Perchloric acid

Short-term toxicity to fish

Description of key information

By analogy with sodium perchlorate, neutralised solution of perchloric acid is not harmful to fish. 

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

1 470 mg/L

Additional information

No data on perchloric acid is available for this endpoint. However, two reliable studies are available for sodium perchlorate (Dean et al., 2004), which is used in a read-across approach (See the endpoint study summary "Aquatic toxicity" for the read-across justification). Both studies were performed according to requirements of the U.S. EPA guidelines (U.S. EPA OPPTS 850.1075 and ASTM E729-96 Guidelines) without GLP statement. Both studies show that sodium perchlorate is not harmful to fish. On a worst case approach, the study showing the lowest LC50 value has been selected as key study, the second one as supporting study. The results are expressed in perchlorate moiety in order to be applicable for the derivation of PNEC and determination of the classification of perchloric acid.

In the key study, twenty juvenile bluegill sunfish (Lepomis macrochirus) per treatment level were exposed to sodium perchlorate in 15-L glass aquaria for 96 h. The temperature of the test chambers was maintained at 21.2 to 23.7°C. Nominal exposure concentrations in the definitive test were 0 (control), 625, 1250, 2500, 5000, and 10000 mg/L perchlorate ion. The mean measured perchlorate concentrations ranged from 547 to 9715 mg/L (88–104% of the nominal concentrations). To account for potential toxicity from the sodium cation of the sodium perchlorate, sodium chloride controls were included. The sodium chloride controls were additional exposures with sodium chloride added to dilution water at the same sodium concentration as that in the two highest sodium perchlorate treatment concentrations.

No sublethal effects were observed during the test; all observations were either of mortality or normal behavior. No mortality was observed in the control, the 547 mg/L treatment, or the level 4 (5220 mg/L equivalent) sodium control, but one fish (5%) died in the level 5 (9715 mg/L equivalent) sodium control. Five fish (25%) died in the 1260 mg/L treatment, and all 20 (100%) died in the 2530, 5220, and 9715 mg/L treatments.

The 96-h NOEC for L. macrochirus was 547 mg/L, and the LOEC was 1260 mg/L. The 96-h EC50 was calculated to be 1470 mg/L based on mean measured perchlorate concentrations, with a 95% confidence interval of 1270 to 1710 mg/L.

This study is well documented but all validity criteria cannot be assessed. The control mortality was lower than 10% (maximum of 5%) and constant conditions have been maintained during the test. However, no information was provided on the dissolved oxygen concentrations. These criteria are equivalent to those of OECD Guideline 203. Therefore, this study is considered reliable with restrictions.