Dibutyl terephthalate

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

1.3 µg/L

Assessment factor:

10

PNEC freshwater (intermittent releases):

0.13 µg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.13 µg/L

Assessment factor:

100

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

1.45 mg/L

Assessment factor:

10

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

6.94 mg/kg sediment dw

Assessment factor:

100

Extrapolation method:

assessment factor

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.694 mg/kg sediment dw

Assessment factor:

1 000

Extrapolation method:

assessment factor

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

0.068 mg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

Table 1 contains a listing of ecotoxicity values considered in the derivation of preliminary PNEC values for dibutyl terephthalate.

 

Table 1:Summary of key and supporting studies

 

Study/Endpoint	Details/Results	NOEC/L(E)C50
Aquatic Toxicity
Pimephales promelasFathead Minnows, Static, 96-Hour, Acute	Measured concentration (mean): 0.17 mg/L. No mortality or abnormal effects. Note: the LC50and NOEC values reported in this study are greater than the measured aqueous solubility.	LC50> 0.17 mg/L   NOEC ≥ 0.17 mg/L
Pimephales promelasFathead Minnows, Early Life Stage, Flow-through, 32 day (28 days post hatch), Long-Term	Measured concentrations (mean): 5.1, 11, 24, 58 and 100 µg/L. No effects on hatching success or percent normal larvae. Length and dry weight were reduced at the highest concentration. Mortality was the most sensitive indicator and was reduced at the two highest exposure concentrations. Note: it was believed that concentrations greater than the measured water solubility were achieved with a carrier solvent and that a lack of chronic toxicity at the limit of solubility was demonstrated.	NOEC (4 d) ≥ 100 µg/L (no. hatched and larval development)   NOEC (32 d) ≥ 58 µg/L (length / weight)   NOEC (32 d) ≥ 24 µg/L (mortality)
Daphnia magna, Static, 96-Hour, Acute	Measured concentrations (mean): 0.02, 0.04, 0.08, 0.16 and 0.34 mg/L. Endpoint immobility. At the highest exposure concentration, six immobile and one missing organism. Note: EC50and NOEC values greater than the measured aqueous solubility of the test substance.	EC50(48 h) > 0.34 mg/L   NOEC (48 h)³0.16 mg/L
Daphnia magna,Flow-through, 21 d, Full Life Cycle Toxicity Test, Long-Term	Measured (time-weighted averages): 5.2, 13, 29, 50 and 98 µg/L. No test concentration resulted in a 50% reduction in survival (mobility), growth or reproductive output. Note: it was believed that concentrations greater than the measured water solubility (4.51 µg/L, deionized water) were achieved with a carrier solvent and that a lack of chronic toxicity at the limit of solubility was demonstrated.	EC50(21 d) ≥ 98 µg/L (immobility, reproduction, growth)   NOEC (21 d) ≥ 98 µg/L (immobility)   NOEC (21 d) ≥ 50 µg/L (reproduction, growth)
Pseudokirchneriella subcapitata,Algae Growth Inhibition, Static, 72 Hour	Measured concentration (mean): 0.013 mg/L. Growth rate was inhibited 14 and 3% (duplicate runs) at 72 hours. OECD Guideline 201 suggests EC20 value may be used as the NOEC. Note: the measured average concentration (0.013 mg/L) closely matched the functional limit of solubility of the test material in the algal media.	EC50> 0.013 mg/L (growth rate/biomass)   EC20(72 h) ≥ 0.013 mg/L (growth rate/biomass)   NOEC ≥ 0.013 mg/L (growth rate/biomass)

 

Calculation of PNECs from Aquatic Freshwater Values - Using Assessment Factors and the Equilibrium Partitioning Method (EPM)

 

Reliable test data are available for the three principle trophic levels: primary producers, represented by algae; plant eating animals, represented by daphnids; and predators, represented by fish (see Guidance on Information Requirements and Chemical Safety Assessment. Chapter R.10, May 2008).

 

Aquatic organisms

 

freshwater:

 

The acute and long-term LC₅₀, EC₅₀, EC₂₀or NOEC values obtained for the three primary aquatic trophic levels are summarized in Table 1. Given that an algal toxicity study may serve as a long-term toxicity test, the three trophic levels are thus represented by long-term toxicity information. Algae were selected to represent the most sensitive aquatic species with a NOEC ≥ 13 µg/L. According toGuidance on Information Requirements and Chemical Safety Assessment (Chapter R.10, Section R.10.3.1.2 and Table R.10-4, May 2008), a default assessment factor of 10 is employed in this situation. Thus, ThePNEC_freshwateris calculated by dividing 13 µg/L by 10 yielding 1.3 µg/L.

 

A PNEC_marine-wateris derived by applying the standard assessment factor of 100 to the NOEC value of 13 µg/L, resulting in a PNEC_marine-waterof 0.13 µg/L (see Guidance on Information Requirements and Chemical Safety Assessment. Chapter R.10, Section R.10.3.2.3 and Table R.10-5, May 2008).

 

A PNEC_{water, intermittent}is derived by applying the standard assessment factor of 100 to the lowest L(E)C₅₀value from at least three short-term tests from three trophic levels (see Guidance on Information Requirements and Chemical Safety Assessment. Chapter R.10, Section R.10.3.3, May 2008). In the present case, the PNEC_{water, intermittent}is obtained by dividing the EC₅₀value of algae (13 µg/L) by 100 to yield 0.13 µg/L.

 

STP microbes

No test for inhibition of sewage sludge microorganisms is available for dibutyl terephthalate. Based on a lack of toxicity or inhibition to the inoculum in a reliable test for biodegradability at a concentration of 10 mg C/L, a NOEC of 14.5 mg/L for sewage sludge inhibition is assumed based on a nominal dibutyl terephthalate concentration (10 mg/L as dissolved organic carbon, corrected for a molecular formula of C₁₆H₂₂O₄). The PNEC_{STP microbes}was derived by applying an assessment factor of 10, resulting in a value of 1.45 mg/L (see Guidance on Information Requirements and Chemical Safety Assessment. Chapter R.10, Section R.10.4.1 and Table R.10-6, May 2008).

 

Sediment

One long-term sediment test is available for exposure of dibutyl terephthalate to the chironomid, Chironomus riparious. This endpoint was used to calculate PNEC values for this environmental compartment (see Guidance on Information Requirements and Chemical Safety Assessment. Chapter R.10, Section R.10.5.2.1 and Equation R.10-2, May 2008). An assessment factor of 100 was applied to the 28 -day NOEC value of 694 mg/kg dwt (based on the geometric mean measured calculation) resulting in a PNEC_{sediment-freshwater} of 6.94 mg/kg dwt. The PNEC_{sediment-marine} was calculated by applying an assessment factor of 1000 based on recommendation in Guidance on Information Requirements and Chemical Safety Assessment. Chapter R.10, Section R.10.4.1 and Table R.10-6, May 2008 and resulted in a value of .694 mg/kg dwt.

 

 

Terrestrial (Soil) Compartment

 

There are no available terrestrial effects testing results for dibutyl terephthalate for any soil-dwelling organism. Based on the safety assessment guidance for this endpoint (Chapter R.7c, R.7.11.5.3), extrapolating aquatic toxicity data using the Equilibrium Partitioning Method is recommended. In the same way as the above PNEC values for sediment were obtained, a PNEC_soilvalue was calculated using the EUSES program (see Guidance on Information Requirements and Chemical Safety Assessment. Chapter R.10, Section R.10.6.1 and Equation R.10-5, May 2008). The EUSES program gave the following:

 

PNEC_soil= 0.0682 mg/kg dry wt.

 

 

Secondary Poisoning

 

There is no available information on the long-term or reproductive toxicity of dibutyl terephthalate to birds (see REACH, Annex X). The assessment of secondary poisoning is most relevant for certain lipophilic organic materials and some metal compounds (see Guidance on Information Requirements and Chemical Safety Assessment. Chapter R.10, Section R.10.8). Dibutyl terephthalte is a readily biodegradable substance with a low potential for bioaccumulation. Thus, an assessment of secondary poisoning and the calculation of a PNEC_oralvalue for dibutyl terephthalate were not performed.

 

Conclusion on classification

Dibutyl terephthalate is not classified for environmental effects.