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

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

fish life cycle toxicity

Type of information:

(Q)SAR

Remarks:

The substance is a complex UVCB. Test data for the substance was not available; hence, QSAR modelling was used to assess the toxicity to fish.

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.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Remarks on exposure duration:

Chronic; QSAR

Key result

Duration:

28 d

Dose descriptor:

NOELR

Effect conc.:

1.69 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Conclusions:

A NOEL of 1.69 mg/L can be considered as the chronic toxicity value of naphtha in fish.

Executive summary:

The substance, which is designated in this report as ‘naphtha’, is a complex UVCB consisting of a combination of different hydrocarbon constituents with a range of different molecular weights and structures. As test data for the substance was not available, QSAR modelling was used to assess the toxicity to fish 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.

 

Using hydrocarbon blocks divided up into 16 chemical classes, representative structures are chosen by the software based on similarities in chemical composition. 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. Within naphtha (EC 942-492-8), in the specific case of the substance C8-alkyne (unspecified isomer) 0.47% could not be placed in any of the specific hydrocarbon classes within the PETROTOX software, as such the concentration of this constituent was assigned to the C8 i-olefins block.

The simulation was performed using the default parameters of the PETROTOX software with a 10% headspace volume to account of volatilisation of some constituents. In addition, particulate organic carbon level was set at 0.05 mg/L for fish toxicity testing based on value reported in published papers (Redman et al., 2017).

 

A NOEL of 1.69 mg/L can be considered as the chronic toxicity value of naphtha in fish.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

NOEC

Remarks:

Predicted value

Effect concentration:

1.69 mg/L