6-chlorohexyl methacrylate

Ecotoxicological Summary

Additional information

No experimental data for 6-chlorohexyl methacrylate (6-CHMA) is available to assess the environmental fate of this substance. An alert regarding aquatic toxicity classification by ECOSAR for 6-CHMA is raised by OECD QSAR Toolbox based on the substance is a methacrylates.

Some concern for aquatic toxicity of 6-CHMA is expected also based on the similarity with short chain alkyl methacrylates and in particular with 2-ethylhexyl methacrylate CAS 688-84-6 (see document "Read -across hypothesis and justification" in section 13 of this IUCLID dossier). As reported in SIDS Dossier of " Short chain alkyl methacrylates" approved at SIAM 18 (20-23 April 2004), the methacrylates esters are of low to high toxicity to aquatic organisms as toxicity increases with increasing lipophilicity and molecular size across the category with ethyl metachacrylates CAS 97-63-2 (EMA) being the least toxic and 2-ethylhexyl methacrylate CAS 688-84-6 (2-EHMA) the most toxic. However, the predicted values by ECOSAR v.1.11 for 2-ethylhexyl methacrylate are more precautionary than the experimental values reported by SIDS Dossier of " Short chain alkyl methacrylates" approved at SIAM 18 (20-23 April 2004) and they are similar to the predicted values for 6 -CHMA. For classification purpose regarding aquatic toxicity of 6-chlorohexyl methacrylate the experimental values for similar substance 2-ethylhexyl methacrylate are used based on they are less precautionary but more realistic than ECOSAR prediction for 6-CHMA.

	Target substance	Source substance- predicted	Source substance experimental
Reference substance	6-chlorohexyl methacrylate (predicted values, ECOSAR class methacrylates)	2-ethylhexyl methacrylate (predicted values, ECOSAR class methacrylates)*	2-ethylhexyl methacrylate (experimental values)**
Short-term fish	LC50 96h fish = 1.463 mg/l	LC50 96h fish = 0.568 mg/l	Oryzias latipes LC50 96h = 2.78 mg/l (OECD203 ref.MoE,1998)
Short-term invertebrates	LC50 48h Daphnid = 1.267 mg/l	LC50 48h Daphnid = 0.505 mg/l	Daphnia magna EC50 48h = 4.6 mg/l (OECD 202, ref.MoE,1998)
Short-term algae	EC50 96h green algae = 0.099 mg/l	EC50 96h green algae = 0.067 mg/l	Selenastrum capricornutum EC 72h growth rate= 7.68 mg/l (OECD 201, ref. MoE,1998)
Long-term invertebrates	ChV Daphnid= 0.141 mg/l (estimated by acute to chronic ratio per method)	ChV Daphnid= 0.058 mg/l (estimated by acute to chronic ratio per method)	NOEC Daphnia magna 21 days = 0.105 mg/l (OECD211, ref.Schäfers,2004)

*The melting point = - 7.79, Log Kow =4.54 and water solubility = 5.922 mg/l predicted by EPI Suite v.4.1.for CAS 688-84-6 were used by ECOSAR v. 1.11 for the estimation of ecotox properties of 2-ethylhexyl methacrylate

**The experimental values for 2-ethylhexyl methacrylate(2-EHMA) are based on study reported in SIDS Dossier of " Short chain alkyl methacrylates" approved at SIAM 18 (20-23 April 2004) inside the specific section of 2-EHMA.

- MoE, Japan, 1998 Ministry of the Environment, unpublished data for 2-Ethylhexyl methacrylate. Note: in this study the concentrations, included EC50, are above the limit of solubility

- Schäfers C.,2004, 2-Ethylhexyl methacrylate: Daphnia magna, reproduction test in closed vessels. Unpublished report no. MPA-001/4-21 on behalf of Methacrylate Producers Association.

The predicted values for 2-ethylhexyl methacrylate are lower than experimental data reported in SIDS Dossier of " Short chain alkyl methacrylates" approved at SIAM 18 (20-23 April 2004). Based on the predicted values for 6-chlorohexyl methacrylate (6-CHMA) are higher that the predicted value for 2-ethylhexyl methacrylate (2-EHMA) the experimental data for 2-EHMA can be used for classification purpose of 6-chlorohexyl methacrylate: these data are higher than predicted data for 6-CHMA but are more realistic (see table ABOVE) and this approach is precautionary based on the predicted data for 6-EHMA is lower than predicted data for 6-CHMA.

The similar behaviour of 6-CHMA and 2-EHMA regarding aquatic toxicity reflects their comparable solubility in water, positive logKow, and low potential of bioaccumulation common to both substances.

Based on experimental data available for the similar substance 2-ethylhexyl methacrylate and considering 6-chlorohexyl methacrylate to be ready-biodegradability like all the other short chain alkyl methacrylates, the classification H412 (Chronic aquatic toxicity cat.3) is proposed according to the CLP Regulation (EC n. 1272/2008).

Conclusion on classification

Based on experimental data available for the similar substance 2-ethylhexyl methacrylate (see document "Read -across hypothesis and justification" in section 13 of this IUCLID dossier) and considering 6-chlorohexyl methacrylate to be ready-biodegradability like all the other short chain alkyl methacrylates, the classification H412 (Chronic aquatic toxicity cat.3) is proposed according to the CLP Regulation (EC n. 1272/2008).