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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.


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.