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

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24th - 28th November, 2019

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity 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: 1.5, 2.4, 3.9, 6.2, 10 mg/L and a blank control.
- Sampling method: A sample of ~20 mL was taken from each test solution and control solution. 5 mL of the sample was pre-treated before analysis. The remaining sample was stored in refrigerator (2-8 °C) for possible re-analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 0.1607-0.1612 g of test item was weighted and added into a glass bottle with 11L of test water. A magnetic stirrer was added, the bottle was capped, and the solution mixed for 24 hours (210 rpm). The solution was allowed to stand for 30 minutes and test solutions were drawn from a tap at 7cm from the bottom of the bottle. From these samples, 0.154, 0.822, 1.336, 2.123, and 3.425L of the saturated solutions were pipetted into test vessels, diluted with 5L of test water, and mixed for 2-3 minutes.
- Controls: Test medium without test substance or other additives.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: Zebrafish
- Source: Breeding stock from Hangzhou Hunter Biotechnology Inc. Test fish spawned in house.
- Age at study initiation: 36 days:
- Length at study initiation: 1.6-1.9 cm
- Weight at study initiation: 0.0202-0.0289 g
- Acclimation conditions: Fish were held in water of the quality to be used in the test
- Feeding frequency during acclimation: Twice on weekday and one time on weekend until 24 hours before the test was started.
- Health during acclimation: No signs of disease or significant number of mortalities

FEEDING DURING TEST: No feeding during test

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

190 mg/L (CaCO3)

Test temperature:

21.5-22.3°C

pH:

8.29-8.44

Dissolved oxygen:

91.0-98.7 %ASV

Nominal and measured concentrations:

Nominal: 1.5, 2.4, 3.9, 6.2 and 10 mg/L
Time weighted mean measured concentrations: 0.37, 0.67, 1.20, 2.32, 3.33 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass bottles with glass stopper.
- Material, size, headspace, fill volume: 5L fill volume (diameter: 16 cm, height: 26 cm)
- Aeration: Yes. Before usage, the dilution water was aerated for more than 24 hours to attain dissolved oxygen saturation. No aeration during the test.
- Renewal rate of test solution: Every 24 hours
- No. of organisms per vessel: 7
- No. of vessels per concentration: 1
- No. of vessels per control: 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Tap water treated with Aquapro Pure Water System
- Total organic carbon:<2 mg/L
- Particulate matter: <5 mg/L
- 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: None
- Photoperiod: 12 hours light: 12 hours darkness, cool white light
- Light intensity: 869-912 Lux

EFFECT PARAMETERS MEASURED: Observations for mortality and other sub-lethal effects such as stress, dark pigmentation, loss of balance, and swimming near the surface were measured by observation at 2, 5, 24, 30, 48, 54, 72, 78 and 96 hours.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.6x
- Range finding study : Yes
- Test concentrations: 0.146, 1.46 and 10 mg/L
- Results used to determine the conditions for the definitive study: Yes

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

0.98 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95 % CI: 0.83-1.15 mg/L

Details on results:

- For abnormalities and other biological observations see Table 2
- Mortality of control: No mortality in controls

Results with reference substance (positive control):

24 hour LC50=299.75 mg/L (95% CI: 252.84-355.38 mg/L) Test 4 days prior to definitive test.

Reported statistics and error estimates:

Trimmed Spearman-Karber method (EPA, v. 1.5) were used to derive LC50 and Confidence limits.

Sublethal observations / clinical signs:

Table 2. Mortality and Abnormalities in Defninitive Test

Nominal conc. (mg/L)	Observation Time	# Live Fish	Cumulative Mortality (%)	Abnormalities
Control	2	7	0	7 AN
	24	7	0	7 AN
	48	7	0	7 AN
	72	7	0	7 AN
	96	7	0	7 AN
1.5	2	7	0	7 AN
	24	7	0	7 AN
	48	7	0	7 AN
	72	7	0	7 AN
	96	7	0	7 AN
2.4	2	7	0	7 AN
	24	7	0	7 AN
	48	7	0	7 AN
	72	7	0	7 AN
	96	7	0	7 AN
3.9	2	7	0	7 AN
	24	7	0	7 AN
	48	6	14	4 AN 2 G
	72	3	57	3AN
	96	1	86	1B
6.2	2	7	0	7 AN
	24	7	0	6 AN 1Q
	48	1	86	1B
	72	0	100	/
10	2	7	0	4 AN, 3Q
	24	7	0	4 AN, 3Q
	48	0	100	/

AN: no abnormalities, G: dark pigmentation, B: loss of balance, Q: swimming near surface, /: no observation due to 100% mortality.

Validity criteria fulfilled:

yes

Remarks:

yes <10% mortality in controls (0%), DO >60% ASV (91.0%-98.7%)

Conclusions:

96 hour LC50=0.98 mg/L (time weighted average) in Danio rerio (OECD 203)

Executive summary:

The 96 hour LC50 of MTDID 44428 to Danio rerio was determined in a definitive test according to OECD 203 guidelines. Nominal concentrations of 1.5, 2.4, 3.9, 6.2 and 10 mg/L and a blank control were run using 7 animals per tank, with one replicate per concentration, and no dispersant. An LC50=0.98 mg/L mg/L (time-weighted average) was determined.

Study was conducted under international guidelines and was compliant with GLP criteria. Due to low retention of the test material within solution (~47-63% of the initial measured concentrations), the study is considered reliable with restrictions. The results from this study are considered suitable for Risk Assessment, Classification and Labeling, and PBT Analysis.

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

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

Adequacy of study:

supporting 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

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

0.67 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% C.I.:  0.56 to 0.82 mg/L

Sublethal observations / clinical signs:

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 96hr LC50=0.67 mg/L to Danio rerio 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 short term toxicity to fish. 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 short term toxicity to fish 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

96 hour LC50=0.98 mg/L (time weighted average) in Danio rerio (OECD 203)

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

0.98 mg/L

Additional information

The key value for acute fish toxicity was a 96 hour LC50=0.98 mg/L of MTDID 44428 to Danio rerio was determined in a definitive test according to OECD 203 guidelines. This is supported by a 96 hour LC50=0.67 mg/L of isooctyl acrylate to Pimephales promelas in a test according to OECD 203 guidelines. The two results are in agreement and would lead to the same classification. In this case, the study with MTDID 44428 was valid and read across was not necessary. However, the result is provided to support read across for other species.