Trixylyl phosphate

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

other: Published data

Adequacy of study:

supporting study

Study period:

1985, unspecified

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Taken from publically available data. The study used shorter uptake durations than what is recommended for the OECD 305 method; however it is deemed suitable on a weight of evidence basis, as the results match other data available.

Qualifier:

no guideline available

Principles of method if other than guideline:

The bioconcentration of a commercial triaryl phosphate product in bleak (Alburnus alburnus) was investigated (Bengtsson et al. 1986). The product tested contained triphenyl phosphate, cresyl diphenyl phosphate (two main components), tricresyl phosphate (three main components) and trixylenyl phosphate (three main components). The tests were carried out using a flow-though system with natural brackish water (7‰ salinity) at 10°C. The experiment consisted of a 14-day uptake period where the fish were exposed to a nominal concentration of 50 μg/l of the triaryl phosphate product, followed by a 14-day depuration period in clean flowing water.

GLP compliance:

not specified

Specific details on test material used for the study:

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

Radiolabelling:

no

Details on sampling:

Samples of fish and water were taken on days 0, I, 2: 4, 7, 17, 18, 21 and 28. One sample of three fish was taken at each sampling except on days 14 and 28, i.e., at the end of the accumulation and elimination periods, when five samples of three fish were taken. The bleaks were killed and rinsed in 100 ml distilled water, each fish for 30 s, and wrapped in aluminium foil and kept frozen at -200c. until analysis. Water samples (450 ml) were Withdrawn on each sampling day and simultaneosly frozen in glass vessels until chemical analysis.

Vehicle:

no

Details on preparation of test solutions, spiked fish food or sediment:

Not specified.

Test organisms (species):

Alburnus alburnus

Details on test organisms:

On 4 March 1981, 1 week before the experiment was started, 53 bleaks were placed in one 70-liter, silicone sealed, glass aquarium (water volume 60
liters) With a continuous tlow of natural Baltic Sea water (salinity 7%). During this period the fish were successively acclimated to a test temperature
or 10 deg C. The fish (average weight 5 g) were fed twtce a day and once on Saturdays and Sundays dunng the course of the experiment; they were fed a 0.25 g portion of commercial food (Tetramin Hauptfiitter; Tetrawerke, F. R.G.). pH and dissolved oxygen levels were measured daily.

Route of exposure:

aqueous

Test type:

flow-through

Water / sediment media type:

natural water: brackish

Total exposure / uptake duration:

14 d

Total depuration duration:

14 d

Hardness:

Not specified

Test temperature:

10 deg C

pH:

7.6 to 7.9

Dissolved oxygen:

>90% throughout the experiment

TOC:

Not specified

Salinity:

7%

Details on test conditions:

Concentrations of product (ug/g) dry weight of product:
TXP Comp 1 TXP Comp 2 TXP Comp 3
Control Not determined Not determined Not determined
100 12 8 8
1000 242 134 120
3000 618 276 238
10,000 2251 1359 1474

Nominal and measured concentrations:

Product concentrations

Reference substance (positive control):

no

Details on estimation of bioconcentration:

To determine if steady state had been reached in the fish the AF values for the eight compounds were plotted against time

Key result

Type:

BAF

Value:

1 900 dimensionless

Basis:

not specified

Time of plateau:

14 d

Calculation basis:

other: non-steady state

Remarks on result:

other: Corresponds to component 10 of the mixture identified as TXP

Remarks:

Conc.in environment / dose:N/A

Key result

Type:

BAF

Value:

1 300 dimensionless

Basis:

not specified

Time of plateau:

14 d

Calculation basis:

other: non-steady state

Remarks on result:

other: Corresponds to component 16 of the mixture identified as TXP

Remarks:

Conc.in environment / dose:N/A

Key result

Type:

BAF

Value:

1 500 dimensionless

Basis:

not specified

Time of plateau:

14 d

Calculation basis:

other: non-steady state

Remarks on result:

other: Corresponds to component 20 of the mixture identified as TXP

Remarks:

Conc.in environment / dose:N/A

Details on kinetic parameters:

Not analysed

Metabolites:

Not analysed

Results with reference substance (positive control):

Not applicable.

Details on results:

Steady state was reached within the 14-day exposure period (steady state was actually attained within two days) for triphenyl phosphate, the cresyl diphenyl phosphate components and two of the tricresyl phosphate components of the mixture. Steady-state bioconcentration factors (BCFs) were determined as 400 l/kg, 100- 220 l/kg and 800 l/kg for these components respectively. For the other components, steady state was approached, but had not been reached by the end of the 14-day uptake period and the non-steady state BCFs estimated at 14 days were 400 l/kg for the remaining tricresyl phosphate component and 1,300-1,900 l/kg for the three trixylenyl phosphate components. All components were found to be rapidly eliminated from the fish, with a depuration half-life of four days or less. Triphenyl phosphate, cresyl diphenyl phosphate and tricresyl phosphate components were almost completely eliminated from the fish within 14 days but the trixylenyl phosphate components were still evident in the fish after 14 days at a concentration of 200 ug/kg wet weight.

Validity criteria fulfilled:

yes

Conclusions:

The study used shorter uptake durations than what is recommended for the OECD 305 method; however it is deemed suitable on a weight of evidence basis, as the results match other data available. Although uptake is demonstrated, subsequent elimination is ongoing of the substance from the organisms. In addition the BAF values are not indicative of bioaccumulation. The substance is therefore proposed to not be bioaccumulative on the basis that it does not meet the threshold values listed in the regulation.

Executive summary:

The study used shorter uptake durations than what is recommended for the OECD 305 method; however it is deemed suitable on a weight of evidence basis, as the results match other data available. Although uptake is demonstrated, subsequent elimination is ongoing of the substance from the organisms. In addition the BAF values are not indicative of bioaccumulation. The substance is therefore proposed to not be bioaccumulative on the basis that it does not meet the threshold values listed in the regulation.

Reference 2

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

other: Published data

Adequacy of study:

supporting study

Study period:

1985, unspecified

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Taken from publically available data. The study used shorter uptake durations than what is recommended for the OECD 305 method; however it is deemed suitable on a weight of evidence basis, as the results match other data available.

Qualifier:

no guideline available

Principles of method if other than guideline:

A long-term dietary accumulation study with a commercial triaryl phosphate product was carried out with minnows (Phoxinus phoxinus) (Bengtsson et al. 1986). The substance tested contained triphenyl phosphate, cresyl diphenyl phosphate (two main components), tricresyl phosphate (three main components) and trixylenyl phosphate (three main components). The test was carried out using a flow-through system with six groups of 30 fish (average body weight 1.9 g), each in 50 litres of natural brackish water (7‰ salinity). The test was started in January and was carried out for 163 days
(although the resulting concentrations in fish were determined after four months only) and the water temperature followed the natural seasonal fluctuations (3.6-4.5°C from January to April, 7°C by the end of April, 13°C by the end of May and 12.to 15°C from June until the end of the experiment).

GLP compliance:

not specified

Specific details on test material used for the study:

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

Radiolabelling:

no

Details on sampling:

At the end of the study

Vehicle:

no

Details on preparation of test solutions, spiked fish food or sediment:

Not specified.

Test organisms (species):

Phoxinus phoxinus

Details on test organisms:

Adult minnows (P. phoxinus) were caught by handnets in Tvaren Bay in November 1980. 1 week before the experiment was started, the minnowa were placed in 6 70-liter, silicone sealed, glass aquarium (water volume 50 liters) With a continuous flow of natural brackish water (salinity 7%) was maintained at 0.4 L/min. The fish (average weight 1.9 g) were fed twice a day and once on Saturdays and Sundays during the course of the experiment; they were fed a 0.25 g portion of commercial food (Tetramin Hauptfiitter; Tetrawerke, F. R.G.). pH and dissolved oxygen levels were measured daily.

Route of exposure:

aqueous

Test type:

flow-through

Water / sediment media type:

natural water: brackish

Total exposure / uptake duration:

120 d

Hardness:

Not specified

Test temperature:

3.6-4.5°C from January to April, 7°C by the end of April, 13°C by the end of May and 12.to 15°C from June until the end of the experiment

pH:

7.7 to 8.0

Dissolved oxygen:

>90% throughout the experiment

TOC:

Not specified

Salinity:

6.5 to 7.7%

Details on test conditions:

The test was carried out using a flow-through system with six groups of 30 fish (average body weight 1.9 g), each in 50 litres of natural brackish water (7‰ salinity). The test was started in January and was carried out for 163 days (although the resulting concentrations in fish were determined after four months only) and the water temperature followed the natural seasonal fluctuations (3.6-4.5°C from January to April, 7°C by the end of April, 13°C by the end of May and 12.to 15°C from June until the end of the experiment). The dissolved oxygen concentration in the test was always above 90 per cent of saturation and the pH of the water was 7.7 to 8.0.

Five concentrations of the test substance were used (100, 300, 1,000, 3,000 and 10,000 mg/kg food) and a control using uncontaminated food was run. The test used a commercial fish food which was spiked by adding the triaryl phosphate as a solution in acetone and evaporating off the solvent. The fish were given two 0.25 g portions of food per day.

Nominal and measured concentrations:

Five concentrations of the test substance were used (100, 300, 1,000, 3,000 and 10,000 mg/kg food) and a control using uncontaminated food was run

Reference substance (positive control):

no

Details on estimation of bioconcentration:

The accumulation was calculated as the ratio between measured dosing and uptake totals

Key result

Type:

BCF

Value:

0.05 other: % w/w from food

Basis:

not specified

Time of plateau:

120 d

Calculation basis:

steady state

Remarks on result:

other: Bioconcentration factors (BCF's) in minnows for triaryl phosphates identified during 4 months in the lowest concentration (100 ug/g) to food. Corresponds to component 10 of the mixture identified as TXP

Remarks:

Conc.in environment / dose:N/A

Key result

Type:

BCF

Value:

0.59 other: % w/w from food

Basis:

not specified

Time of plateau:

120 d

Calculation basis:

steady state

Remarks on result:

other: Bioconcentration factors (BCF's) in minnows for triaryl phosphates identified during 4 months in the lowest concentration (100 ug/g) to food. Corresponds to component 16 of the mixture identified as TXP

Remarks:

Conc.in environment / dose:N/A

Key result

Type:

BCF

Value:

0.51 other: % w/w from food

Basis:

not specified

Time of plateau:

120 d

Calculation basis:

steady state

Remarks on result:

other: Bioconcentration factors (BCF's) in minnows for triaryl phosphates identified during 4 months in the lowest concentration (100 ug/g) to food. Corresponds to component 20 of the mixture identified as TXP

Remarks:

Conc.in environment / dose:N/A

Details on kinetic parameters:

Not analysed

Metabolites:

Not analysed

Results with reference substance (positive control):

Not applicable.

Details on results:

No mortalities or abnormal behaviour were seen in any of the fish, and all food given to the fish was eaten. The concentrations of the various components in the fish after four months exposure are shown in Table 3.2 below. Overall, only around 0.017-0.14 per cent of the total amount of test substance fed to fish was found to be present in the fish at the end of the study. The bioaccumulation factors, based on the estimated concentration in fish and concentration in food, are all very much less than one.

Table 3.2 Concentrations in minnows after four months exposure to contaminated food

 

Food concentration	Total concentration in fish (mg/kg fresh weight)
	Cresyl diphenyl phosphate (sum of two components)	Tricresyl phosphate (sum of three components)	Trixylenyl phosphate (sum of three components)	Triphenyl phosphate
Control	0.005	Not detected	0.005	Not detected
100 mg/kg	0.030	0.023	0.053	0.094
300 mg/kg	0.020	0.016	0.085	0.47
1,000 mg/kg	0.225	0.019	0.225	0.896
3,000 mg/kg	0.12	0.016	0.88	2.01
10,000 mg/kg	0.73	0.043	1.39	2.05

Validity criteria fulfilled:

yes

Conclusions:

Only 0.017-0.14 per cent of the total amount of test substance fed to fish was found to be present in the fish at the end of the study. The bioaccumulation factors, based on the estimated concentration in fish and concentration in food, are all very much less than one. The substance is therefore proposed to not be bioaccumulative on the basis that it does not meet the threshold values listed in the regulation.

Executive summary:

Only 0.017-0.14 per cent of the total amount of test substance fed to fish was found to be present in the fish at the end of the study. The bioaccumulation factors, based on the estimated concentration in fish and concentration in food, are all very much less than one. The substance is therefore proposed to not be bioaccumulative on the basis that it does not meet the threshold values listed in the regulation.

Reference 3

Endpoint:

bioaccumulation: aquatic / sediment

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Study period:

September 2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Validated QSAR calculation method. A validated QPRF and QMRF is attached. The substance is recognised as part of the rulebase utilised by the CAESAR model data set, and is in model Applicability Domain. Further details can be found within the appended report below or at http://www.caesar-project.eu/software/qmrf/QMRF_BCF.zip.

Justification for type of information:

QSAR prediction

Qualifier:

according to guideline

Guideline:

other: QSAR prediction using BCF model (Meylan) (version 1.0.0) (CAESAR).

Deviations:

no

Principles of method if other than guideline:

To evaluate the applicability domain CAESAR used three approaches.

First approach: chemical descriptor space
The values for the training set of the eight descriptors in the combined model were used to define their ranges of validity. The CAESAR software gives a warning in this case.
Second approach: rules
A series of fragments, representing the compounds with greater uncertainty, were manually identified by searching among the structures with highest error (greater than 1 log unit) or misclassified (predicted nB when they are vB, or vice versa). These chemical features have been implemented in our model using short strings called SMARTS to define fragments. In addition, in this case the system gives the user a warning. SMARTS allows to specify substructures that are straightforward extensions of SMILES. Thus, flexible and efficient substructure-search specifications can be made in a way that is meaningful to chemists.
Two free programs have been used to do that: MarvinSketch [MarvinSketch, Calculator Plugin and Chemical Terms Demo [http://www.chemaxon.com/ marvin/sketch/index.jsp]] and Daylight Depict SMARTS Match [Daylight Depict SMARTS Match [http://www.daylight.com/daycgi_tutorials/depictmatch.cgi]]. The first is an advanced, Java-based chemical editor for drawing chemical structures, queries and reactions. We used it to draw 11 SMARTS fragments. To check the match between SMARTS and the actual sub-structure of interest, the Daylight Depict SMARTS Match was used, a web application based on Java code. In this program the structure, depicted by a SMILES, is checked to find the fragment represented by the SMARTS.
Third approach: similarity tool
On the basis of several Dragon descriptors encoding different bi-dimensional characteristics of the molecules, a similarity index was developed to retrieve similar compounds from the CAESAR dataset, directly linked to the CAESAR models. More details of these tools are given in the paper on developmental toxicity [Cassano A, Manganaro A, Martin T, Young Y, Piclin N, Pintore M, Bigoni D, Benfenati E: The CAESAR models for developmental toxicity. Chemistry Central Journal 2010, 4(Suppl 1):S4.], in this issue.

GLP compliance:

no

Specific details on test material used for the study:

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

Radiolabelling:

no

Details on sampling:

Not applicable - QSAR

Vehicle:

no

Details on preparation of test solutions, spiked fish food or sediment:

Not applicable - QSAR

Test organisms (species):

other: Not applicable - QSAR

Details on test organisms:

Not applicable - QSAR

Route of exposure:

other: Not applicable - QSAR

Test type:

other: Not applicable - QSAR

Water / sediment media type:

not specified

Hardness:

Not applicable - QSAR

Test temperature:

Not applicable - QSAR

pH:

Not applicable - QSAR

Dissolved oxygen:

Not applicable - QSAR

TOC:

Not applicable - QSAR

Salinity:

Not applicable - QSAR

Details on test conditions:

Not applicable - QSAR

Nominal and measured concentrations:

Not applicable - QSAR

Details on estimation of bioconcentration:

Please refer to QPRF and QMRF attachments below

Key result

Type:

BCF

Value:

669.24 L/kg

Basis:

other: QSAR

Calculation basis:

other: QSAR (geometric mean)

Remarks on result:

other: log(L/kg) 2.83

Remarks:

Conc.in environment / dose:Not applicable.

Details on kinetic parameters:

Not applicable - QSAR

Metabolites:

Not applicable - QSAR

Results with reference substance (positive control):

Not applicable - QSAR

Details on results:

Model assessment: Prediction is logBCF = 2.62, the result appears reliable. Similar molecules found in the training set have experimental values that slightly disagree with the target compound predicted value, however, the predicted substance could be out of the Applicability Domain of the model.

Global AD Index
AD Index = 0.7
Explanation: predicted substance could be out of the Applicability Domain of the model.
Similar molecules with known experimental value
Similarity index = 0.949
Explanation: strongly similar compounds with known experimental value in the training set have been found.
Accuracy (average error) of prediction for similar molecules
Accuracy index = 0.17
Explanation: accuracy of prediction for similar molecules found in the training set is good.
Concordance with similar molecules (average difference between target compound prediction and
experimental values of similar molecules)
Concordance index = 0.195
Explanation: similar molecules found in the training set have experimental values that agree with the target
compound predicted value.
Maximum error of prediction among similar molecules
Max error index = 0.21
Explanation: the maximum error in prediction of similar molecules found in the training set has a low value,
considering the experimental variability.
Reliability of logP prediction
LogP reliability = 0.7
Explanation: reliability of logP value used by the model is not optimal.
Model descriptors range check
Descriptors range check = true
Explanation: descriptors for this compound have values inside the descriptor range of the compounds of the
training set.

Validity criteria fulfilled:

yes

Conclusions:

The model is considered to be appropriate for assessment. Strongly similar compounds with known experimental value in the training set were found.
The accuracy of prediction for similar molecules found in the training set is good. The model is considered suitable for use in the context of a weight of evidence approach. 50 isomers were assessed, with similar results observed.

Executive summary:

The model is considered to be appropriate for assessment. Strongly similar compounds with known experimental value in the training set were found.

The accuracy of prediction for similar molecules found in the training set is moderate. The model is considered suitable for use in the context of a weight of evidence approach. 60 isomers were assessed, with similar results observed.

The substance is not considered to be bioaccumulative or very bioaccumulative on the basis of the results observed.

Reference 4

Endpoint:

bioaccumulation: aquatic / sediment

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Study period:

September 2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Validated QSAR calculation method. A validated QPRF and QMRF is attached. The substance is recognised as part of the rulebase utilised by the CAESAR model data set, and is in model Applicability Domain. Further details can be found within the appended report below or at http://www.caesar-project.eu/software/qmrf/QMRF_BCF.zip.

Justification for type of information:

QSAR prediction

Qualifier:

according to guideline

Guideline:

other: QSAR prediction using BCF Read-Across (version 1.0.0) (CAESAR).

Deviations:

no

Principles of method if other than guideline:

To evaluate the applicability domain CAESAR used three approaches.

First approach: chemical descriptor space
The values for the training set of the eight descriptors in the combined model were used to define their ranges of validity. The CAESAR software gives a warning in this case.
Second approach: rules
A series of fragments, representing the compounds with greater uncertainty, were manually identified by searching among the structures with highest error (greater than 1 log unit) or misclassified (predicted nB when they are vB, or vice versa). These chemical features have been implemented in our model using short strings called SMARTS to define fragments. In addition, in this case the system gives the user a warning. SMARTS allows to specify substructures that are straightforward extensions of SMILES. Thus, flexible and efficient substructure-search specifications can be made in a way that is meaningful to chemists.
Two free programs have been used to do that: MarvinSketch [MarvinSketch, Calculator Plugin and Chemical Terms Demo [http://www.chemaxon.com/ marvin/sketch/index.jsp]] and Daylight Depict SMARTS Match [Daylight Depict SMARTS Match [http://www.daylight.com/daycgi_tutorials/depictmatch.cgi]]. The first is an advanced, Java-based chemical editor for drawing chemical structures, queries and reactions. We used it to draw 11 SMARTS fragments. To check the match between SMARTS and the actual sub-structure of interest, the Daylight Depict SMARTS Match was used, a web application based on Java code. In this program the structure, depicted by a SMILES, is checked to find the fragment represented by the SMARTS.
Third approach: similarity tool
On the basis of several Dragon descriptors encoding different bi-dimensional characteristics of the molecules, a similarity index was developed to retrieve similar compounds from the CAESAR dataset, directly linked to the CAESAR models. More details of these tools are given in the paper on developmental toxicity [Cassano A, Manganaro A, Martin T, Young Y, Piclin N, Pintore M, Bigoni D, Benfenati E: The CAESAR models for developmental toxicity. Chemistry Central Journal 2010, 4(Suppl 1):S4.], in this issue.

GLP compliance:

no

Specific details on test material used for the study:

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

Radiolabelling:

no

Details on sampling:

Not applicable - QSAR

Vehicle:

no

Details on preparation of test solutions, spiked fish food or sediment:

Not applicable - QSAR

Test organisms (species):

other: Not applicable - QSAR

Details on test organisms:

Not applicable - QSAR

Route of exposure:

other: Not applicable - QSAR

Test type:

other: Not applicable - QSAR

Water / sediment media type:

not specified

Hardness:

Not applicable - QSAR

Test temperature:

Not applicable - QSAR

pH:

Not applicable - QSAR

Dissolved oxygen:

Not applicable - QSAR

TOC:

Not applicable - QSAR

Salinity:

Not applicable - QSAR

Details on test conditions:

Not applicable - QSAR

Nominal and measured concentrations:

Not applicable - QSAR

Details on estimation of bioconcentration:

Please refer to QPRF and QMRF attachments below

Key result

Type:

BCF

Value:

>= 118 - <= 126 L/kg

Basis:

other: QSAR

Calculation basis:

other: QSAR (geometric mean)

Remarks on result:

other: log(L/kg) 2.07-2.1

Remarks:

Conc.in environment / dose:Not applicable.

Details on kinetic parameters:

Not applicable - QSAR

Metabolites:

Not applicable - QSAR

Results with reference substance (positive control):

Not applicable - QSAR

Details on results:

Model assessment: Prediction is logBCF = 2.07-2.1, the result appears reliable. Similar molecules found in the training set have experimental values that slightly disagree with the target compound predicted value, however, the predicted substance could be out of the Applicability Domain of the model.

Global AD Index
AD Index = 0.836
Explanation: read-across seems to be reliable.
Highest similarity found for similar compounds
Highest similarity = 0.869
Explanation: the highest similarity value found for similar compounds is adequate for a reliable read-across.
Lowest similarity found for similar compounds
Lowest similarity = 0.776
Explanation: the lowest similarity value found for similar compounds is adequate for a reliable read-across.

Validity criteria fulfilled:

yes

Conclusions:

The model is considered to be appropriate for assessment. Strongly similar compounds with known experimental value in the training set were found.
The accuracy of prediction for similar molecules found in the training set is good. The model is considered suitable for use in the context of a weight of evidence approach. 50 isomers were assessed, with similar results observed.

Executive summary:

The model is considered to be appropriate for assessment. Strongly similar compounds with known experimental value in the training set were found.

The accuracy of prediction for similar molecules found in the training set is moderate. The model is considered suitable for use in the context of a weight of evidence approach. 60 isomers were assessed, with similar results observed.

The substance is not considered to be bioaccumulative or very bioaccumulative on the basis of the results observed.

Reference 5

Endpoint:

bioaccumulation: aquatic / sediment

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Study period:

September 2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Validated QSAR calculation method. A validated QPRF and QMRF is attached. The substance is recognised as part of the rulebase utilised by the CAESAR model data set, and is in model Applicability Domain. Further details can be found within the appended report below or at http://www.caesar-project.eu/software/qmrf/QMRF_BCF.zip.

Justification for type of information:

QSAR prediction

Qualifier:

according to guideline

Guideline:

other: QSAR prediction using BCF model (CAESAR) (version 2.1.11)

Deviations:

no

Principles of method if other than guideline:

To evaluate the applicability domain CAESAR used three approaches.

First approach: chemical descriptor space
The values for the training set of the eight descriptors in the combined model were used to define their ranges of validity. The CAESAR software gives a warning in this case.
Second approach: rules
A series of fragments, representing the compounds with greater uncertainty, were manually identified by searching among the structures with highest error (greater than 1 log unit) or misclassified (predicted nB when they are vB, or vice versa). These chemical features have been implemented in our model using short strings called SMARTS to define fragments. In addition, in this case the system gives the user a warning. SMARTS allows to specify substructures that are straightforward extensions of SMILES. Thus, flexible and efficient substructure-search specifications can be made in a way that is meaningful to chemists.
Two free programs have been used to do that: MarvinSketch [MarvinSketch, Calculator Plugin and Chemical Terms Demo [http://www.chemaxon.com/ marvin/sketch/index.jsp]] and Daylight Depict SMARTS Match [Daylight Depict SMARTS Match [http://www.daylight.com/daycgi_tutorials/depictmatch.cgi]]. The first is an advanced, Java-based chemical editor for drawing chemical structures, queries and reactions. We used it to draw 11 SMARTS fragments. To check the match between SMARTS and the actual sub-structure of interest, the Daylight Depict SMARTS Match was used, a web application based on Java code. In this program the structure, depicted by a SMILES, is checked to find the fragment represented by the SMARTS.
Third approach: similarity tool
On the basis of several Dragon descriptors encoding different bi-dimensional characteristics of the molecules, a similarity index was developed to retrieve similar compounds from the CAESAR dataset, directly linked to the CAESAR models. More details of these tools are given in the paper on developmental toxicity [Cassano A, Manganaro A, Martin T, Young Y, Piclin N, Pintore M, Bigoni D, Benfenati E: The CAESAR models for developmental toxicity. Chemistry Central Journal 2010, 4(Suppl 1):S4.], in this issue.

GLP compliance:

no

Specific details on test material used for the study:

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

Radiolabelling:

no

Details on sampling:

Not applicable - QSAR

Vehicle:

no

Details on preparation of test solutions, spiked fish food or sediment:

Not applicable - QSAR

Test organisms (species):

other: Not applicable - QSAR

Details on test organisms:

Not applicable - QSAR

Route of exposure:

other: Not applicable - QSAR

Test type:

other: Not applicable - QSAR

Water / sediment media type:

not specified

Hardness:

Not applicable - QSAR

Test temperature:

Not applicable - QSAR

pH:

Not applicable - QSAR

Dissolved oxygen:

Not applicable - QSAR

TOC:

Not applicable - QSAR

Salinity:

Not applicable - QSAR

Details on test conditions:

Not applicable - QSAR

Nominal and measured concentrations:

Not applicable - QSAR

Details on estimation of bioconcentration:

Please refer to QPRF and QMRF attachments below

Key result

Type:

BCF

Value:

36 L/kg

Basis:

other: QSAR

Calculation basis:

other: QSAR (geometric mean)

Remarks on result:

other: log(L/kg) 1.56

Remarks:

Conc.in environment / dose:Not applicable.

Details on kinetic parameters:

Not applicable - QSAR

Metabolites:

Not applicable - QSAR

Results with reference substance (positive control):

Not applicable - QSAR

Details on results:

Model assessment: Prediction is logBCF = 1.56, the result appears
reliable. Similar molecules found in the training set have experimental values that slightly disagree with the target compound predicted value.
The maximum error in prediction of similar molecules found in the training set has a moderate value, considering the experimental variability
The following relevant fragments were found: PO2 residue (SR 03)

Global AD Index
AD Index = 0.85
Explanation: predicted substance is into the Applicability Domain of the model.
Similar molecules with known experimental value
Similarity index = 0.788
Explanation: strongly similar compounds with known experimental value in the training set have been found.

Accuracy (average error) of prediction for similar molecules
Accuracy index = 0.38
Explanation: accuracy of prediction for similar molecules found in the training set is good.

Concordance with similar molecules (average difference between target compound prediction and experimental values of similar molecules)
Concordance index = 0.495
Explanation: similar molecules found in the training set have experimental values that slightly disagree with the target compound predicted value.

Maximum error of prediction among similar molecules
Max error index = 0.55
Explanation: the maximum error in prediction of similar molecules found in the training set has a moderate value, considering the experimental variability.

Atom Centered Fragments similarity check
ACF matching index = 1
Explanation: all atom centered fragment of the compound have been found in the compounds of the training set.

Descriptors noise sensitivity analysis
Noise Sensitivity = 0.975
Explanation: predictions has a good response to noise scrambling, thus shows a good reliability.

Model descriptors range check
Descriptors range check = true
Explanation: descriptors for this compound have values inside the descriptor range of the compounds of the training set.

The full report is appended below.

Validity criteria fulfilled:

yes

Conclusions:

The model is considered to be appropriate for assessment. Strongly similar compounds with known experimental value in the training set were found.
The accuracy of prediction for similar molecules found in the training set is good. The model is considered suitable for use in the context of a weight of evidence approach. 50 isomers were assessed, with similar results observed.

Executive summary:

The model is considered to be appropriate for assessment. Strongly similar compounds with known experimental value in the training set were found.

The accuracy of prediction for similar molecules found in the training set is good. The model is considered suitable for use in the context of a weight of evidence approach. 60 isomers were assessed, with similar results observed.

The substance is not considered to be bioaccumulative or very bioaccumulative on the basis of the results observed.

Reference 6

Endpoint:

bioaccumulation: aquatic / sediment

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Study period:

September 2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Validated QSAR calculation method. A validated QPRF is attached. The substance is recognised as part of the rulebase utilised by the EPI Suite model data set, and is in model Applicability Domain. Further details can be found within the appended report below or at http://www.epa.gov/oppt/exposure/pubs/episuite.htm. This system is recognised in ECHA Guidance document CHAPTER R.6 – QSARS AND GROUPING OF CHEMICALS, ref R.6.1.4.3 Use of (Q)SARs for PBT (vPvB) assessment

Justification for type of information:

QSAR prediction

Qualifier:

according to guideline

Guideline:

other: QSAR prediction using US EPA On-Line EPI Suite™ v4.0 model BCFBAF.

Deviations:

no

Principles of method if other than guideline:

The BCFBAF method classifies a compound as either ionic or non-ionic. Ionic compounds include carboxylic acids, sulfonic acids and salts of sulfonic acids, and charged nitrogen compounds (nitrogen with a +5 valence such as quaternary ammonium compounds). All other compounds are classified as non-ionic.

GLP compliance:

no

Specific details on test material used for the study:

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

Radiolabelling:

no

Details on sampling:

Not applicable - QSAR

Vehicle:

no

Details on preparation of test solutions, spiked fish food or sediment:

Not applicable - QSAR

Test organisms (species):

other: Not applicable - QSAR

Details on test organisms:

Not applicable - QSAR

Route of exposure:

other: Not applicable - QSAR

Test type:

other: Not applicable - QSAR

Water / sediment media type:

not specified

Hardness:

Not applicable - QSAR

Test temperature:

Not applicable - QSAR

pH:

Not applicable - QSAR

Dissolved oxygen:

Not applicable - QSAR

TOC:

Not applicable - QSAR

Salinity:

Not applicable - QSAR

Details on test conditions:

Not applicable - QSAR

Nominal and measured concentrations:

Not applicable - QSAR

Details on estimation of bioconcentration:

Please refer to QPRF and QMRF attachments below

Key result

Type:

BCF

Value:

669.09 L/kg

Basis:

other: QSAR

Calculation basis:

other: QSAR (geometric mean)

Remarks on result:

other: Estimated Log BCF = 2.817

Remarks:

Conc.in environment / dose:Not applicable.

Details on kinetic parameters:

Not applicable - QSAR

Metabolites:

Not applicable - QSAR

Results with reference substance (positive control):

Not applicable - QSAR

Details on results:

Model assessment: Prediction is logBCF = Estimated Log BCF = 2.817, the result appears reliable. Similar molecules found in the training set have experimental values that agree with the target compound predicted value.

Validity criteria fulfilled:

yes

Conclusions:

The model is considered to be appropriate for assessment. Strongly similar compounds with known experimental value in the training set were found.
The accuracy of prediction for similar molecules found in the training set is good. The model is considered suitable for use in the context of a weight of evidence approach. 50 isomers were assessed, with similar results observed.

Executive summary:

The model is considered to be appropriate for assessment. Strongly similar compounds with known experimental value in the training set were found.

The accuracy of prediction for similar molecules found in the training set is good. The model is considered suitable for use in the context of a weight of evidence approach. 60 isomers were assessed, with similar results observed.

The substance is not considered to be bioaccumulative or very bioaccumulative on the basis of the results observed.

Reference 7

Endpoint:

bioaccumulation in aquatic species, other

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1990

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Taken from publically available data published by the World Health Organisation, and is considered accurate based on experience of the effects of the phosphates as a group. This study is read across to Tricresyl phosphate, CAS 1330-78-5 EC 215-548-8 . Justification is provided below.

Qualifier:

no guideline available

Principles of method if other than guideline:

No method available. The results are summarised from papers of 3 different authors as follows:

Muir et al (1983)
Veith et al (1979)
Sitthichaikasem (1978)

Environmental Health Criteria
The World Health Organisation (WHO) is the directing and coordinating authority for health within the United Nations system. It is responsible for providing leadership on global health matters, shaping the health research agenda, setting norms and standards, articulating evidence-based policy options, providing technical support to countries and monitoring and assessing health trends.
The WHO prepares Environmental Health Criteria (EHC) documents provide international, critical reviews on the effects of chemicals or combinations of chemicals and physical and biological agents on human health and the environment.
Each EHC follows a standard outline or format giving a summary of the whole document followed by information on identity, sources of exposure, environmental transport, distribution and transformation, environmental levels and human exposure, kinetics and metabolism in laboratory animals and humans, effects on laboratory animals and in vitro test systems. Effects on humans; effects on other organisms in the laboratory and field. An overall evaluation and conclusions for the protection of human health and the environment is found at the end of each document together with needs for further research and details of previous evaluations by international bodies e.g. IARC, JEFCA.
Two different series of Environmental Health Criteria (EHC) documents are available: (1) on specific chemicals or groups of related chemicals; and (2) on risk assessment methodologies. Both are accessible from the numerical listing below. In addition the EHCs on risk assessment methodologies are accessible from the listing of all IPCS methodology publications and projects.
The definitive list is available at:
http://www.who.int/ipcs/publications/ehc/en/
Review of this list has highlighted that the analogue, Tricresyl Phosphate is listed as a substance that has been subjected to an EHC. This is referenced at:
No. 110 - Tricresyl phosphate (1990)
http://www.inchem.org/documents/ehc/ehc/ehc110.htm

GLP compliance:

no

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
PHYSICO-CHEMICAL PROPERTIES
- Melting point: < -20 °C
- Boiling point: > 400 °C
- Vapour pressure: 0.28 KPa at 20 °C
- Water solubility (under test conditions): 0.271 mg/L
- Henry's law constant: Not calculated
- log Pow: 5.93
- pKa: Not measureable
- Stability in water: Not calculated
- Stability in light: Not calculated
- pH dependance on stability: Not calculated
OTHER PROPERTIES (if relevant for this endpoint)
- Results of test for ready biodegradability: mean of 24.2 % after 28 days. Not readily biodegradable.

Radiolabelling:

no

Details on sampling:

None - published data

Vehicle:

not specified

Details on preparation of test solutions, spiked fish food or sediment:

None - published data

Test organisms (species):

other: Rainbow trout (salmo gairdneri); Fathead minnows (pimephales promelas); Bluegill (Leptomis macrochirus)

Details on test organisms:

None - published data

Route of exposure:

aqueous

Test type:

other: Static and flow through

Water / sediment media type:

natural water: freshwater

Hardness:

None - published data

Test temperature:

None - published data

pH:

None - published data

Dissolved oxygen:

None - published data

TOC:

None - published data

Salinity:

None - published data

Nominal and measured concentrations:

See summary tables below

Reference substance (positive control):

not specified

Details on estimation of bioconcentration:

Data on the bioconcentration and depuration of TCP are given in Table 7. None of the exposures were considered to be representative of realistic environmental levels. Moreover the bioconcentration factor (BCF) measured in the laboratory must be considered as a bioaccumulation poten-
tial rather than an absolute bioaccumulation factor (Veith et al., 1979).

Several equations have been used in attempts to predict the BCF of organic chemicals in various fish strains using the octanol-water partition coefficient (Pow) or water solubility values (Neely et al., 1974; Lu & Metcalf, 1975; Kanazawa, 1978; Veith et al., 1979; Sasaki et al., 1982).

Key result

Type:

BCF

Value:

776 L/kg

Basis:

other: Read-across to structural analogues

Calculation basis:

other: Not specified

Remarks on result:

other: Read-across to structural analogues

Details on kinetic parameters:

See summary tables below

Metabolites:

See summary tables below

Results with reference substance (positive control):

See summary tables below

Details on results:

See summary tables below

Reported statistics:

See summary tables below

Summary of results for Read Across Data to Tricresyl Phosphate.

Species	Compound	Flow/Stat (temp)	Analytical method	BCF (K1/K2)	Exposure concentration (mg/l)	Uptake Rate (K1 h-1)	Clearance rate (K2 x 103 h-1)	Depuration rate half life (hour)	Reference
Rainbow trout (salmo gairdneri)	para isomer	Stat (10°C)	total radioactivity	2768 ± 641	0.005-0.05		9.6 - 13.3	72.2	Muir et al (1983)
			total radioactivity	1420 ± 42		14.0
			total radioactivity	1466 ± 138		17.0
			hexane-extractable radioactivity	770 ± 24				65.4
	meta isomer		total radioactivity	1162 ± 313			11.5 - 24.2	30.3
			total radioactivity	784 ± 82		18.5
			total radioactivity	1102 ± 137		21.2
			hexane-extractable radioactivity	310 ± 52				25.8
Fathead minnows (pimephales promelas)	para isomer	Stat (10°C)	total radioactivity	2199 ± 227	0.005-0.05		7.0 - 9.6	90	Muir et al (1983)
			total radioactivity	928 ± 78		4.9
			total radioactivity	588 ± 129		9.6
			hexane-extractable radioactivity	709 ± 76				73.7
	meta isomer		total radioactivity	1653 ± 232			8.5-14.7	59.2
			total radioactivity	596 ± 103		7.9
			total radioactivity	385 ± 92		8.7
			hexane-extractable radioactivity	62 ± 3				53.3
	Commercial TCP	Flow (25°C)	GC-FPD	165	0.0316				Veith et al (1979)
Bluegill (Leptomis macrochirus)	para isomer		total radioactivity	1589					Sitthichaikasem (1978)

Validity criteria fulfilled:

yes

Conclusions:

This study is read across to Tricresyl phosphate, CAS 1330-78-5 EC 215-548-8 . Justification is provided above. The clearance of tri- m-cresyl phosphate has been shown to be biphasic, with higher rates of clearance in the first 6 days after transfer to clean water, especially for rainbow trout. The clearance rate constants for rainbow trout were about 50% more than those for fathead minnows (Muir et al., 1983).
The data is proposed to be acceptable in the context of a weight of evidence approach as:
1) The parameters noted measure well against calculated and known values for the substance.
2) The values are comparable across the tests conducted

As a weight of evidence approach, it is considered that the analogous substance, tricresyl phosphate does not demonstrate a propensity towards bioaccumulation, based on the measured values within the studies. As such, it is considered that on structural grounds, the same conclusion can be applied to trixylyl phosphate.

Executive summary:

This study is read across to Tricresyl phosphate, CAS 1330-78-5 EC 215-548-8 . Justification is provided above. The clearance of tri- m-cresyl phosphate has been shown to be biphasic, with higher rates of clearance in the first 6 days after transfer to clean water, especially for rainbow trout. The clearance rate constants for rainbow trout were about 50% more than those for fathead minnows (Muir et al., 1983).

The data is proposed to be acceptable in the context of a weight of evidence approach as:

1) The parameters noted measure well against calculated and known values for the substance.

2) The values are comparable across the tests conducted

As a weight of evidence approach, it is considered that the analogous substance, tricresyl phosphate does not demonstrate a propensity towards bioaccumulation, based on the measured values within the studies. As such, it is considered that on structural grounds, the same conclusion can be applied to trixylyl phosphate.

Reference 8

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

January 21 to March 3, 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study performed in accordance with OECD and US EPA test guidelines in compliance with GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 305 (Bioconcentration: Flow-through Fish Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1730 (Fish Bioconcentration Test)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
None specified

Radiolabelling:

no

Details on sampling:

Collection of Water Samples
Water samples were collected from the solvent control and each of the 3.5 and 35 μg/L treatment groups, 5 and 2 days prior to the start of the exposure period to confirm the concentrations after conditioning the diluter system. In the solvent control and both treatment groups, water samples were collected on days 0 (hours 0 and 4), 1, 3, 7, 14, and 21 of the uptake phase, and days 1, 3, 5, and 7 of the depuration phase for the analysis of Reofos 35. On each sampling day, one water sample was analyzed from the control test chamber and two from each treatment group test chambers. All water samples were collected in 20-mL preconditioned glass LSC vials from mid-depth in the test chamber using a glass volumetric pipette.
Water samples were processed immediately for analysis. In addition, two 1 L water samples were collected after steady state was confirmed. These samples were collected on Day 23 of the uptake phase from the control and both treatment groups. Water samples were then stored frozen for possible analysis of metabolites.

Collection of Tissue Samples
Tissue samples were collected from the solvent control and both treatment groups on uptake days 0 (hour 4), 1, 3, 7, 14 and 21 and on depuration days 1, 3, 5 and 7. At each tissue sampling interval, a sufficient number of fish were collected to provide at least four replicate samples of solvent control fish and four replicate samples from each Reofos 35 treatment group. Fish were impartially removed from the test chambers, rinsed with dilution water, blotted dry and euthanized by making an incision from just posterior to the base of the pectoral fin dorsally through the spinal cord. The fish were measured for total length and wet weight within approximately 15 minutes of collection. Each fish was then dissected and divided into edible tissues and non-edible tissues. The head, fins and viscera were removed from the body and were considered to be non-edible tissue. The remaining tissue was considered the edible tissue. Edible and non-edible tissue samples were transferred to pre-weighed glass vials and weighed. All tissue samples were processed immediately or stored frozen.

Lipid Sampling
Twenty-seven additional fish were collected from the control and each treatment group to determine lipid content (nine from the control and each treatment group). Of these fish sampled, two fish were analyzed for lipid content from the control and each treatment group on day 0 of the uptake phase, one fish was analyzed for lipid content from the control and each treatment group on Day 23 of uptake and Day 10 of depuration and the remaining were held as back-ups. Fish for lipid analysis were sampled on Day 0 of uptake, after confirmation of steady state (Day 23 uptake) and at the end of depuration (Day 10 depuration). All fish collected for lipid content were stored frozen until analysis.

Vehicle:

yes

Details on preparation of test solutions, spiked fish food or sediment:

A primary stock solution of Reofos 35 was prepared by mixing a calculated amount (0.1610 g) of test substance into HPLC-grade DMF (460 mL) at a nominal concentration of 0.35 mg/mL. The primary stock was prepared four times throughout the study. The primary stock solutions were mixed by inversion and were clear and colorless with no visible precipitates. One secondary stock solution (410 mL) was prepared in DMF at a nominal concentration of 0.035 mg/mL by proportional dilution of the primary stock. The secondary stock solution was mixed by inversion and appeared clear and colorless with no visible precipitates.
Stock solutions were stored refrigerated in glass amber bottles, and aliquots of each stock were placed in the syringe daily during the uptake phase of the study. The stocks were pumped into the diluter mixing chambers assigned to the treatment groups at a target rate of 35.0 μL/min and were mixed with well water in the mixing chambers, delivered at a target rate of 350 mL/min, to achieve the nominal test concentrations of 3.5 and 35 μg/L. The solvent control was prepared by delivering DMF to the mixing chamber for the solvent control. The concentration of DMF in the solvent control and all treatment groups was 0.1 mL/L. Dilution water was delivered at a target rate of 197 mL/min during the depuration phase. Flows to the test system were initiated 9 days prior to initiation of the uptake phase. The test solutions in the mixing chambers and test chambers appeared clear and colorless during both the uptake and depuration phases, with no evidence of precipitation observed in any control or treatment solution.

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

The bluegill, (Lepomis macrochirus), was selected as the test species for this study. This species is representative of an important group of aquatic vertebrates and was selected for use in the test based upon past history of use in the laboratory. It is also a recommended test species in the cited test guidelines for performing fish bioaccumulation studies. Bluegill used in the test were obtained from Osage Catfisheries, Inc., Osage Beach, Missouri and hatched on May 12, 2014 (fish were approximately 8 months old at test initiation). Identification of the species was verified by the supplier. The recommended length for fish used in the study was 5.0 ± 2.0 cm. The average length and weight of fish sampled on Day 0 of the uptake phase was 4.8 ± 0.40 cm (4.2 – 5.6 cm) and 1.42 ± 0.352 g (0.93 – 2.10 g), respectively.
The fish were held for at least 14 days prior to the test in water from the same source and at approximately the same temperature as used during the test. During the 2-week period immediately preceding the test, water temperatures ranged from 21.1 to 22.6°C, measured with a hand-held liquid-in-glass thermometer. The pH of the water ranged from 8.3 to 8.6, measured with a Thermo Orion Benchtop 4 Star Plus pH/ISE meter. Dissolved oxygen ranged from 8.3 to 8.7 mg/L (96% of saturation), measured with a Thermo Orion Benchtop 3 Star Plus dissolved oxygen meter. All fish in the culture during this time appeared normal. At test initiation, the bluegill were collected from the holding tanks and impartially distributed one to three at a time to the test chambers until the solvent control and each treatment level test chamber contained 80 fish.

Loading
Biomass loading rates were calculated using the wet weights of the fish collected on Day 0 since this was considered to be representative of the biomass in test chambers during the test. All fish used in the test were from the same source and year class. Loading was defined as the total wet weight of fish per liter of test water that passed through the test chamber in 24 hours, and was determined to be 0.23 g fish/L/day. Instantaneous loading (the total wet weight of fish per liter of water in the tank) was 1.4 g fish/L.

Feeding
During the holding period and the test, fish were fed at least once daily a commercially-prepared diet of Sera Vipan supplied by Sera, North America of Montgomeryville, Pennsylvania. The fish were not fed on the last day of the test so that the gut contents could be purged. Uneaten food and faeces were siphoned daily from the test chambers shortly after feeding.
The diet was fed at a rate of 2% of fish body weight. To ensure that the feeding rate per fish remained constant, the amount of food supplied to each test chamber was adjusted at least weekly based on weight of the fish. Specifications for acceptable levels of contaminants in fish diets has not been established. However, there were no known levels of contaminants reasonably expected to be present in the diet that were considered to interfere with the purpose or conduct of the test.

Dilution water
The water used for holding and testing was freshwater obtained from a well approximately 40 meters deep located on the Wildlife International site. The well water is characterized as moderately-hard water. The well water was passed through a sand filter to remove particles greater than approximately 25 um, and pumped into a 37,800-L storage tank and aerated with spray nozzles. Prior to use, the water was filtered to 0.45 um to remove fine particles and was passed through an ultraviolet (UV) sterilizer. The results of periodic analyses performed to measure the concentrations of selected contaminants in well water used by Wildlife International are presented in Appendix 4 of the report and are considered appropriate.The specific conductance, hardness, alkalinity, pH and total organic carbon (TOC) of the well water during the four-week period immediately preceding the test are presented in Appendix 5, and are considered appropriate.

Route of exposure:

aqueous

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

23 d

Total depuration duration:

10 d

Hardness:

Hardness (mg/L as CaCO3)
141 (Mean) (N = 4)
136 – 144 (Range)

Test temperature:

Uptake: 21.4 – 21.8°C
Depuration: 21.4 – 22.0°C

pH:

8.0 (Mean) (N = 4)
8.0 – 8.0 (Range)

Dissolved oxygen:

Uptake Phase (mg/L) (A dissolved oxygen concentration of 5.2 mg/L represents 60% saturation in freshwater at 22°C.)
6.6 – 8.7 mg/L

Depuration Phase (mg/L) (A dissolved oxygen concentration of 5.2 mg/L represents 60% saturation in freshwater at 22°C.)
8.6 – 8.7 mg/L

TOC:

(mg C/L) <1 (N=1)

Salinity:

Not applicable - freshwater

Conductivity:

Not specified

Details on test conditions:

The bioconcentration test was conducted using an exposure system consisting of a continuous-flow diluter to deliver each concentration of the test substance and a solvent control to test chambers. A syringe pump (Harvard Apparatus, Holliston, Massachusetts) was used to deliver volumes of test substance stock solutions and dimethylformamide (DMF) for the solvent control to mixing chambers indiscriminately assigned to each treatment and the control. The stock solutions or solvent were diluted with well water in the mixing chambers in order to obtain the desired test concentrations prior to delivery to the test chambers. The flow of dilution water into each mixing chamber was controlled using rotameters, and was adjusted to provide approximately 6 exchange additions of test solution in each test chamber per day. The general operation of the diluter was checked at least two times a day during the test, and at least once at the beginning and end of the test. The pumps used to deliver stock solutions and solvent to the mixing chambers were calibrated prior to the test. The rotameters used to control the flow of dilution water to the mixing chambers, were calibrated prior to the test and verified weekly throughout the uptake phase.
Test chambers were positioned in a temperature-controlled water bath designed to maintain the target temperature throughout the test period. Test chambers used during the uptake phase were 127-L Teflon®-lined stainless steel aquaria filled with 80 L of test solution. The depth of the test water in one representative test chamber during uptake was approximately 17.4 cm. On day 23 of uptake, the fish were transferred to a clean set of 54-L stainless steel aquaria filled with 45 L of dilution water (well water) for 10 days of depuration. The depth of the test water in one representative test chamber during depuration was approximately 23.6 cm. Two separate water baths of the same type were used for the uptake and depuration phases. Test chambers were siphoned daily during the test to remove excess feed, faecal matter, algae and bacterial growth. Test chambers were identified by the project number and test concentration.

Biological Observations
Assessments of survival and general observation (behavioral and physical) were made daily in order to assess the health of the fish. Any mortalities, external abnormalities or abnormal behaviour (relative to controls) were noted if observed.

Environmental Conditions
Fluorescent light bulbs that emit wavelengths similar to natural sunlight were used for illumination of the test chambers. A photoperiod of 16 hours of light and 8 hours of dark was controlled with an automatic timer. A 30-minute transition period of low light intensity was provided when lights went on and off to avoid sudden changes in lighting. Light intensity at the surface of the water at the start of the uptake phase was 751 lux and 589 lux at the start of the depuration phase. Light intensity was measured using a SPER Scientific Model 840006C light meter.
The target test temperature during the test was 22 ± 1°C. Temperature was measured in the test chamber at the beginning and end of the test and approximately weekly intervals during the test using a liquid-in-glass thermometer. Temperature was also monitored continuously in the solvent control test chamber using an Amegaview Central Monitoring system, which was verified prior to test initiation and at approximately weekly intervals thereafter using a digital thermometer and a liquid-in-glass thermometer, respectively.
Dissolved oxygen measurements were made in each test chamber daily during the uptake and depuration phases using a Thermo Orion Model 850Aplus dissolved oxygen meter. Measurements of pH were made in each test chamber at the beginning and end of the test and approximately weekly during the test using a Thermo Orion Model 525Aplus pH meter.
Hardness, alkalinity and conductivity were measured in the dilution water, the solvent control, and high treatment level at the beginning and end of the test, and approximately weekly during the test. Total organic carbon (TOC) was measured in the dilution water, the solvent control, low treatment level and high treatment level at the beginning and end of the test, and approximately weekly during the test. Hardness and alkalinity were measured by titration based on procedures in Standard Methods for the Examination of Water and Wastewater (4). Conductivity was measured using an Acorn Series CON 6 conductivity meter. Total organic carbon was measured using a Shimadzu model TOC-VCSH total organic carbon analyzer.

Nominal and measured concentrations:

3.5 μg/L; 35 μg/L (nominal). Measured concentrations are presented in table form - see Any other information

Reference substance (positive control):

no

Details on estimation of bioconcentration:

The steady-state bioconcentration factor (BCF) values were determined from the mean tissue concentrations at apparent steady-state divided by the average water concentration. Tissue concentrations were considered to be at apparent steady-state if three or more consecutive sets of tissue concentrations are within ±20% of each other, and there is no significantly increasing trend in residue concentration in time between the first and last successive analyses (p > 0.05). All statistical tests were performed using a personal computer with The SAS System for Windows software. Nonlinear regression was used to sequentially solve for k1 and k2 using fish tissue data from the uptake phase and depuration phase. These rate constants were used to calculate a kinetic bioconcentration factor (BCFK = k1/k2) and also to calculate half-life for clearance in tissue (t½) and, time to reach 95% of steady state (t95).
The kinetic uptake and depuration rate constants were determined using nonlinear regression described by Newman. In the sequential method, data from the depuration (elimination) phase was used to first estimate k2, and then using both the k2 estimate and fish tissue from the uptake phase to estimate k1. In addition, lipid-normalized and growth-corrected kinetic and steady state bioconcentration factors (BCFSSL, BCFKL, BCFKg and BCFKLG) as well as growth corrected half-life (t½g) were determined.

Substance Uptake and Depuration Rate Constants and Bioconcentration Factors (BCF)
kg (growth rate constant; day-1)
k1 (overall uptake rate constant; L kg-1 day-1)
k2 (overall depuration rate constant; day-1)
k2g (growth-corrected depuration rate constant, day-1)
Cr (chemical concentration in the fish at steady-state; μg kg-1)
Cw (chemical concentration in the water; μg L-1)
Ln (lipid normalization factor)
BCFSS (steady-state BCF; L kg-1)
t1/2 (half-life, day)
t95 (time to reach 95% of steady state)
BCFSSL (lipid-normalized steady-state BCF; L kg-1)
BCFK (kinetic BCF; L kg-1)
BCFKg (growth-corrected kinetic BCF; L kg-1)
t1/2g (growth-corrected half-life; day)
BCFKL (lipid-normalized kinetic BCF: L kg-1)
BCFKLG (lipid-normalized growth-corrected kinetic BCF; L kg-1)

Lipid content:

>= 7.24 - <= 8.83 %

Time point:

end of exposure

Remarks on result:

other: Edible & non-edible fraction

Key result

Conc. / dose:

3.1 µg/L

Type:

BCF

Value:

225 dimensionless

Basis:

edible fraction

Time of plateau:

17.9 d

Calculation basis:

steady state

Remarks on result:

other: Conc.in environment / dose:3.1

Key result

Conc. / dose:

3.1 µg/L

Type:

BCF

Value:

281 dimensionless

Basis:

edible fraction

Time of plateau:

17.9 d

Calculation basis:

kinetic

Remarks on result:

other: Conc.in environment / dose:3.1

Key result

Conc. / dose:

3.1 µg/L

Type:

BCF

Value:

773 dimensionless

Basis:

non-edible fraction

Time of plateau:

7.2 d

Calculation basis:

steady state

Remarks on result:

other: Conc.in environment / dose:3.1

Key result

Conc. / dose:

3.1 µg/L

Type:

BCF

Value:

733 dimensionless

Basis:

non-edible fraction

Time of plateau:

7.2 d

Calculation basis:

kinetic

Remarks on result:

other: Conc.in environment / dose:3.1

Key result

Conc. / dose:

3.1 µg/L

Type:

BCF

Value:

512 dimensionless

Basis:

whole body w.w.

Time of plateau:

8.9 d

Calculation basis:

steady state

Remarks on result:

other: Conc.in environment / dose:3.1

Key result

Conc. / dose:

3.1 µg/L

Type:

BCF

Value:

516 dimensionless

Basis:

whole body w.w.

Time of plateau:

8.9 d

Calculation basis:

kinetic

Remarks on result:

other: Conc.in environment / dose:3.1

Key result

Conc. / dose:

24 µg/L

Type:

BCF

Value:

293 dimensionless

Basis:

edible fraction

Time of plateau:

4.9 d

Calculation basis:

steady state

Remarks on result:

other: Conc.in environment / dose:24

Key result

Conc. / dose:

24 µg/L

Type:

BCF

Value:

311 dimensionless

Basis:

edible fraction

Time of plateau:

4.9 d

Calculation basis:

kinetic

Remarks on result:

other: Conc.in environment / dose:24

Key result

Conc. / dose:

24 µg/L

Type:

BCF

Value:

922 dimensionless

Basis:

non-edible fraction

Time of plateau:

3.7 d

Calculation basis:

steady state

Remarks on result:

other: Conc.in environment / dose:24

Key result

Conc. / dose:

24 µg/L

Type:

BCF

Value:

776 dimensionless

Basis:

non-edible fraction

Time of plateau:

3.7 d

Calculation basis:

kinetic

Remarks on result:

other: Conc.in environment / dose:24

Key result

Elimination:

yes

Parameter:

DT50

Depuration time (DT):

4.13 d

Details on kinetic parameters:

Reported in table form - see Any other information

Results with reference substance (positive control):

Not applicable - reference substance not used in this study.

Details on results:

Concentrations of Reofos 35 in Water
The measured concentrations of Reofos 35 in the pretest samples collected 5 days prior to initiation were approximately 89 to 97% of nominal concentrations. Aeration was added to the test system 5 days prior to test initiation, after which the mean measured concentrations were 72 to 92% of nominal.
The measured concentrations ranged from 63.7 to 108% of the nominal concentration in the low level. Measured concentrations ranged from 48.9 to 85.7% of the nominal concentration in the high level. This resulted in an overall mean measured percent of nominal of 89% in the low level and 67% in the high level. The diluter system was checked one to two times daily and calibrated weekly during the study and indicated that the correct test concentrations were being delivered to the test chambers. The results of the study were based on the mean measured test concentrations for the uptake phase of 3.1 and 24 μg/L.
The measured concentrations in water during the depuration phase were below the LOQ in the low and high levels.

Concentrations of Reofos 35 in Fish Tissues
The mean measured tissue concentration of Reofos 35 of fish exposed to a mean measured test concentration of 3.1 μg/L edible, non-edible and whole fish at Day 21 of uptake was 701, 2408 and 1595 μg/kg, respectively.
The mean measured tissue concentration of Reofos 35 of fish exposed to a mean measured test concentration of 24 μg/L in edible, non-edible and whole fish at Day 21 of uptake was 6918, 21725 and 14953 μg/kg, respectively.

Determination of Steady State
It was determined the study had reached steady state on days 7, 14 and 21 in the low and high treatment groups. The steady-state BCF values for the low level (3.1 μg/L), based on Reofos 35 concentrations in tissue and water were 225, 773 and 512 in edible, non-edible and whole fish tissue, respectively. The steady-state BCF values for the high level (24 μg/L), based Reofos 35 concentrations in tissue and water were 293, 922 and 634 in edible, non-edible and whole fish tissue, respectively.

BCFK and Depuration Characteristics
Using nonlinear regression, similar kinetic BCF (BCFK) values were determined from total radioactivity data resulting in BCFK values of 281, 733 and 516 in edible, non-edible and whole fish tissue, respectively for the low level and 311, 776 and 559 in edible, non-edible and whole fish tissue, respectively for the high level. The estimated time to reach 95% of steady state (t95) in edible, non-edible and whole fish was 17.9, 7.2 and 8.9 days, respectively for the low level and 4.9, 3.7 and 4.0 days, respectively for the high level.
The mean measured concentration of total radioactivity in edible, non-edible and whole fish by Day 7 of depuration was
Growth Rate
Growth rate constants (kg), were calculated by performing a linear least squares correlation on the individual data of the two treatment groups. The slopes of the linear regression were compared statistically using the student’s t-test (p = 0.05).
There were no statistical differences between the slopes of the uptake and depuration phase growth data in the 3.1 μg/L treatment group (p > 0.05), therefore the uptake and depuration data was pooled to estimate the growth rate constant (kg). The growth rate constant (kg) for the 3.5 μg/L treatment group was -0.00797. In the 3.1 μg/L treatment group, the growth corrected depuration rate constant (k2g) was 0.3460, the growth corrected half-life (t1/2g) was 2.0 days and the growth corrected kinetic BCF (BCFKg) in whole fish tissue was 504.
There were no statistical differences between the slopes of the uptake and depuration phase growth data in the 24 μg/L treatment group (p > 0.05), therefore the uptake and depuration data was pooled to estimate the growth rate constant (kg). The uptake growth data was used to estimate the growth rate constant (kg). The growth rate constant (kg) for the 24 μg/L treatment group was -0.00681. In the 24 μg/L treatment group, the growth corrected depuration rate constant (k2g) was 0.7568, the growth corrected half-life (t1/2g) was 0.92 days and the growth corrected kinetic BCF (BCFKg) in whole fish tissue was 553.

Lipid Analysis
The mean measured percent lipid content in edible tissue from the fish sampled at the beginning of the test, Day 23 of uptake and Day 10 of depuration were 2.59, 2.26 and 2.80%, respectively. The mean measured percent lipid content in non-edible tissue from the fish sampled at the beginning of the test, Day 23 of uptake, Day 10 of depuration were 7.24, 8.83 and 8.57%, respectively. The lipid content in the edible and non-edible tissue remained fairly consistent over the course of the study.
The whole fish mean measured percent lipid content was calculated for each treatment group. Both the steady-state and kinetic BCF values for whole fish were normalized to 5% lipid content wet weight based on the procedures in the OECD 305 Guideline. Since there were no significant differences in growth between the treated and control fish, the lipid content of the control fish were used for lipid calculations. The mean lipid content of whole fish on Day 23 of the uptake phase from the solvent control (9.2%) was used in the lipid correction. The lipid-normalized steady state BCF (BCFSSL) in whole fish tissue was 278 and 344 in the low and high treatment groups, respectively. The lipid-normalized kinetic BCF (BCFKL) in whole fish tissue was 280 and 303 in the low and high treatment groups, respectively. The lipid normalized growth corrected kinetic BCF (BCFKgL) in whole fish tissue was 273 and 300 in the low and high treatment groups, respectively.

Physical and Chemical Measurements of Water
Water temperatures in the test chambers ranged from 21.4 to 22.0°C, and both manual and continuous temperature measurements were within the range of 22 ± 1°C established for the test. Measurements of water pH ranged from 7.9 to 8.4 during the test. Dissolved oxygen remained ≥ 6.6 mg/L (76% of saturation) throughout the test. Measurements of hardness, alkalinity and conductivity were typical of Wildlife International well water.
Total organic carbon (TOC) in the solvent control ranged from 5.304 to 54.12 mg C/L during uptake and was < 1 mg C/L during depuration. Total organic carbon (TOC) in the dilution water ranged from < 1 to 9.22 mg C/L during the uptake phase and ranged from < 1 to 1.607 mg C/L during the depuration phase. Total organic carbon (TOC) in the low treatment level ranged from 45.19 to 55.75 mg C/L during uptake and ranged from < 1 to 2.45 mg C/L during depuration. Total organic carbon (TOC) in the high treatment level ranged from 46.73 to 57.67 mg C/L during uptake and was < 1 mg C/L during depuration.

Observations of Mortality and Clinical Signs of Toxicity
There were no mortalties in the control or treatment groups during the study. At the end of the uptake phase (Day 23), the fish were enumerated during the transfer to depuration tanks.
All remaining fish appeared normal and healthy throughout the test.

Reported statistics:

None specified in the study report

Kinetic Estimates of the BCFK for Bluegill

Tissue Type	Nominal Exposure (μg/L)	Uptake Rate Constant (k1, Day-1)^1	Depuration Rate Constant (k2, Day-1)^1	Kinetic Bioconcentration Factor (BCFK) 2	Estimated Time to Reach 95% Steady State (Days)^2	Estimated Time to Reach 50% Clearance (Days)^2
Edible	3.5	47.1	0.168	281	17.9	4.13
Non-edible	3.5	303.9	0.414	733	7.2	1.67
Whole fish	3.5	174.4	0.338	516	8.9	2.05
Edible	35	188.4	0.607	311	4.9	1.14
Non-edible	35	629.2	0.811	776	3.7	0.86
Whole fish	35	418.8	0.750	559	4.0	0.92

¹Calculated using SAS

²Calculated using methods outline in OPPTS guideline 850.1730

Mean Measured Concentrations of Reofos 35 in Edible, Non-edible and Whole Fish Tissues in the Low and High Exposure Groups by Day During the Uptake and Depuration Phases

Nominal Concentration Reofos 35 (μg/L)	Study Phase	Sampling Interval (Day)	Mean Edible Tissue Conc. (μg/kg)	Mean Non-Edible Tissue Conc. (μg/kg)	Mean Whole Fish Conc.^1,2,3,4(μg/kg)
3.5	Uptake	0.17	<LOQ	<LOQ	<LOQ
3.5	Uptake	1	404	1066	750
3.5	Uptake	3	608	1605	1179
3.5	Uptake	7	711	1923	1345
3.5	Uptake	14	702	2297	1499
3.5	Uptake	21	701	2408	1595
35	Uptake	0.17	1340	3315	2396
35	Uptake	1	3195	9875	6702
35	Uptake	3	5933	13550	10189
35	Uptake	7	7848	19625	14112
35	Uptake	14	7273	16375	11838
35	Uptake	21	6918	21725	14953
3.5	Depuration	0	701	2408	1595
3.5	Depuration	1	<LOQ	845	485
3.5	Depuration	3	<LOQ	<LOQ	<LOQ
3.5	Depuration	5	<LOQ	<LOQ	<LOQ
3.5	Depuration	7	<LOQ	<LOQ	<LOQ
35	Depuration	0	6918	21725	14953
35	Depuration	1	2863	16050	9901
35	Depuration	3	509	4223	2573
35	Depuration	5	<LOQ	295	<LOQ
35	Depuration	7	<LOQ	<LOQ	<LOQ

¹Whole Fish Conc. = [(edible wt. * edible conc.) + (nonedible wt. * nonedible conc.)] / (edible wt. + nonedible wt.)

²Results were generated using Excel 2010 and SAS. Manual calculations may differ slightly.

³LOQ = 250 μg/kg.

⁴When equivalents were <LOQ, ½ LOQ (125 μg/kg) was used for calculations

 

Confirmation of Steady State

Mean Measured Tissue Concentration (μg/kg)
Tissue Type	Nominal Water Concentration (μg/L)	For the Last Three Sampling Intervals			Mean	SD	p^1
		Day 7	Day 14	Day 21
Edible	3.5	711.0	702.0	701.0	704.7	5.51	0.2791
Non-Edible	3.5	1922.5	2296.7	2407.5	2208.9	254.14	0.0562
Whole Fish	3.5	1344.8	1498.5	1594.8	1479.4	126.08	0.1587
Edible	35	7847.5	7272.5	6917.5	7345.8	469.32	0.8792
Non-Edible	35	19625.0	16375.0	21725.0	19241.7	2695.52	0.2321
Whole Fish	35	14111.6	11838.5	14952.7	13634.2	1611.05	0.2791

¹p = 0.05

 

Steady-State BCF Values for Bluegill

Tissue Type	Mean Measured Test Concentration (μg/L)	Uptake Days at Steady State	Mean Measured Steady-State Tissue Concentration (μg/kg)	Steady-State BCF
Edible	3.1	7-14-21	701.0	225
Non-Edible	3.1	7-14-21	2407.5	773
Whole Fish	3.1	7-14-21	1594.9	512
Edible	24	7-14-21	6917.5	293
Non-Edible	24	7-14-21	21725.0	922
Whole Fish	24	7-14-21	14952.7	634

 

Kinetic Estimates of the BCFK for Bluegill

Tissue Type	Nominal Exposure (μg/L)	Uptake Rate Constant (k1, Day-1) 1	Depuration Rate Constant (k2, Day-1)^1	Kinetic Bioconcentration Factor (BCFK)^2	Estimated Time to Reach 95% Steady State (Days)^2	Estimated Time to Reach 50% Clearance (Days)^2
Edible	3.5	47.1	0.168	281	17.9	4.13
Non-Edible	3.5	303.9	0.414	733	7.2	1.67
Whole Fish	3.5	174.4	0.338	516	8.9	2.05
Edible	35	188.4	0.607	311	4.9	1.14
Non-Edible	35	629.2	0.811	776	3.7	0.86
Whole Fish	35	418.8	0.750	559	4.0	0.92

¹Calculated using SAS

²Calculated using methods outlined in OPPTS guideline 850.1730

 

Growth Rate Constants

Kg values
	3.1 μg/L^1,2	24 μg/L^1,2
Uptake	-0.00569	-0.00339
Depuration	0.00192	-0.00330
Pooled	-0.00797	-0.00681

¹No statistical difference between slopes of uptake and depuration phases (p>0.05)

²Growth measurements from both the uptake and depuration phases were pooled for the overall growth rate constant.

Validity criteria fulfilled:

yes

Conclusions:

The substance is not considered to be bioaccumulative.

Executive summary:

The study was conducted according to the procedures outlined in the protocol, “Reofos 35: An Aqueous Exposure Bioaccumulation Test with the Bluegill (Lepomis macrochirus)”. The protocol was based on procedures outlined in U.S. Environmental Protection Agency Series 850 – Ecological Effects Test Guidelines, OPPTS Number 850.1730: Fish BCF; ASTM Standard E1022-94, Standard Guide for Conducting Bioconcentration Tests with Fishes and Saltwater Bivalve Molluscs and OECD Guideline for Testing of Chemicals 305, Bioaccumulation in Fish: Aqueous and Dietary Exposure.

 

The test was divided into two phases: uptake and depuration. During the uptake phase, bluegill were exposed to two test concentrations of Reofos 35 and a solvent control (dilution water containing 0.1 mL/L DMF). The nominal concentrations of 3.5 and 35 μg/L were selected in consultation with the Sponsor and were based on existing toxicity data and preliminary trials. Each group consisted of one test chamber with 80 fish in the solvent control and each treatment level test chamber. During the depuration phase, fish were exposed to dilution water only. The duration of the uptake phase was 23 days for both of the treatment groups. After confirmation of steady state, fish were moved into the depuration phase which lasted for 10 days for both treatment levels. During both phases of the test, test organisms and water samples were collected and analyzed for Reofos 35.

These values were used to determine the substance-specific half-life (t1/2), the kinetic bioconcentration factor (BCFK) and the steady state bioconcentration factor (BCFSS) for the test substance in fish, as well as lipid-normalized and growth-corrected kinetic and steady state bioconcentration factors (BCFSSL, BCFKL, BCFKgand BCFKLg).

 

Bluegill were exposed to mean measured water concentrations of 3.1 and 24 μg/L.

Steady-state concentrations of Reofos 35 were achieved in the tissues of Bluegill (Lepomis macrochirus) after 21 days of uptake in the low and high treatment groups. Steady-state BCF values for the low treatment group were 225, 773 and 512 in edible, non-edible and whole fish, respectively.

Steady-state BCF values for the high treatment group were 293, 922 and 634 in edible, non-edible and whole fish tissue, respectively. Reofos 35 quickly depurated from all fish tissue and by Day 7 of depuration tissue concentrations were approximately <LOQ in both treatment groups.

Kinetic BCFK values derived by nonlinear regression for the low treatment group were 281, 733 and 516 for edible, non-edible and whole fish tissue, respectively. The time to reach 95% steady state based on kinetics was 17.9, 7.2 and 8.9 days and time to reach 50% clearance was 4.1, 1.7 and 2.1 days for edible, non-edible and whole fish, respectively.

Kinetic BCFK values derived by nonlinear regression for the high treatment group were 311, 776 and 559 for edible, non-edible and whole fish tissue, respectively. The time to reach 95% steady state based on kinetics was 4.9, 3.7 and 4.0 days and time to reach 50% clearance was 1.1, 0.86 and 0.92 days for edible, non-edible and whole fish, respectively.

The substance is not considered to be bioaccumulative.

Reference 9

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

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

Adequacy of study:

weight of evidence

Justification for type of information:

Please see the attached justification. A full justification RAAF is enclosed in Section 13 below.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Key result

Conc. / dose:

3.1 µg/L

Type:

BCF

Value:

225 dimensionless

Basis:

edible fraction

Time of plateau:

17.9 d

Calculation basis:

steady state

Remarks on result:

other: Conc.in environment / dose:3.1

Key result

Conc. / dose:

3.1 µg/L

Type:

BCF

Value:

281 dimensionless

Basis:

edible fraction

Time of plateau:

17.9 d

Calculation basis:

kinetic

Remarks on result:

other: Conc.in environment / dose:3.1

Key result

Conc. / dose:

3.1 µg/L

Type:

BCF

Value:

773 dimensionless

Basis:

non-edible fraction

Time of plateau:

7.2 d

Calculation basis:

steady state

Remarks on result:

other: Conc.in environment / dose:3.1

Key result

Conc. / dose:

3.1 µg/L

Type:

BCF

Value:

733 dimensionless

Basis:

non-edible fraction

Time of plateau:

7.2 d

Calculation basis:

kinetic

Remarks on result:

other: Conc.in environment / dose:3.1

Key result

Conc. / dose:

3.1 µg/L

Type:

BCF

Value:

512 dimensionless

Basis:

whole body w.w.

Time of plateau:

8.9 d

Calculation basis:

steady state

Remarks on result:

other: Conc.in environment / dose:3.1

Key result

Conc. / dose:

3.1 µg/L

Type:

BCF

Value:

516 dimensionless

Basis:

whole body w.w.

Time of plateau:

8.9 d

Calculation basis:

kinetic

Remarks on result:

other: Conc.in environment / dose:3.1

Key result

Conc. / dose:

24 µg/L

Type:

BCF

Value:

293 dimensionless

Basis:

edible fraction

Time of plateau:

4.9 d

Calculation basis:

steady state

Remarks on result:

other: Conc.in environment / dose:24

Key result

Conc. / dose:

24 µg/L

Type:

BCF

Value:

311 dimensionless

Basis:

edible fraction

Time of plateau:

4.9 d

Calculation basis:

kinetic

Remarks on result:

other: Conc.in environment / dose:24

Key result

Conc. / dose:

24 µg/L

Type:

BCF

Value:

922 dimensionless

Basis:

non-edible fraction

Time of plateau:

3.7 d

Calculation basis:

steady state

Remarks on result:

other: Conc.in environment / dose:24

Key result

Conc. / dose:

24 µg/L

Type:

BCF

Value:

776 dimensionless

Basis:

non-edible fraction

Time of plateau:

3.7 d

Calculation basis:

kinetic

Remarks on result:

other: Conc.in environment / dose:24

Key result

Type:

BCF

Value:

776 L/kg

Basis:

other: Read-across to structural analogues

Calculation basis:

other: Not specified

Remarks on result:

other: Read-across to structural analogues

Remarks:

CAS 1330-78-5

Summary of results for Read Across Data to Tricresyl Phosphate.

Species	Compound	Flow/Stat (temp)	Analytical method	BCF (K1/K2)	Exposure concentration (mg/l)	Uptake Rate (K1 h-1)	Clearance rate (K2 x 103 h-1)	Depuration rate half life (hour)	Reference
Rainbow trout (salmo gairdneri)	para isomer	Stat (10°C)	total radioactivity	2768 ± 641	0.005-0.05		9.6 - 13.3	72.2	Muir et al (1983)
			total radioactivity	1420 ± 42		14.0
			total radioactivity	1466 ± 138		17.0
			hexane-extractable radioactivity	770 ± 24				65.4
	meta isomer		total radioactivity	1162 ± 313			11.5 - 24.2	30.3
			total radioactivity	784 ± 82		18.5
			total radioactivity	1102 ± 137		21.2
			hexane-extractable radioactivity	310 ± 52				25.8
Fathead minnows (pimephales promelas)	para isomer	Stat (10°C)	total radioactivity	2199 ± 227	0.005-0.05		7.0 - 9.6	90	Muir et al (1983)
			total radioactivity	928 ± 78		4.9
			total radioactivity	588 ± 129		9.6
			hexane-extractable radioactivity	709 ± 76				73.7
	meta isomer		total radioactivity	1653 ± 232			8.5-14.7	59.2
			total radioactivity	596 ± 103		7.9
			total radioactivity	385 ± 92		8.7
			hexane-extractable radioactivity	62 ± 3				53.3
	Commercial TCP	Flow (25°C)	GC-FPD	165	0.0316				Veith et al (1979)
Bluegill (Leptomis macrochirus)	para isomer		total radioactivity	1589					Sitthichaikasem (1978)

Validity criteria fulfilled:

yes

Conclusions:

The substance, CAS 25155-23-1; EC 246-677-8, is analogous to the substances to be read across to, in terms of basic form, and the degree of substitution of functional groups is not considered to effect the proposed read across for the endpoint of bioaccumulation. The substance is considered to be not bioacummulative for the defined endpoints on the basis of read across.

Executive summary:

The substance, CAS 25155-23-1; EC 246-677-8, is analogous to the substances to be read across to, in terms of basic form, and the degree of substitution of functional groups is not considered to effect the proposed read across for the endpoint of bioaccumulation. The substance is considered to be not bioacummulative for the defined endpoints on the basis of read across.

Description of key information

An assessment of the propensity towards bioaccumulation was undertaken, utilizing appropriate techniques such as:

·        Read across to structural analogues.

·        QSAR derivation, using recognized tools

·        Literature data

The results are as follows:

Read across to Structural Analogues:

Phenol, isopropylated, phosphate (3:1).

As a recently conducted study, this is considered as the key substance for evaluation. The highest BCF of 922 is assigned to the substance from read across to this study.

Bluegill were exposed to mean measured water concentrations of 3.1 and 24 μg/L. Steady-state concentrations of Reofos 35 were achieved in the tissues of Bluegill (Lepomis macrochirus) after 21 days of uptake in the low and high treatment groups. Steady-state BCF values for the low treatment group were 225, 773 and 512 in edible, non-edible and whole fish, respectively. Steady-state BCF values for the high treatment group were 293, 922 and 634 in edible, non-edible and whole fish tissue, respectively. Reofos 35 quickly depurated from all fish tissue and by Day 7 of depuration tissue concentrations were approximately <LOQ in both treatment groups.

Kinetic BCFK values derived by nonlinear regression for the low treatment group were 281, 733 and 516 for edible, non-edible and whole fish tissue, respectively. The time to reach 95% steady state based on kinetics was 17.9, 7.2 and 8.9 days and time to reach 50% clearance was 4.1, 1.7 and 2.1 days for edible, non-edible and whole fish, respectively.

 Kinetic BCFK values derived by nonlinear regression for the high treatment group were 311, 776 and 559 for edible, non-edible and whole fish tissue, respectively. The time to reach 95% steady state based on kinetics was 4.9, 3.7 and 4.0 days and time to reach 50% clearance was 1.1, 0.86 and 0.92 days for edible, non-edible and whole fish, respectively.

The substance is not considered to be bioaccumulative, and all BCF’s are less than 1000.

Tricresyl phosphate.

Assessment of structural analogue data was undertaken. From this, the substance tricresyl phosphate was selected, as this data is listed on the World Health Organisation website. The paper contains various bioaccumulation assessment studies on this structural analogue and demonstrate thattricresyl phosphate does not demonstrate a propensity towards bioaccumulation, based on the measured values within the studies.

 As a weight of evidence approach, it is considered that on structural grounds, the same conclusion can be applied to trixylyl phosphate.

QSARs for substance:

QSAR prediction using BCF model (CAESAR) (Version 2.1.1.11) = BCF 36.0 L/kg based on log(L/kg) 1.56

QSAR prediction using BCF model (Meylan) (version 1.0.0) (CAESAR).= BCF 669.24 L/kg Based on log(L/kg) 2.83

QSAR prediction using BCF Read-Across (version 1.0.0) (CAESAR) = BCF >=118.0 - <=126.0 Based on log(L/kg) 2.07-2.1

QSAR prediction using US EPA On-Line EPI Suite™ v4.0 model BCFBAF = BCF  669.09 L/kg Based on Estimated Log BCF = 2.817

It is understood that Annex XI, section  1.3  allows  adaptation of the standard testing requirements by making use of (Q)SAR only if the following conditions are met:

(i) results are derived from  a (Q)SAR  model  whose  scientific validity has  been  established,

(ii) the substance falls within the applicability domain of the (Q)SAR model,

(iii) results are adequate for the purpose of classification and labelling and/or risk assessment, and

(iv) adequate and reliable documentation of  the  applied method is  provided.

Within the four models used, the conditions (i) through (iv) are considered to be met. As the substance has some 729 potential structures, an assessment of 60 of these, taken at random, was undertaken. The structures assessed were deemed to fall within the applicability domain of the model, and this is demonstrated within the relevant QPRF’s. The models are recognized, and are referenced within ECHA’s own guidance and/or have relevant QMRF’s which are also detailed.

As a result, the QSAR’s conducted all generally agree with each other that the substance is not bioaccumulative.

Literature data:

Two studies by Bengtsson et al are presented. It is acknowledged that both used shorter uptake durations than what is recommended for the OECD 305 Guideline; however it is considered that these can be used in the context of a weight of evidence approach. The trixylyl phosphate quotient of the study indicates that there was no significant bioaccumulation of the substance in the 14-day study, and depuration was observed, although not completed within the 14-day depuration period. In addition, in a 120 day study in the minnow, no significant bioaccumulation was noted, despite the fact that the test substance was fed consistently throughout the study period. It is therefore considered that the data set within this literature study provides adequate information in the context of a weight of evidence approach.

Conclusion:

On the basis of a weight of evidence approach, there is sufficient information available to state that the substance is not bioaccumulative without the need for further testing as requested by ECHA. Results observed across the data available indicate that the substance, as part of the phosphates group, is unlikely to be bioaccumulative within the aquatic environment.

 

 

Key value for chemical safety assessment

BCF (aquatic species):

922 L/kg ww