4-(1,1,3,3-tetramethylbutyl)phenol

Sediment toxicity

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

unknown

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study meets generally accepted scientific standards and is acceptable for assessment. Some testing information is missing.

Qualifier:

equivalent or similar to guideline

Guideline:

other: Emery et al. 1997

Principles of method if other than guideline:

Study references Emery et al. (1997) as the method adapted for use in this study. However, procedures were modifed by using a smaller 250 ml test chamber with 50 g wet sediment and 200 ml overlying seawater.

GLP compliance:

not specified

Analytical monitoring:

yes

Details on sampling:

not known

Vehicle:

not specified

Details on sediment and application:

Study references Fay et al (2000) for amending reference sediment with NP. Spiking solutions of toxicant were added to glass jars. Reference sediment and seawater were added to each jar to create 50% sediment water slurry mix. Jars were shaken for 7 days on shaker at 125 rpm. After 7 days, sediments were centrifuged to remove excess seawater and homogenized.

Test organisms (species):

Leptocheirus plumulosus

Details on test organisms:

TEST ORGANISM
- Common name:crustacean
- Source: lab cultures
- Age of animals at beginning of exposure:< 2 weeks old, juveniles
- Feeding during test: sediment available

ACCLIMATION
- Acclimation period: none as lab cultured

Study type:

laboratory study

Test type:

static

Water media type:

saltwater

Type of sediment:

natural sediment

Limit test:

no

Duration:

28 d

Exposure phase:

total exposure duration

Post exposure observation period:

none

Hardness:

NA

Test temperature:

23 +/-1 °C

pH:

not provided

Dissolved oxygen:

not provided

Salinity:

20 ppt

Ammonia:

not provided

Nominal and measured concentrations:

measured: control, 2.1, 4.5, 10.5, 27.2, 61.5 mg/kg NP

Details on test conditions:

TEST SYSTEM
- Test container (material, size): 250 ml chamber
- Sediment volume: 50 g
- Weight of wet sediment with and without pore water: 50 g wet
- Overlying water volume: 200 ml
- Depth of sediment: 2 cm

EXPOSURE REGIME
- No. of organisms per container (treatment): 15
- No. of replicates per treatment group: 5
- No. of replicates per control / vehicle control: 5
- Feeding regime: 3 times a week
- Type and preparation of food: "gorp" - mixture of TetraMin, dried alfalfa, wheat grass powder and shrimp maturation feed
- Amount of food: 1mg/organism

OVERLYING WATER CHARACTERISTCS
- Type of water (e.g. deionized, ground water, sea water, Elendt medium acc. to OECD 219): synthetic seawater
- Salinity: 20ppt

SOURCE OF NATURAL SEDIMENT
- Location and description of sampling site: "Flax Pond", a sparsely populated coastal inlet on north shore of Long Island
- Contamination history of site: used as reference site
- Total organic carbon (%): 2.6%

HANDLING OF NATURAL SEDIMENT
The top 5 cm were collected from surface of four grabs from Ponar grab and homogenized. Sediment was sieved to 500 µm and stored for up to 1 year at 4 °C until use.


OTHER TEST CONDITIONS
- Photoperiod: 16L:8D


EFFECT PARAMETERS MEASURED (with observation intervals if applicable): not provided

VEHICLE CONTROL PERFORMED: unknown

TEST CONCENTRATIONS
- Range finding study: Yes
- Test concentrations: 0, 62.5, 118.8, 200, 400 mg/kg
- Results used to determine the conditions for the definitive study: yes

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

> 61.5 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

> 61.5 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

reproduction

Details on results:

99% survival in control

Results with reference substance (positive control):

none provided

Reported statistics and error estimates:

Reproductive output analyzed using two-sample, two-tailed T-test after square root transformation.

Survivorship of Leptocheirus plumulosus exposed to NP in 28 -day test. Results are average of 5 tests.

Measured Conc. (ug/g) dw	% Survival
Control	99 +/-3
2.1	99 +/-3
4.5	96 +/-3
10.5	97 +/-3
27.2	96 +/-5
61.5	96 +/-5

Validity criteria fulfilled:

not specified

Remarks:

some water characteristics missing

Conclusions:

Study authors concluded that NP was not the cause of toxicity in sewage-impacted sediment of concern.

Executive summary:

This study, on the toxicity of nonylphenol, is being included in support of the read-across approach for the toxicity of octylphenol to sediment organisms.

The 28-day chronic toxicity of nonylphenol to the benthic crustacean, Leptocheirus plumulosus, was studied under static conditions. Crustaceans were exposed to control and nonylphenol at average measured concentrations of 2.1, 4.5, 10.5, 27.2, 61.5, mg/kg dw nonylphenol.  The 28 -day NOEC based on survival and reproduction was > 61.5 mg /Kg dw nonylphenol for both effects. Eventhough, reproduction was the more sensitive endpoint.

The assessed sublethal effect included was reproduction. 

 

Results Synopsis

 

Test Organism Age (e.g. 1^stinstar): juvenile

Test Type (Flowthrough Static, Static Renewal): static

 

72 -hr NOEC (survival, reproduction and growth): >61.5 mg/kg dw nonylphenol

Zulkosky et al.(2002) was chosen as a supporting study because it provides toxicity results of nonylphenol to the sediment organism, Leptocheirus plumulosus. Although this study provides results that show Leptocheirus plumulosus could be more sensitive than Tubfix sp. or Chironomus riparius, as presented by Bettinetti and Provini (2002), it was not chosen as key study due to the lack of testing information provided by the authors. However, this study can provide support for the key study, Bettinetti and Provini (2002) in the toxicity of nonylphenol to sediment organisms.

Reference 2

Endpoint:

sediment toxicity: long-term

Type of information:

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

Adequacy of study:

weight of evidence

Justification for type of information:

In accordance with Regulation (EC) 1907/2006 Annex XI (1.5) and the relevant ECHA guidance documents, the substances detailed in the table below are grouped for the purposes of read across to reduce the need for unnecessary repeat testing on the basis that the substances are similar on the basis of a common functional groups.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

> 61.5 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

> 61.5 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

336.7 other: 59.1-235.2

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

cocoon production

Remarks on result:

other: 295-384.4

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

382.7 other: ug/g dw

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

cocoon production

Remarks on result:

other: 363.7-403.7

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

335 other: ug/g

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

number of young worms

Remarks on result:

other: 311.6-360.3

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

382.8 other: ug/g

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

number of young worms

Remarks on result:

other: number of young worms

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

258.9 other: µg/g dw

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

emergence rate

Remarks on result:

other: 217.8-285.6

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

203 other: µg/g dw

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

emergence rate

Remarks on result:

other: 59.1-235.2

Conclusions:

The read across for 4-tert-octylphenol (CAS: 140-66-9); is based upon the analogous substances to which basic form, degree of substitution of functional groups is not considered to effect the proposed read across for the endpoint of Sediment toxicity. Based on the information available for the read across substances, the substance is expected to be toxic to organisms in sediment.

Reference 3

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

unknown

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study is comparable to a guideline study with acceptable restrictions which do not impair the overall conclusion from the data.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD 225 or EPA OPPTS 850.6200

Deviations:

yes

Remarks:

study notes minor modifications to guideline, but does not specify

Principles of method if other than guideline:

Study references the following as test guidance. Test procedures described in the paper are similar to OECD 225 or EPA OPPTS 850.6200

Reynoldson, T.B., Thompson, S.P., and Bamsey, J.L. (1991). A sediment bioassay using the tubificid oligochaete work Tubifex tubifex. Environ. Toxicol. Chem. 10, 1061-1072.

GLP compliance:

not specified

Analytical monitoring:

yes

Details on sampling:

none provided

Vehicle:

no

Details on sediment and application:

PREPARATION OF SPIKED SEDIMENT
- Method of mixing:1g of NP was directly added to 250 g wet sediment (50% water content) and mixed with 250 ml of water. The mixture was mixed for 20 hr and left to settle for 72 hr. Sediment then separated from water by centrifugation.
- Details of spiking: Spiked sediment generated by mixing stock sediment with reference sediment
- Controls: yes

Test organisms (species):

Tubifex tubifex

Details on test organisms:

TEST ORGANISM
- Common name: worm
- Source:on-site cultures started from adults collected in Lake Suviana Italy
- Breeding conditions: kept in the dark at 21 deg C in glass containers half filled with sterilized sand and dechlorinated tap water, 25 adults per beaker. Fed frozen spinach thawed to room temperature
- Details on collection: cocoons removed from sand every week
- Age of animals at beginning of exposure: appro.imately 6 weeks, at their first reproductive event
- Feeding during test: yes
- Food type: Tetramin during test
- Amount:80 mg dry power/ test chamber
- Frequency:food mixed with sediment before test initiation

ACCLIMATION
- Acclimation period:none needed as cultured in lab
- Acclimation conditions (same as test or not): same dilution water

Study type:

laboratory study

Test type:

semi-static

Water media type:

freshwater

Type of sediment:

natural sediment

Limit test:

no

Duration:

28 d

Exposure phase:

total exposure duration

Post exposure observation period:

none

Hardness:

320 mg/L CaCO3

Test temperature:

21+/- 1 deg C

pH:

not provided, but varied by 0.2 s.u. during test

Dissolved oxygen:

not provided, but test chambers aerated for 2 hr prior to test initiation, at test termination D.O was 65% saturation

Salinity:

NA

Ammonia:

< 0.02 mg/L

Nominal and measured concentrations:

nominal: Test 1 0, 180, 380, 420, 460, 650 ug/L
nominal: Test 2 0, 90, 190, 310, 430, 610 ug/L

Details on test conditions:

TEST SYSTEM
- Test container (material, size): 250 ml glass beakers covered with petri dish
- Weight of wet sediment with and without pore water: 70 g 50% water
- Overlying water volume: 150 ml
- Aeration: yes- 2hr before test and during test continuously
- Replacement of evaporated test water, if any: yes, every 2 days, if needed

EXPOSURE REGIME
- No. of organisms per container (treatment):4
- No. of replicates per treatment group:5
- No. of replicates per control / vehicle control:5
- Feeding regime: at test initiation
- Type and preparation of food: Tetramin powder
- Amount of food: 80mg powdered food per chamber

OVERLYING WATER CHARACTERISTCS
- Type of water (e.g. deionized, ground water, sea water, Elendt medium acc. to OECD 219): dechlorinated tap
-temperature, pH, and DO measured in all beakers before and end of test
SOURCE OF NATURAL SEDIMENT
- Location and description of sampling site: Lake Monate Northern Italy
- Contamination history of site: unpolluted sediment. Chemical analysis confirmed NP was not present and other parameters were in range of previous suggestions by Salomons and Forstner (1984)

HANDLING OF NATURAL SEDIMENT
- Water depth:10 m
- Storage conditions:stored in the dark at 4 deg C

OTHER TEST CONDITIONS
- Photoperiod:none, test performed in the dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : adult survival, number of cocoons and young worms assessed at end of test. Qualittaive observations included "reworking activity" and gonadal malformations.

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

336.7 other: ug/g dw

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

cocoon production

Remarks on result:

other: 295-384.4

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

382.7 other: ug/g dw

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

cocoon production

Remarks on result:

other: 363.7-403.7

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

335 other: ug/g

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

number of young worms

Remarks on result:

other: 311.6-360.3

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

382.8 other: ug/g

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

number of young worms

Remarks on result:

other: 366-400.4

Details on results:

Results for Test 1 and Test 2 are presented.
There was no significant difference in production of cocoons or young worms between controls in Test 1 or Test 2. No information of % survival of adults, but assume not significant based on statement below from text of paper.
"In both bioassays breeding adults started to die at 600 ug/g NP in sediments."

Some histological or gonadal malformations seen at 190 ug/g NP dw.

Results with reference substance (positive control):

none provided

Reported statistics and error estimates:

Probit used to calculate EC50 values. p<0.05

For cocoon production:

Test 1 EC50 = 429.3 ug/g dw nonylphenol

Test 2 EC50 = 427.3 ug/g dw nonylphenol

For young worm production:

Test 1 EC50 = 422.2 ug/g dw nonylphenol

Test 2 EC50 = 417.8 ug/g dw nonylphenol

Study states that analytical measurements were generally within 20% of nominal concentrations but does not present actual data. It is not clear if the results were calculated based on nominal or actual concentrations. Overlying water concentrations were within 5 -20 ug/L NP, depending on sediment concentration.

Validity criteria fulfilled:

yes

Conclusions:

Study authors conclude that although results from this study showed that environmental concentrations of NP in sediments for those mentioned in the paper, are lower than the toxicity results of this study. However, further investigation is needed to define long-term effects such as population disruption and community dynamics effects.

Executive summary:

This study, on the toxicity of nonylphenol, is being included in support of the read-across approach for the toxicity of octylphenol to sediment organisms.

The 28-day-chronic toxicity of nonylphenol to Tubifex tubifex was studied under semi-static conditions. Worms were exposed to control, and nonylphenol at nominal concentrations of 180, 380, 420, 460, and 650 ug./L nonylphenol in Test 1 and 90, 190, 310, 430, and 610 ug/L nonylphenol in Test 2.  The 28 -day EC₁₀ based on reproduction (cocoon production) was 0.3367 mg /L nonylphenol for Test 1 and 0.3827 mg/L nonylphenol for Test 2.

The 28 -day EC₁₀based on reproduction (young worms present) was 0.335 mg /L nonylphenol for Test 1 and 0.3828 mg/L nonylphenol for Test 2.

The sublethal effects assessed included cocoon and young worm production. However survival, worm activity and gonadal malformations were also assessed but no statistical results were provided.  The most sensitive end point was reproduction.

 

This study is classified as acceptable and satisifies the guideline requirements for a sediment toxicity test.

 

Results Synopsis

 

Test Organism Age (e.g. 1^stinstar): adult

Test Type (Flowthrough Static, Static Renewal): semi-static

 

EC₁₀(reproduction - cocoon production): 0.360 ug/g nonphenol (average of Test 1 and Test 2 results)

EC₁₀(reproduction - young worms): 0.359 ug/g nonphenol (average of Test 1 and Test 2 results)

Bettinetti and Provini(2002) was chosen as a key study because provides toxicity results of nonylphenol to the sediment organism, Tubifex tubifex. Results from this study are the only reliable results available for this test species and are therefore, included for assessment.

Reference 4

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

unknown

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study is comparable to a guideline study with acceptable restrictions which do not impair the overall conclusion from the data.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 218 (Sediment-Water Chironomid Toxicity Test Using Spiked Sediment)

Deviations:

yes

Remarks:

study notes minor modifications to guideline, but does not specify

Principles of method if other than guideline:

Study used the 1998 version of the Guideline

GLP compliance:

not specified

Analytical monitoring:

yes

Details on sampling:

none provided

Vehicle:

no

Details on sediment and application:

PREPARATION OF SPIKED SEDIMENT
- Method of mixing: 1g of NP was directly added to 250 g wet sediment (50% water content) and mixed with 250 ml of water. The mixture was mixed for 20 h and left to settle for 72 h. Sediment then separated from water by centrifugation.
- Details of spiking: Spiked sediment generated by mixing stock sediment with reference sediment
- Controls: yes

Test organisms (species):

Chironomus riparius

Details on test organisms:

TEST ORGANISM
- Common name: Chironomid
- Source: on-site cultures maintained for several generations, original source feral organisms collected from River Lambro in Milan, Italy
- Breeding conditions: 21 +/- 1 °C, in dechlorinated tap water under daily photoperiod in 40 L aquaria with control sediment.
- Details on collection: egg ropes transferred from culture to glass vessels containing culture water. First instar hatch occurred within 3 days at 21 °C.
- Age of animals at beginning of exposure: first instar
- Feeding during test: yes
- Food type: Tetramin
- Amount: 3.5 ml/ test chamber
- Frequency: every 3 days

ACCLIMATION
- Acclimation period: none needed as cultured in lab
- Acclimation conditions (same as test or not): same dilution water

Study type:

laboratory study

Test type:

semi-static

Water media type:

freshwater

Type of sediment:

natural sediment

Limit test:

no

Duration:

28 d

Exposure phase:

total exposure duration

Post exposure observation period:

none

Hardness:

320 mg/L CaCO3

Test temperature:

21+/- 1 °C

pH:

not provided, but varied by 0.2 s.u. during test

Dissolved oxygen:

not provided, but test chambers aerated for 2 h prior to test initiation, at test termination D.O was 65% saturation

Salinity:

NA

Ammonia:

< 0.02 mg/L

Nominal and measured concentrations:

nominal: Test 1 0, 270, 290, 320, 410, 480, 580 µg/L
nominal: Test 2 0, 290, 520, 735, 880, 960, 1100 µg/L

Details on test conditions:

TEST SYSTEM
- Test container (material, size): 250 ml glass beakers covered with petri dish
- Weight of wet sediment with and without pore water: 70 g 50% water
- Overlying water volume: 200 ml
- Aeration: yes- 2 h before test
- Replacement of evaporated test water, if any: yes

EXPOSURE REGIME
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 5
- No. of replicates per control / vehicle control: 5
- Feeding regime: every 3 days
- Type and preparation of food: Tetramin suspension
- Amount of food: 3.5 ml

OVERLYING WATER CHARACTERISTCS
- Type of water (e.g. deionized, ground water, sea water, Elendt medium acc. to OECD 219): dechlorinated tap
- Temperature, pH, and DO measured in all beakers before and end of test
SOURCE OF NATURAL SEDIMENT
- Location and description of sampling site: Lake Monate Northern Italy
- Contamination history of site: unpolluted sediment. Chemical analysis confirmed NP was not present and other parameters were in range of previous suggestions by Salomons and Forstner (1984)

HANDLING OF NATURAL SEDIMENT
- Water depth: 10 m
- Storage conditions: stored in the dark at 4 °C

OTHER TEST CONDITIONS
- Photoperiod: 16L8D

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): emergence recorded daily, egg deposition recorded

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

258.9 other: µg/g dw

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

emergence rate

Remarks on result:

other: 217.8-285.6

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

203 other: µg/g dw

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

emergence rate

Remarks on result:

other: 59.1-235.2

Details on results:

Results for Test 1 and Test 2 are presented.
Control beakers had 100% emergence for both tests.

Midges started to emerge after 14-16 days in all treatments and control with emergence period lasting 8-10 days in controls. Number of males vs females emerged was not significantly different between controls and treatments.

Results with reference substance (positive control):

none provided

Reported statistics and error estimates:

Probit used to calculate EC50 values. p<0.05

Test 1 EC50 = 385 µg/g dw nonylphenol

Test 2 EC50 = 381 µg/g dw nonylphenol

Study states that analytical measurements were generally within 20% of nominal concentrations but does not present actual data. It is not clear if the results were calculated based on nominal or actual concentrations. Overlying water concentrations were within 5 -20 µg/L NP, depending on sediment concentration.

Validity criteria fulfilled:

not specified

Conclusions:

Study authors conclude that although results from this study showed that environmental concentrations of NP in sediments for those mentioned in the paper, are lower than the toxicity results of this study. However, further investigation is needed to define long-term effects such as population disruption and community dynamics effects.

Executive summary:

This study, on the toxicity of nonylphenol, is being included in support of the read-across approach for the toxicity of octylphenol to sediment organisms.

The 28-day-chronic toxicity of nonylphenol to Chironomus riparius was studied under semi-static conditions. Chironomids were exposed to control, and nonylphenol at nominal concentrations of 270, 290, 320, 410, 480, and 580 µg/L nonylphenol in Test 1 and 290, 520, 735, 880, 960, 1100 µg/L nonylphenol in Test 2.  The 28 -day EC₁₀based on emergence was 0.2589 mg /L nonylphenol for Test 1 and 0.203 mg/L nonylphenol for Test 2.

The sublethal effects assessed included emergence and egg production.  The most sensitive end point was emergence.

 

This study is classified as acceptable and satisifies the guideline requirements for a sediment toxicity test.

 

Results Synopsis

 

Test Organism Age (e.g. 1^stinstar): first instar

Test Type (Flow through Static, Static Renewal): semi-static

 

EC₁₀(emergence): 0.231 µg/g nonylphenol (average of Test 1 and Test 2 results)

Bettinetti and Provini(2002) was chosen as a key study because provides toxicity results of nonylphenol to the sediment organism, Chironomus riparius. Although results from this study are less sensitive than findings from Kahl et al. (1997) for a sediment organism of the same genus, results from this study are deemed more reliable as it was well documented and did not appear to have analytical issues as described in Kahl et al.(1997).

Description of key information

Read-across approach from nonylphenol.
Bettinetti and Provini (2002) provided 28 day EC10 = 231 mg nonylphenol/kg dw based on emergence.  This value is the mean of two test results (203 and 259 mg/kg) dw.  

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater sediment:

231 mg/kg sediment dw

EC10, LC10 or NOEC for marine water sediment:

61.5 mg/kg sediment dw

Additional information

Read Across

Studies on the toxicity of nonylphenol were included in using the read-across approach to meet data requirements for the toxicity of octylphenol to sediment organisms. Argumentations based on the structural similarity of the substances, their purity and the reliability of studies are the same as for the aquatic species and are provided below.

It has been determined according to this information that read-across from nonylphenol to octylphenol for toxicity to sediment organisms can be used for four reasons; (i) the two substances are considered analogue substances, (ii) the toxicities of the substances are similar, and (iii) the information is reliable and (iv) the substances tested were without impurities.

Structure

A structural analogue is a source chemical whose physico-chemical and toxicological properties are likely to be similar to the target chemical as a result of structural similarity. The structural similarity and similar properties between PTOP and NP support consideration of these substances as structural analogues for the purpose of read-across. Thus, endpoint information is read-across between structural analogues.

The similarity between PTOP and NP is based on their structural likeness (→similar chain length: eight and nine C-atoms for PTOP and NP, respectively) and their common functional group (→phenol group). PTOP and NP display very similar physico-chemical properties that determine environmental distribution and fate (e.g. molecular weight, partition coefficients such as log Kow, water solubility) and ecotoxic effects.

Toxicity

In the absence of reliable toxicity data for sediment organisms, the aquatic toxicity of the two substances was compared (data are summarised in the table below). The data for both short- and long-term toxicity are within the same orders of magnitude with comparable ranges of toxicity. It would be reasonable to assume that comparable ranges of toxicity between NP and PTOP would also be exhibited by sediment organisms. Accordingly, reliable NP sediment toxicity data are used to fill the data gap for PTOP sediment toxicity. Reliable data for nonylphenol toxicity to aquatic organisms is also used in the calculation of the PNEC_sedimentfor octylphenol.

A Comparison of Ecotoxicity Data for the Same Aquatic Species (where available) Exposed to NP and PTOP
Species               and Type of Test	NP Toxicity Range (mg/L)	PTOP Toxicity Range (mg/L)
Ceriodaphnia sp. 48 hr L(E)C50	0.02 to 0.47	0.07 to 0.28
Americamysis bahia 96 hr LC50	0.043 to 0.06	0.048 to 0.113
Oncorhynchus mykiss    96 hr LC50	0.11 to 0.22	>0.1
Fundulus heteroclitus     96 hr LC50	0.26 to 5.44	0.29 to 3.86
Daphnia magna               21-d NOEC	0.013 to 0.116	0.03
Fish        NOEC	>0.0019 to 0.078	0.012 to 0.035

 

Reliability, Adequacy and Accuracy of the Source Studies

All of the ecotoxicity studies used in the CSR were carried out in accordance with OECD or similar guidelines and scored a Klimisch I or II. In particular, the studies represented in the table above showed consistent results indicating that octylphenol is ecotoxic to aquatic organisms. These studies are considered to be reliable for use in read-across between NP and PTOP and the same argumentations of consistency and reliability are made for sediment data.

Evaluation of the purity and impurity profiles of the Test Substance

The purity of PTOP used in the key studies for ecotoxicological endpoints ranged from 98.97 to 100%. The purity of NP used in key studies was 85 to 100%, with all but one study being ≥90% purity. Impurities were not reported these ecotoxicity studies evaluated for the CSR. Because of the high purity of the test substance, impurities probably do have a negligible or no impact on the ecotoxicity of PTOP.

In summary, NP and PTOP are similar in structural composition and both exert similar short- and long-term toxic effects to aquatic organisms. The studies used to make these comparisons are highly reliable (Klimisch I or II) and the NP or PTOP test substance in toxicity studies were of high purity. Therefore, it is considered scientifically for sediment toxicity data relating to NP studies to be read-across to PTOP endpoints and used in PNEC_sedimentderivation.

Summary of the ecotoxicity data

A review of reports for nonylphenol exposure to sediment organisms resulted in selection of two reliable studies that included two freshwater organisms and one marine organism.  The study of nonylphenol exposure to Chironomus riparius andTubifix tubifix in spiked sediment tests by Bettinetti and Provini (2002) was selected as the key study because it provided calculated EC₁₀concentrations for endpoints derived from duplicate tests for more than one sediment organism. The EC₁₀concentration is accepted as an equivalent substitute for the NOEC value, and has the added benefit of being a calculated response-based concentration rather than an estimate derived from the treatment dilution series. The average EC₁₀concentration reported in the key study for inhibition of Chironomus riparius emergence was 231 nonylphenol/Kg dw, which was comparable to an average EC₁₀concentration of 360 and 359 mg nonylphenol/Kg dw for production of cocoons and production of young worms, respectively, for Tubifix tubifix (Bettinetti and Provini 2002).  

 

In supporting documents, the 28 -day NOEC for Leptocheirus plumulosus, a marine benthic crustacean, survival and reproduction from exposure to nonylphenol was reported by Zulkosky et al. (2002) to be >61.5 mg nonylphenol/Kg dw for both endpoints.