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Environmental fate & pathways

Hydrolysis

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Description of key information

Cyclohexyl methacrylate has is readily biodegradable and has a low water solubility; therefore according to Regulation (EC) No 1907/2006, Annex VII-X, part 9.2. Degradation; 9.2.2. Abiotic; 9.2.2.1. Hydrolysis as a function of pH: 

The study does not need to be conducted if:

— the substance is readily biodegradable, or

— the substance is highly insoluble in water.

Based on the structural related methacrylates (methyl methacrylate; ethyl methacrylate; n-butyl methacrylate and 2-ethylhexylmethacrylate) and the Q(SAR) data using SRC HYDROWIN v2.00 a high water stability is also expected for cyclohexyl methacrylate. In contact with water cyclohexyl methacrylate will hydrolyse slowly. Calculated half-life at pH 7 and 25 °C: 274 years.

Key value for chemical safety assessment

Half-life for hydrolysis:
274 yr
at the temperature of:
25 °C

Additional information

Cyclohexyl methacrylate has is readily biodegradable and has a low water solubility; therefore according to Regulation (EC) No 1907/2006, Annex VII-X, part 9.2. Degradation; 9.2.2., Abiotic; 9.2.2.1. Hydrolysis as a function of pH:

The study does not need to be conducted if:

- the substance is readily biodegradable, or

- the substance is highly insoluble in water.

Based on the structural related methacrylates (methyl methacrylate; ethyl methacrylate; n-butyl methacrylate and 2-ethylhexylmethacrylate) only a very slow hydrolysis is expected for cyclohexyl methacrylate.

- Abiotic degradation by hydrolysis of methyl methacrylate was measured in a GLP U.S.-EPA guideline study. The measured half-life (t 1/2 ) for 14C-methyl methacrylate at 25 °C is 143 minutes at pH 11. Since less than 2 % hydrolysis occurred for 14C-methyl methacrylate at pH 7 over 28 days, the approximate half-life calculated from the initial and final concentration for pH 7 was 1600 days (Ricerca Inc., 1990)

- The measured half-life for 14C ethyl methacrylate at 25 °C is 410 min. at pH 11. The calculated half-life were 4800 and 2400 days at pH 3 and 7, respectively, indicated no appreciable hydrolysis (Miller, 1989)

- Abiotic degradation by hydrolysis of n-butyl methacrylate was measured in an OECD guideline study. N-BMA was stable at pH 3 and pH 7. At pH 9 the measured half-life (t 1/2 ) for n-BMA at 25 °C is 34 days. (CERI, 1998a)

- Abiotic degradation by hydrolysis of 2-ethylhexyl methacrylate was measured in an OECD guideline study. 2-EHMA was stable at pH 4 and pH 7. At pH9 the measured half-life (t 1/2 ) for 2-EHMA at 25 °C is 58 days. (CERI, 1998b)

References

Ricera Inc., A; Hydrolysis Study at 14C-Methyl methacrylate, Department of Environmental Sciences, US Methacrylat Producers Association (MPA), Washington DC, 88-0211, 02-05-1990

Miller DE; A Hydrolysis Study at 14C-Ethyl methacrylate, Department of Environmental Sciences, Ricera Inc. Doc. No 3191-88-0206-EF-01,, US Methacrylat Producers Association (MPA), Washington DC, 88-0211, 02-28-1989

CERI 1998 a, Alkyl Methacrylate (C = 2-20), n-Butyl methacrylate according to the OECD-Guideline 301C, Biodegradation test of Material Number K-670C, Results published on Japan's Chemical Risk Information Platform: http://www.safe.nite.go.jp/english/db.html, CERI (Chemicals Evaluation and Research Institute) Kurume Laboratory, Test No. 20670CK, METI, Ministry of Economy, Industry and Trade, Japan

CERI 1998 b, Alkyl Methacrylate (C = 2-20), 2-Ethylhexyl methacrylate, Physicochemical Analysis of Material Number K-670D,Results published on Japan's Chemical Risk Information Platform:http://www.safe.nite.go.jp/english/db.html,CERI (Chemicals Evaluation and Research Institute) Kurume Laboratory,80670DK,METI, Ministry of Economy, Industry and Trade, Japan

 

QSAR-disclaimer

 

In Article 13 of Regulation (EC) No 1907/2006, it is laid down that information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI (of the same Regulation) are met. Furthermore according to Article 25 of the same Regulation testing on vertebrate animals shall be undertaken only as a last resort.

 

According to Annex XI of Regulation (EC) No 1907/2006 (Q)SAR results can be used if (1) the scientific validity of the (Q)SAR model has been established, (2) the substance falls within the applicability domain of the (Q)SAR model, (3) the results are adequate for the purpose of classification and labeling and/or risk assessment and (4) adequate and reliable documentation of the applied method is provided.

 

For the assessment of cyclohexyl methacrylate (Q)SAR results were used for hydrolysis. The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint(s) sufficiently covered and suitable for risk assessment.

 

Therefore, further experimental studies on Hydrolysis are not provided.

 

The high water stability is supported by Q(SAR) data. According to Q(SAR) data using SRC HYDROWIN v2.00, cyclohexyl-methacrylate will be slowly hydrolysed in contact with water (calculated half-life at pH 7 and 25 °C: 274 years; at pH 8 and 25 °C: 27 years) (BASF SE, 2013).

 

Therefore, the substance will hydrolyse slowly in contact with water under environmental conditions. Hydrolysis will not contribute significantly to the degradation of cyclohexyl-methacrylate under environmental conditions.