Bis(2-ethylhexyl) hydrogen phosphate

Long-term toxicity to fish

Description of key information

For bis(2-ethylhexyl) hydrogen phosphate in an Embryo-larval toxicity test a 48d-NOEC of 20.6 mg/L was obtained for Salmo gairdneri under semi-static conditions. A further test with the same test design revealed a 10d-NOEC of 21 mg/L for Brachydanio rerio.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

20.6 mg/L

Additional information

The toxicity of bis(2-ethylhexyl) hydrogen phosphate was investigated in embryos and larvae of rainbow trout (Salmo gairdneri) and zebrafish (Danio rerio) following the procedure for the embryo-larval toxicity test by American scientists (the U.S. EPA procedure) with deviations. The three main differences are (1) that a static renewal instead of a flow-through procedure was used, (2) that no food was offered during the test, which accordingly cannot be extended as long as the EPA procedure and, (3) that the results are based on nominal values instead on measured values. The studies were valuated as long-term toxicity as the fish were exposed at the most sensitive developmental stages.

In the experiments, stock solutions of bis(2-ethylhexyl) hydrogen phosphate were made up with acetone. A defined amount of the stock solutions was used to achieve the desired test concentrations. Acetone was evaporated to dryness at room temperature. After addition of water to the vessels, and equilibration during the night embryos or larvae of rainbow trout were introduced. In the study with zebrafish, acetone was also evaporated to dryness at room temperature and after addition of water to the petri-dishes 10–15 viable fertilized eggs of zebrafish were introduced. Control vessels are prepared in each test in the same manner. Rainbow trout embryos and larvae were exposed to bis(2-ethylhexyl) hydrogen phosphate at 8 +/- 1°C and a 12 h light-dark photoperiod. No feeding of the test animals took place during the experiment, which was terminated 48 days after hatching. Renewal of test solutions was every third to fourth day at the beginning and every week at the end of test. Fertilized eggs (5 h after fertilization) of zebrafish were exposed to bis(2-ethylhexyl) hydrogen phosphate at 25°C and a 12 h light-dark photoperiod. No feeding of the test animals took place during the experiment, which was terminated after 10 days. Renewal of test solutions was every second day by transferring survivors to new dishes. Mortality was recorded daily. Dead eggs got an opaque white to yellowish colour and the larvae were defined as dead if they did not respond to mechanical stimulation. For rainbow trout a result of 20.6 mg/l is reported and for zebrafish a result of 21 mg/l is reported. Both values are given as threshold concentration and in combination with a presented graph, each value is interpreted as NOEC.

Despite no details on amount of test concentrations were reported the studies were considered as reliable and useful for assessment.