Reaction mass of ethanol and propan-2-ol

Endpoint summary

Description of key information

Ethanol:
Oral route (mg/kgbw/day):
Rat NOAEL (90 day): 3250 (male), 3900 (male/female), <4400 (female).
Mouse NOAEL (90 day) >9400 (female), <9700 (male)
Monkey NOEL (chronic) <6200mg/kg/day
Isopropanol:
Inhalation route (mg/m3)
Rat (chronic) NOAEC  = 12500 mg/m3

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Dose descriptor:

NOAEL

3 250 mg/kg bw/day

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Dose descriptor:

NOAEC

12 500 mg/m³

Additional information

There are no data available for the reaction mass. The oral NOAEL from ethanol, being 3250 mg/kg bw/day, and the inhalatory NOAEC from isopropanol, being 12500 mg/m3, will be used for the reaction mass representing worst case values.

Ethanol:

ORAL ROUTE

In a 90 day sub-chronic repeat dose study, male rats were given a liquid diet containing ethanol at a level of 1 -5% by weight. The only significant effect seen in the 1 and 2% dose groups were centrilobular steatosis. This is often associated with ethanol consumption but in its mild form is not considered to be a pathological condition. There was also evidence from glucose dosed animals, used as calorific controls which also showed the effect, that this finding is actually related to the caloric content of ethanol rather than being substance specific. It is not therefore considered an adverse effect. On this basis, the no effect level from this study was 2%, which was approximately equivalent to a dose of 3900mg/kg/day. It should be noted that the study did not conform fully to a guideline study in that a number of end points, e.g. haematology and urinalysis, were not carried out and only partial clinical chemistry and organ pathology/histology was undertaken. Notwithstanding this, the study did concentrate on the likely known toxicity targets for this substance.

In a well conducted GLP that closely followed guidelines, rats and mice were dosed exposed to ethanol in drinking water at a level of 5% for a period of 90 days. Only a single dose level was used as the study was primarily looking at the toxicology of urethane. To establish the effect of ethanol on urethane disposition, two parallel studies were run, one using distilled water as the vehicle for the urethane, the second using 5% ethanol solution as the vehicle. The study allowed a comparison of the two vehicles used. In female rats, there were small but clear and significant histopathological changes in the liver (diaphragmatic nodules), accompanied by a non-statistically significant liver weight increase, and an increase in nephropathy (although male rats showed 100% evidence of this in every dose group). Male rats showed an increase in thymus weights, but it was not clear if this was biologically significant and it may have a chance observation. Male rats also showed some slight but inconsistent changes to haematology (reticulocyte count) and clinical chemistry (serum bile acid concentrations), with the latter also seen in females. It was unclear if these changes were biologically significant. A marginal NOAEL of 5% (>3250mg/kg) is selected for males and a LOAEL of 4400mg/kg for females. In male mice, relative and absolute liver weight was increased and there were increases in absoluted heart, liver, kidney and lung weight. There was some evidence for a marginal increase in nephropathy in male mice, but the increase was not statistically clear. Sperm count in the cauda epididymis was also decreased (~30%). Female mice showed no effects apart from a small change to the time spent in dioestrus and pro-oestrus but it was unclear whether this was either statisticall or biologically significant. Cycle length was not significantly changed. A marginal NOAEL of >5% (>9400mg/kg) is selected for females and a LOAEL of 9700mg/kg for males.

The effect of chronic ethanol feeding was determined on parameters of hepatic collagen metabolism in monkeys. The animals were fed a nutritionally adequate diet with 50% of the calories provided as ethanol (equivalent ot 6200mg/kg) with controls consuming ethanol isocalorifically substituted by carbohydrate. Feeding was carried out for 48 months, with intermediate liver biopsies taken at 3, 12 and 24 months. Blood and urine were monitored to determine ethanol concentrations. The ethanol fed animals developed various degrees of liver fatty infiltration but no necrosis, inflammation or fibrosis. There was no effect on the amount or distribution of collagen types, liver free proline or protein bound hydroxyproline levels or in collagen prolyl hydroxylase activity. A no effect level was not established due to the fatty infiltration but a no effect level for the more severe adverse liver effects normally associated with ethanol (cirrhosis and fibrosis) was established at 6200mg/kg.

DERMAL ROUTE

There is no repeat dose toxicity data available by the dermal route. However, there is sufficient information available to conclude that under non-occlusive conditions, evaporation is so rapid that dermal exposure would be negligible. Available data also shows that skin absorption under practical use conditions is negligible. There is also sufficient toxicokinetic data available to enable reliable route to route extrapolation from the oral to dermal routes if required.

INHALATION ROUTE

There is limited repeat dose toxicity information available by the inhalation route. The only reliable studies identifed are sub-acute studies that do not assess all end points. Both of these established no adverse effects at the single dose tested (20mg/l and 6130ppm for 26 and 28 days respectively). This is however supplemented by reproductive toxicity data by the inhalation route; testing up to maximum safe concentration (~50% of the lower explosive limit - 16000ppm), produce no significant adverse effects in a 6 week study (see chapter 7.8.1). Such conditions would cover all conceivable handling and use scenarios, both normal and abnormal. In addition, there is also sufficient toxicokinetic data available to enable reliable and robust route to route extrapolation from the oral to inhalation routes if required.

All available information indicates that toxicity by the inhalation route is not likely to be of concern.

Isopropanol:

INHALATION ROUTE

A GLP whole-body inhalation oncogenicity study in Fischer 344 rats with IPA concentrations of 0, 500, 2500, 5000 ppm for 6 hours/day 5 days/week for 104 weeks was conducted according to OECD test guideline 451. The report allows to conclude on a NOAEL = 5000 ppm.Exposure of rats to isopropanol vapor for 24 months produced clinical signs of toxicity, changes in body weight, and urinalysis and urine chemistry indicative of kidney changes in the 2500 and 5000 ppm groups. These changes were considered by the study authors to be indicative of chronic progressive nephropathy, a spontaneous lesion in aging rats which tends to be more prominent in male than female rats. Based on human and animal evidence relating to CPN, Hard et al. (2009;Gordon C. Hard, Kent J. Johnson, Samuel M. Cohen; Critical Reviews in Toxicology; 2009, Vol. 39, No. 4, Pages 332-346; A comparison of rat chronic progressive nephropathy with human renal disease) have concluded that this is a rodent-specific lesion which should not be regarded as an indicator of human toxic hazard. The only neoplastic lesion which was elevated was an increase in Leydig cell tumors in male rats.This is also a common spontaneous lesion in male rat which is very common in the rat strain used for this evaluation, F-344. The authors observed that the statistical significance attached to the frequency of this observation was probably due to the unusually low incidence in the concurrent control group. No increase in neoplastic lesions were noted in female rats.

A shorter duration key study was a subchronic inhalation study in Fischer 344 rats and CD-1 mice with IPA administered at concentrations of 0, 500, 2500, 5000 ppm for 6 hours/day 5 days/week for 98 days (Burleigh-Flayeret al.,1991). This GLP study was conducted according to OECD test guideline 413. During the 14th week, male and female rats (excluding those animals designated for neuroanatomic pathology evaluation) received 2 and 3 consecutive days of exposure, respectively. The 10 female rats of the 500, 1500, and 5000 ppm group designated for neuroanatomic pathology evaluation were exposed for 1 day during the 14th week; the male rats of the 500, 1500, and 5000 ppm group designated for neuroanatomic pathology evaluation were not exposed during the 14th week. Male and female mice received 4 and 5 consecutive days of exposure during the 14th week, respectively. NOAECs were not identified by the authors. Rats showed acute signs of toxicity (including ataxia, narcosis, lack of a startle reflex, and/or hypoactivity), decreases in absolute body weight and body weight gain, and changes in hematology parameters in animals exposed to 1500 and 5000 ppm of isopropanol, increased relative liver weight in male and female rats exposed to 5000 ppm, as well as increased motor activity for female rats in the 5000 ppm group. Mice showed clinical signs of acute toxicity (including ataxia, narcosis, lack of a startle reflex, and/or hypoactivity) in animals exposed to 1500 and 5000 ppm of isopropanol, increased body weight and body weight gain observed in female mice of the 5000 ppm group, various changes in hematologic and serum clinical chemistry parameters observed in female mice of the 5000 ppm group, and increased relative liver weight in female mice of the 5000 ppm group.

Supportive information on the repeated dose inhalation toxicity of IPA also is provided. A 78-week inhalation oncogenicity study (GLP and based on OECD test guideline 453) in CD-1 mice identified a NOEL[equivalent to a no-observed effect concentration (NOEC)] for toxic effects of 500 ppm due to clinical signs of toxicity and increases in body weights and body weight gains noted at the higher doses, and a NOEL for oncogenicity effects of 5000 ppm (the highest dose tested) as an increased frequency in neoplastic lesions was not noted (Burleigh-Flayer and Wagner, 1993). A 9-day inhalation study in Fischer 344 rats and CD-1 mice conducted according to OECD test guideline 412 was conducted according to GLP (Burleigh-Flayer et al., 1990). Animals were administered IPA for 6 hours/day, 5 days/week at 1000, 5000, 10000, and 15000 ppm. Mortality was observed in rats and mice at the highest two doses. Histologic lesions observed in the kidneys of male rats at 1000 and 5000 ppm are considered to be species and sex specific.

Justification for classification or non-classification

Based on data for the two constituents the reaction mass does need to be classified for repeated dose toxicity according to DSD or CLP.

Ethanol:

It is clear that adverse findings are only seen at extremely high dose, well above those that would trigger classification for repeat dose effects.

Isopropanol:

The substance does not meet the criteria for classification and labelling for this endpoint, as set out in Regulation (EC) NO. 1272/2008.