Registration Dossier

Ecotoxicological information

Short-term toxicity to aquatic invertebrates

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

The most critical 48-h EC50 is 472 mg/l in Daphnia magna. For marine invertebrates the most critical toxicity value was the harmonised 96-h LC50 of106 mg/l in Americamysis bahia.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
472 mg/L
EC50/LC50 for marine water invertebrates:
106 mg/L

Additional information

There are several studies available both for freshwater and marine invertebrates, most of which are guideline studies.

For the freshwater compartment, results obtained with Daphnia are preferred with the most critical value for this species(48 hr EC50, 472 mg/l) chosen as the key study (Wildlife International Ltd., 1999c).

For marine species the effect concentrations range from 44 mg/l for mysid shrimp (Americamysis bahia) to 306 mg/l for blue crab (Callinectes sapidus). Results from several studies indicate that the mysid shrimp is the most sensitive marine species, but the results from the different are inconsistent. In one semi-static GLP-compliant near guideline study, in which the MTBE concentrations were not monitored the 96-h LC50 was 44 mg/l (T. R. Wilbury Laboratories, Inc., 1994). In a second semi-static EPA OPPTS 850.1035 study, with analytical monitoring, the observed 96-h LC50 was 136 mg/l (BennKinney et al., 1994). A third semi-static GLP-compliant EPA OPPTS 850.1035 study, with analytical monitoring, reported a 96-h LC50 of 200 mg/l and a 96-EC50 of 187 mg/l based on erratic swimming (Rausina et al., 2002).

Comparing the study by T. R. Wilbury Laboratories, Inc. (1994) with the available 28-d NOEC of the same species of 26 mg/l, it can be concluded that the effect in the short-term test is higher than in the long-term test. The study is well reported and executed and apart from the lack of analytical monitoring no deviations from standard guidelines (e. g. EPA OPPTS 850.1035) were observed and no explanation could be found why the results are inconsistent with those from other studies.

Because no technical reason is apparent to explain these differences, and since the results from the three studies are less than one order of magnitude apart, the results were harmonised by a geometric mean. The resultant 96-h LC50 of 106 mg/l in mysid shrimp (Americamysis bahia) and the 48-h EC50 of 472 mg/l in Daphnia magna will be used in the assessment.