(S)-p-mentha-1,8-diene

Endpoint summary

Description of key information

Aquatic organisms

- Several studies were conducted and validated on daphnia and fish with d-limonene, the enantiomer of l-limonene. The available EC50 for daphnia were 0.36 mg/L, 0.924 mg/L, and 0.577 mg/L. The available fish LC50 were 0,702 mg/l and 0.720 mg/L. These studies were conducted in flow through conditions or static conditions, however always with analytical monitoring of the tested concentrations. The acute toxicity of the orange oil orangenöl WMB towards the algaeDesmodesmus subspicatuswas investigated according to OECD guideline 201 using WAFs, under GLP. The 72h-ECr50 and 72h-NOECr were circa 8 and 2.6 mg/L (measured, hydrocarbons), respectively. The composition of orange oil is considered to be > 90% of d-limonene however no substance purity was reported in this test.

- Data were also available on dipentene, containing dl-limonene racemic form, from the Japan Ministry (formerly MITI). The acute toxicity values belong to the same range than d-limonene: daphnia: 48h-EC50 = 0.7 mg/L, fish 96h-LC50 = 1.1 mg/L, algae 72h-ECr50 > 1.6 mg/L. Chronic values were also measured for daphnia: 21day-EC50= 0.49 mg/L, 21 day-NOEC= 0.27 mg/L and algae 72h-NOECr= 1.6 mg/L. The MITI studies on which we have little information, were conducted in conditions that were accurate enough to measure effects at the very low concentrations levels corresponding to the one measured in the d-limonene validated study. It reveals that the properties of the substance as regard to degradation or volatilisation were taken into account and/or the real concentrations measured. Therefore the studies were evaluated as non assignable but coming from a reliable source.

 

-The software ECOSAR was used to assess the toxicity of l-limonene. The substance was assessed based on the measured logKow value and the water solubility of d-limonene because it is expected that these values are similar for both enantiomers. The results for the acute toxicity were 0.678 and 0.115 mg/L for 48h-LC50 and chronic daphnia, respectively, 0.845 mg/L for 96h-LC50 fish, 0.904 and 0.514 mg/L for 96h-EC50 and chronic algae, respectively. These results are similar to the experimental results with dipentene and d-limonene with only lower toxicity values calculated for algae.

 

From these results, it can be concluded that the toxicity of the two enantiomers, d and l limonene, regarding daphnids and fish is similar and that d-limonene and dipentene can be used as analogue of l-limonene in a read-across approach to fill data gaps. Among these studies, the geometric mean 96h-LC50 of 0,71 mg/L for fish, the lowest 48h-EC50 of 0,36 mg/L and the 21d-NOEC= 0.27 mg/L for daphnia are considered as the relevant values to be used for the purpose of risk assessment and classification and labelling. Nevertheless, for algae the lower estimated values, 72h-ErC and 72h-NOErC of 0.904 and 0.514 mg/L,for l-limonene with ECOSAR is prefered as more conservative values because detailed information on the purity of d-limonene and dipentene in the available tests is missing