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Ecotoxicological information

Toxicity to terrestrial plants

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Description of key information

A terrestrial plant study conducted on monocotyledons and dicotyledons did not show a high level of concern for 1,3 -diphenylguanidine in these species (Brassica rapa: EC50 = 358 mg/kg; Avena sativa: EC50 = 1169 mg/kg).

Key value for chemical safety assessment

Short-term EC50 or LC50 for terrestrial plants:
316 mg/kg soil dw

Additional information

Studies on the influence of urea derivatives on the germination rate of higher plants were carried out on lettuce seeds (Lactuca sativa) by Kefford et al. (1965). The seedlings were first preincubated for 24 hours in the absence of light on pre-treated filter paper at 25°C (negative control 1 ml water; positive control 1 ml germination-inducing kinetin solution, 5E-05 mol/l) and then illuminated with red light. The lighting intensity was selected to achieve a 20% germination rate in the negative controls; in the positive controls the germination rate was 85 -95%. The germination rate was determined after a further 48 -hour incubation in the absence of light.

At 0.21 mg/l 1,3 -diphenylguanidine did not affect the germination rate compared to the negative controls. At a concentration of 2.1 mg/l it induced a germination rate of 57 % and at 21.1 mg/l of 104% compared to the positive controls. A parallel investigation showedno influence on the cell division activity to tobacco cells.

Bempong & McCoy (1972) studied the effect of 1,3 -diphenylguanidine on the mitotis cycle of root cells of fiels beans (Vicia faba). The cells were pre-treated for three hours with 0.02% colchicine, transferred for 5, 10 or 16 hours to aerated water, exposed to the tested substance (1 -10 mg/l 1,3 -diphenylguanidine) under intensive aeration for 30 -minutes and finally, after thorough washing, transferred to aerated water for 5 -29 hours. A concentration-related reduction in the mitotis index was observed (0.43 - 9.48; control 13.94) and the appearance of chromosome aberrations in 5 -55% of the cells tested.

These two studies have been considered as not relevant for the hazard assessment due to their unsuitable test systems and their methodological deficiences. In a more recent terrestrial plant study conducted on monocotyledons and dicotyledons did not show a high level of concern for 1,3 -diphenylguanidine in these species (Brassica rapa:EC50 = 358 mg/kg;Avena sativa: EC50 = 1169 mg/kg).