Sodium 2-sulphonatoethyl laurate

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

fish early-life stage toxicity

Type of information:

calculation (if not (Q)SAR)

Remarks:

estimated by calculation

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study reports the output from a Toxic Unit approach calculation for lauric acid, 2-sulfoethyl ester, sodium salt.

Reason / purpose for cross-reference:

reference to other study

Guideline:

other: REACH guidance on QSARs R.6 May 2008

Duration:

32 d

Dose descriptor:

NOEC

Effect conc.:

ca. 0.4 mg/L

Nominal / measured:

estimated

Conc. based on:

act. ingr.

Basis for effect:

mortality

The results in Table 4 indicate that the soluble concentrations of C12 chain length contribute only 4% of the observed toxicity of the mixture. The C14, C16 and C18 chain lengths are estimated to account for approximately 96% of the observed toxicity of the mixture. The results of the study KLS090107 should, therefore, be considered to be an overly conservative estimate for the chronic toxicity to fishto sodium lauroyl isethionate.

Table 4. Calculation of Toxic Unit contribution for sodium lauryl isethionate during ELS study KLS090107

Chainlength	MW	Concentration at NOEC (mg/L)[1]	Concentration at NOEC (mol/L)	Log Kow[2]	Log predicted toxicity (mol/L)	Predicted toxicity (mol/L)	TU[3]	Contribution to toxicity of mixture (%)[4]	TU as a relative contribution to total TU of mixture from each chain length[5]	Predicted NOEC (mol/l)[6]	Predicted NOEC (mg/l)
8	251	0.00666	2.65E-08	-1.56	1.537	0.02903	0.00000091	0.0876	0.00088	3.0E-5	8
10	279	0.00459	1.65E-08	-0.48	2.218	0.00606	0.0000027	0.260	0.0026	6.3E-6	1.8
12	307	0.01638	5.34E-08	0.6	2.898	0.00126	0.000042	4.0	0.04	1.3E-6	0.4
14	335	0.00648	1.93E-08	1.68	3.578	0.00026	0.000073	7.0	0.07	2.8E-7	0.09
16	363	0.00828	2.28E-08	2.76	4.259	0.00006	0.00041	40	0.40	5.8E-8	0.02
18	391	0.002295	5.87E-09	3.84	4.939	0.00001	0.0005	49	0.49	1.2E-8	0.005

[1]Concentration at NOEC (mg/L)–dissolved concentration of each chain length (as measured during the study) at the exposure concentration determined to be the NOEC i.e. % dissolved x 0.045 mg/L(% dissolved from study KLS090107: C8 = 14.8%, C10= 10.2%, C12= 36.4%, C14= 14.4%, C16= 18.4%, C18=5.1%)

[2]Log K_ow– C8 based on measured value, subsequent chain lengths calculated by the addition of 0.54 per additional CH₂unit which equates to the fragment value (inc bond contribution)[11].

[3]TU – toxic unit contribution of each chain length i.e. Concentration at NOEC (mol/L)/predicted toxicity (mol/L)

[4]Calculated as a relative TU of each chainlength/ total TU

[5]Total TU = 1 for all chainlengths at NOEC of the mixture since all act by same MoA

[6]Calculated by rearranging Equation 1 to give: NOEC_i= C_i/TU_i(e.g. Predicted NOEC(mol/L) for C12 = 5.34E-8/0.04 = 1.3E-6)

 

Validity criteria fulfilled:

not applicable

Conclusions:

The results in Table 4 indicate that the soluble concentrations of C12 chain length contribute only 4% of the observed toxicity of the mixture. The C14, C16 and C18 chain lengths are estimated to account for approximately 96% of the observed toxicity of the mixture. The results of the study KLS090107 should, therefore, be considered to be an overly conservative estimate for the chronic toxicity to fish to sodium lauroyl isethionate.

Executive summary:

The toxicity of a mixture comprising mainly of a distribution of homologues can be predicted from an applicable QSAR, the inclusion level of each homologue and the assumption of concentration addition (given that the homologues all have the same MoA). For a defined class of surfactanttoxicity normally increases logarithmically with increase in chain length of the hydrophobic tail [16]. The measured toxicity of a commercial surfactant, therefore, may be driven predominately by a limited number of the more hydrophobic homologues i.e. those that have toxicity orders of magnitude greater than the shorter chain length homologues.

The results in Table 4 indicate that the soluble concentrations of C12 chain length contribute only 4% of the observed toxicity of the mixture. The C14, C16 and C18 chain lengths are estimated to account for approximately 96% of the observed toxicity of the mixture. The results of the study KLS090107 should, therefore, be considered to be an overly conservative estimate for the chronic toxicity to fish to sodium lauroyl isethionate.

Reference 2

Endpoint:

fish early-life stage toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009.08.13 to 2009.09.15

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study Conducted According to GLP and OECD 210, Fish, Early-life Stage Toxicity Test Guideline. Read-across is based upon a commonality of functional groups, constituents, breakdown products and metabolic pathways. A detailed justification is appended in Section 13.

Qualifier:

according to guideline

Guideline:

OECD Guideline 210 (Fish, Early-Life Stage Toxicity Test)

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Not applicable

Analytical monitoring:

yes

Details on sampling:

- Nominal Concentrations: 0.32, 0.56, 1.0, 1.8 mg/L
- Measured Total Concentrations: 0.11, 0.22, 0.36, 0.58 mg/L
- Measured Dissolved Concentrations: 0.045, 0.11, 0.20, 0.33 mg/L

- Sampling method (total concentration):
1. 10 ml of sample taken by syringe (Plastic 10ml Luer-Lok syringe)
2. 5.0 ml expressed to waste
3. Remaining 5.0 ml collected in a glass centrifuge tube
4. 5.0 ml of methanol added to the centrifuge tube using the same syringe
5. Sample thoroughly mixed and ultra-sonicated for 15 minutes
6. Sample centrifuged at 960 g for 30 minutes at 22 °C
7. Aliquot of the supernatant taken by for analysis

- Sampling method (dissolved concentrations)
1. 10 ml of sample taken by syringe (Plastic 10ml Luer-Lok syringe)
2. Luer lock syringe filter (Millex – HV, Durapore PVDF, 25mm, 0.45µm) attached to syringe
3. 5.0 ml filtered to waste
4. Remaining 5.0 ml filtered into a glass centrifuge tube
5. Filter discarded
6. 5.0 ml of methanol added to the centrifuge tube using the same syringe
7. Sample thoroughly mixed and ultra-sonicated for 15 minutes
8. Sample centrifuged at 960 g for 30 minutes at 22 °C
9. Aliquot of the supernatant taken by for analysis

- Sample storage conditions before analysis: No data

Vehicle:

no

Test organisms (species):

Pimephales promelas

Details on test organisms:

TEST ORGANISM
- Common name: fathead minnow
- Source: embryos used in this study (batch 167-09) were obtained from brood stock held at Brixham Environmental Laboratory
- Source: adult fish used in this study (batch 207-08) were received, as embryos, at Brixham Laboratory from Aquatic Research Organisms, PO Box 1271, 1 Lafayette Road, Hampton, NH 03842, USA.

During the months prior to the start of the exposure they showed no evidence of disease and were held at a temperature of 25 ± 1 degrees C.

The broodstock used for the study were held in 45 l glass tanks under artificial lighting and were contained in water as described for the test dilution water, except that the water was only filtered to 10 µm before use. They were fed daily using a proprietary brand of high protein pelleted fish food, supplemented with frozen brine shrimp. No mortalities were recorded within seven days prior to the start of the study.

METHOD FOR PREPARATION AND COLLECTION OF FERTILIZED EGGS
The adult fish were separated into breeding groups with approximately 3 males and 6 females in each tank. The eggs from the spawnings in 6 brood tanks were collected and pooled in a dish filled with dilution water. Each batch of eggs was less than 24 hours old, and all batches were at either early-cleavage or morula stage of development. Sets of 5 eggs were impartially selected, microscopically examined for viability and placed into incubation cups. This process was repeated until each incubation cup contained a nominal 15 impartially selected eggs.

POST-HATCH FEEDING
- Start date: 2009-08-17
- Type/source of feed: rotifers for first 4 days followed by rotifers and artemia
- Amount given: 0-7 d: 4.5 mL rotifers per tank per feed; 5-26 d: 0.30 to 4.5 mL artemia (increasing amounts during study period)
- Frequency of feeding: twice per day

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

32 d

Post exposure observation period:

No data

Hardness:

Measured once per week in all test concentrations and control vessels. Reported total hardness at start of study was 35.1 (SD = 1.1) mg/L CaCO3 and at the end of the study was 50.3 (SD = 1.1) mg/L CaCO3.

Test temperature:

25.0 to 25.7 degrees C

pH:

7.43 to 7.80

Dissolved oxygen:

7.8 to 9.0 mg/L

Salinity:

0.1

Nominal and measured concentrations:

- Nominal Concentrations: 0.32, 0.56, 1.0, 1.8 mg/L
- Measured Total Concentrations: 0.11, 0.22, 0.36, 0.58 mg/L
- Measured Dissolved Concentrations: 0.045, 0.11, 0.20, 0.33 mg/L

Details on test conditions:

TEST SYSTEM
- Emybro cups (if used, type/material, size, fill volume):
Egg incubation cups (2 per replicate tank) were made from 80 mm standard lengths of 50 mm diameter glass tubing with nylon mesh attached to the bottom of each cup using silicone sealant. The cups were suspended in the test vessels and oscillated vertically over a distance of approximately 20 - 50 mm at a rate of 2 oscillations min-1.
- Test vessel:
The test vessels were of all glass construction, rectangular in shape with external dimensions of 305 mm x 205 mm x 210 mm (standard length x width x depth) and a maximum capacity of approximately 12 L. The test solution volume used was nominally 9.5 L. Two replicate test vessels (termed A and B) were employed for each treatment.

- Type of flow-through (e.g. peristaltic or proportional diluter):
A dynamic (flow through) test system was used for the study. The test apparatus was constructed of glass with a minimum of other materials (silicone tubing and sealant) in contact with the test solutions. Settling vessels, 2 L glass beakers with a nominal working volume of 1000 ml, were introduced to remove as much particulate matter from the system prior to the test solution reaching the test vessels.
- Renewal rate of test solution (frequency/flow rate): 35 tank volumes per day
- No. of fertilized eggs/embryos per vessel: 2x15 per vessel
- No. of vessels per concentration (replicates): 2 tanks
- No. of vessels per control (replicates): 2
- No. of vessels per vehicle control (replicates): Not applicable
- Biomass loading rate: no data

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
The dilution water was dechlorinated tap water, which had been passed through activated carbon, coarsely filtered to remove particulate material and dechlorinated with sodium thiosulphate. Salts were added, as required, to maintain minimum hardness levels, and the treated water was then passed through an ultraviolet steriliser to a set of 20 and 10 µm filters. The supply was then delivered to a temperature controlled header tank in the test laboratory set to the nominal test temperature of 25 ± 1 degrees C and finally re-filtered at 5 µm before use.
- Dissolved organic carbon: 0.440 mg/L
- Suspended solids: <3.0 mg/L
- Metals:

Metals reported as µg/L (sampled on 3 June 2009)

Cd Hg Ag Al As Cr Co
<0.100 <2.000 <1.00 <10.0 <1.00 <0.500 <1.00

Cu Fe Pb Mn Ni Zn B
<1.000 <30.0 <2.000 <10.0 <1.00 <5.00 <100.

- Pesticides:

Pesticides, highest values reported as µg/L (sampled on 3 June and 16 September# 2009)

Organochlorine pesticides Organophosphorous pesticides PCBs
<0.0500 <0.0100 <0.00500

- Chlorine: <2 µg/L
- Alkalinity: 22.9 mg/L
- Ca/Mg ratio: 11.2:3.0
- Conductivity:208 µS/cm
- Salinity: <0.1
- Culture medium different from test medium: No
- Intervals of water quality measurement: pH and conductivity were measured daily. Alkalinity, hardness and free and residual chlorine measured once per week. All other water quality parameters were measured quarterly.

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: 16 hrs light, 8 hrs dark (with a 20 minute dawn and dusk transition)
- Light intensity: 680, 740 and 540 lux taken from centre and either end of test rig.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Hatch, Survival, length and weight

VEHICLE CONTROL PERFORMED: no

RANGE-FINDING STUDY
A range finder study was conducted but not according to GLP and not included in this report.

POST-HATCH DETAILS
- Begin of post-hatch period: 2009-08-17
- No. of hatched eggs (alevins)/treatment released to the test chamber:
For each concentration and control there were 4 replicates of 15 eggs (a total of 60 eggs)
Control: 60 hatched
Dissolved measured
0.045 mg/L: 57 hatched
0.11 mg/L: 60 hatched
0.20 mg/L: 58 hatched
0.33 mg/L: 3 hatched
- Release of alevins from incubation cups to test chamber on day no.: 24 h after hatch day

FERTILIZATION SUCCESS STUDY
- Number of eggs used: 60 x 5 (300)
- Removal of eggs to check the embryonic development on day no.: no data

Reference substance (positive control):

no

Duration:

32 d

Dose descriptor:

NOEC

Effect conc.:

>= 0.2 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

number hatched

Duration:

32 d

Dose descriptor:

NOEC

Effect conc.:

>= 0.36 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

number hatched

Duration:

32 d

Dose descriptor:

NOEC

Effect conc.:

>= 0.045 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

mortality

Duration:

32 d

Dose descriptor:

NOEC

Effect conc.:

>= 0.11 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

32 d

Dose descriptor:

NOEC

Effect conc.:

>= 0.2 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

length

Duration:

32 d

Dose descriptor:

NOEC

Effect conc.:

>= 0.36 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

length

Duration:

32 d

Dose descriptor:

NOEC

Effect conc.:

>= 0.045 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

weight

Duration:

32 d

Dose descriptor:

NOEC

Effect conc.:

>= 0.11 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

weight

Duration:

32 d

Dose descriptor:

LOEC

Effect conc.:

>= 0.33 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

number hatched

Duration:

32 d

Dose descriptor:

LOEC

Effect conc.:

>= 0.58 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

number hatched

Duration:

32 d

Dose descriptor:

LOEC

Effect conc.:

>= 0.11 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

mortality

Duration:

32 d

Dose descriptor:

LOEC

Effect conc.:

>= 0.22 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

32 d

Dose descriptor:

LOEC

Effect conc.:

> 0.2 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

length

Duration:

32 d

Dose descriptor:

LOEC

Effect conc.:

>= 0.36 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

length

Duration:

32 d

Dose descriptor:

LOEC

Effect conc.:

>= 0.11 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

weight

Duration:

32 d

Dose descriptor:

LOEC

Effect conc.:

>= 0.22 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

weight

Details on results:

- Mortality/survival at embryoand larval stages (see table 1 below)
- Days to hatch or time to release of young: 4 days
- Numbers hatched (see table 1 below)
- Observations on body length and weight of young and/or exposed parents at one or more time periods (see table 2 and 3)
- Number of healthy fish at end of test - see table 1
- Type of and number with morphological and behaviour abnormalities:
Observations of the behaviour and any symptoms of abnormality were made throughout the test and the following were described:
Four of the newly hatched fry appeared to be paler and weaker than the rest (nominal 0.32, 0.56 & 1.0 mg/L). On Day 7 post hatch two smaller, weaker fry were noted as well as 2 deformed fry (nominal 0.56 mg/L). By Day 14 post hatch six small fry were observed within the study (nominal 0.32, 0.56 & 1.0 mg/L) and on Day 21 post hatch five small fry were observed (DWC and nominal 0.32, 0.56 & 1.0 mg/L). It was also noted that a number of the fry appeared to be paler in appearance to the rest (not concentration related). At the end of the study, Day 28 post hatch, 4 of the small fry remained (DWC and nominal 0.32, 0.56 & 1.0 mg/L) but there were no longer any pale or deformed fry present and the remainder of the fry appeared to be healthy.
- Effect concentrations exceeding solubility of substance in test medium: no data
- Incidents in the course of the test which might have influenced the results: none

Results with reference substance (positive control):

not applicable

Reported statistics and error estimates:

The acceptability of the test was considered from the Relative Standard Deviation (RSD), of the dry weights of the fish, which were alive at the end of the test in the controls. The values obtained were 34 and 25 % for A and B replicates, respectively. The RSD is defined as the standard deviation expressed as a percentage of the mean (this is equivalent to the coefficient of variation). The RSD for weight data were all less than 40% and are, therefore, considered acceptable according to the EPA Standard Evaluation Procedure.

Table 1: HATCH AND SURVIVAL DATA

 

Nominal conc of SLI (76) STRIPPED	Mean measured conc of SLI (76) STRIPPED Dissolved (Total)   (mg l^-1)	Replicate	Number of eggs at start	Number of larvae^a		Percentage hatch		Number of larvae surviving at	Percentage survival of larvae from release to 28 days post hatch
				Hatched^a	Released^b	Individual	Pooled	28 days	Individual	Pooled
(mg l^-1)						replicates	replicates	post hatch	replicates	replicates
Dilution water control	Dilution water control	A1	15	15	15	100	100	28	93	90
		A2	15	15	15	100
		B1	15	15	15	100		26	87
		B2	15	15	15	100
0.32	0.045 (0.11)	A1	15	14	14	93	95	24	83	81
		A2	15	15	15	100
		B1	15	13	13	87		22	79
		B2	15	15	15	100
0.56	0.11 (0.22)	A1	15	15	15	100	100	21	70	73*
		A2	15	15	15	100
		B1	15	15	15	100		23	77
		B2	15	15	15	100
1.0	0.20 (0.36)	A1	15	15	15	100	97	17	59	67*
		A2	15	14	14	93
		B1	15	14	14	93		22	76
		B2	15	15	15	100
1.8	0.33 (0.58)	A1	15	1	0	7	5*	0	-	50*
		A2	15	0	0	0
		B1	15	0	0	0		1	50
		B2	15	2	2	13

a: Live fry hatched

b: Surviving fry released into tank;boldfigures indicate an incubation cup in which there were fry which were dead when hatched (numbers of deaths are by subtraction from the number hatched)

*: Statistically significant difference between treatment and DWC (p <0.05)

Table 2 LARVAL STANDARD LENGTHS (mm) AT 28 DAYS POST-HATCH

Pooled replicates

 

Nominal conc of SLI (76) STRIPPED         (mg l^-1)	Mean measured conc of SLI (76) STRIPPED Dissolved (Total)   (mg l^-1)	Number of fish	Mean	Minimum	Maximum	Standard deviation	Relative standard deviation (%)
Dilution water control	Dilution water control	54	20.18	10.34	23.94	2.32	11
0.32	0.045 (0.11)	46	21.76	13.01	26.81	2.33	11
0.56	0.11 (0.22)	44	21.34	13.00	24.62	2.08	10
1.0	0.20 (0.36)	39	21.54	10.27	25.17	2.99	14

 The nominal 1.8 mg l^-1concentration was not included in the calculations as only 1 larvae survived.

No significant differences were found.

Table 3: LARVAL DRY WEIGHTS (mg) AT 28 DAYS POST-HATCH

 

Nominal conc of SLI (76) STRIPPED   (mg l^-1)	Nominal conc of SLI (76) STRIPPED   (mg l^-1)	Number of fish	Mean	Minimum	Maximum	Standard deviation	Relative standard deviation (%)
Dilution water control	Dilution water control	54	31.81	1.90	51.00	9.54	30
0.32	0.045 (0.11)	54	31.66	5.10	65.70	16.75	30
0.56*	0.11* (0.22)	44	37.44	6.80	58.50	10.84	29
1.0*	0.20* (0.36)	39	39.14	2.50	62.10	14.02	36

 

* Statistically significant difference between treatment and DWC (p <0.05)

A statistically significant increase in dry weight was detected in the 0.56 and 1.0 mg l^-1when compared with the dilution water control, however, this was not considered to be an adverse biological effect.

The nominal 1.8 mg l^-1concentration was not included in the calculations as only 1 larvae survived.

Validity criteria fulfilled:

yes

Conclusions:

For all the biological parameters included in the evaluation (hatch, survival, standard length, and dry weight) the overall results based on mean measured dissolved concentrations (numbers in brackets are mean measured total concentrations) are:
No Observed Effect Concentration (NOEC): 0.045 (0.11) mg/L
Lowest Observed Effect Concentration (LOEC): 0.11 (0.22) mg/L

Executive summary:

An OECD 210 Fish Early Life stage toxicity of SLI(76) stripped to fathead minnow was conducted.

For all the biological parameters included in the evaluation (hatch, survival, standard length, and dry weight) the overall results based on mean measured dissolved concentrations (numbers in brackets are mean measured total concentrations) are: No Observed Effect Concentration (NOEC): 0.045 (0.11) mg/L Lowest Observed Effect Concentration (LOEC): 0.11 (0.22) mg/L.

Description of key information

A 32 day NOEC for fish was calculated for the target substance using a polar narcosis QSAR and Toxic unit approach methodology from the results obtained in a study using C12-18 and C18-unsatd., 2-sulfoethyl esters, sodium salts (CAS no 85408-62-4)

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

0.4 mg/L

Additional information

There is no chronic fish toxicity studyavailable for lauric acid 2-sulfoethyl ester, sodium salt (sodium lauroyl isethionate) CAS No 7381-01-3. There is however a study on the source chemical Fatty acids, C12-18 and C18-unsatd., 2-sulfoethyl esters, sodium salts CAS No 85408-62-4, which isKlimisch rated 2and was carried out according to theOECD guideline 210 under GLP,as described in Hurd 2009.

The results from the Hurd study were used as the starting point for calculating the NOEC for for lauric acid 2-sulfoethyl ester, sodium salt using a Toxic Unit approach.

The toxicity of a mixture comprising mainly of a distribution of homologues can be predicted from an applicable QSAR, the inclusion level of each homologue and the assumption of concentration addition (given that the homologues all have the same MoA). For a defined class of surfactanttoxicity normally increases logarithmically with increase in chain length of the hydrophobic tail [16]. The measured toxicity of a commercial surfactant, therefore, may be driven predominately by a limited number of the more hydrophobic homologues i.e. those that have toxicity orders of magnitude greater than the shorter chain length homologues.

The results indicate that the soluble concentrations of C12 chain length contribute only 4% of the observed toxicity of the mixture. The C14, C16 and C18 chain lengths are estimated to account for approximately 96% of the observed toxicity of the mixture. The results of the study KLS090107 should, therefore, be considered to be an overly conservative estimate for the chronic toxicity to fish to sodium lauroyl isethionate.