methyl acrylate; methyl propenoate

Endpoint summary

Additional information

Additional information:

Following the Read-Across Assessment Framework (RAAF), the read-across approach for ecotoxicity endpoints is described according to scenario 6 (different compounds have quantitatively similar properties) and governed by AE 6.3 (common underlying mechanism, quantitative aspects).

As discussed in the review of structural and physical-chemical properties, acrylic acid has a different profile from the six acrylate esters included in the read-across approach for aquatic toxicity. As presented below, existing data on aquatic toxicity illustrates the different in hazard profile of acrylic acid and the acrylate esters. The available data indicates toxicity at the same order of magnitude across all three trophic levels for all acrylate esters within the category. Acrylic acid is the only outliers to this trend, displaying a lower level of toxicity. It can therefore be concluded that the read-across apporach is applied with a high level of certainty to the acrylate esters and is suitably precautionary.

The category document provided in IUCLID section 13 provides further information on the category and the read-across approach. An overview of the ecotoxicity information on acrylate esters is provided below.

Summary of relevant ecotoxicity endpoints:

Parameter	Acrylate esters considered in the read-across strategy
	MA	EA	nBA	iBA	tBA	2EHA
Short-Term Toxicity Testing on Fish (LC50) (Fresh Water)	3.4 mg/L	4.6 mg/L	5.2 mg/L	2.1 mg/L	2.37 mg/L	1.81 mg/L
Short-Term Toxicity Testing on Fish (LC50) (Marine Water)	1.1 mg/L	2.0 mg/L	2.1 mg/L	Read-across from nBA	Read-across from nBA	Read-across from MA, EA and nBA
Long-Term Toxicity Testing on Fish	No data available	No data available	No data available	No data available	No data available	No data available
Short-Term Toxicity Testing on Invertebrates (EC50)	2.6 mg/L (fresh water) 1.6 mg/L (marine water)	7.9 mg/L (fresh water)	8.2 mg/L (fresh water)	Read-across from nBA	8.74 mg/L (fresh water)	1.3 mg/L
Long-Term Toxicity Testing on Invertebrates	Read-across from nBA	0.19 mg/L (NOEC)	0.136 mg/L (NOEC)	Read-across from nBA	Read-across from nBA	0.85mg/l
Growth Inhibition Study Aquatic Plants (ErC50)	3.55 mg/L	4.5 mg/L (Cell number)	2.65 mg/L (Cell number)	5.28 mg/L	14.6 mg/L	1.71 mg/L
Algae (NOEC)	No data available	No data available	No data available	0.82 mg/L	3.85 mg/L	0.45 mg/L
Activated Sludge Respiration Inhibition	EC10 (3d) > 100 mg/L	EC10 (72h) > 100 mg/L	EC0 (3d) > 150 mg/L	EC20 (30 min) > 1000 mg/L	EC20 = ca. 950 mg/L	EC20 (30 min) > 1000 mg/L

 

The aquatic toxicity of methyl Acrylate has been assessed in acute and chronic studies. In addition, the information on the aquatic toxicity of the six acrylic esters (methyl, ethyl, n-butyl, isobutyl, tert-butyl acrylate, 2-ethylhexyl)) evaluated as a category is presented in section 13.2 of IUCLID.

Data of the acute toxicity in freshwater organisms are available for all three trophic levels (fish, aquatic invertebrates and algae). Effect values were all in the same range of concentrations, i.e. between 1 and 10 mg/L.

Freshwater fish:

Information on the acute toxicity to freshwater fish is available. LC50 values for Oncorhynchus mykiss were determined to be 3.4 mg/L (measured) for methyl acrylate (BAMM 1995)

As described in section 13.2 of IUCLID, testing information is consistent within the six acrylic esters evaluated as a category, with LC50 values for freshwater fish between 1.81 and 5.2 mg/L.

LC50 values for Oncorhynchus mykiss were determined to be 3.4 mg/L (measured) for methyl acrylate (BAMM 1995) and 1.81 mg/L (measured) for 2-ethylhexyl acrylate (BASF AG 1999). The LC50 value for Salmo gairdneri was 5.2 mg/L (measured) for n-butyl acrylate (BAMM 1990) and the LC50 value for Pimephalis promelas was approx. 2.1 mg/L (measured) for isobutyl acrylate (Russom et al. 1988). Tert-butyl acrylate was tested in an acute toxicity study with Leuciscus idus under static test conditions without analytical monitoring and in an open system (BASF AG, 1978). Test concentrations were recalculated based on the nominal test concentrations at test start and the assumption that at test termination all concentrations were below the limit of detection (0.1 mg/L) as worst case. The 96-hour LC50 was recalculated to be 2.37 mg/L.

Freshwater invertebrates:

Information on the acute toxicity to freshwater invertebrates is available. EC50 values for Daphnia magna were 2.6 mg/L (measured) for methyl acrylate (BAMM 1995).

As described in section 13.2 of IUCLID, testing information is consistent within the six acrylic esters evaluated as a category:

EC50 values for freshwater invertebrates were between 1.3 and 8.74 mg/L.

EC50 values for Daphnia magna were 1.3 mg/L (measured) for 2-ethylhexyl acrylate (BASF AG 2001), 8.2 mg/L (measured) for n-butyl acrylate (BAMM 1990), and 8.74 mg/L (measured) for tert-butyl acrylate (BASF AG, 2001), respectively. No acute toxicity studies in invertebrates involving analytical monitoring available for isobutyl acrylate.

Freshwater algae:

Information on the acute toxicity to freshwater invertebrates is available. The EC50 value for Selenastrum capricornutum was 3.55 mg/L (measured) for methyl acrylate (BAMM 1995).

No observed effect concentration (NOEC) values could not be derived from this study. The NOEC of 0.45 mg/L for 2-ethylhexyl acrylate based on growth rate is used as a conservative value in support of the chronic algal endpoint.

As described in section 13.2 of IUCLID, testing information is consistent within the six acrylic esters evaluated as a category: EC50 values for freshwater algae were between 1.71 and 14.6 mg/L. The NOEC values ranged from 0.45 to 3.85 mg/L.

EC50 values for Selenastrum capricornutum were , and 2.65 mg/L (measured) for n-butyl acrylate (BAMM 1990) based on cell number, respectively. No observed effect concentrations could be derived from those studies

The EC50 (growth rate) for Desmodesmus subspicatus was 1.71 mg/L (measured) for 2-ethylhexyl acrylate (BASF AG 2002), 5.28 mg/L (measured) for isobutyl acrylate (BASF AG 2002), and 14.6 mg/L (measured) for tert-butyl acrylate (BASF AG, 2002), respectively.

The NOEC for Desmodesmus subspicatus was determined to be 0.45 mg/L (measured) for 2-ethylhexyl acrylate, 0.82 mg/L (measured) for isobutyl acrylate, and 3.85 mg/L (measured) for tert-butyl acrylate, respectively.

Results for the testing of 2-ethylhexyl acrylate are selected as a conservative approach (lowest NOEC) in support of the support the chronic algal endpoint. The NOEC for 2-EHA on growth rate is 0.45 mg/L.

Based on the presented acute toxicity data, the most sensitive freshwater organism for the acrylic esters was Daphnia magna (EC50 = 1.3 mg/L).

In addition, there is a number of acute toxicity studies in marine organisms for two trophic levels (fish, invertebrates) available.

 

Marine organisms

Marine fish:

Information on the acute toxicity of methy acrylate to marine fish is available. LC50 values in Cyprinodon variegatus were estimated to be 1.1 mg/L for methyl acrylate (BAMM, 1995).

As described in section 13.2 of IUCLID, testing information is consistent with six acrylic esters evaluated as a category: LC50 values for marine fish ranged from 1.1 to 2.1 mg/L.

LC50 values in Cyprinodon variegatus were estimated to be 1.1 mg/L for methyl acrylate (BAMM, 1995),
and 2.1 mg/L (measured) for n-butyl acrylate (BAMM, 1996), respectively.

Marine invertebrates:

In an acute toxicity study with the seawater invertebrate Mysidopsis bahia (BAMM, 1996) a 96-hr LC50 of 1.6 mg/L based on mean measured concentrations was determined for methyl acrylate.

Long-term toxicity:

As described in section 13.2 of IUCLID, testing information is consistent within the six acrylic esters evaluated as a category: Studies on long-term effects to invertebrates are available on ethyl acrylate, n-butyl acrylate and 2 -Ethylhexal acrylate. The results of the three long-term invertebrate (Daphnia magna) studies conducted on the acrylate esters yield very similar results, with NOEC / EC10 for reproduction ranging between 0.136 mg/L and 0.85 mg/L, supporting the broader use of the category approach.

A 21 -day chronic study with ethyl acrylate in Daphnia magna was conducted according to EPA guideline under flow-through conditions and with analytical monitoring (BAMM 1997). The NOEC for reproduction was 0.19 mg/L (measured).

A 21 -day chronic study with 2 -Ethylhexyl acrylate in Daphnia magna was conducted according to OECD guideline 211 under flow-through conditions and with analytical monitoring (Charles River, 2020). The EC10 for reproduction was 0.85 mg/L (TWM concentrations).

In addition, a 21-day Daphnia magna reproduction Test was performed with n-butyl acrylate under semi-static conditions in accordance with OECD TG 211 (BASF SE, 2009). The effect concentrations were based on the time-weighted mean analytically detected concentrations: NOEC (reproduction) = 0.136 mg/L; LOEC (reproduction) = 0.457 mg/L.

Testing information for n-butyl acrylate is selected as a conservative approach (lowest NOEC) to support the chronic inverterbrate endpoint. The NOEC for nBA is 0.136 mg/L.

Microorganisms:

The assessment of toxicity towards microorganisms was based solely on data acquired with methyl acrylate.

Effect values after 72 hrs exposure to methyl acrylate in a microbiological inhibition test with domestic activated sludge (BODm test) were: threshold inhibition concentration > 100 mg/L; EC10 > 100 mg/L (BAMM 1996).