(1-methylethyl)-1,1'-biphenyl

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.54 µg/L

Assessment factor:

50

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

3 µg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.054 µg/L

Assessment factor:

500

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

2 mg/L

Assessment factor:

10

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

1.355 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

135.5 µg/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:

269.9 µg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential to cause toxic effects if accumulated (in higher organisms) via the food chain

Additional information

As justified under aquatic toxicity, test results obtained with the supporting substance 4-ethylbiphenyl are taken into account in the toxicity evaluation of (1-methylethyl)-1,1'-biphenyl.

Deduction of PNECs is based on the Guidance Document "Guidance on information requirements and chemical safety assessment - Chapter R.10: Characterisation of dose [concentration]-response for environment" (TGD R.10) published by the European Chemicals Agency, 2008.

Using the equilibration partitioning method in calculating the PNECs for sediment and soil, values for Koc and Henry's Law Constant (HLC) are required. A value for Koc was calculated using the estimation program US EPA EPI Suite (25055 L/kg; IUCLID Sect. 5.4.1). For HLC, a measured value is available (173.3 Pa m³/mol; IUCLID Sect. 5.4.2). When different values are reported, the values resulting in lower PNECs are chosen.

PNECs aqua (freshwater / marine water) derived above are entered in the equilibrium partitioning calculations.

PNEC sediment (freshwater)

According to chapter R.10.5.2.1 of TGD R.10, the PNEC sediment can provisionally be calculated in the absence of data for sediment-dwelling organisms using the equilibrium partitioning method (EPM).

PNEC derivation following procedures of TGD R.10 and R.16:

PNEC aqua (freshwater): 0.54 µg/L,

Koc: 25,055(US EPA EPI Suite estimate, program KOCWIN v2.00, Koc estimate from MCI; see IUCLID sect. 5.4.1);

The PNEC sediment (freshwater) was calculated to 294.55 µg/kg ww. This value was converted to dry weight (conversion factor of 4.6) resulting in a PNEC sediment (freshwater) of 1.355 mg/kg sediment dw.

PNEC sediment (marine water)

According to chapter R.10.5.3.1 of TGD R.10, the PNEC sediment can provisionally be calculated in the absence of data for sediment-dwelling organisms using the equilibrium partitioning method (EPM).

PNEC derivation following procedures of TGD R.10 and R.16:

PNEC aqua (marine water): 0.024 µg/L,

Koc: 25055 (US EPA EPI Suite estimate, program KOCWIN v2.00, Koc estimate from MCI; IUCLID sect. 5.4.1);

The PNEC sediment (marine water) was calculated to 29.45 µg/kg ww. This value was converted to dry weight (conversion factor of 4.6) resulting in a PNEC sediment (marine water) of 135.5 µg/kg sediment dw.

PNEC soil

According to chapter R.10.6.1 of TGD R.10, the PNEC soil can provisionally be calculated in the absence of data for soil organisms using the equilibrium partitioning method (EPM).

PNEC derivation following procedures of TGD R.10 and R.16:

PNEC water (freshwater): 0.24 µg/L,

Koc: 25055 (US EPA EPI Suite estimate, program KOCWIN v2.00, Koc estimate from MCI; IUCLID sect. 5.4.1),

HLC: 173.3 Pa*m³/mol (measured, Mendoza/DOW 1981; IUCLID sect. 5.4.2);

The PNEC soil was calculated to 238.83 µg/kg ww. This value was converted to dry weight (conversion factor of 1.13) resulting in a PNEC soil of 269.9 µg/kg soil dw.

Conclusion on classification

(1-Methylethyl)-1,1'-biphenyl [CAS no. 25640-78-2] shows acute aquatic toxicity below 1 mg/L on all three trophic levels: 0.15 =< EC/LC50 =< 0.7 mg/L.

According to Regulation (EC) No 1272/2008, this triggers classification 'Aquatic Acute 1', H400 (very toxic to aquatic life).

In addition, chronic aquatic toxicity data is in the range of 0.01 =< NOEC =< 0.1 mg/L, based on the structure-analogous 4-ethylbiphenyl [CAS no. 5707-44-8], and in combination with easy/rapid biodegradability leads to classification with 'Aquatic Chronic 2', H411 (toxic to aquatic life with long lasting effects).