Cyanoacetic acid

Endpoint summary

Description of key information

ORAL 
Oral LD50 Combined = 1010 mg/kg bw (95% C.I. 831 - 1228). 
Cyanoacetic acid is of SLIGHT Toxicity based on the LD50 in males and females(OECD GHS Toxicity Category IV).
DERMAL 
Dermal LD50 Combined > 2000 mg/kg bw (no mortality occurred, limit test). 
Cyanoacetic acid is of LOW Toxicity based on an LD50 exceeding 2000 mg/kg bw. 
INHALATION 
LC50 Males = 1.4 mg/L. 
LC50 Females = 2.6 mg/L. 
LC50 Combined = 1.9 mg/L. 
Cyanoacetic acid is of SLIGHT Toxicity based on the LD50 in males (OECD GHS Toxicity Category IV).

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

1 010 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

LC50

Value:

0.002 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Additional information

ORAL

In an acute oral toxicity study (BASF 1980), groups of fasted Sprague-Dawley (5/sex) were given a single oral dose of Cyanoacetic acid (purity not given) in water at doses of 464, 681, 1000, 1470, or 2150 mg/kg bw and observed for 14 days.

Oral LD50 Combined = 1010 mg/kg bw (95% C.I. 831 - 1228).

Clinical signs of toxicity were unspecific in nature and occurred at doses of 1000 and more. Mortality was 0/10, 1/10, 7/10, 7/10 and 10/10 in the groups administered 464, 681, 1000, 1470, and 2150 mg/kg bw, respectively; all deaths occurred within 24 hours after dosing. Stagnation/loss of body weight was observed during the first days after dosing at 1000 and 1470 mg/kg bw in both sexes. At the end of the observation period, body weight gain of the females were similar in all groups, whereas those of 1000- and 1470-mg/kg bw males was still slightly retarded when compared to the lower dose groups. Pathology of the decedents revealed unspecific changes of the heart, liver, and stomach while no pathological abnormalities were found in survivors that had been sacrificed at the end of the observation period.

DERMAL

In an acute dermal toxicity study (BASF 1980), groups of male and female Sprague-Dawley rats were dermally exposed to Cyanoacetic acid (purity not given) in water at a dose of 2000 mg/kg bw. Animals then were observed for 14 days.

Dermal LD50 Combined > 2000 mg/kg bw (no mortality occurred, limit test).

Signs of systemic toxicity were unspecific in nature. Signs of local irritation were noted at the application sites. Slight erythema, marked edema, and yellow-coloured residues of the test substance were observed at 24 hours after beginning of application. At 7 days after beginning of application, scaling and partially encrustation was observed. No pathological findings were observed.

INHALATION

In an acute inhalation toxicity study (BASF 1981), groups of young adult Sprague-Dawley rats (10/sex) were exposed by inhalation route to Cyanoacetic acid (purity 97%) in water for 4 hours to nose/head only at concentrations of 0.25, 0.65, 1.53, 2.56, or 3.94 mg/L. Animals then were observed for 14 days.

LC50 Males = 1.4 mg/L.

LC50 Females = 2.6 mg/L.

LC50 Combined = 1.9 mg/L.

Clinical signs of toxicity were mostly unspecific in nature (secretion at the eyes and nose, salivation, eyelid closure, swollen snouts with reddish encrustations, dyspnea, retarded pain reflex, tremor, squatting posture, high-legged gait, anemic paleness, and/or piloerection) and occurred at all dose levels. The symptoms persisted throughout the observation period at dose levels of 1.53 mg/L and more, but were reversible at lower concentrations. Mortality was 0/20, 3/20, 8/20, 9/20, and 19/20 in the groups exposed to 0.25, 0.65, 1.53, 2.56, or 3.94 mg/L, respectively; late deaths were observed. Animals exposed to 3.94 mg/L lost weight throughout the study. Body weight gain was retarded at 2.56 and 1.53 mg/L for both sexes and at 0.65 mg/L for males. No effect on body weight gain was noted at 0.25mg/L. Pathology of the decedents revealed changes of the heart, lungs, and liver while no pathological abnormalities were found in survivors that had been sacrificed at the end of the observation period.

Justification for classification or non-classification

Based on the oral LD50 of approximately 1010 mg/kg bw in rats, Cyanoacetic acid has to be classified as “harmful if swallowed” according to the Directive 67/548/EC. According to the GHS criteria, Cyanoacetic acid has to be classified as follows: Acute Oral Toxicity Cat. 4.

Based on the dermal LD50 of > 2000 mg/kg bw in rats, there is no need for classification according to the Directive 67/548/EC. According to the GHS criteria: On the basis of the available data on acute dermal toxicity, there is no need for classification.

Based on the inhalation LD50 of approximately 1.9 mg/L, Cyanoacetic acid has to be classified as “harmful by inhalation” according to the Directive 67/548/EC. According to the GHS criteria, Cyanoacetic acid has to be classified as follows: Toxicity by Inhalation Cat. 4.