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Ecotoxicological information

Toxicity to birds

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Description of key information

No data are available for tocity of tungsten carbide to birds. Therefore, read across to tungsten metal data was used for this endpoint. An LD50 for mallards orally dosed with tungsten-polymer shot was determined.  Results indicated that tungsten-polymer shot orally administered to mallards did not adversely affect them during a 30-day trial and an LD50 of  > 3.07 g tungsten/kg bw was identified (Kelly et al., 1998).  

In a separate study in which mallards were dosed with tungsten-nylon pellets once per month over a period 150 days (days 0, 30, 60, 90, 120 and 150),  the NOAEL determined was ≥ 1.21 g tungsten/kg bodyweight per month.  This study revealed that mallard ducks did not have deleterious health effects during the 150-day trial based on mortality, body weights, organ weights, and histology of the liver and kidneys (Mitchell et al., 2001a) or hematological effects (Mitchell et al., 2001b) compared to the control. There were no significant differences in egg production and fertility and hatchability of eggs from tungsten-polymer-dosed ducks compared to control ducks. There was no evidence of differences in percent survivability and body weight of ducklings from tungsten-iron and tungsten-polymer mallards compared to ducklings from control ducks (Mitchell et al., 2001c).  Ingested tungsten does not seem to adversely effect mallards after chronic exposures.

Key value for chemical safety assessment

Additional information

Due to similar transformation/dissolution results for tungsten carbide (the target substance) and tungsten metal (the source substance), the resulting toxicity potential would also be expected to be similar, so read-across is appropriate. In addition, read-across is justified because the classification and labelling is less severe for the target substance and the PBT/vPvB profile is the same. Finally, the dose descriptor for the target substance is expected to be similar to that of the source chemical, and read-across to the source chemical is adequately protective. For more details refer to the attached description of the read across approach.