Salicylic acid

Short-term toxicity to fish

Description of key information

In an acute toxicity study (Geiger et al. 1985), fishes from the species Pimephales promelas were exposed under flow-through conditions to salicylic acid sodium salt (CAS n° 54 -21 -7) to average measured concentrations of 0 (in duplicate), <50 (in duplicate), 497, 536, 837, 867, 1238, 1272, 2211, 2217, 3442 and 3573 mg/L. 
The LC50 (96h) was 1370 mg/L (CI: 1270 - 1470 mg/L), based on measured concentrations. 
Therefore, salicylic acid sodium salt is not dangerous to Pimephales promelas in the conditions tested. 
This study was not performed according to GLP but authors followed a method similar to OECD 203 and gave sufficient details to check all validity criteria, which were all fulfilled. Therefore this study is considered as reliable with acceptable restrictions. 
Moreover, a second test has been performed by these authors in slightly different conditions but showing a lower concern (i.e. 96h LC50 = 2160 mg/L) and therefore supporting the first results. 

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

1 380 mg/L

Additional information

Six toxicity studies on fish are available for salicylic acid. However, the study giving rise to the highest concern with a 96h LC50 = 37 mg/L (Henschel et al., 1997) has been performed without pH adjustment. Therefore, the effect observed may have been the result of the acidic condition of the test solution which should not be considered as toxic effect. That's why this study has been considered as not reliable. Two other studies (Gersdorff, 1943 and Knie et al., 1983) have been considered as not reliable because of deviations (e.g. test duration of 8 hours or not specified). An in vitro study is also available but as currently there is no validated guideline available for in vitro test, this study can only be used as a supporting data (no effect was observed up to a concentration of 500 mg/L).

Based on the absence of reliable data, the read-across approach is proposed with the sodium salt of salicylic acid (Geiger et al. 1985). The main assumption to justify the read-across approach is that the sodium ion is not significant in respect of environmental properties under consideration. Indeed, in dilute aqueous conditions of defined pH, a salt will behave no differently to the parent acid and will be fully dissociated. Hence, some properties measured in aqueous media, like aquatic ecotoxicity, for a salt can be directly read-across to the parent acid and vice versa. But suitable mass-correction should be applied:

(Pimephales promelas) 96h LC50 = 1370 mg/L of sodium Salicylate (MW = 160.11)

Considering that the effect is due to the salicylate without the conter ion Na (MW = 22.99), the corresponding result in concentration of salicylic acid (MW = 138.12) is :

(Pimephales promelas) 96h LC50 = 1370 / (160.11 -22.99) x 138.12 = 1380 mg/L of Salicylic acid.