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Ecotoxicological information

Toxicity to terrestrial plants

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Description of key information

It can be concluded that short-term toxicity testing of terrestrial plants is not required based on the unlikely exposure of plants to the DMDMH product or its degradation product (DMH), rapid biodegradability in the environment and the additional evidence of no toxicity observed in plants based on long-term toxicity testing of the breakdown product.

Key value for chemical safety assessment

Additional information

In Annex IX of Regulation (EC) No 1907/2006, it is laid down that short-term toxicity to terrestrial plants shall be proposed by the registrant if the chemical safety assessment indicates the need to investigate the effects of the substance and/or relevant degradation products on terrestrial plants. Column 2 of Annex IX states that studies do not need to be conducted if direct and indirect exposure of the soil compartment is unlikely.

 

The product is not supposed to be directly applied to soil and indirect exposure of terrestrial plants is unlikely since the test substance and its degradation product (DMH) are readily biodegraded in the aquatic environment and STP processes. Therefore no short-term tests on terrestrial plants are required in accordance with Annex IX of Regulation (EC) No 1907/2006.

 

For information, there are no reliable toxicity data for plants relating to DMDMH. However, reliable toxicity data for terrestrial plants are available for DMH, the hydrolysis product of DMDMH. DMDMH readily undergoes hydrolysis to DMH and therefore data are provided for both substances when available. In the case of long-term testing, the data on DMH are considered more relevant for environmental fate and ecotoxicology and are considered in this dossier.

Goodband (2007) conducted a reliable (Klimisch 1) GLP compliant study following OECD 208 methods. Soybean (Glycine max), cucumber (Cucumis sativa) and oat (Avena sativa) were exposed to concentrations of DMH,(application rate of 40, 100, 160, 400 and 1000 mg/kg) in a test for 21 days to measure seedling emergence and growth. The 21-day EC50, based on emergence, for the oat and soybean test species was >1000 mg/kg and 990 mg/kg for the cucumber. The EC50, based on growth, for all three species is 1000mg/kg. The 21-day NOECs, based on emergence, for the oat, soybean and cucumber were 100, 400, and 400 mg/kg, respectively. The 21-day NOECs, based on growth, for the oat, soybean and cucumber were 400, 160, and 1000 mg/kg, respectively.

 

It can be concluded that short-term toxicity testing of terrestrial plants is not required based on the unlikely exposure of plants to the DMDMH product or its degradation product (DMH), rapid biodegradability in the environment and the additional evidence of no toxicity observed in plants based on long-term toxicity testing of the breakdown product.