Thermal cracking oil from blends of rubber, fuel oils and paraffin waxes, steam distillation concentrate

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Study period:

2021

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: An assessment was performed based on the predictive model PetroTox and for the other polar constituents, a combination of available data in literature and the use of QSAR modelling with ECOSAR (2.0)

Justification for type of information:

The aquatic toxicity was estimated by a QSAR, the Petrotox computer model (v.4). This model combines a partitioning model used to calculate the aqueous concentration of hydrocarbon components with the Target Lipid Model used to calculate acute and chronic toxicity of non-polar narcotic chemicals. Petrotox computes toxicity based on the summation of the aqueous-phase concentrations of hydrocarbon block(s) that represent a hydrocarbon substance and membrane-water partition coefficients (KMW) that describe the partitioning of the hydrocarbons between the water and organism.

The other polar constituents of the substance were assessed using predicted toxicity data from ECOSAR 2.0 made available by the EPA. ECOSAR groups structurally similar organic chemicals with available experimental effect levels that are correlated with physicochemical properties in order to predict toxicity of new or untested industrial chemicals.

Qualifier:

no guideline followed

Principles of method if other than guideline:

The aquatic toxicity was estimated by a QSAR, the Petrotox computer model (v.4). This model combines a partitioning model used to calculate the aqueous concentration of hydrocarbon components with the Target Lipid Model used to calculate acute and chronic toxicity of non-polar narcotic chemicals. Petrotox computes toxicity based on the summation of the aqueous-phase concentrations of hydrocarbon block(s) that represent a hydrocarbon substance and membrane-water partition coefficients (KMW) that describe the partitioning of the hydrocarbons between the water and organism.

The other polar constituents of the substance were assessed using predicted toxicity data from ECOSAR 2.0 made available by the EPA. ECOSAR groups structurally similar organic chemicals with available experimental effect levels that are correlated with physicochemical properties in order to predict toxicity of new or untested industrial chemicals.

Key result

Dose descriptor:

NOEC

Effect conc.:

2.95 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Remarks on result:

other: QSAR predicted value

Details on results:

See attached expert assessment

Conclusions:

The chronic toxicity (Geometric mean NOEC and LOEC) of naphtha to invertebrates is predicted to be 53.2 mg/L on the basis of polar fraction and 2.95 mg/L on the basis of hydrocarbon fraction. Hence, a NOEL of 2.95 mg/L can be considered as the chronic toxicity value of naphtha in invertebrates.

Executive summary:

Thermal cracking oil from blends of rubber, fuel oils and paraffin waxes, steam distillation condensate (EC 942-492-8) is a complex UVCB consisting of a combination of different hydrocarbon constituents with a range of different molecular weights and structures. As toxicity test data to invertebrates for the substance was not available, QSAR modelling was used to assess the toxicity to invertebrates for this substance.
For the hydrocarbon fraction the predictive model PetroTox, made available by CONCAWE was used, and for the other polar constituents, a combination of available data in literature and the use of QSAR modelling with ECOSAR (2.0) from the EPA was used.

The chronic toxicity (Geometric mean NOEC and LOEC) of naphtha to invertebrates is predicted to be 53.2 mg/L on the basis of polar fraction and 2.95 mg/L on the basis of hydrocarbon fraction. Hence, a NOEL of 2.95 mg/L can be considered as the chronic toxicity value of naphtha in invertebrates.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

NOEC

Remarks:

predicted value

Effect concentration:

2.95 mg/L