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Short-term toxicity to aquatic invertebrates

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Description of key information

Not expected as harmful/toxic for aquatic invertebrates after short-term exposures.

Key value for chemical safety assessment

Additional information

The relative toxicity of propiophenone was evaluated in the static Tetrahymena pyriformis population growth assay. The test organism belongs to the protist kingdom and ciliophora phylum. The test was conducted following the protocol described by Schultz et. 1990 and an IC50 equal to 0.875 mmol/l (≈ 117.4 mg/l) has been recorded (Schultz et al., 1995).

In the same publication data on the acetophenone and butyrophenone, structural analogous, are also reported: the IC50 values indicated are 0.356 mmol/l (≈ 43 mg/l) and 1.671 mmol/l (≈ 248 mg/l), respectively.

Because of the above mentioned investigation has been conducted on an unusual testing organism, available data on the structural analogous acetophenone have been taken into account. The Read Across approach can be considered appropriate for the assessement of short-term toxicity to aquatic invertebrates. Details can be found in the Read Across justification document attached in section 13 of IUCLID.

Assessement of the sensitivity of Daphnia magna to test item sublethal levels of exposure was assayed. Sublethal exposure was begun by placing 20 daphnids vials containing different sublethal solutions. After 24 hours, animals were removed with a pipet, rinsed with clean water and all, but five animals from each vial, were transferred to another vial containing 18 ml of a toxic solution of the same chemical and exposed for another 24 hours. The five remaining animals from each vial are termed “sublethally exposed”, whereas narcotized animals removed from the lethal solutions 24 hours later are termed “previously exposed”. Regression between the sublethal body burdens and the sublethal exposure concentrations for test item was not significant (P > 0.05). That lack of trend suggests that the body burdens in the sublethally exposed animals are independent of the sublethal water concentrations. The hypothesis that prior exposure to the sublethal concentration of narcotics has no effect on the internal concentration needed to immobilize animals implies that prior exposure to sublethal concentrations of contaminants should not affect the body burdens of animals narcotized by subsequent lethal exposure. In the publication an EC50 (48h) of 4.4 mmol/l (≈ 529 mg/l) is indicated (Pawlisz and Peters, 1995).

The EC50 value recorded confirms that propiophenone can be expected as non harmful/toxic substance for aquatic invertebrates, after short-term exposures.