 100 in the presence of hamster or rat liver S9. In addition, Propargyl alcohol was not mutagenic in TA1535 without S9 (this strain was not tested with S9) and in TA 98 with (hamster or rat liver) or without S9. Considering the results from all bacterial reverse gene mutation assays, the equivocal response in TA 100 without S9 obtained in the NTP study (2008) represents an isolated finding. Based on the assessment of all available data, it is concluded that Propargyl alcohol is not mutagenic in this in vitro test system.

In a mammalian cell cytogenetics assay (chromosome aberration;Blakey et al., 1994), CHO cell cultures were exposed for 1 hour to Propargyl alcohol (97% a.i.) at concentrations of 0, 3.0, 6.0 or 10.0 mM and 0, 0.4, 0.6 or 0.8 mM without and with metabolic activation, respectively (10-hours incubation period), and at concentrations of 0, 2.0, 3.0, 6.0 or 10.0 mM and 0, 0.4, 0.6, 0.8 or 1.0 mM without and with metabolic activation, respectively (16-hours incubation period). Following incubation, chromosomes were prepared and metaphase cells were analyzed for chromosome aberrations. Positive controls induced the appropriate response. For the 10-hours timepoint, no increase in chromosome aberrations over background was noted.

For the 16-hours timepoint, there was evidence that Propargyl alcohol induced a small but significant increase in chromosome aberrations in the absence of metabolic activation. Although the response at only the highest dose was significantly higher than the control, there was a positive trend. A larger, dose-related increase was induced in the presence of metabolic activation. This study is classified as acceptable and satisfies in general the requirement for the Test Guideline OECD GL 473 (“In Vitro Mammalian Chromosome Aberration Test”) with some limitations.

Propargyl alcohol 99.5%. was assessed for its potential to induce gene mutations at the hypoxanthine-guanine phosphoribosyl transferase (HPRT) locus in Chinese hamster ovary (CHO) cells in vitro. Three independent experiments were carried out, with and without the addition of liver S9 mix from induced rats (exogenous metabolic activation). The vehicle controls gave mutant frequencies within the range expected for the CHO cell line. Both positive control substances,and MCA, led to the expected increase in the frequencies of forward mutations.

In this study, in the 1st and 3rd Experiment in the absence and presence of metabolic activation the highest concentrations tested for gene mutations were clearly cytotoxic.

On the basis from the results of the present study, the test substance did not cause any relevant increase in the mutant frequencies both either without S9 mix or after adding a metabolizing system in two valid experiments performed independently of each other.

 

2. Genetic toxicity in vivo

In a NRMI mouse bone marrow micronucleus assay (Hoechst, 1990) 5 animals (sex/dose) were treated orally by gavage with Propargyl alcohol (99.4% a.i.) as aqueous solution at doses of 0 and 70 mg/kg bw (the vehicle was water). The animals were treated once with the test compound and according to the test procedure the animals were killed 24, 48 and 72 hours after administration. Subsequently, bone marrow cells were harvested at 24, 48 and 72 hours post-treatment. Propargyl alcohol was tested at an adequate dose (based on a preliminary study). Only the females of the 24 and 72 hours killing times showed a very small but statistically significant increase in the number of micronucleated polychromatic erythrocytes. The increase was within the normal range of the negative control values and therefore considered as of no toxicological significance. The ratio of polychromatic/normochromatic erythrocytes in both male and female animals remained unaffected by the treatment and was statistically not different from the control values. The positive control induced the appropriate response. The results demonstrate that Propargyl alcohol is not mutagenic in the micronucleus test. This study is classified as acceptable and satisfies the requirement for Test Guideline OECD 474 for in vivo cytogenetic mutagenicity data.

The result is supported by a further micronucleus test in C57BL mice (Blakey et al., 1994). In this test, groups fo 5 mice/sex were treated twice with 24 h between each treatment at Propargyl alcohol dose levels of 24, 48 and 72 mg/kg bw/day by oral gavage. All males of the 72 mg/kg bw/d group died. Bone marrow cells of the remaining groups were prepared 36 h following the second treatment and evaluated. Propargyl alcohol did not increase the number of micronucleated cells in this assay.

In a mouse peripheral blood micronucleus assay (NTP, 2008) 10 B6C3F1 mice per sex per dose were treated by inhalation with Propargyl alcohol vapour at concentrations of 0, 4, 8, 16, 32, or 64 ppm for 6 hours plus T90 (12 minutes) per day, 5 days per week for 14 weeks. At the end of the 3‑month study period, peripheral blood samples were obtained from male and female mice, slides were prepared and analysed for frequency of micronuclei in 1000 normochromatic erythrocytes (NCEs) in each animal. In addition, the percentage of polychromatic erythrocytes (PCEs) in a population of 1000 erythrocytes was determined as a measure of bone marrow toxicity.

No significant changes in the percentage of PCEs were observed in either male or female mice over the exposure range tested, indicating an absence of treatment-related toxicity to the bone marrow. No significant increases in micronucelated NCEs were seen in male mice exposed to 4, 8, 16, 32, or 64 ppm. In female mice, the trend test was significant. However, none of the exposed female mice groups showed a significantly increased micronulceus frequency in comparison to the control group. The NTP scientists judged the test in female mice to be equivocal. This seems to be over conservative, as no individual female exposure group had a significantly increased micronucleated erythrocyte frequency and the frequencies were within the normal range. Thus, it is concluded that Propargyl alcohol is negative in this micronucleus assay.

Taking into account the results of all in vivo studies, it is concluded that Propargyl alcohol is not genotoxic in vivo.

Short description of key information:
In reverse gene mutation assays in bacteria (Ames test) Propargyl alcohol was not mutagenic. In a mammalian cell cytogenetic assay Propargyl alcohol did not cause in vitro chromosome aberrations after a 10 hour incubation period (with and without S9), however, after an incubation period of 16 hours (with and without S9). In this assay no details were given as to the cytotoxicity of Propargyl alcohol. Mouse micronucleus assays showed no indication of aneugenic activity in bone marrow cells or erythrocytes in vivo after treatment with Propargyl alcohol.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on the results of an Ames test, one chromosomal aberration test on HPRT test and an in vivo mouse bone marrow micronucleus assay, Propargyl alcohol is not subject to classification for mutagenicity according Regulation 1272/2008/EC.