Registration Dossier
Registration Dossier
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EC number: 910-245-3 | CAS number: -
Endpoint summary
Administrative data
Description of key information
Additional information
Sodium Hydroxide: Source - the sodium hydroxide summary risk assessment report JRC EC 2008
The results of single species acute toxicity tests with NaOH include tests with fish and invertebrates; all but one test were performed with freshwater species. The tests with fish resulted in acute LC50values and toxic / lethal concentrations ranging from 35 to 189 mg/l. The results for invertebrates are very similar, with a range of 33 to 450 mg/l. There are no data for algae and higher aquatic plant species. For chronic toxicity of NaOH only one limited study is available, with fish (guppy) Lebistes reticulatus.This study clearly showed effects on survival, growth and reproduction of fish at long-term exposure to NaOH concentrations of 25 mg/l and higher. The available data indicate that NaOH concentrations of 20 to 40 mg/l may be acutely toxic to fish and invertebrates. Data on pH-increases due to the addition of these amounts of NaOH in the used test waters are lacking. In waters with a relatively low buffering capacity, NaOH concentrations of 20-40 mg/l may result in a pH increase with one to several pH units.
The data on the pH tolerance of fish show that an increase in pH value from around 8.5 to 9.5-10.5. i.e. an increase with 1 to 2 pH units results in acute lethality in fish that were not acclimatized to intermediate values. The data further show that pH values of 9-10 may be toxic or lethal to some fish species and above a pH value of 10 mortalities may be expected for many species exposed for a prolonged period.
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