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EC number: 234-842-7 | CAS number: 12036-22-5
Reported statistics and error estimates (continued):
Estimates of the EC50 concentration values and their 95 % confidence limits for immobilisation were calculated using the probit method and trimmed Spearman-Karber method. When the p value for goodness of fit was > 0.05 and there was no other evidence of questionable convergence, the probit method was selected for reporting. When this criterion was not met, the trimmed Spearman-Karber method was selected for reporting.
No long-term toxicity to aquatc invertebrates of sufficient quality are available for tungsten dioxide (target substance). However, long-term toxicity to aquatic invertebrates data are available for sodium tungstate (source substance), which will be used for reading across. Due to lower water solubility and lower toxicity for the target substance compared to the source substance, the resulting read across from the source substance to the target substance is appropriate as a conservative estimate of potential toxicity for this endpoint. In addition, read across is appropriate because the classification and labelling is more protective for the source substance than the target substance, the PBT/vPvB profile is the same, and the dose descriptors are, or are expected to be, lower for the source substance. For more details, refer to the read-across category approach included in the Category section of this IUCLID submission and/or as an Annex in the CSR.
Tungsten dioxide was not tested for chronic toxicity to invertebrates and read-across to sodium tungstate dihydrate was used for this endpoint. In a reproduction test using Daphnia magna and testing sodium tungstate dihydrate, the 21-day NOEC for reproduction and growth was found to be 44.2 mg/L sodium tungstate dihydrate/L or approximately 25.9 mg W/L). Read-across to sodium tungstate is appropriate as sodium tungstate is of higher solubility under simulated environmental conditions and has the same classification and PBT profile as tungsten dioxide.
Due to similar or lower transformation/dissolution results for tungsten dioxide (the target substance) than sodium tungstate dihydrate (the source substance), the resulting toxicity potential would also be expected to be similar or lower, so read-across is appropriate. Therefore, the dose descriptors are expected to be sufficiently similar or higher for the target substance, and read-across to the source chemical is adequately protective. For more details refer to the attached description of the read-across approach.
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