Citric acid

Endpoint summary

Description of key information

Citric acid has been extensively studied as a remediation agent in aquatic and soil compartments to sequester metals and other elements. While the data generated does not assess the intrinsic hazardous properties of citric acid, it does indicate that the substance has low toxicity in order for it to be used as a remediation agent

Three non-guideline studies indicate the low hazard potential of citric acid:

Snow et al. 2014 exposed chickens Gallus domesticus to citric acid. A 14 day NOEC value of > 4 g/kg body weight has been determined for the effects of the test substance on mortality of the chicken.

In Pitt et al. 2014 bats (Eptesicus fuscus) were exposed to citric acid: after 48 hours no effects was observed up to a concentration of 759 mg/kg bw, where emsis was observed, while at 2811 mg/kg bw mortalities were observed.

Agnello et al. 2015 investigated the potential toxicity of citric acid to plants (Medicago sativa): a 14 day study of already emerged 14 day old plants exposed to citric acid, showed no difference in biomass compared to the control up to a concentration of 17230 mg/kg dw.

In addition, a study is available on terrestrial plants which have beene exposed to citric acid via aqueous routes. The study is reported under the IUCLID section 6.1.6:

Hartung et al. (1990) report a 72h IC₅₀ value of 1.58 g/L for the effects of citric acid on germination (root length) of Lepidium sativum through an aqueous exposure. The publication does not provide sufficient details on the test system and environmental conditions during the test and has been assigned reliability 4.

Overall, it is concluded that the risk characterisation conclusion is sufficiently conservative in respect of any uncertainties and therefore further in vivo testing is not considered necessary, because:

• Non-standard terrestrial toxicity data are available that indicate low or no effects are associated with exposure to citric acid.
• The substance is naturally occurring in terrestrial organisms
• The substance has a negative log K_ow value and is not expected to bioaccumulate.
• The substance is rapidly degradable and has a negative log K_ow, therefore partitioning to the terrestrial compartment is expected to be minimal.
• The substance is of low toxicity to aquatic organisms (EC/LC50 >100 mg/L)
• Citric acid is used as a remediation agent against metals and other elements in soil and aquatic compartments.

Additional information

Citric acid is highly water soluble and has a negative log K_ow value. Therefore, it is not expected to be taken up and accumulated by terrestrial organisms. In addition, citric acid is rapidly degradable.

Due to its nature as a complexing agent, citric acid may have the potential to adsorb. However, if citric acid is released to water, the probability of its partition into other environmental compartments is expected to be low due to the ready degradability of the substance.

Citric acid is naturally occurring in terrestrial organisms and is a key intermediate in the metabolic pathways of most organisms. Low toxicity was observed in short-term aquatic tests and the occurrence of more severe toxic effects in the terrestrial compartment that were not expressed in the aquatic studies would be considered unlikely.

The attached report "189 06 Citric acid and Citrate Salts - Metabolism and Toxicity 20100618.pdf" summarises the TCA cycle and presents data on the amounts citric acid found in plants and animals.

Overall, it is concluded that the risk characterisation conclusion is sufficiently conservative in respect of any uncertainties and therefore further testing is not considered necessary.