Methacrylic acid, monoester with propane-1,2-diol

Endpoint summary

Description of key information

LC50 fish (96h): > 100 mg/l

EC50 Daphnia magna (48h): > 143 mg/l

NOEC Daphnia magna (21d): 45.12 mg/l

EC50 Algae (72h): > 97.2 mg/l (growth rate)

NOEC Algae (72h): 97.2 mg/l (growth rate)

Additional information

Aquatic toxicity studies with methacrylic acid, monoester with propane-1,2-diol were conducted in fish, invertebrates, and algae.

For fish, one acute study with the golden orfe (Leuciscus idus melanotus) was available for assessment. The LC50 was >493 mg/L and based on an acute 48-hour static exposure (Hüls AG, 1987). Though the exposure was conducted for 48 hours instead of the standard 96-hour exposure, LC50 96h was assessed based on a read across approach with 2-hydroxyethyl methacrylate (CAS 868-77-9). A read across approach was performed with the structurally very similar substance 2-hydroxyethyl methacrylate. Although log Pow of hydroxypropyl methacrylate (0.97) is slightly higher than that of 2-hydroxyethyl methacrylate (0.42), the hydrophobicity of both substances is low and does not expect a strong impact on aquatic toxicity. The Environmental Agency of Japan has performed two limit tests with 2-Hydroxyethyl methacrylate: a standard test acc. OECD 203 for 96 h and a prolonged test acc. OECD 204 for 14 d. In both test EC 50 was > 100 mg/l. (E.A Japan, 1997)

For invertebrates, one acute and one chronic study with Daphnia magna  are  available for assessment. The EC50 was >143 mg/L, based on the acute 48-hour semi-static limit test exposure (Mitsubishi, 2004). Based on the chronic 21-day semi-static exposure, the NOEC for reproduction was 45.2 mg/L (Mitsubishi, 2005). 

For the algal species, one study with Pseudokirchnerella subcapitata is available for assessment. The EC50 and NOEC for the freshwater species were both >97.2 mg/L, the highest concentration tested and based on growth rate following 72-hours of exposure. 

Toxicity to microorganisms testing is waived for hydroxypropyl 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). EC10/NOEC of 100 mg/l is used for assessement.

Long-term testing in fish is waived for hydroxypropyl methacrylate shows that the PEC/PNECaqua ratio for the aquatic environment is <1, indicating no need for further information or testing.  

Taken together, the lowest aquatic toxicity value for hydroxypropyl methacrylate was the NOEC of 45.2 mg/L, based on the 21 -day chronic toxicity test with Daphnia magna.