[No public or meaningful name is available]

Toxicity to soil microorganisms

Administrative data

Endpoint:

toxicity to soil microorganisms

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Using the ionic compound log Kow correlation based regression equation, the Koc of the test substance was calculated to be 138.04 L/kg (log Koc: 2.14).

Koc at 20 °C:

138.04

Given the limitation of the publicly available QSAR models for log Koc estimation of ionic compounds, the endpoint has been assessed using log kow based log Koc regression equations proposed for ionisable compounds, along with other general and class specific equations, as a comparison.

The soil adsorption coefficient (Koc) value for the test substance, ‘mono- and di- C16-18 PSE and C16-18 AE10 PSE’, was determined using the well-known log Kow based log Koc regression models equations. To calculate a more reliable value and to reduce the overall uncertainty, multiple equations, which could be categorised as general, class-specific (i.e., ester) (Doucette WJ, 2000) and ionisable compound based (Franco and Trapp, 2008), were used for the calculations. The log Koc was calculated from the equations using the log Kow value of 3.19 determined for the test substance (based on individual solubility ratio) and a maximum фn of 0.1 and a minimum фion of 0.9, for the Franco et al., equation. The log Koc values were calculated to range from 2.68 to 3.11, using general equations, 2.59 to 2.61, using ‘ester class’ specific equations, and was 2.14 using the ionisable compound based equation. This range of Koc indicates low to moderate sorption to soil / sediment and moderate to slow migration potential to ground water (US EPA, 2012). Given that the test substance is ionic, the prediction of log Koc by treating neutral and ionic fractions separately is considered superior to methods that merge both fractions without considering the differences between neutral compounds and ions (Franco and Trap, 2008). Therefore, the log Koc of 2.14 (i.e., equivalent to Koc of 138.04 L/kg) calculated from Franco and Trapp (2008) equation has been selected as key value for this endpoint.

Possible processes behind the sorption of organic chemicals to soil and sediment are ion bonding or ligand exchange, chemiosorption (formation of a bond, usually covalent, with the soil molecular structure), ion–dipole and dipole–dipole interactions, charge transfer, hydrogen bonding, and hydrophobic bonding (Van der Waals forces). The most chemically active component of the soil is the colloidal fraction, which consists of organic matter and inorganic clay minerals. Both components display a negative electrical charge at the surface. The effect of this charge can be measured by the cationic exchange capacity, which on average is 50 meq/100 g for clays and 290 meq/100 g for humic acids. Electrical forces involving charge transfer (40 kJ/mol) are stronger than hydrophobic bonding (4 kJ/mol) so that they dominate when present. Thus, a different degree of sorption of anions, cations, and neutral molecules can be expected, with cations showing the highest potential for sorption, due to electrical attraction (Franco and Trapp, 2008).

Therefore, considering that the test substance is an anionic surfactant, its sorption potential can be expected to be much lesser than other known cationic surfactants, which is in line with the calculated log Koc derived based on Franco and Trapp, 2008 proposed equation for ionisable compounds.

Cross-reference 2

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Using the Arnot-Gobas BAF-BCF sub-model, the upper trophic BCF value for constituents was predicted to range from 0.893 to 590.50 L/kg ww (log BCF -0.05 to 2.77), leading to an weighted average value of 124.11 L/kg ww and indicating low bioaccumulation potential.

BCF (aquatic species):

591 L/kg ww

The bioconcentration factor (BCF) value for the test substance ‘mono- and di- C16-18 PSE and C16-18 AE10 PSE’ was estimated using the regression-based and/or Arnot-Gobas BAF-BCF methodology of the BCFBAF v3.01 program (EPI SuiteTM v4.11). Since the test substance is a UVCB, the bioaccumulation (BCF) values were estimated for the individual substances representative of the major components. Considering the structures of test substance, the regression-based equations as well as the Arnot-Gobas BAF-BCF methodology were used for the BCF predictions. Using the regression-based equations, the BCF values for the constituents were predicted to range from 3.16 to 1650 L/kg ww (log BCF 0.50 to 3.22) with weighted average value of 552.25 L/kg ww. While using the Arnot-Gobas BAF-BCF sub-model, the upper trophic BCF value for constituents was predicted to range from 0.893 to 590.50 L/kg ww (log BCF -0.05 to 2.77), leading to an weighted average value of 124.11 L/kg ww (US EPA, 2020). Therefore, considering that the constituents of the test substance are non-ionic and the BCF predictions from Arnot-Gobas method takes into account mitigating factors, like growth dilution and metabolic biotransformations, the BCF values from the Arnot-Gobas method has been taken into consideration from this model. Based on either the individual (0.893 to 590.50 L/kg ww) or weighted average (124.11 L/kg ww) predictions from the Arnot-Gobas method, the test substance can be considered to have a low bioaccumulation potential. On comparing with domain descriptors, one constituent for molecular weight and 3 out 12 constituents for log Kow did not meet the descriptor criteria as defined in the BCFBAF user guide of EPISuite. Therefore, overall, the BCF prediction for the test substance using BCFBAF model of EPI SuiteTM is considered to be reliable with moderate confidence.

Cross-reference 3

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

toxicity to soil macroorganisms except arthropods: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 28 May 2019 to 15 January 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 222 (Earthworm Reproduction Test (Eisenia fetida/Eisenia andrei))

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

not specified

Vehicle:

yes

Details on preparation and application of test substrate:

The test substance was added to a solvent (acetone) which was then placed over dry soil and the acetone allowed to evaporate before being mixed into an appropriate amount of moist soil and sufficient water added to achieve the final test concentration at a water holding capacity of 50%.

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Details on test organisms:

TEST ORGANISM
- Common name: Earthworms
- Source: Not specifies
- Age at test initiation (mean and range, SD): Adults
- Weight at test initiation (mean and range, SD): 312-314 mg

ACCLIMATION
- Acclimation period: No data
- Acclimation conditions (same as test or not): No data
- Health during acclimation (any mortality observed): No data

Study type:

laboratory study

Substrate type:

artificial soil

Remarks:

ISO earthworm soil containing 10% peat

Limit test:

no

Total exposure duration:

8 wk

Remarks:

Exposure time of offspring: till Day 56 (extended another 28 d)

Post exposure observation period:

None

Test temperature:

Not specified

pH:

Not specified

Moisture:

50% (sufficient water added to achieve the final test concentration at a water holding capacity of 50%)

Details on test conditions:

TEST SYSTEM
- Test container (material, size): Not specified
- Amount of soil or substrate: Not specified
- No. of organisms per container (treatment): 8 replicates of 10 earthworms for the water control, solvent control and toxic reference and 4 replicates of 10 earthworms for each test substance
- No. of replicates per treatment group: 4 replicates for test substance
- No. of replicates per control: 8 replicates for water control
- No. of replicates per vehicle control: 8 replicate for solvent control

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Composition (if artificial substrate): 10% peat

OTHER TEST CONDITIONS
- Photoperiod: Not specified
- Light intensity: Not specified

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Mortality, weight
change, behaviour and reproduction rate were determined.

VEHICLE CONTROL PERFORMED: yes

TEST CONCENTRATIONS
- Test concentrations: 16.3, 29.4, 52.9, 95.3, 171.5, 308.6, 555.6 and 1000 mg a.i./kg dry soil.

Nominal and measured concentrations:

16.3, 29.4, 52.9, 95.3, 171.5, 308.6, 555.6 and 1000 mg a.i./kg dry soil

Reference substance (positive control):

yes

Remarks:

Carbendazim (5 mg a.i./kg dry soil)

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

ca. 1 000 other: mg a.i/kg dry soil

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: Body weight

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

ca. 1 000 other: mg a.i/kg dry soil

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

Details on results:

Health and Mortality dose response test
Adult mortality at rates of 16.3, 95.3, 171.5, 555.6 and 1000 mg a.i./kg dry soil of 2.5, 7.5, 2.5, 5 and 5% was recorded respectively. Mortality of 1.25% was recorded in the water and solvent control with 12.5% mortality in the toxic reference group. The LC50 for the mortality on Day 28 could not be statistically estimated due to a lack of a dose response relationship, it is therefore concluded that the LC50 is >1000 mg a.i./kg dry soil. The No Observed Effect Concentration NOEC for mortality at Day 28 was 1000 mg a.i./kg dry soil.

Bodyweights dose response test
No effect at any treatment rate was observed in the adult bodyweight. The 5 mg a.i./kg dry soil carbendazim treated group had significantly lower body weight on Day 28 than the water control group. The LC50 for the mean body weight of the adult earthworms at Day 28 could not be estimated due to a lack of dose response. The LC50 was concluded to be >1000 mg a.i./kg dry soil. The NOEC for the mean bodyweight at Day 28 was 1000 mg a.i./kg dry soil.

Juvenile Worms dose response test
Water control and solvent group productivity was acceptable (mean of 298 and 287 juveniles respectively per replicate). The coefficient of variation of the number of juveniles in the solvent control group was 9.49% and in the water control 4.86%. The 29.4, 52.9, 171.5, 308.6, 555.6 and 1000 mg a.i./kg dry soil Test substance treated groups had significantly fewer juveniles than the solvent control group using the Dunnett’s statistical test. The 5 mg a.i./kg dry soil carbendazim treated group had significantly fewer juveniles than the water control group. The EC50 for the number of juveniles on Day 56 could not be estimated due to a lack of dose response. The NOEC for the number of juvenile worms on Day 56 could not be estimated due to the variability in the juvenile numbers.

Health and Mortality limit test
Adult mortality of 3.75% at Test substance treatment rate of 1000 mg a.i./kg dry soil was observed. Mortality of 0% was recorded in the water control, 2.5% in the solvent control and 7.5% mortality in the toxic reference group. The LC50 for the mortality on Day 28 could not be statistically estimated due to a lack of a dose response relationship. The No Observed Effect Concentration (NOEC) for adult mortality on Day 28 was 1000 mg a.i./kg dry soil.

Bodyweights limit test
The Test substance treatment group had lower body weights on Day 28 than the solvent control group. The solvent control group had lower bodyweights than the water control group. The 5 mg a.i./kg dry soil carbendazim treated group had lower body weights on Day 28 than the solvent control group. The EC50 for the mean body weight of the adult earthworms at Day 28 could not be statistically calculated as only one dose level was treated. As an effect in bodyweight was observed at 1000 mg a.i./kg dry soil the NOEC for mean bodyweight at Day 28 was <1000 mg a.i./kg dry soil.

Juvenile worms limit test
Water control and solvent group productivity was acceptable (mean of 237 and 259 juveniles respectively per replicate). The coefficient of variation of the number of juveniles in the solvent control group was 8.23% and in the water control 3.29%. No effect was observed on the number of juvenile worms for the Test substance treatment group in comparison to the solvent control. The water control group had fewer juveniles than the solvent control group. The 5 mg a.i./kg dry soil carbendazim treated group had no juveniles. The EC50 for the number of juveniles on Day 56 could not be estimated due only one dose level being treated. The NOEC for the number of juvenile worms on Day 56 was 1000 mg a.i./kg dry soil.

Please refer to the attached background material for tables.

Reported statistics and error estimates:

The Dunnett’s statistical test for weight changes, percent mortality and reproduction.

Conclusion

Dose response test

The LC50 for mortality on Day 28 could not be statistically estimated due to a lack of a dose response relationship. The No Observed Effect Concentration (NOEC) for adult mortality on Day 28 was 1000 mg a.i./kg dry soil. The LC50 for the mean body weight of the adult earthworms at Day 28 could not be estimated due to a lack of dose response. The NOEC for the mean bodyweight at Day 28 was 1000 mg a.i./kg dry soil. The EC50 for the number of juveniles on Day 56 could not be estimated due to a lack of dose response. The NOEC for the number of juvenile worms on Day 56 could not be estimated due to the variability in the juvenile numbers.

Limit test

The LC50 for mortality on Day 28 could not be statistically estimated due to a lack of a dose response relationship. The No Observed Effect Concentration (NOEC) for adult mortality on Day 28 was 1000 mg a.i./kg dry soil. The EC50 for the mean body weight of the adult earthworms at Day 28 could not be statistically calculated as only one dose level was treated. As an effect in bodyweight was observed at 1000 mg a.i./kg dry soil the NOEC for mean bodyweight at Day 28 was <1000 mg a.i./kg dry soil. The EC50 for the number of juveniles on Day 56 could not be statistically calculated as only one dose level was treated. The NOEC for the number of juvenile worms on Day 56 was 1000 mg a.i./kg dry soil. Both the definitive and the limit tests were considered valid as there was ≤ 10% adult mortality at four weeks and ≥30 juveniles had been produced in each water control and solvent control replicates by the end of the test with the coefficient of variation of reproduction ≤ 30%. In addition the application of carbendazim at 5 mg a.i./kg dry soil resulted in significant and unequivocal toxic effects (reduction in growth and reproduction) that were within the acceptable range for this toxic reference item.

Validity criteria fulfilled:

yes

Conclusions:

Under the study conditions, the NOEC of the test substance for mortality, body weight of the earthworm Eisenia fetida was determined to be 1000 mg a.i/kg dry soil and 1000 mg a.i/kg dry soil (highest tested concentration) respectively, whereas the NOEC for reproduction could not be estimated due to the variation in the juvenile numbers.

Executive summary:

A study was conducted to evaluate the chronic toxicity of the test substance, 'mono- and di- C16-18 PSE and C16-18 AE10 PSE' to adult Eisenia fetida using ISO earthworm soil (according to the OECD TG 222), in compliance with GLP. Four replicates of ten adult earthworms were exposed to the test substance 16.3, 29.4, 52.9, 95.3, 171.5, 308.6, 555.6, and 1000 mg a.i./kg dry soil for 56 days. The test substance was added to a solvent (acetone) which was then placed over dry soil and the acetone allowed to evaporate before being mixed into an appropriate amount of moist soil and sufficient water added to achieve the final test concentration at a water holding capacity of 50%. In addition, eight replicates of 10 earthworms each were used for the water control, solvent control, and toxic reference control carbendazim, applied at 5 mg a.i./kg dry soil. Assessment of adult worm mortality, body weight was carried out after 28-day exposure and the number of juvenile worms (reproduction rate) was assessed after 56 days of exposure. The adult mortality rate was recorded to range from 2.5 to 5% in the test substance treated groups, 1.25% in both water and solvent control groups, and 25% in the reference control groups. The body weight change of the earthworms after 28 days of exposure to test substance was not statistically significantly different compared to the control up to and including the highest test concentration of 1000 mg a.i./kg dry soil. The reproduction rate evaluated on the basis of the number of juveniles was found to be significantly fewer at concentrations ≥29.4 mg a.i./kg dry soil compared to the solvent control group. The study was considered valid as there was ≤10% adult mortality at four weeks and ≥30 juveniles had been produced in each solvent and water control replicate by the end of the test with the coefficient of variation of reproduction ≤ 30%. In addition, the application of the toxic reference carbendazim at 5 mg a.i./kg dry soil resulted in substantial toxic effects. be statistically estimated due to a lack of a dose-response relationship. Under the conditions of the study and due to a lack of a dose-response relationship, the EC50 values for mortality, effects on body weight and the number of juvenile worms could not be statistically estimated. However, the NOEC values for mortality and effects on body weight on Day 28 were determined to be 1000 and 1000 mg a.i./kg dry soil respectively. A NOEC for the number of juvenile worms on Day 56 could not be estimated due to the variability in the juvenile numbers (Covance, 2021).

Cross-reference 4

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Type of CSR:

Own CSR (own uses)

CSR contains:

Part A

Part B section 1 to 8

Part B section 9 and 10

Chemical safety assessment/report tool used:

Chesar