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Diss Factsheets

Ecotoxicological information

Toxicity to microorganisms

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Administrative data

Link to relevant study record(s)

Description of key information

3-hour EC50 (activated sludge respiration): >1000 mg/L (OECD 209)

Key value for chemical safety assessment

Additional information

Toxicity of 2-methylbutyl acrylate (2-MBA) to microorganisms was measured in a 3-hour OECD 209 assay with activated sludge of a predominantly domestic sewage.  The study was conducted under GLP criteria and is reliable without restrictions.  Additional supporting studies are available.  2-MBA had a 15-minute EC50 (fluorescence) of 5.6 mg/L in a Microtox ® assay.  The reliability of this study cannot be assessed.  However, the key result is similar to supporting test results for n-butyl acrylate (n-BA).  A three-day EC0 >150 mg/L to activated sludge was reported for n-BA (ASTM method STP 528).  The n-BA study was considered reliable without restriction for n-BA, but as read-across to 2-MBA is reliable with restriction (Klimisch 2).  2-MBA and n-BA are acrylate esters which exert toxicity by virtue of electrophilic (Michael-type) addition to cellular nucleophiles such as glutathione(1)or cellular proteins(2).  The result of this addition is glutathione depletion followed by oxidative damage to cells, or alternatively protein inactivation.  Detoxification is by ester hydrolysis followed by downstream conversion and entry of acrylic acid to the citric acid cycle(3).  n-Butyl acrylate (n-BA) differs from 2-MBA by the latter's additional methyl branch adjacent to the ester moiety on the alcoholic side of the molecule.  Molecular weight, hydrophobicity and vapor pressure are similar between 2-MBA and n-BA.  The entirely linear structure of n-BA is expected to be somewhat more amenable to esterase activity and beta-oxidation than the 2-methyl branched structure of 2-MBA.  In addition, n-BA has a slightly lower log Kow.  Taken together, n-BA may be slightly less toxic than 2-MBA with slightly faster detoxification (by ester hydrolysis), but is expected to have generally similar toxicity values.

 

References:

1. A. P. Freidig, H. J. M. Verhaar, J. L. M. Hermens.  1999.  Comparing the Potency of Chemicals with Multiple Modes of Action in Aquatic Toxicology:  Acute Toxicity Due to Narcosis versus Reactive Toxicity of Acrylic Compounds.  Env. Sci. Technol. 33 (17): 3038–3043.

2. K. Chan & P. J. O’Brien.  2008. Structure–activity relationships for hepatocyte toxicity and electrophilic reactivity of a,b-unsaturated esters, acrylates and methacrylates.  J. Appl. Toxicol. 28 (8): 1004–1015.

3.  H. Greim, J. Ahlers, R. Bias, B. Broecker, H. Hollander, H.-P. Gelbke, S. Jacobi, H.-J. Klimisch, I. Mangelsdorf, W. Mayr, N. Schön, G. Stropp, P. Stahnecker, R. Vogel, C. Weber, K. Ziegler-Skylakakis, E. Bayer.  1995.  Assessment of structurally related chemicals: Toxicity and ecotoxicity of acrylic acid and acrylic acid alkyl esters (acrylates), methacrylic acid and methacrylic acid alkyl esters (methacrylates).  Chemosphere 31 (2): 2637–2659.

Data matrix – Analog approach (all data experimental except as noted)

Target substance

Source substance

CHEMICAL NAME

2-methylbutyl acrylate

n-butyl acrylate

CAS#

44914-03-6

141-32-2

Molecular formula

C8H14O2

C7H12O2

Molecular Weight

142.2

128.2

PHYSICO-CHEMICAL DATA 

Melting Point

≤ -75 °C

Not available

Boiling Point

161.7 °C at 1013hPa

147 °C at 1013hPa

Density

0.8886 g/cm3 at 25 °C

0.9 g/cm3 at 20.0 °C

Vapour Pressure

1.7 hPa at 20°C

5 hPa at 22.2°C

Partition Coefficient (log Kow)

2.9

2.38 (at 25°C)

Water Solubility

316 mg/L at 23 °C

Not available

ENVIRONMENTAL FATE and PATHWAYS

Photodegradation

DT50 1.04 d (QSAR: AOPWIN v1.92)

Not determined

Stability in Water

Adaptation, readily biodegradable

DT50, 1100 day at pH 7, 25 °C (40CFR796.3500)

Aerobic Biodegradation

60% after 11 days (OECD 301D)

80 - 90% after 28 days (OECD 310)

Bioconcentration

Not bioaccumulative
(Low log Kow, extensive metabolism)

Not bioaccumulative
(Low log Kow, extensive metabolism)

Transport and Distribution

Koc 263 – 302 (Calculated by TGD method)

Koc 40-148 (EPA OTS 796.2750)

Henry's Law constant

96 Pa*m3/mol at 23.1 °C

Not determined

ENVIRONMENTAL TOXICITY

Toxicity to Microorganisms (activated sludge respiration)

3-hour EC50 >1000 mg/L (OECD 209)

3d EC50 >150 mg/L (ASTM STP 528)