3-hydroxypropiononitrile

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study sufficient documented, meets generally scientific principles, acceptable for assessment - Evaluated small, but adequate, groups of male and female rats for a subchronic duration - Doses carefully calculated in drinking water - Only reported results were slight but significant increases in absolute weights of brain and heart - Numerical data not provided for these changes in the manuscript

Data source

Reference

Reference Type:

publication

Title:

Toxicological evaluation and pharmacokinetic profile of beta-hydroxypropionitrile in rats.

Author:

Sauerhoff MW, Braun WH, Ramsey JC

Year:

1976

Bibliographic source:

J. Toxicol. Environ. Health 2(1): 31-44

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Ninety-Day Toxicity Study: Male/female Sprague-Dawley rats were treated orally with drinking water, containing sufficient Ethylene cyanohydrin (beta-Hydroxy-propionitrile) to provide dose-levels of 0 (control), 270, 90, 30, 10 mg/kg bw (body weight) per day for 90 days.

GLP compliance:

no

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

3-hydroxypropiononitrile

EC Number:

203-704-8

EC Name:

3-hydroxypropiononitrile

Cas Number:

109-78-4

Molecular formula:

C3H5NO

IUPAC Name:

3-hydroxypropanenitrile

Details on test material:

Name of test material (as cited in study report): beta-Hydroxypropionitrile (beta-HPN)
- Substance type: aliphatic nitrile
- Physical state: colourlesss liquid
- Analytical purity: > 99% (by 1H-NMR)

Test substance: purified by fractional destillation and analyzed by 1H-NMR

Impurities: Ethylene glycol 0.2 +/- 0.1 wt %
Acrylonitrile 0.3 +/- 0.2 wt %
Formic acid 0.3 +/- 0.2 wt %
Acrylamide < 0.01 wt %
ß-Hydroxypropionamide 0.1 +/- 0.1 wt % (*)
a-Hydroxypropionitrile 0.12 +/- 0.03 wt % (*)
(*) probable composition of these compounds.

- Purity test date: no data
- Lot/batch No.: no data
- Stability under test conditions: stable in water under test conditions

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Spartan Research Animals Inc., Haslett, Michigan
- Age at study initiation: 6-7 weeks old
- Weight at study initiation: male: 235g; female: 195g
- Fasting period before study: no data
- Housing: individual housing
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: no data

ENVIRONMENTAL CONDITIONS
no data

Administration / exposure

Route of administration:

oral: drinking water

Vehicle:

water

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: no data
VEHICLE
- Concentration in vehicle: "To provide a constant dose of Ethylene cyanohydrine in drinking water (270, 90, 30, 10, 0 mg/kg bw a day) weekly
adjustments were made in the concentration of the test substance in drinking water to correct changes in water consumption and body weight
(bw)."

- Purity: "Fresh solutions were supplied twice a week. Water solutions, prepared on day 4, 40, and 80 of the study, were analyzed for the test
substance using gas chromatography. The anticipated concentrations of the test substance were confirmed."

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

GC-Analysis of Ethylene cyanohydrin in water solutions, administered as drinking water to the test animals.
GC-conditions: coloumn, Porapak Q; temperature: 210°C, flow: helium 40cc/min; detector: flame ionization 280°C; injector: 230°C.

Duration of treatment / exposure:

90 days

Frequency of treatment:

continuously in drinking water

Doses / concentrations

Remarks:

Doses / Concentrations:
0; 10; 30; 90 and 270 mg/kg bw/day
Basis:
nominal in water

No. of animals per sex per dose:

10 male, 10 female Sprague Dawley rats

Control animals:

yes, concurrent vehicle

Details on study design:

- Post-exposure period: no
- Dose selection rationale: no data
- Rationale for animal assignment (if not random): randomly

Positive control:

no

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: No changes in physical appearance or demeanor were observed in any of the rats

DETAILED CLINICAL OBSERVATIONS: Yes
Table with mean cleanical chemistry values (BUN, AP; SGPT) respectiv. with mean hematologic values (RBC, Hb, Neutrophils, Lymphocytes) for the
rats (in dependance of the dosis group) is shown in table2 respectiv. table3 as an attachement in the field "attached documents".
- Time schedule for examinations of morbidity and mortality: No deaths occurred during the subchronic toxicity study.

BODY WEIGHT: Yes
- Time schedule for examinations: Mean Body weight development as a function of time (in dependance of the dosis group) is shown in figure 1 as an attachment in the field "attached documents".

other:
"Sporadic increases in food and water consumption were also not considered to be associated with treatment"

Sacrifice and pathology:

GROSS PATHOLOGY: "Slight, but significant differences in the mean weights of the heart and brain of female rats receiving 270 and 90 mg/kg a day
were observed, but there were no gross or microscopic pathologic changes in these organs."
HISTOPATHOLOGY: No data

Other examinations:

Hematologic evaluations and urinalysis were conducted on five rats/sex from the controls and those receiving 270 mg/kg ethylene
cyanohydrin a day.
At necropsy blood samples were collected from five rats/sex-dose for determination of the serum levels of blood urea nitrogen(BUN), alkaline
phosphatase (AP) activity, and serum glutamic pyruvic transaminase (SGPT) activity.

Statistics:

An analysis of variance and Dunnetts test were used to determine whether Ethylen cyanohydrin induced significant alterations in body weight,
food consumption, water consumption, hematological values, clinical chemical parameters, organ weights and organ to body weight ratios. A level of significance of p<0.05 was considered indicative of significant difference between control and treated rats.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

no effects observed

Water consumption and compound intake (if drinking water study):

no effects observed

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
No changes in physical appearance or demeanor were observed in any of the rats and there were no deaths.

BODY WEIGHT AND WEIGHT GAIN
Compared with the control, the mean body weights of female rats receiving 30 and 90 mg/kg bw a day, Ethylene cyanohydrin were sporadically
elevated during the study. These non-dose related increases most likely were not due to the treatment.

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study)
Sporadic increases in food and water consumption were not considered to be associated with treatment.

OPHTHALMOSCOPIC EXAMINATION
no data

HAEMATOLOGY/CLINICAL CHEMISTRY
There were no treatment-related differences in the clinical chemistry or hematology parameters measured. (see: Attachment; table2 and 3)

URINALYSIS
No untowardeffects of Ethylene cyanohydrin were revealed by urinalysis including specific gravity, pH, sugar, protein, ketones, occult blood, and
bilirubin.

NEUROBEHAVIOUR
no data

ORGAN WEIGHTS
No significant differences occurred between the mean organ weights or organ to body weight ratios of male rats receiving Ethylene cyanohydrin and controls. Absolute, but not relative, brain and heart weights of females receiving 270 and 90 mg/kg bw a day were slightly but significantly p<0.05=
lower than controls. The weight differences in this tissues were not accompanied by pathologic alterations.

GROSS PATHOLOGY
Examinations were done grossly and microscopically on all tissues collected from 5 rats/sex from the control ,group and those receiving
270 mg/kg bw a day. The only alterations observed were considered to be spontaneous and unrelated to treatment with Ethylene cyanohydrin.

HISTOPATHOLOGY: NON-NEOPLASTIC
No effects

HISTOPATHOLOGY: NEOPLASTIC (if applicable)
No effects

HISTORICAL CONTROL DATA (if applicable)
no data

OTHER FINDINGS
no data

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

No other treatment related effects were observed.

Proposed mode of action
- Cyanohydrin compounds are known to generate free cyanide ion.
- While alpha-cyanohydrins tend to liberate cyanide more readily, beta-
cyanohydrin compounds, like Ethylene cyanohydrin, are also believed to 
liberate cyanide ion in vivo 
- Free cyanide may have effects on oxygen-sensitive tissues, such as
the brain and the heart
- With this mechanism of action under consideration, the slight changes 
in absolute brain and heart weights reported additional weight.
- The 90 mg/kg-day dose level was selected as a LOAEL.
- The 30 mg/kg-day dose level was selected as a NOAEL.

Applicant's summary and conclusion

Conclusions:

Repeated dose toxicity study result: Ethylene cyanohydrin, administered in the drinking water for 90 days with dose levels ranging to 270 mg/kg bw resulted in no mortality in all dose groups. 90 and 270 mg/kg Ethylene cyanohydrin per day showed slight but significantly altered brain and heart
weights compared to the controls. No gross or microscopic pathologic changes in these organs.