Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Toxicity to Soil Macroorganisms:No sufficiently reliable studies were identified for fused tungsten carbide toxicity in soil macroorganisms; therefore, read-across to sodium tungstate was used The 56-day NOEC for earthworms (Eisenia fetida) found in a test conducted according to OECD 222, under GLP standards, and with analytical verification of the test concentrations was1000 mg sodium tungstate/kg soil dw (586 mg W/kg). Other studies withEisenia fetidawere not considered for the risk characterisation, as they were found to be less reliable.

Toxicity to Terrestrial Plants: No sufficiently reliable studies were identified for fused tungsten carbide toxicity in plants; therefore, read-across to sodium tungstate was used. In a Seedling Emergence and Seedling Growth Test using Avena sativa, Raphanus sativus and Lactuca sativa and testing sodium tungstate, Lactuca sativa (lettuce) was found to be the most sensitive species with an identified NOEC of 37 mg/kg soil d. w. sodium tungstate (nominal) (approximately 22 mg W/kg soil) based on: % Emergence, Individual Shoot Height, and Individual Shoot Weight.

Toxicity to Soil Microorganisms: No sufficiently reliable studies were identified for fused tungsten carbude toxicity in soil microorgansims; therefore, read-across to sodium tungstate was used. In both a Carbon and a Nitrogen Transformation Test using sodium tungstate the 28-day EC50 was found to be > 1000 mg sodium tungstate/kg soil d.w. (approximately  586 mg W/kg soil d.w.).

Additional information

No toxicity data for soil macroorganisms, terrestrial plants, soil microorganisms and birds are available for fused tungsten carbide (target substance). However, data are available for sodium tungstate and tungsten metal (source substances), which were used for read-across. Due to lower transformation/dissolution results for fused tungsten carbide (target substance) than sodium tungstate (source substance), the resulting toxicity potential would also be expected to be lower, so read-across is appropriate.

In addition, read-across is justified because the classification and labelling is less severe for the target substance than the source substance and the PBT/vPvB profile is the same. Finally, the dose descriptors are, or are expected to be, sufficiently similar or lower 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.