Reactionmass of octan-2-yl prop-2-enoate and octan-3-yl prop-2-enoate and octan-4-yl prop-2-enoate

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Study period:

19th November - 10th December, 2019

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 3M FMRD, S352546
- Expiration date: 2020.05.01
- Purity: 99.7%
- Physical state: Clear and colorless liquid

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Stored at room temperature (15-25°C).
- Stability under test conditions: Due to analytical issus, stability during the test is unknown.

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 5, 10, 20, 50, 100, 200, 500 ug/L, control and solvent control.
- Sampling method: A sample of ~20 mL was taken from excess of each test solution, media blank and acetone control for fresh solution sampling. For old media sampling, 2mL solution was sampled from each replicate of the test group and control solution, then pooled. Samples were processed and analyzed the same day as their collection.

Vehicle:

yes

Remarks:

Acetone

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 0.2004 g of the test item was dissolved in 20 mL acetone and mixed to get the stock concentration of 10000 mg/L. Volumes of 0.313, 0.625, 1.25, 2.50 and 5.0 mL of the stock solution were diluted with acetone (10 mL), resulting in acetone solutions of 313, 625, 1250, 2500, 5000 mg/L in addition to the 10000 mg/L. 0.10 mL of solution was added to 1 L of test water whilst mixing by magnetic stirring for 1 hour to get nominal concentrations of 0.0313, 0.0625, 0.125, 0.25, 0.5 and 1.0 mg/L. A solvent control solution was also prepared by adding 0.10 mL acetone into 1L test water and stirred for 1 hour. Test solutions were clear.
- Concentration of vehicle in test medium: 100 uL/L

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
Common name: Water flea
- Strain/clone: Daphnia magna (Straus)
- Source: Applied Chemistry Department Pesticide Environmental Evaluation Lab of the ChinaAgricultural University
- Age of parental stock: <24 hours old
- Culture conditions: Adult daphnids were cultured in tap water treated with Aquapro Pure Water Systems. During the period preceding the test, water temperatures were 18 - 22°C, photoperiod of 16h light, 8h dark. Daphnids in the cultures were fed daily a suspension of concentrated alga suspension. Neonates were not the first brood.
- Health: The test Daphnia magna was derived from a healthy stock (i.e. showing no signs of stress such as high mortality, presence of males and ephippia, delay in the production of the first brood, discolored animals, etc.)
- Food type: Living algal cells of Chlorella sp and Desmodesmus subspicatus
- Amount: 0.1 ~ 0.2 mg C/Daphnia/day
- Frequency: Once daily

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

160-170 mg CaCO3

Test temperature:

18.2-19.8

pH:

8.22-8.48

Dissolved oxygen:

8.46-9.39

Nominal and measured concentrations:

Nominal: 0.0313, 0.0625, 0.125, 0.25, 0.5, 1.0 mg/L, blank and solvent controls.

Details on test conditions:

TEST SYSTEM
- Test vessel: 200 mL glass beakers
- Fill volume: 90 mL per vessel
- Aeration: Water was aerated for more than 24 hours before use to attain dissolved oxygen saturation of at least 80% ASV. No aeration during the test.
- Renewal rate: 24 hours
- No. of organisms per vessel: One
- No. of vessels per concentration: Ten
- No. of vessels per control: Ten
- No. of vessels per vehicle control: Ten

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Tap water treated with Aquapro Pure Water System
- Total organic carbon:<2 mg/L, measured every three months.
- Particulate matter: <5 mg/L suspended solids
- Metals: All less than detection limits, except fluoride (0.31 mg/L)
- Pesticides:all less than detection limits
- Culture medium different from test medium: No

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: 16h light, 8h dark
- Light intensity: 1025 ~ 1240 lux for cool white light

EFFECT PARAMETERS MEASURED: Effects measured during the definitive test include total number of broods per parent, mortality of parents daphnids, body length of parent daphnids, time to first brood, and total living offspring daphnid per parent. These parameters were measured daily. In addition, number of aborted eggs or dead offspring were recorded daily.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2-fold
- Range finding study: yes
- Test concentrations: Nominal concentrations: 0.1, 1.0 and 10 mg/L
- Results used to determine the conditions for the definitive study: In the 1.0 and 10 mg/L test group, all daphnids were dead after 6 and 2 days, respectively. Actual concentration at the 0.1 and 1.0 mg/L concentration was about 0.0633 and 0.485 mg/L for fresh media (0-hours) and below the LOD for both in old media (48-hours).

Reference substance (positive control):

no

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.25 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Details on results:

- Reproduction data summary in Table 2
- Time until first brood summary in Table 2, NOEC was 1.0 mg/L (nominal)
- Body Length summary in Table 2, NOEC was 1.0 mg/L (nominal)
- Broods per parent summary in Table 2, NOEC was 0.5 mg/L (nominal)
- There was no mortality in the parent animals
- Other: During the test, there were no dead offspring, aborted eggs, or male offspring.
- Mortality of control: No mortality in control Daphnids (0%), within guideline criteria
- Effect concentrations exceeding solubility of substance in test medium: No

Reported statistics and error estimates:

Statistical analyses were performed on survival of first-generation daphnids, the number of live young, and the length and dry weight of the surviving first-generation daphnids. The F-test was used to analyze homogeneity of variance for live offspring, first brood time, total # of broods, and parental body length. Reproduction and growth (length) data were evaluated to determine significance via a one-side Student´s T-test using a 5% significance level in an EXCEL document. For body length of parent, the P-value in the F-test was <0.05, and therefore an unequal-variance T-test was done.

Table 2. Mean Chronic Toxic Effects to Daphnia magna in Definitive Tests

Nominal conc. (mg/L)	Mean Offspring ± Std Dev  (p-value)	Mean Time to First Brood ± Std Dev (p-value)	Mean Total Brood ± Std Dev (p-val)	Mean Body Length ± Std Dev (p-val)
Blank control	143±21 (-)	8.3±0.7 (-)	5.9±0.6 (-)	3.31±0.29 (-)
Solvent control	136±14 (0.38)	8.7±0.9 (0.29)	5.6±0.5 (0.23)	3.17±0.32 (0.32)
0.0313	134±19 (0.81)	8.4±0.7 (0.43)	5.6±0.7 (1.00)	3.16±0.32 (0.91)
0.0625	132±16 (0.65)	9.0±0.8 (0.46)	5.5±0.7 (0.72)	3.09±0.24 (0.52)
0.1250	137±14 (0.84)	8.9±0.9 (0.63)	5.8±0.4 (0.36)	3.07±0.28 (0.45)
0.2500	130±19 (0.50)	9.3±1.2 (0.22)	5.7±0.8 (0.75)	2.91±0.28 (0.07)
0.5000	113±14** (0.002)	9.2±1.1 (0.30)	5.4±0.5 (0.40)	3.06±0.15 (0.32)
1.0000	107±16*** (0.0005)	9.7±1.4 (0.08)	5.0±0.7* (0.04)	3.01±0.16 (0.18)

/: Not calculated

p-value of test groups compared with the solvent control

* : there was signficant differences when p value (t-test) was below 0.05

Validity criteria fulfilled:

yes

Remarks:

Mortality of the parent animals in the controls (0%) did not exceed 20%, mean number of living offspring in the controls (143 blank, 136 solvent) was ≥60, CV in living offspring produced per parent (14.7%, 10.3%, blank and solvent), was <25%

Conclusions:

21 day NOEC = 0.25 mg/L (OECD 211) in Daphnia magna (nominal) for reproduction

Executive summary:

The 21 day NOEC to Daphnia magna was determined in a definitive test according to OECD 211 guidelines. Nominal concentrations of 0.0313, 0.0625, 0.125, 0.25, 0.5, 1.0 mg/L, a solvent control, and a blank control were run using 1 animals per vessel (10 replicates per concentration) and acetone as a dispersant at 100 ug/L. Analytical monitoring of fresh and 24-hour-old solutions was done twice per week. A NOEC of 0.25 mg/L (nominal concentration) was determined.

This study was conducted under international guidelines and was compliant with GLP criteria. However, the analytical data for the test indicates that the NOEC value reported in this study is not reliable. Qualifying transitions for the calibration curves and qualifying transitions for old samples were out of spec. Due to failing qualitative ion criteria in many solutions and presence of interference/possible contaminations in the blank and solvent control, nearly all measured concentrations could not be relied upon. From available data in the study report, the analytical data does not confirm test substance concentration and strongly suggests the test substance was not maintained throughout the test. For these reasons the study has been deemed unreliable. Thus, these results are not considered suitable for use in Risk Assessment, Classification & Labeling, and PBT analysis.

Reference 2

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The target chemical (MTDID 44428 (CAM-8) CASRN 87015-11-0) and the source chemical (isooctyl acrylate (IOA) CAS 29590-42-9) are isomers that contain the same functional acrylate moiety attached to primarily C8 alkyl hydrocarbon chains (C7-C9, C8 rich for the source chemical) with variable branching. The source chemical differs from the target chemical in both the degree and position of branching of the alkyl ester group with the source chemical being branched at the terminal end of the alkyl chain while the target chemical is branched near the acrylate functional group. The acrylate group is expected to be metabolized in the same manner in both substances and the remaining alkyl chain will be metabolized and excreted via the same pathway. The source chemical and target chemical have the same molecular weight and very similar log Kow values (Target: 4.7-4.8, Source: 4.5-4.7). Similar ADME profiles are expected between the two substances as the metabolic pathway of acrylate esters has been well characterized. Acrylate and methacrylate functionalities are electrophilic and both may participate in Michael addition reactions. Metabolism is expected to occur through the same pathways, hydrolysis by carboxylesterases into two metabolites, an alcohol and
an acrylic acid moiety with minor conjugation to gluthathione. Hydrolysis is similar across the acrylate family and enhances the elimination of the chemical upon exposure (McCarthy & Witz, 1997). Studies with n-butyl acrylate and 2-ethylhexyl acrylate confirm that the acrylic acid metabolite enters aerobic oxidation and in completely metabolized to CO2 with only a minor proportion be conjugated to glutathione and excreted in the urine as a N-acetyl cysteine conjugate (Sanders, JM et. al, 19188; Gut, I, et al. 1988). The previously mentioned studies have also demonstrated that enzymatic hydrolysis kinetic constants for methacrylate and acrylate esters are similar.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Target Chemical
The target molecule, MTDID 44428 (CASRN 87015-11-0), is a multi-constituent substance defined as the reaction mass of octan-2-yl acrylate, octan-3-yl acrylate and octan-4-yl acrylate as represented by the following structures (see attached read-across justification document). Molecular weight of the target chemical is 184.3
Source Chemical:
The source chemical, isooctyl acrylate (IOA) CAS 29590-42-9, is defined as a UVCB and is represented by the following structure (see attached read-across justification document). The average molecular weight of the source substance is ca. 184.0. The source chemical differs from the target chemical in the degree and position of branching of the alkyl ester group with the source chemical having variable methyl branching along the alkyl chain while the target chemical is branched immediately adjacent to the acrylate functional group.
Purity and Impurities :
MTDID 44428 is a multi-constituent substance and the three acrylate constituents contribute >99% of the content. There are very low levels of residual reactants and reaction side products. Isooctyl acrylate is a UVCB substance, based on the mixed-isomer nature of the material. As a UVCB substance, all components are considered part of the substance and the concept of impurities has little meaning. Acrylate ester content of IOA is >99 %, with very low levels of residual reactants and reaction side products. These non-acrylate components are substantially similar and do not impact the read-across of test results from IOA.

3. ANALOGUE APPROACH JUSTIFICATION
The target chemical and source chemical are closely related alkyl acrylate compounds. They differ slightly in the structure of the alkyl ester portion of the molecule. MTDID 44428 contains a methyl, ethyl or propyl branch at the 1-carbon of the alkyl chain portion of the molecule, which is always C8 in total. IOA may have methyl or ethyl branches at one or more positions along the alkyl ester group. The carbon chain is predominantly C8 in total with lesser contributions of C7 and C9 (C8 on average). The environmental toxicity of low molecular weight acrylate esters (aquatic mortality and immobilization) is by protein adduct formation via a Michael-type addition mechanism. In the environment, toxicity increases on a molar concentration basis with molecular weight (and concomitantly, hydrophobicity) due to increased ability of the molecule to reach its active site. The excess toxicity is mitigated in high molecular weight acrylate esters with log P > 5. The mammalian toxicity of IOA and MTDID 44428 is also based on protein adduct formation via a Michael-type addition with the acrylate groups. Both the target and source chemical are weak dermal sensitizers (section 5 in attached read-across justification and data matrix table) indicating that an equivalent mechanism of toxicity is at work for both substances based on identical functional groups and molecular weights and very similar log Kow values and water solubilities. The number of hydrophobic carbons of IOA relative to MTDID 44428 is predicted to be similar resulting in very similar octanol water partition coefficient values. This was confirmed experimentally and the log Kow for IOA is 4.5-4.7 while the log Kow for MTDID 44428 is 4.7-4.8. Additionally, IOA and MTDID 44428 have very similar water solubility at 12.44 and 14.6 mg/L, respectively. IOA is expected to be metabolized via the same hydrolytic and enzymatic pathways as MTDID 44428, forming acrylic acid and isooctanol. Similar mammalian metabolic pathways are expected for IOA and MTDID 44428 based on Sanders, et. al and Gut, et al. The source chemical and target chemical have the same molecular weight and very similar log Kow values. Similar ADME profiles are expected between the two substances as the metabolic pathway of acrylate esters has been well characterized. Acrylate and methacrylate functionalities are electrophilic and both may participate in Michael addition reactions. Metabolism is expected to occur through the same pathways, hydrolysis by carboxylesterases into two metabolites, 2an alcohol and an acrylic acid moiety with minor conjugation to gluthathione. Hydrolysis is similar across the acrylate family and enhances the elimination of the chemical upon exposure (McCarthy & Witz, 1997). Studies with n-butyl acrylate and 2-ethylhexyl acrylate confirm that the acrylic acid metabolite enters aerobic oxidation and in completely metabolized to CO2 with only a minor proportion be conjugated to glutathione and excreted in the urine as a N-acetyl cysteine conjugate (Sanders, JM et. al, 1988; Gut, I, et al. 1988). The previously mentioned studies have also demonstrated that enzymatic hydrolysis kinetic constants for methacrylate and acrylate esters are similar. As can be seen in section 5 in attached read-across justification and data matrix table, the source and target substances have very similar environmental and mammalian hazard profiles for endpoints where each substance has experimental data. This further supports the hypothesis that the target and source substances are expected to behave similarly in mammalian and environmental systems with the same mechanism of action and that read-across of the data for higher-tier endpoints is appropriate in an effort to reduce unnecessary animal testing.


4. DATA MATRIX
See 'Other Information Including Tables' or attached justification.
Supporting References
Gut, I, Vodička, Cikrt, M, Sapota, A, and Kavan, I (1988) Distribution and elimination of (14C)-2-ehtylheyxyl acrylate radioactivity in rats. Archives of Toxicology 62:346-350.
McCarty, TJ and Witz, G (1997) Structure-activity relationships in the hydrolysis of acrylate and methacrylate esters by carboxylesterase in vitro. Toxicology 116: 153-158.
Sanders, JM, Burka, LT, and Matthews, HB (1988) Metabolism and disposition of n-butyl acrylate in male Fischer rats. Drug Metabolism and Disposition 16(3): 429-434

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.065 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks on result:

other: NOEC for reproduction was calculated as one-half of the LOEC. 21-day NOEC (immobilization), 1.06 mg/L.

Read-Across Data Matrix

	Target substance	Source substance
CHEMICAL NAME	Reaction mass of octan-2-yl acrylate, octan-3-yl acrylate and octan-4-yl acrylate	Isooctyl acrylate
CAS#	44914-03-6	29590-42-9
Molecular formula	C11H20O2	C11H20O2 (on average)
Molecular Weight	184.3	184.3 (on average)
Melting Point	Experimental: <-35 °C	Experimental: < -90 °C at 1004 hPa
Boiling Point	Experimental: 217.6 °C (normalized).	Experimental: 196.8 °C at 1016 hPa
Density	Experimental: 0.8665 at 23 °C	Experimental: 0.885 g/cm3 at 20.0 °C
Vapour Pressure	Experimental: .06 hPa at 18 °C	Experimental: 1 hPa at 20 °C
Partition Coefficient (log KOW)	Experimental: 4.7-4.8	Experimental: 4.5 - 4.7
Water Solubility	Experimental: Individual isomers had solubilites of 4-5 mg/L, total was 14.6 mg/L	Experimental: 12.44 mg/L at 23.1 °C
Stability in Water	Experimental: t1/2at 25 °C, pH 9, 37.7-116 days t1/2at 25 °C, pH 7, 137 days - not determinable t1/2at 25 °C, pH 4, 154 days - not determinable. Hydrolysis product could be detected at pH 9 but not pH 7 and 4. Half-life increased from 2-octyl < 3-octyl < 4-octyl isomers.	Adaptation, readily biodegradable
Aerobic Biodegradation	Experimental: 54.7% after 28 days, biodegradation essentially stopped at day 11 (OECD 301F)   67% after 28 days. No residual material could be detected in test chambers on day 28. In abiotic control, residual test material was 4.8% of initial result (OECD 302C)	Experimental: 93-95% after 28 days (OECD 301D)
Bioconcentration		Not bioaccumulative (Extensive metabolism)
Transport and Distribution	Experimental: Koc 630 (OECD121)	Experimental: Koc 650-3900 (OECD121)
Henry's Law constant	NDA	Experimental: 1780 Pa*m3/mol at 23.1 °C
Acute Toxicity to Fish  (P. promelasunless noted)	NDA	Experimental: 96-hour LC50 0.67 mg/L (OECD 202)
Chronic Toxicity to Fish	NDA	Waived
Acute Toxicity to Aquatic Invertebrates (D. magna)	NDA	Experimental: 48-hour EC50 0.4 mg/L (OECD 202)
Long-Term Toxicity to Aquatic Invertebrates (D. magna)	NDA	Experimental: 28-day NOEC 0.065 mg/L (OECD 202 rev 1984)
Toxicity to Algae and Aquatic Plants (P. subcapitata)	NDA	QSAR result. Not read across
Toxicity to Microorganisms (activated sludge respiration)	Experimental: 3-hour EC50 >1000 mg/L (OECD 209)	Experimental: 3-hour EC50 >1000 mg/L (OECD 209)
Acute Oral Toxicity	Experimental: Rat oral LD50 > 2,000 mg/kg	Experimental: Rat oral LD50 > 5,000 mg/kg
Acute Dermal Toxicity	Read-across from source: Rabbit dermal LD50 > 2,000 mg/kg	Experimental: Rabbit dermal LD50 > 2,000 mg/kg
Acute Inhalation Toxicity	Read-across from source: NDA	Experimental: NDA
Skin Irritation	Experimental: Irritating (GHS Cat. 2)	Experimental: Not irritating
Eye Irritation	Experimental: Not Irritating	Experimental: Not irritating
Skin Sensitization	Experimental: Weak sensitizer (GHS Category 1B)	Experimental: Weak sensitizer (GHS Category 1B)
Ames Assay	Experimental: Non-mutagenic	Experimental: Non-mutagenic
in vitroChromosome Aberration	Read-across from source: Clastogenic at cytotoxic concentrations	Experimental: Clastogenic at cytotoxic concentrations
in vitroMouse Lymphoma Assay	Read-across from source: Non-mutagenic	Experimental: Non-mutagenic
28 Day Oral Toxicity	Read-across from source: NOAEL = 1,000 mg/kg/day	Experimental: NOAEL = 1,000 mg/kg/day
90 Day Oral Toxicity	Read-across from source: NOAEL = 600 mg/kg/day	Experimental: NOAEL = 600 mg/kg/day
Reproductive/Developmental Screening Study (Dermal)	Read-across from source: NOAEL = 20% Dermal Exposure	Experimental: NOAEL = 20% Dermal Exposure
Prenatal Developmental Study (Oral)	Read-across from source: NOAEL = 1,000 mg/kg/day	Experimental: NOAEL = 1,000 mg/kg/day
Carcinogenicity (Dermal)	Read-Across from source: Not Carcinogenic	Experimental: Not Carcinogenic (5% Dermal Exposure)

Conclusions:

MTDID 44428 is estimated to have a 21d NOEC=0.065 mg/L to Daphnia magna by read across from isooctyl acrylate.

Executive summary:

The similarities between the structural, physical & chemical, toxicity, and predicted metabolic properties of the source and target substances presented above support the read-across hypothesis for long term toxicity to aquatic invertebrates. The data are adequate and reliable scientific information to support the hypothesis. Therefore, based upon the data and considerations presented in the above sections, it can be concluded that the results of the long term toxicity to aquatic invertebrates study with source substance will accurately predict the results for the target substance and are considered as adequate to fulfill the information requirement of Annex VIII, of the REACH Regulation for the target substance.

Description of key information

21 day NOEC=0.065 mg/L (arith. mean) in Daphnia magna (OECD 211)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

NOEC

Effect concentration:

0.065 mg/L

Additional information

A study performed using MTDID 44428 with Daphnia magna under OECD 211 was considered unreliable due to methodological deficiences. The data gap for invertebrate acute toxicity was filled by using read across from isooctyl acrylate. The key value for acute invertebrate toxicity was a 21 day NOEC=0.065 mg/L of isooctyl acrylate to Daphnia magna, determined in a definitive test according to OECD 211 guidelines.