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Aquatic toxicity studies with 2-hydroxyethyl methacrylate were conducted in fish, invertebrates, and algal species.

For fish, one reliable acute study with the fathead minnow and one acute (96-hour exposure) and one short-term (14-day exposure) study with the orange killifish (Oryzias latipes) were available for assessment. The lowest LC50 for fish was >100 mg/L and based on both the 96-hour and 14-day exposure to orange killifish. Long-term testing in fish is waived for 2-hydroxyethyl methacrylate since the substance is classified as readily biodegradable and has a low potential for bioaccumulation (log Pow = 0.42). In addition, the risk characterization shows that the PEC/PNECaqua ratio for the aquatic environment is <1, indicating no need for further information or testing.

For invertebrates, one reliable acute and chronic study with Daphnia magna was available for assessment. The EC50 was 380 mg/L, based on the acute 48-hour exposure. Based on the chronic 21-day exposure, the NOEC for reproduction was 24.1 mg/L.

For the algal species, one reliable study with Selenastrum capricornutum as the test species was available for assessment. The EC50 and NOEC for the freshwater species were 836 mg/L and 400 mg/L, respectively and based on growth rate following 72-hours of exposure.

An investigation with a similar substance (methacrylic acid) and 12 marine species (fish, invertebrates, several algae) gave no indication of a higher sensitivity of marine species compared to freshwater species. To the contrary, LC/EC50 values and NOECs tended to be higher than the corresponding freshwater data (Sverdrup, et al., 2001).

Toxicity to microorganisms testing is waived for 2-hydroxyethyl methacrylate since it is classified as readily biodegradable at an application concentration (100 mg/L), which is greater than the predicted environmental concentration (PEC) in the influent of the sewage treatment plant (STP).

Taken together, the lowest aquatic toxicity value for 2-hydroxyethyl methacrylate was the NOEC of 24.1 mg/L, based on the 21-day chronic toxicity test with Daphnia magna.

References:

Sverdrup LE, Kaellqvist T, Kelley AE, Fuerst CS, Hagen SB (2001). Comparative toxicity of acrylic acid to marine and freshwater microalgae and the significance for environmental effects assessments. Chemosphere 45(4-5) 653 - 658.