Succinic acid

Endpoint summary

Description of key information

The acute toxicity of succinic acid is low.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

6 740 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

LC50

Value:

1 284 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Dose descriptor:

LD50

Value:

6 740 mg/kg bw

Additional information

Oral:

Key study: Acute oral toxicity, rat, guideline study of 1990, read-across from monosodium succinate: LD50 = >8000 mg/kg body weight and corresponding for succinic acid to >6740 mg/kg bw.

Justifications for a read-across from data of monosodium succinate to succinic acid: The read-across from the succinate to succinic acid seems justified, as both are well water soluble and will be in the ionised form in dilute aqueous solutions, to give the same anion. The different molecular weights were considered.

Supporting study: Acute oral toxicity, rat: From a handbook and the HSDB database; original probably of 1981: LD50 = 2260 mg/kg body weight.

Dermal:

The LD50 for the oral route is also adopted for the dermal route as it is generally accepted that the dermal LD50 is usually higher than the oral one and taking the same LD50 also for the dermal situation is a worst case assumption, see Guidance Document on Information Requirements Chapter R.8.4.2.

Inhalation:

A waiver is based on the low toxicity in other exposure routes, a read across to the results for fumaric acid and the relatively large particle size. The calculated LC50 from the read-across from fumaric acid to succinic acid is >1.284 mg/L for succinic acid.

Justifications for a read-across from data of fumaric acid to succinic acid:

# Fumaric acid (FA) and succinic acid (SA) are chemically analogous substances distinguished only by a double bond in the fumaric acid.

# Both anions of the substances, succinate and fumarate, are naturally occurring substances that are elements of the citric acid cycle. Fumarate is the successor of succinate in this cycle.

# Both substances have similar characteristics: Melting temperature: FA: 287 °C; SA: 185 °C. Water solubility: FA: 7 g/L; SA: 83 g/L. Partition coefficient (logPow): FA: 0.46; SA: -059. Acute toxicity (LD50oral,rat): FA: 9300 mg/kg; SA: >6700 mg/kg. Eye irritation: FA: Xi R36; SA: Xi R41.

# DEREK, a knowledge-based system to detect toxicity alerts, which is repeatedly cited in the Guidance on information requirements and chemical safety assessment, Chapter R.6 "QSARs and grouping of chemicals" was applied to succinic acid and also to fumaric acid. DEREK did not find any substructures in its database that fired an alert that would predict succinic acid to be toxic or reproductive toxic. Also for the chemically analogous substance fumaric acid no indications for toxicity were detected.

Justification for classification or non-classification

No classifications are derived as the oral and dermal LD50s are >2000 mg/kg bw and the LC50 is estimated to be greater than the maximum technically feasible concentration of 1.284 mg/L.