Fusel oil

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 068 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Effect on fertility: via inhalation route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

7 580 mg/m³

Study duration:

subchronic

Species:

rat

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

Fusel oil is a UVCB substance comprising a complex mixture of alcohols, aldehydes, esters and other substances. The constituents and their concentration ranges are known. Fusel oil contains 4 main constituents being above ≥ 10%. In total, the 4 main constituents account for ≥ 80% of all constituents. In order to fulfil the standard information requirements set out in Annex IX in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from surrogate substances was conducted.

In accordance with Article 13 (1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met.” In particular for human toxicity, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from surrogate substances (grouping or read-across).

The physicochemical, toxicological and ecotoxicological properties of the main constituents of Fusel oil determine, to a great extent, the physicochemical, toxicological and ecotoxicological properties of Fusel oil itself. Therefore, having regard to the general rules for grouping of substances and read-across approach laid down in Annex XI, 1.5, of Regulation (EC) No 1907/2006, a read-across is appropriate as their physicochemical, toxicological and ecotoxicological properties are likely to be similar. A detailed justification for use of read-across is given in chapter 13 of the technical dossier.

In conclusion, hazard assessment was based on the main constituents, when no experimental data was available with Fusel oil itself. The main constituents are ethanol (CAS No. 64-17-5), 3-methylbutan-1-ol (CA 123-51-3), 2-methylbutan-1-ol (CAS No. 137-32-6), and 2-methylpropan-1-ol (CAS No. 78-83-1).

Toxicity to reproduction

Oral administration

Data from subchronic gavage study are available for 3-methylbutan-1-ol (CAS No. 123-51-3) where also reproductive organs were examined (testes / ovaries, prostate and seminal vesicle, female mammary gland, uterus) (Schilling et al., 1997). No effects on reproductive organs were observed by histological analysis up to the highest dose tested. In conclusion, a NOAEL for reproductive effects of ≥1068 and ≥1431 mg/kg bw/day was deduced for male and female rats, respectively.

In a reliable 2-generation study in mice, ethanol (CAS No. 64-17-5) in drinking water at concentrations up to 15% (equivalent to 20.7 g/kg bw/day) had no demonstrable effect on fertility (George, 1985). The F1 offspring of the 15% ethanol pairs had fewer live pups per litter but ethanol treatment had no effect on the proportion of breeding pairs producing at least 1 litter during the continuous breeding phase or the number of litters per pair. The F1 offspring from the 15% group had decreased bodyweight at weaning and mating, and a decreased weight of testis, epididymides and seminal vesicles which was no longer evident when these were adjusted for body weight. There was also a significantly decreased percentage motile sperm but no changes in sperm concentration, and percentage of abnormal sperm or tailless sperm. When reproductive performance of F1 control and 15% ethanol-treated breeding pairs was assessed at 74 days of age, there was no significant difference in mating and fertility between the groups. However, adjusted live pup weight for the ethanol group was significantly reduced compared to controls, which was likely due to generalized maternal toxicity. A decrease of body weight gain and water consumption of maternal animals was observed. No influence on sperm motility and morphology was observed in the parental animals.

 

In a one-generation study only male mice were exposed to a nutritionally balanced diet providing 10% or 25% of ethanol-derived calories (equivalent to 21.5 g/kg bw/day) and mated with untreated females for 4 hours a day sequentially for 7 weeks. No toxic responses were noted in treated males other than decreased bodyweight gain at 25% ethanol-derived calories in diet. Paternal treatment did not affect fertility during the period studied nor litter size, or weight at birth or at weanling (Abel, 1989).

Further gavage studies revealed no effect on fertility after treatment of male rats (Abel, 1993 and 1995).

An adverse effect on fertility was noted in male rats with administration of ethanol in the diet (10% ethanol derived calories) for 15 days prior to and throughout the mating period (Klassen, 1976). Only six pregnancies were initiated when the six exposed males were each paired with two untreated females. However, this study was confounded by general toxicity manifest as ataxia, lethargy and weight loss during the study period.

Reductions in ovary weight and reductions in oestradiol and progesterone in female rats receiving liquid diets containing 5% ethanol (36% EDC) for 49 days during the peri-pubertal period have been demonstrated (van Thiel, 1976). The reported blood ethanol level was relatively low (1100 ± 90 mg/L) but the timing of the sample (taken 09.00 – 11.00 hours) was probably inappropriate to detect the peak likely at the usual time of feeding during the previous evening. Irregular cycles and longer oestrous cycles were noted in rats fed liquid diets containing 5% ethanol (36 % EDC) for 16 weeks but not after 8 weeks with 8 weeks recovery period (Krueger, 1982). Again, ovarian function was suppressed in rats that achieved blood alcohol levels of 2500 mg/L (Bo, 1982).

A further study demonstrated reduction in testis and epididymis weights related to effects on spermatogenesis in pubertal male mice given 5% ethanol containing liquid diets that achieved a blood ethanol level of 1600 mg/L (Anderson, 1985). Lower dose levels were not investigated, however, virtually all changes observed were found to be reversible.

Male rats exposed to ethanol vapour concentrations of 22, 23, 25 and 27mg/L (11500 to 14000ppm) continuously for 3-4 weeks achieved blood ethanol levels of 94-187 mg/100mL (Rivier, 1983). blood ethanol levels of ≥163 mg/mL were associated with inhibition of androgen secretion, but only in those animals that failed to grow. These results suggest that there is a threshold for adverse effects of around 130 mg/100 mL (equivalent to NOAEC inhalation exposure of 23 mg/L) by this relevant route of exposure.

In a study to evaluate morphological sperm and oocyte alterations after sub-acute ethanol intake in the CF-1 outbred mouse strain, ethanol was administered in drinking water over a period of 27 days. Intake was in the range 22-23g/kg/day. Such doses caused abnormal effects in sperm (head and tail defects) and elevated parthenogenetic activated oocyte frequency was also seen. Ethanol plasma concentrations were in the range 198 -281 mg/L. Effects at such high concentrations typical of beverage consumption are difficult to extrapolate to hazards likely to be present from exposure during use of ethanol in the workplace or from the use of ethanol containing consumer products (Cebral et al., 2011).

Inhalation exposure

A two-generation inhalation reproductive toxicity study has been conducted with 2-methylpropan-1-ol (CAS No. 78-83-1) (OECD, 2004a).Groups of male and female rats were exposed whole-body (6 hours/day, seven days/week) to 0, 500, 1000, or 2500 ppm (1520, 3030, or 7580 mg/m³) 2-methylpropan-1-ol for two generations. Daily treatments were continuous with the exception of the period between gestation day 21 through postnatal day 4 (removal of the dams from the pups during this period typically causes pup mortality). Exposure to 2500 ppm (7580 mg/m³) 2-methylpropan-1-ol did not cause any parental systemic, reproductive, or neonatal toxicity when administered for two generations via whole-body exposure. Therefore, the NOEL was 2500 ppm (7580 mg/m³) for 2-methylpropan-1-ol.

In male rats exposed to ethanol (CAS No. 64-17-5) by inhalation for 7 hours /day for 6 weeks in a combined fertility and developmental toxicity study there was no effect on fertility at 16000 ppm (Nelson, 1985; Nelson, 1988). All 19 males at this dosage successfully initiated a pregnancy. The route of exposure would have resulted in the measured blood ethanol levels (approximately 500 mg/L) being steadily maintained throughout the exposures.

Male rats exposed to ethanol (CAS No. 64-17-5) vapour concentrations of 22, 23, 25 and 27 mg/L (11500 to 14000 ppm) continuously for 3-4 weeks achieved blood ethanol levels of 94-187 mg/100mL (Rivier, 1983). Blood ethanol levels of ≥ 163 mg/mL were associated with inhibition of androgen secretion, but only in those animals that failed to grow. These results suggest that there is a threshold for adverse effects of around 130 mg/100 mL (equivalent to NOAEC inhalation exposure of 23 mg/L) by this relevant route of exposure.

In conclusion no effect on fertility was observed with the main constituents of Fusel oil, being ethanol (CAS No. 64-17-5), 3-methylbutan-1-ol (CAS No. 123-51-3), and 2-methylpropan-1-ol (CAS No. 78-83-1). Based on the similar structure and toxicokinetics read-across from 3-methylbutan-1-ol to 2-methylbutan-1-ol can be performed (see Read-across justification document in chapter 13 of the technical dossier). Therefore no effects on fertility is expected for 2-methylbutan-1-ol (CAS No. 137-32-6).The minor constituents of Fusel oil do not influence fertility as they either have no toxic properties or are present in small concentrations only, not affecting the hazard assessment of Fusel oil. The available data indicate that Fusel oil has no effects on fertility.

 

References

OECD (2004a) SIDS Initial assessment report for SIAM 19. Isobutanol. CAS No: 78-83-1. UNEP Publications

 

Short description of key information:

Data from one- and two-generation studies as well as subchronic toxicity studies with investigation of reproductive organs of the main constituents of Fusel oil revealed no effects on reproduction. The lowest NOAEL was ≥ 1068 mg/kg bw, which was observed with 3-methylbutan-1-ol. The minor constituents of Fusel oil do not influence fertility as they either have no toxic properties or are present in small concentrations only, not affecting the hazard assessment of Fusel oil. The available data from the main constituents of Fusel oil indicate that Fusel oil has no effects on reproduction.

Justification for selection of Effect on fertility via oral route:

Most reliable data of the main constituents of Fusel oil were used for hazard assessment.

Justification for selection of Effect on fertility via inhalation route:

Most reliable data of the main constituents of Fusel oil were used for hazard assessment.

Effects on developmental toxicity

Description of key information

Data from prenatal developmental toxicity studies of the main constituents of Fusel oil revealed no effects on development. The lowest NOAEC was ≥ 9800 mg/kg bw, which was observed with 3-methylbutan-1-ol. The minor constituents of Fusel oil do not influence fertility as they either have no toxic properties or are present in small concentrations only, not affecting the hazard assessment of Fusel oil. The available data from the main constituents of Fusel oil indicate that Fusel oil has no effects on development.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

5 200 mg/kg bw/day

Study duration:

subacute

Species:

rat

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

9 800 mg/m³

Study duration:

subacute

Species:

rat

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

Fusel oil is a UVCB substance comprising a complex mixture of alcohols, aldehydes, esters and other substances. The constituents and their concentration ranges are known. Fusel oil contains 4 main constituents being above ≥ 10%. In total, the 4 main constituents account for ≥ 80% of all constituents. In order to fulfil the standard information requirements set out in Annex IX in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from surrogate substances was conducted.

In accordance with Article 13 (1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met.” In particular for human toxicity, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from surrogate substances (grouping or read-across).

The physicochemical, toxicological and ecotoxicological properties of the main constituents of Fusel oil determine, to a great extent, the physicochemical, toxicological and ecotoxicological properties of Fusel oil itself. Therefore, having regard to the general rules for grouping of substances and read-across approach laid down in Annex XI, 1.5, of Regulation (EC) No 1907/2006, a read-across is appropriate as their physicochemical, toxicological and ecotoxicological properties are likely to be similar. A detailed justification for use of read-across is given in chapter 13 of the technical dossier.

In conclusion, hazard assessment was based on the main constituents, when no experimental data was available with Fusel oil itself. The main constituents are ethanol (CAS No. 64-17-5), 3-methylbutan-1-ol (CA 123-51-3), 2-methylbutan-1-ol (CAS No. 137-32-6), and 2-methylpropan-1-ol (CAS No. 78-83-1).

Developmental toxicity

Oral administration

In a feeding study ethanol (CAS No. 64-17-5) was added to the diets of female rats for six weeks (from 3 weeks prior to mating to gestational day (GD) 21) in an attempt to determine effects on fetal growth and skeletal development (Simpson et al., 2005). The animals had an ethanol intake of 5.2, 8.2, or 10.4 g/kg bw/day. Prenatal ethanol exposure at 36% ethanol-derived calories (about 10.4 g ethanol/kg bw/day) decreased fetal body weight and length, and skeletal ossification (a developmental delay), compared with pair-fed and ad libitum controls at GD 21. Significant effects on ossification, but not body weight or length, were seen at 8.2 g ethanol/kg bw/day, compared to the isocaloric controls. The NOAEL for this study can be considered to be 5.2 g ethanol/kg bw/day, as at this dose level, no significant effects on fetal growth or ossification were seen compared to the isocaloric controls. A delay in the development of body weight and skeletal ossification was seen in the ethanol-treated (8.2 and 10.4 g/kg bw/day) fetuses on GD21, compared to the ad libitum controls. There were no skeletal malformations or variations (other than the delay in ossification) reported for any of the ethanol-treated groups. The data indicate that ethanol has differential effects on fetal weight and skeletal development, when dosed at high amounts, and that the skeletal sites differ in their sensitivity to ethanol.

 

Inhalation exposure

For 3-methylbutan-1-ol (CAS No. 123-51-3) prenatal developmental toxicity studies in rats and rabbits performed according to OECD guideline 414 and in compliance with GLP are available (Klimisch and Hellwig, 1995). In the first study 25 female Wistar rats per dose group were exposed whole-body to a vapour of the test substance from day 6-15 of gestation to either 0.51, 2.5 or 9.8 mg/L (analytical concentration) 3-methylbutan-1-ol for 6 h per day.

Slight changes of the body weight gain were observed in the rats of the high dose group. No biologically relevant or clearly concentration-related differences were apparent between the groups regarding corrected body weight gain. No substance-induced clinical findings were observed. One female rat was found dead on day 12 in the 0.51 mg/L exposure group.

Examination of the rats for gross-pathological findings revealed no effects that could be attributed to exposure to 3-methylbutan-1-ol. The uterine weights of exposed rats were not significantly different from their respective controls. The analyses of the reproduction data show for all groups of rats that compound-related effects occurred neither for conception rate, mean number of corpora lutea, and implantation sites nor in the values calculated for the pre- and postimplantation loss and the number of resorptions as well as viable fetuses. The sex distribution did not differ significantly between treated groups and controls. The mean placental and fetal weights were not affected by the treatment of the dams. The NOAEC for maternal and developmental toxicity was ≥ 9800 mg/m³, as no substance-related effects were observed up to the highest concentration tested.

In the prenatal developmental toxicity study with rabbits,using the same experimental settings, a NOAEC for maternal and developmental toxicity of ≥ 9800 mg/m³ was observed, as no substance-related effects occurred up to the highest concentration tested (Klimisch and Hellwig, 1995).

 

For 2-methylpropan-1-ol (CAS No. 78-83-1) prenatal developmental toxicity studies performed in rats and rabbits according to OECD guideline 414 and in compliance with GLP are available(Klimisch and Hellwig, 1995). In the first study 25 Wistar rats per dose group were whole-body exposed to a vapour of the test substance from day 6-15 of gestation to 0.49, 2.5 or 10.1 mg/L (analytical concentration) 2-methylpropan-1-ol for 6 h per day.

2-methylpropan-1-ol inhalation did not significantly influence the body weight changes of rats. Examination of the dams for gross-pathological findings revealed no effects that could be attributed to exposure to 2-methylpropan-1-ol. Findings such as hydrometra, edema, or marginal emphysema of lungs which occurred in a few rats without any relation to treatment were considered to be spontaneous events.

The uterine weights of the exposed rats were not significantly different from their respective controls. The analyses of the reproduction data show for all groups of rats that compound-related effects occurred neither for conception rate, mean number of corpora lutea, and implantation sites nor in the values calculated for the pre- and postimplantation loss and the number of resorptions as well as viable fetuses.

The sex distribution did not differ significantly between treated groups and controls. The mean placental and fetal weights were not affected by the treatment of the dams. When examining the fetuses for soft tissuechanges, one malformation, dilation of both heart ventricles, was observed in a fetus after exposure to 10.1 mg/L 2-methylpropan-1-ol. Variations were seen in all groups including the controls. The skeletal examination of the fetuses revealed no treatment-related influence of malformations. In conclusion, a NOAEC of ≥ 10100 mg/m³, which was the highest concentration tested, was deduced for maternal and developmental toxicity of 2-methylpropan-1-ol.

In the prenatal developmental toxicity study with rabbits, using the same experimental settings, a NOAEC for maternal and developmental toxicity of ≥ 10000 mg/m³ was observed after administration of 2-methylpropan-1-ol, as no substance-related effects occurred up to the highest concentration tested (Klimisch and Hellwig, 1995).

 

Most relevant for occupational exposure hazard assessment is a series of inhalation developmental toxicity studies of ethanol (CAS No. 64-17-5) conducted by Nelsonet al.,(1985; summarized in OECD, 2004b). In the first of these studies, the potential teratogenesis of inhalation exposure to ethanol was assessed (Nelson et al.,1985). Groups of 15 or 16 mated female Sprague-Dawley rats were exposed 7 hours/day throughout gestation (GD 1-19, based on the presence of sperm on GD 0) to ethanol concentrations of 10000, 16000 or 20000 ppm (corresponding to 19000, 30400, and 38000 mg/m³). These resulted in average blood ethanol levels of 27, 420 and 1480 mg/L. Ethanol elicited severe maternal toxicity at 20000 ppm. At the lower exposure levels, dams appeared hyperactive after exposures. The authors reported male (but not female) foetal weights to be depressed at the 16000 and 20000 ppm exposures, but the differences were small and not significant. There were also no significant differences in the incidences of external, visceral or skeletal malformations or variations. NOAELs for maternal toxicity and teratogenicity were 30400 and 38000 mg/m³ ethanol, respectively.

 

Conclusion

In conclusion, no effects on intrauterine development were observed with the main constituents of Fusel oil, being ethanol (CAS No. 64-17-5), 3-methylbutan-1-ol (CAS No. 123-51-3), and 2-methylpropan-1-ol (CAS No. 78-83-1). Based on the similar structure and toxicokinetics read-across from 3-methylbutan-1-ol to 2-methylbutan-1-ol can be performed (see Read-across justification document in chapter 13 of the technical dossier). Therefore no effects on fertility is expected for 2-methylbutan-1-ol (CAS No. 137-32-6).The minor constituents of Fusel oil do not influence the developmental toxicity as they either have no toxic properties or are available in small concentrations only, not affecting the hazard assessment of Fusel oil. The available data from the main constituents of Fusel oil indicate that Fusel oil has no effects on developmental toxicity.

References

OECD (2004b) SIDS Initial assessment report for SIAM 19. Ethanol. CAS No: 64-17-5. UNEP Publications

Justification for selection of Effect on developmental toxicity: via oral route:

Most reliable data of the main constituents of Fusel oil were used for hazard assessment.

Justification for selection of Effect on developmental toxicity: via inhalation route:

Most reliable data of the main constituents of Fusel oil were used for hazard assessment.

Justification for classification or non-classification

Based on available data of the main constituents of Fusel oil on toxicity to reproduction, Fusel oil does not meet the classification criteria according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and is therefore conclusive but not sufficient for classification.