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EC number: 233-162-8
CAS number: 10049-04-4
Chlorine dioxide is highly toxic for acute toxicity to fish , its extremely short half-life in the environment following use and the fact that there is no direct release of the active substance to aquatic systems, means that there is no concern for the aquatic compartment. Chlorine dioxide in aqueous solution reacts rapidly, abiotically with organic matter and oxidisable metals, generating chlorite, chlorate and ultimately chloride as dominant species. Under the conditions of use, no chlorine dioxide is expected to be found in the environment (see justification for non-submission), however the principal decomposition products, chlorite, chlorate and chloride will be. Therefore, key studies concerning these substances (except chloride) have been included in this section where appropriate, such that their toxicity and ultimately risk can be characterised in the CSR.
Based on the data available, the LC50 of chlorite for fish is more than 10 times higher than that of daphnia or algae. Therefore, according to the decision table, a long term fish study on chlorite is not required as part of the long term dataset in order to obtain an assessment factor of 10 for chronic data. A long term study on fish for chlorate found no effects at 500 mg/L (as sodium chlorate).
While chlorine dioxide presence is not relevant in aquatic compartment
(see JNS), presence of transformation products (chlorite and/or
chlorate) needs to be assessed.
For chlorite, due to LC50 values far greater than 10 times higher for
fish compared to other aquatic organisms, and in order to reduce studies
on vertebrate animals, no long term study on fish has been carried out.
One long-term toxicity study on chlorate was found for fresh water
fish (Thomas et al. 2004). The purpose of this study was to
assess the toxicity of the test substance dissolved in fresh water, on
the early life stages of Danio rerio, in a GLP 36-day
flow-through test complying with the OECD Guideline No. 210,17 July
1992. The test criterion of toxicity used was the effects on hatching,
larvae mortality, morphological abnormalities and growth of Danio
rerio exposed to the test substance over the test period.
However, as all embryos hatched at the highest concentration
tested of 500 mg/l as well as in the control and post-hatch mortality
was less than that of the control, a statistical test was not used for
this parameter and the NOEC was considered to be at or greater than the
highest concentration tested. No teratogenic malformations were noted
for any larvae at any concentration.
Based on results from weight and length, the Lowest Observed
Effect Concentration (LOEC) cannot be calculated and the No Observed
Effect Concentration (NOEC) was determined as greater than or equal to
the highest concentration tested, 500 mg/L.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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