Amitrole

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.032 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.003 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

100 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

0.303 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

30.3 µg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

0.77 µg/kg soil dw

Extrapolation method:

assessment factor

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

Aquatic toxicity:

Long-term and short-term toxicity data are available for the three trophic levels (fish, aquatic invertebrate and algae) in freshwater.Among all data available, a toxic effect was observed for the aquatic invertebrates. Daphnia magnais the most sensitive species with a 96h-LC50 value at 18 mg/L based on nominal concentrations. A chronic study was performed on Daphnia magna giving a 21-day NOEC (body length) of 0.32 mg/L and a 21-day NOEC (reproduction) of 0.56 mg/L. For the algae, Pseudokirchneriella subcapitata, the 72h-NOECr value based on growth rate is greater or equal to 1.2 mg/L (the maximum concentration tested) based on measured values.

For fish, two acute studies were performed which resuilted in LC50s (96h) greater than 1000 mg/L.While the long-term (2 generation) study in fish was not performed at a concentration high enough to be able to define a genuine NOEC (maximum concentration test = 9 µg/L, well below the NOEC for invertebrates and algae), the difference in sensitivity of the fish and the invertebrates in the acute study is so high that it is scientifically justifiable to consider the fish will not be the most sensitive species and to use an assessment factor based on 3 long term studies.

Terrestrial toxicity:

Valid chronic studies based on international guidelines are available for terrestrial plants and soil microorganisms.

Sunflower, cabbage and lettuce appeared to be the most sensitive species with : 18d-EC25 (Helianthus annuus) = 0.026 lb/acre (sunflower vegetative vigor test), 14d-EC25 (Brassica oleracera) = 0.21 lb/acre (cabbage fresh weight, seeling emergence test) and 14d-EC25 (Lactuva sativa) = 0.23 lb/acre (lettuce fresh weight, seedling emergence test). In the seed germination test, lettuce appeared as the most sensitive species with : 7d-EC25 (Lactuva sativa) = 0.28 lb/acre. The lowest NOEL observed was for dicots with : 0.016 lb/acre< NOEL (dicots) < 2 lb/acre, in the vegetative vigor test.

In addition, the test substance appeared to cause only a slight retardation in nitrification to soil microorganisms, but this effect disappeared 90 days after treatment : NOEC (soil microorganisms) >= 100 mg/L.

Environmental fate and pathways

The registered substance is not readily biodegradable and is considered as mobile with a Koc value ranging from 66 to 266 L/kg. Based on biodegradation simulation studies, the substance is not considered as persistent in soil and sediment (half-life below 120 days) and does not meet the criterion for persistence (P).

As the log Kow value is equal to -0.77, the registered substance is not considered as bioaccumulative according to CLP (<4.0) and PBT criteria (<4.5).

Conclusion on classification

Classification according to the Annex VI of the Regulation (EC) No 1272/2008 (CLP): Aquatic Chronic 2 H411

0.1 <NOEC value (chronic toxicity) < 1 mg/L; not readily biodegradable; log Kow=-0.77

Classification according to the Annex VI of the Regulation (EC) No 1272/2008 (CLP): the registered substance is classified for the environment as aquatic chronic 2.