Distillation residue, butyl alcohols production, rectification

Carcinogenicity

Description of key information

There are no studies available made from the target UVCB-substance. Oncogenicity studies performed with the main constituent of the target substance, 2-ethylhexanol. Studies performed with Fischer F344 rats and B6C3F1 mice followed the current U. S. EPA Good Laboratory Practice Guidelines (1987b).

Key value for chemical safety assessment

Carcinogenicity: via oral route

Link to relevant study records

Reference

Endpoint:

carcinogenicity: oral

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Study period:

1996-01-24

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Oncogenicity studies performed with the main constituent of the registered substance, 2-ethylhexanol. Studies performed with Fischer F344 rats and B6C3F1 mice followed the current U.S. EPA Good Laboratory Practice Guidelines. In the absence of oncogenicity study with the registered substance this study serves as a good surrogate studies: a) it represents the effects of the only identified and quintified consituent of the substance, since the consituents of this registered UVCB-substance cannot be recognized and its composition varies to the degree that composition cannot be fixed. b) studies have been performed following U.S. EPA Good Laboratory Practice. c) they provide information on oncogenic and genetic toxicity of 2-ethylhexanol and information what also is predicted to happen when this registered UVCB-substance is metabolized.

Qualifier:

according to guideline

Guideline:

EPA OTS 798.3320 (Combined Chronic Toxicity / Carcinogenicity)

Deviations:

not specified

Principles of method if other than guideline:

Publication describes studies done via oral cavage following Health Effects Guidelines (U.S. EPA, 1987b).

Oncogenic study: 50 males and females, rats and mice.

GLP compliance:

yes

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source:not disclosed, age: rats 33-35 days upon arrival, mice 43-44 days upon arrival.
- Age at study initiation: 42 days rats, 44 days mice
- Weight at study initiation: rats: males 103g (86-128) and females 81g (64-95), mice: males 23g (21-26) and females 19g (17-23)
- Fasting period before study: 16-20 hours
- Housing: following U.S. EPA GLP: rats housed singly in suspended stainless steel wire mesh cages and mice singly in plastic cages arranged in racks.
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: one week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24
- Humidity (%):30-70
- Air changes (per hr): not disclosed
- Photoperiod (hrs dark / hrs light): 12 hours

Route of administration:

oral: gavage

Vehicle:

polyethylene glycol

Remarks:

0.005% Cremophor EL (polyoxyl-35 castor oil)

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:

DIET PREPARATION
- Rate of preparation of diet (frequency): daily
- Mixing appropriate amounts with (Type of food): cavage solution in Cremophor LE
- Justification for vehicle choice: most stable dose formulation and minimized tract irritation and inflammation.

VEHICLE
- Justification for use and choice of vehicle (if other than water): 2-ethylhexanol forms a stable emulsion with0.005% Cremophor EL. To minimize any possible interfering effects of nonaqueous vehicles. A water (double-distilled) cavage control was included for the dose vehicle.
- Concentration in vehicle: Oncogenicity: rats 50, 150, 500 mg/kg bw and mice 0, 50, 200 and 750 mg/kg bw.
- Amount of vehicle (if gavage): 10ml/kg bw or 1ml in mice 3ml in rats (solution of 0,005% Cremophor EL)
Oncogenicity (76 weeks in mice, 104 weeks in rats) and prechronic studies (13 weeks both in mice and rats) also discussed and studied the metabolites of 2-ethylhexanol.
- Lot/batch no. (if required):not disclosed
- Purity: not disclosed

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

HOMOGENEITY AND STABILITY OF TEST MATERIAL: see test material details.

Duration of treatment / exposure:

Mice 18 months
Rats 24 months

Frequency of treatment:

5 times a week

No. of animals per sex per dose:

Oncogenic study: 50 males and females, rats and mice.

Details on study design:

Oncogenicity:
rats 0 (water), 0 (vehicle), 50, 150, 500 mg/kg bw
and mice 0 (water), 0 (vehicle), 50, 200 and 750 mg/kg bw.

Positive control:

No.

Observations and examinations performed and frequency:

On-life observations
Body weights were determined before the onset of dosing, weekly in the first 13 weeks and monthly thereafter. Daily food consumption was averaged for 1 week every month. Observations for clinical signs and mortalities were made twice daily on dosing days and once daily on weekends. Detailed examination and palpations were made weekly. Differential blood counts were on blood collected by tail vein puncture at 52 weeks and termination. Blood smears were counted visually.

Sacrifice and pathology:

Observations at necropsy
complete gross necropsies were performed on all animals at sacrifice, on decedents, and on sacrificed moribund animals. Weights of exsanguinated animals and of stomachs, livers, kidneys, spleens, brains, and testes were taken for all animals sacrificed according to schedule. Tissues from gross lesions and all organs and tissues listed in the guidelines were fixed in 4% formaldehyde solution. Microscopic examination was performed after hematoxylin and eosin staining. Gross lesions, all tissues from water and vehicle controls and from high-dose groups, and kidneys, fore- and glandular stomachs, livers, lungs, and testes from low- and mid-dose groups were examined microscopically.

Statistics:

Means and standard deviations were calculated for body weights, food consumption, and absolute and relative organ weights. Data from water and vehicle controls were compared with vehicle controls by ANOVA followed by Dunnett's tes. Microscopic observations were tested for significance by pair-wise (one-tailed) comparison with vehicle controls using Fisher's exact test. Hepatocellular carcinoma data were also tested for trends among dose levels by the time-independent Cochran-Armitage and the simple Peto tests and by the time-dependent Peto-test. Mortality and hepatocellular carcinoma data were fitted by the time-dependent multi-stage Weibull dose-response model.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

female rat mortality markedly increased at 500 mg/kg bw/day, dose-related increase poor general condition, lethargy, unkemptness and laboured breathing

Mortality:

mortality observed, treatment-related

Description (incidence):

female rat mortality markedly increased at 500 mg/kg bw/day, dose-related increase poor general condition, lethargy, unkemptness and laboured breathing

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

reduced body weight gain 150 and 500 (mg/kg bw/day)

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

mice at 750 (mg/kg bw/day) significant (9-12%) decrease in food intake

Food efficiency:

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

highest dose levels manifested in slight morphological changes in red blood cells, slight increase neutrophils and slight decrease in lymphocytes.

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Behaviour (functional findings):

effects observed, treatment-related

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

dose-related increases in relative liver, stomach, brain, kidney and testis weights.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

highest doses moderate increases of focal lesions and discoloration in the lung and stomach

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

rats, 500 mg/kg bw/day, mesenteric and mandibular lymph node hyperplasia

Histopathological findings: neoplastic:

no effects observed

Details on results:

2-ethylhexanol is a weak nongenotoxic hepatic peroxisome proliferator in the rat. Under the conditions of these studies 2-ethylhexanol was not oncogenic in rats, but there were weak adverse trends in hepatocellular carcinoma incidence in mice at high dose levels which may have been associated with toxicity.

The target organs of 2-ethylhexanol in rodents are the liver, the kidney, the central nervous system and the mucosa of respiratory and gastrointestinal tracts, depending on the route of administration.

Aspiration-induced bronchopneumonia in rats 500 mg/kg bw/day

At 750 mg/kg bw/day a slight increase in nonneoplastic focal hyperplasia in the forestomach of mice, 12% incidence of hepatic basophilic foci and 18% incidence of hepatocellular carcinomas in male mice, which was not statistically significant compared with either control by Fischer's exact test. There were no metastases. Time-dependent and -independent statistical analyses showed on adverse trend in the incidence of hepatocellular in the incidence of hepatocellular carcinomas in male and female mice, correlated with toxicity (expressed as mortality) at 750mg/kg bw/day. There were no treatment -related differences from controls in the incidence of liver adenomas in male or female mice.

There were no metastases from the hepatocellular carcinomas and no other treatment-related differences from controls in tumor incidence for any other organ in surviving or decreased male or female mice. Water and vehicle control animals gave closely similar microscopic findings, with the exceptions of slightly decreased glandular stomach erosion and mandibular lymph node hyperplasia in female rat water controls and of slightly decreased liver focal hyperplasia in male mice water controls, compared with vehicle controls.

The major effects of chronic dosing were mortality in female rats at 500 mg/kg and in male and female mice at 750 mg/kg, accompanied by reduction in body weight gain in rats at 150 and 500 mg/kg and in mice at 750 mg/kg. Direct comparison of any tumorigenic effects of 2-ethylhexanol given alone to female mice with those due to 2-ethylhexanol formed in vivo from DEHA, DEHP, or TEHP is limited by the high mortality caused by 2-ethylhexanol in female mice at equivalent doses of 2-ethylhexanol. While 2-ethylhexanol may be a contibuting factor in the hepatocellular carconogenesis in female mice associated with the chronic administration of DEHA and DEHP, it is unlikely to be the entire proximate carcinogen.

Relevance of carcinogenic effects / potential:

These studies meet generally accepted criteria for a valid negative oncogenic study (U.S. EPA, 1987b) which suggest that survival in each group should not be less than 50% at termination. Under the conditions of this this study 2-ethylhexanol in non-oncogenic in rats. Also it can be considered to be non-oncogenic in male mice since there is marked toxicity at the high dose and the survival-adjusted tumor incidence at that dose within the historical control range. While it is likely that 2-ethylhexanol is a weak or equivocal carcinogen in female mice, it is unlikely to be the entire proximate carcinogen for the hepatocellular tumors in female mice associated with DEHP, DEHA and TEHP.

Dose descriptor:

NOAEL

Effect level:

> 50 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Reduced weight gain

Remarks on result:

other: Effect type: toxicity (migrated information)

Conclusions:

Since the site of carcinogenic activity for the precursors of 2-ethylhexanol (DEHP, DEHA, TEHP and EHS) was the liver, careful attention was paid to the morphological changes in the livers of treated animals usually associated with preneoplastic and neoplastic changes. It is reasonable to conclude that 2-ethylhexanol is not a hepatocellular carcinogen in male and female rats. Almost all statistical treatments of incidence data show either absence of significant differences from controls or the absence of adverse trends, in time-dependent or - independent tests. Statistical tests on male mouse incidence data suggest that 2-ethylhexanol at most is an equivocal hepatocellular carcinogen in male mice, high mortality at the highest doses may be associated with this phenonema.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

50 mg/kg bw/day

Study duration:

chronic

Species:

rat

Carcinogenicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Carcinogenicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the available data there is currently no need for classification of the target substance concerning carcinogenicity according to the CLP Regulation (EC) 1272/2008 and EU Directive 67/548/EEC.

Additional information

In the absence of carcinogenicity study conducted for the target UVCB-substance the study published study by Astill, et al. (1996) serves as a good supportive study:

a) It represents the effects of the only identified and quantified constituent of the substance, since the constituents of this target UVCB-substance cannot be recognized, quantified and its composition varies to the degree that composition cannot be fixed.

b) Studies have been performed following U. S. EPA Good Laboratory Practice, with doses based on studies presented in section “5.6.1 Repeated dose toxicity- oral”

c) They provide information on oncogenic and genetic toxicity of 2-ethylhexanol properties, which might be of relevance for the target UVCB-substance.

For the above mentioned reasons, it would be against animal welfare to further test this substance for carcinogenicity.

Furthermore, the GC-MS analysis performed during dossier update by Elek, J. (2013) shows that the test substance is primarily composed of 2 -ethylhexanol, alcohols C<8, alcohols C8, alcohols C>8, alcohols C4 and acetals. No aromatics were found to be present in the test item. This results is consistent with the previous analysis and composition data provided in the CSR section 1.2. composition of the substance.

Justification for selection of carcinogenicity via oral route endpoint:
There are no studies available from the target UVCB-substance. Oncogenicity study was performed with the main constituent of the target substance, 2-ethylhexanol.