Chlorine dioxide

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Data waiving:

exposure considerations

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
CHLORINE DIOXIDE According to the TNsG on Data Requirements for Active Substances and Biocidal Products, and REACH Guidance the effects on reproduction and growth rate of invertebrates may be required. Although chlorine dioxide is acutely toxic to invertebrates, its short half-life in the environment following use and the fact that there is no direct release to aquatic systems, means that there is no concern for the aquatic compartment. A study investigating the effects on reproduction and growth rate in invertebrates is therefore unjustified on the basis of low exposure. CHLORITE However, it is recognised that the immediate degradation product of chlorine dioxide, chlorite, may reach the receiving water. For this reason, a flow-through study on chlorite has been carried out. CHLORATE A long-term study on sodium chlorate has been carried out.

Description of key information

Chlorine dioxide reacts in aqueous solution rapidly generating chlorite and chlorate as dominant species under normal environmental conditions. In the absence of oxidisable substances, and in the presence of pH > 9, chlorine dioxide dissolves in water and decomposes with the slow formation of chlorite and chlorate ions.

Additional information

Although chlorine dioxide is acutely toxic to invertebrates, its short half-life in the environment following use and the fact that there is no direct release to aquatic systems, means that there is no concern for the aquatic compartment.

A study investigating the effects on reproduction and growth rate in invertebrates is therefore unjustified on the basis of low exposure.

However, one long-term toxicity study valid was found in Sodium chlorite for aquatic invertebrate Daphnia magna (Thomas et al. 2008, GLP according to OECD guideline 211), and one long-term toxicity study valid was found in Sodium chlorate for the same species (Thomas 2004, GLP according to OECD guideline 211).

Chlorine dioxide reacts in aqueous solution rapidly generating chlorite and chlorate as dominant species under normal environmental conditions. In the absence of oxidisable substances, and in the presence of pH > 9, chlorine dioxide dissolves in water and decomposes with the slow formation of chlorite and chlorate ions. Based on results from Thomas, EC50 (22 d) and NOEC (22 d) were 64.87 µg/L of Chlorite, and 15.02 µg/L of Chlorite respectively, and for Chlorate NOEC (21 d) > 372.84 mg/L.

In addition, One long-term study (valid without restrictions) is available for the rotifer Brachionus plicatilis with sodium chlorate. This study by Tobiesen (2010b) was performed according to standard guideline with GLP and chemical analysis of the test substance. B. Plicatilis turned out to be the most sensitive marine species with an EC₁₀ of 21 mg/l sodium chlorate.