Carbonohydrazide

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.002 mg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.015 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0 mg/L

Assessment factor:

10 000

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

2.5 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

no exposure of sediment expected

Sediment (marine water)

Hazard assessment conclusion:

no exposure of sediment expected

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

no exposure of soil expected

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

A long-term 7-day static-renewal Ceriodaphnia dubia chronic test was conducted on the substance. However, the results of this study have not been used to derive PNECs, nor reduce assessment factors, as algae is considered the most sensitive species based on the acute toxicity data.

Conclusion on classification

The environmental classification of the substance has been assessed based on the results of testing in algae, Daphnia and fish, biodegradation and bioaccumulation data and physico-chemical data (water solubility, octanol-water partition coefficient).

In acute toxicity testing in algae, Daphnia and fish, the most sensitive species (giving the lowest E(L)C₅₀) was the algae, Pseudokirchnerella subcapitata, which gave a 72 hour ErC₅₀ (based on growth rate) of 1.5 mg/l.

As classification for algal studies is based on the growth rate parameter, the substance does not meet the criteria for classification in Acute Category 1 (72 or 96 hr ErC₅₀ for algae <1 mg/l), as the result is greater than 1 mg/l.

The substance is highly water soluble, readily biodegradable, has a very low partition coefficient (log K_ow -2.94) and has an experimentally determined bioconcentration factor (BCF) of ≤6.

Based on the acute toxicity results and these properties, the substance would not meet the criteria for environmental classification in chronic categories 1, 2, 3 or 4.

However, in addition to the acute toxicity data one chronic/long-term study is available, a 7 -day static-renewal Ceriodaphnia dubia chronic toxicity study. This study gave the following results:

NOEC (7 d): 3.93 mg/L act. ingr. (nominal) based on: survival

NOEC (7 d): 0.98 mg/L act. ingr. (nominal) based on: reproduction

For rapidly degradable substances for which adequate chronic toxicity data is available, a Chronic Category 3 classification may apply if the chronic NOEC is >0.1 to ≤1 mg/l.

Based on the NOEC for reproduction (0.98 mg/l) this classification could apply.

However, as the NOEC (reproduction) result of 0.98 mg/l is so close to the 1 mg/l cut-off for classification, and that the NOEC based on survival is substantially above 1 mg/l, it is considered classification may not be appropriate. Normal biological differences between animals can account for slight differences in test results i.e. further 7 -day static-renewal Ceriodaphnia dubia chronic toxicity studies could be expected to show some NOEC (reproduction) results at greater than 1 mg/l, taking into account differences between animals, slight variations in test water/medium, slight variations in test sample.

In addition, although the ceriodaphnia dubia study is considered to be a valid study and appropriate for evaluation of chronic/long-term toxicity based on the lifecycle of ceriodaphna dubia, it is not the standard long-term Daphnia reproduction study (OECD Guideline 211 (Daphnia magna Reproduction Test) conducted.

Based on evaluation of all the above data, it is therefore proposed that the substance should not currently be classified for the environment.