Perchloric acid

Long-term toxicity to fish

Description of key information

By analogy with ammonium perchlorate, perchloric acid is considered as having no effect on the growth and behaviour of fish in a long-term exposure study at 10 mg/L.  

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

10 mg/L

Additional information

No data on perchloric acid is available for this endpoint. However, one reliable key study is available for ammonium perchlorate (Mukhi et al., 2005), which is used in a read-across approach. Although the read-across approach is preferentially performed with the sodium salt (See the endpoint study summary "Aquatic toxicity" for the read-across justification), results obtained on the ammonium salt of perchloric acid is applicable. Indeed, the sodium salt is preferred to the ammonium salt because, contrary to the latter, sodium is not toxic to the aquatic organisms. But ammonium perchlorate (CAS RN 7790-98-9) fulfils all other parameters for a read-across approach (i.e. structural similarity and similar bioavailability than perchloric acid). For the ecotox profile, the effects observed with ammonium salts may overestimate the toxicity of the perchlorate moiety. Therefore, this read-across approach can be used as a worst case approach. 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 selected key study, a non-standard long-term aquatic semi-static method but equivalent to OECD Guideline 215 has been applied. Juvenile rainbow trout (Danio rerio) were exposed to ammonium perchlorate nominal concentrations of 0, 0.01, 0.1, 1 and 10 mg/L (perchlorate anion), corresponding to measured concentrations of 0, 0.011, 0.090, 1.131 and 11.48 mg/L (perchlorate anion), to assess seven different biological endpoints as possible markers of exposure: thyroid follicle angiogenesis, thyroid follicle hypertrophy, thyroid follicle colloid depletion, intensity of colloidal T4 ring, whole-body T4 concentration, body growth (weight and length), and condition factor.

The results obtained indicated that the 12 weeks (chronic) NOEC for standard endpoints (mortality, growth, general condition, behavior) as well as whole-body T4 levels was 10 mg/L of perchlorate ion. These endpoints were not affected by perchlorate under the conditions of the test.

However, the 12 weeks LOEC for colloidal T4 ring intensity, the most sensitive markers, was 0.01 mg/L of perchlorate ion.

All changes were reversible, but residual effects on angionenesis and colloidal T4 ring intensity were still present after 12 weeks of recovery.

No information was provided on iodine content of the test medium.

 

As discussed in the document justifying the PNEC derivation (attached document in the headchapter 6 of iuclid), the NOEC for the growth and behavior of the entire organisms are selected rather than the histopathological effect on thyroid.