2,4-di-tert-butylphenol

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.001 mg/L

Assessment factor:

50

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.004 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0 mg/L

Assessment factor:

500

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

0.1 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

0.661 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.066 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

1.2 mg/kg soil dw

Assessment factor:

10

Extrapolation method:

assessment factor

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

33.33 mg/kg food

Assessment factor:

90

Additional information

Effects on Aquatic Organisms

Micro-organisms

A 3 hour respiration inhibition study carried out according to OECD 209 was used to assess the effect of 2,4-DTBP on STP micro-organisms. An EC₅₀ of >10 mg/l was determined (no NOEC was determined). According to the TGD an AF of 100 should be applied to derive a PNEC_STP of 0.10 mg/l.

Species	Endpoint	Comments	Reference
Activated sludge respiration inhibition testing	EC50= >10 mg/l	Key Study	Sewell I.G. (1991) Activated sludge respiration inhibition test, Safepharm Laboratories Ltd., Derby, UK, SI Group, Report No. S0052/E349
	Inhibition of bacterial O2consumption (mean) = 1711 mg/l   EC10could not be established.	Supporting Study	Schöberl P. (1991) Bestimmung der Bakterientoxizität von 2,4-di-tert.-Butylphenol im Sauerstoff-Konsumptions-Test (Huels Methode), Huels AG, Sasol Germany GmbH, Report No. SK-91/2

Water compartment

The current strategy for deriving a protective PNEC_water, outlined in the Technical Guidance Document for risk assessment (2003), indicates that the appropriate assessment factor should be applied to the lowest acute L(E)C₅₀value obtained from toxicity testing in fish, aquatic invertebrate and algal species. In the event that chronic toxicity data are available from three separate trophic levels, the lowest NOEC value is used with an assessment factor of 10 applied for fresh water and 100 applied for marine water.

Detailed below is an assessment of the available data ecotoxicological data together with recommendations for the endpoints which should be used to determine the Predicted No Effect Concentration for 2,4-DTBP in the fresh water environment (PNEC_freshwater) and marine environment (PNEC_marinewater):-

Fish

Two studies were conducted in fish using 2,4-DTBP; a rainbow trout 96h study and a Golden ide 48h study. The LC₅₀from the rainbow trout was found to be greater than the highest value tested and is therefore not considered appropriate for setting the PNEC. The second study conducted using Golden ide is also not considered appropriate for setting the PNEC as the study was performed over 48h and not 96h, and the test species is not a standard species as defined in the OECD Guideline 203. It was therefore considered more appropriate to read across to the studies conducted using 2,6-DTBP.

Four studies were conducted in fish. Two acute studies (rainbow trout and zebra fish) and two prolonged toxicity tests (14 days; rainbow trout and fathead minnows). From the 14 day studies conducted in fathead minnows and rainbow trout it was also possible to determine 96 h LC₅₀values thereby satisfying the requirements of an acute toxicity test. Due to a poor dose response relationship the results from the 14 day prolonged toxicity test with rainbow trout were considered to have lower reliability than the fathead minnow results.

The two rainbow trout 96h LC₅₀ results were greater than the highest value tested. The 96 h LC₅₀ fathead minnow result therefore represents the lowest and most accurate result for basing the PNEC.

There were no long-term fish studies.

Species	Endpoint	Comments	Reference
Fish toxicity	LC50in Golden ide(48h) = 1.8 mg/l	Non-standard species and time period	Scholz N. (1987) Bestimmung der akuten Wirkungen von 2,4-di-tert-Butylphenol gegenüber Fischen, Huels AG, Sasol Germany GmbH, Report No. F 786
	96 h LC50in rainbow trout = >0.10 mg a.i./L	Highest value tested	Sewell I.G. (1991) Acute toxicity to rainbow trout, Safepharm laboratories Ltd., Derby, UK, SI Group, Report No. 47/1594
	Read across to 2,6-DTBP 96 h LC50in rainbow trout = >1.0 mg a.i./L	Highest value tested-no effects found	Sewell I.G. (1991) Acute toxicity to rainbow trout, Safepharm laboratories Ltd., Derby, UK, SI Group, Report No. 47/1612
	Read across to 2,6-DTBP 96 h LC50in zebra fish = 13 mg/L LC0 (96 h) = 10 mg/L	nominal concentrations	Rufli H. (1987) Report on the test for acute toxicity of TK 12891 to Zebra fish, OECD-Guideline No. 203 Paris (1984), US EPA OTS 86-870000305, Ciba-Geigy Ltd., Report No. 87 40 50
	Read across to 2,6-DTBP 96 h LC50in rainbow trout = >0.10 mg a.i./L	Highest value tested	Surprenant D.C. (1989) Acute Toxicity of 2,6-di-tert-butylphenol to Rainbow Trout (Salmo gairdneri) during a 14-day flow-through exposure, Springborn Life Sciences, Albemarle, Report No. 89-05-2948
	Read across to 2,6-DTBP 14 day LC50Rainbow Trout = 0.74 mg/l
	Read across to 2,6-DTBP 96 h LC50in fathead minnows = 1.4 mg a.i./L NOAEL (14 days) = 0.30 mg/L.	KEY STUDY	Surprenant D.C. (1989) Acute toxicity of 2,6-di-tert-butylphenol to fathead minnows (Pimephales promelas) during a 14-day flow-through exposure, Springborn Life Sciences, Inc., Albemarle, Report No. 86-12-2876
	Read across to 2,6-DTBP 7 day LC50fathead minnows = 1.1 mg/l
	Read across to 2,6-DTBP 14 day LC50fathead minnows = 1 mg/l

Invertebrates

Species	Endpoint	Comments	Reference
Invertebrate toxicity	48 h EC50in Daphnids = 0.50 mg a.i./L NOEC = 0.20 mg a.i./L	KEY STUDY	Lebertz H. (2001)Study on the acute toxicity towards Daphnia of 2,4,di-tert-Butylphenol, Institut Fresenius Chemische un Biologische laboratorien AG, Taunusstein, Germany, SI Group/Sasol, Report No. IF-202/24135-00

Daphnids were found to be more sensitive than fish with an endpoint of 0.50 mg a.i./L. 

As a result of a testing proposal, a chronic Daphnia magna study was conducted on 2,4 -DTBP:

Species	Endpoint	Comments	Reference
Invertebrate toxicity	21 d NOEC = 0.1 mg a.i./L	KEY STUDY	Migchielsen M. (2014) Daphnia magna, reproduction test with 2,4-di-tert-butylphenol (flow-through), WIL Research Europe B.V., Report No. 503526

Aquatic Plants

Species	Endpoint	Comments	Reference
Algal toxicity	ErC50in Algae = 0.37 mg/l NOErC = 0.073 mg/l	KEY STUDY LOWEST ENDPOINT	Hafner, C. (2010) Algae, Growth Inhibition Test with 2,4-di-tert-Butylphenol according to OECD 201 (March 23rd, 2006)

Algae were shown to be the most sensitive aquatic species (ErC₅₀= 0.37 mg/l; NOErC = 0.073 mg/l)and will therefore be used to derive the PNEC. 

Summary Water Compartment

From the aquatic tests described above, the proposed PNEC_freshwater 0.00146 mg a.i./L,is based on the most sensitive species which was found to be algae with an assessment factor of 50 (2 long-term tests available). The proposed PNEC_marinewater 0.000146 mg a.i./L, is based on the application of an additional assessment factor of 10 to the assessment factor of 50 applied to the NOEC value obtained in the algae toxicity study.

Sediment

A PNEC_{sediment,freshwater} has been determined using the equilibrium partitioning method based on the PNEC_freshwater derived above in accordance with the TGD (equation 70).

Where:-

RHO_susp= 1150 kg/m³
PNEC_freshwater= 0.00146 mg/l
K_susp-water= 113 m³/m³(calculated using TGD equation 24)
PNEC_{sediment,freshwater}= 0.144 mg/kg wwt (0.661 mg/kg dwt)

A PNEC_{sediment,marine}has been determined using the equilibrium partitioning method based on the PNEC_waterderived above in accordance with the TGD (equation 70).

Where:-

RHO_susp= 1150 kg/m³
PNEC_marinewater= 0.000146 mg/l
K_susp-water= 113 m³/m³(calculated using TGD equation 24)
PNEC_{sediment,marine}= 0.0144 mg/kg wwt (0.0661 mg/kg dwt)

Terrestrial Compartment

A PNECsoil has been determined using the respective assessment factor for the derivation of PNECsoil based on available long-term data for three species of three trophic levels in accordance with the Guidance on information requirements and chemical safety assessment Chapter R.10 (Table R.10 -10).

Terrestrial microorganisms

Species	Endpoint	Comments	Reference
Toxicity to microorganisms	28d-NOEC = 49.4 mg/kg dw	KEY STUDY	Tunink A (2015)

The effects of 2,4 -DTBP were also tested on the microbial community as a third terrestrial trophic level. Effects were determined as the percent inhibition on Day 28, based on nitrate concentration, 25.9, -1.2, -1.2, -2.4, and -0.4% in the 1,000, 49.4, 2.49, 0.125, and 0.00619 μg/g treatments, respectively. The derived effect values EC50, EC25, and NOEC are >1000µg/g, ~1000µg/g and 49.4 µg/g, respectively.

Terrestrial plants

Species	Endpoint	Comments	Reference
Toxicity to six mono- and dicot species	21d-EC20 in oat = 13.1 mg/kg dw(lowest derived effect value in this study)	KEY STUDY	Lee B (2015)

The lowest effect concentration determined in the Seedling Emergence study following OECD test guideline 208, assessing the toxicity of 2,4 -DTBP towards mono- and dicot plant species is the EC20 of 13.1 mg/kg dry soil for shoot weight reduction in oat. The lowest obtained effect concentration for shoot length is found in oat as well with an EC10 of 29 mg/kg dry weight. For both, emergence and survival, onion is the most sensitive species with a NOEC of 37.0 mg/kg dry weight. Terrestrial soil macroorganisms except arthropods

Species	Endpoint	Comments	Reference
Toxicity to Eisenia foetida	56d-NOEC = 12 mg/kg dw	KEY STUDY-LOWEST ENDPOINT	Aufderheide J (2015)

The terrestrial toxicity of 2,4-di-tert-butylphenol towards soil macroorganisms was assessed in a Survival and Reproduction Test with the Earthworm, Eisenia fetida according to OECD test guideline 222. The NOEC and LOEC values after 56 days of exposure for reproduction are 12 and 23 mg/kg, respectively, and hence the NOEC is used for PNECsoil derivation.

 PNEC_soil derivation 

Assessment Factor	10
min. long term effect value	NOEC(OECD222)=12 mg/kg soil
PNEC	1.2 mg/kg soil

Environmental No effect Concentrations (PNECs)

Compartment	Value	Units
Microorganisms in STP	0.10	mg/L
Freshwater aquatic	0.00146	mg/L
Freshwater sediment (to be updated from partition coefficient when new efate data available)	0.1438 0.661	mg/kg wwt mg/kg dwt
Marine water	0.000146	mg/L
Marine sediment (to be updated from partition coefficient when new efate data available)	0.01438 0.0661	mg/kg wwt mg/kg dwt
Terrestrial compartment	1.2	mg/kg dwt
Man via the environment (total daily intake)	3.75	mg/kg bw/d
Secondary Poisoning of Birds and Mammals	33.33	mg/kg

 

Conclusion on classification

According to GHS 2,4 -di-tert-butylphenol should be classified as follows:-

ACUTE CATEGORY 1

(M Factor = 1)

Hazard Phrase H400

CHRONIC CATEGORY 1

Hazard Phrase H410

(Due to Algae being <1.0 mg/l)