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To assess the terrestrial toxicity of OPP (CAS-No. 90-43-7) studies for three trophic levels are available. In an earthworm test the effects of OPP on individuals of Eisenia fetida were investigated. The LC50 value was 198.2 mg test item/kg dw. The NOEC for mortality as well as the NOEC for biomass was determined to be 125 mg test item/kg dw.

The effects of OPP on terrestrial plants were studied in three plant species of three different families: Brassica napus, Glycine max and Avena sativa. Test parameters were germination rate, mortality and phytotoxicity. Phytotoxic effects observed were growth reduction (all species), slight chlorosis (Brassica napus and Glycine max) and slight necrosis (all species). Additionally, Brassica napus showed abnormal growth of the leaves, and Glycine max showed abnormal growth of the leaves and the stems.

The most sensitive species in terms of fresh weight was Avena sativa with EC50 value of 53.9 mg/kg soil dry weight and NOEC 12.5 mg/kg soil dry weight. It was followed by Brassica napus (EC50 62.9 and NOEC 25 mg/kg soil dry weight). The least sensitive species was Glycine max which showed an EC50 value of 89.7 and NOEC 25 mg/kg soil dry weight.

Furthermore, the effects of OPP on soil nitrification of soil micro-organisms were tested over a exposure period of 100 days. The NOEC of OPP was calculated to be 300 mg/kg soil dry weight 28 days and 100 days after application. The EC50 was calculated to be 633.5 mg/kg and 829.1 mg/kg soil dry weight 28 days and 100 days after application, respectively. In an additional test on soil respiration and nitrification, the results show that OPP has no impact on respiration and nitrogen transformation of soil microflora when applied up to 1.0 mg a.i./kg soil.

As OPP is readily biodegradable and has a DT50 in soil of < 1 d, only low amounts of the active substance are expected to reach the soil. Thus, the exposure of terrestrial organisms like terrestrial arthropods is considered to be low. Since only low amounts of the active substance are expected to reach the soil and the available data on microorganisms, terrestrial plants and earthworms are sufficient for the risk assessment, no further testing is required.