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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Reference
Endpoint:
bioaccumulation in aquatic species: fish
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
2015
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Accepted calculation method.
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
Guideline:
other: REACH guidance on QSARs R.6, May 2008
Principles of method if other than guideline:
Calculated with BCF Program BCFBAF v.3.01 included in the Estimation Programs Interface (EPI)-Suite. The estimation methodology is based on the chemical structure of an organic compound and its log octanol-water partition coefficient (log Kow). Depending on chemical structure, structural correction factors are applied.
GLP compliance:
no
Radiolabelling:
no
Test organisms (species):
other: none, estimated by calculation
Type:
BCF
Value:
31.2 L/kg
Basis:
other: calculation

Any decomposition of the substance in water is not considered by the program.

Validity of model:

- Defined endpoint: bioconcentration of a substance in biota

- Unambiguous algorithm: linear regression QSAR.

Because of the deviation from rectilinearity, different models were developed for different log Kow ranges. Metals (tin and mercury), long chain alkyls and aromatic azo compounds are specially treated.

- Applicability domain: the model is applicable to ionic as well as non-ionic compounds. It is applicable to substances with a logKow in the following range: -6.50 to 7.86(ionic compounds) and -1.37 to 11.26 (non-ionic compounds). Applicable to substances with a molecular weight in the following range: 102.13 to 991.80 g/mole (ionic substances) and 68.08 and 959.17 g/mole (non-ionic compounds). ). Model predictions may be highly uncertain for chemicals that have estimated logKow values > 9. The model is not recommended at this time for chemicals that appreciably ionize, for pigments and dyes, or for perfluorinated substances.

- Statistical characteristics:

number in dataset = 527

correlation coef (r2) = 0.833

standard deviation = 0.502

- Mechanistic interpretation:

The BCF is an inherent property used to describe the accumulation of a substance dissolved in water by an aquatic organism based on the lipophilicity of the compound.

Adequacy of prediction: N-isopropyl-N'-phenyl-p-phenylenediamine falls within the applicability domain described above and, therefore, the predicted value can be considered reliable taking into account that the standard deviation error of prediction of the external test set is 0.59 (logBCF). Considering that error, the predicted value is not above or close to the criterion to consider a substance as potential bioaccumulative, and thus provides evidence that the substance does not fulfil the B-criterion.

Validity criteria fulfilled:
not applicable
Conclusions:
The QSAR determination of the bioaccumulation factor for Substance using the model BCFBAF included in the Estimation Program Interface (EPI) Suite v4.1 revealed values of 31.2 L/kg for the unaffected molecule of the substance as any decomposition (e.g. hydrolysis) of the substance is not taken into account by the program.
Executive summary:

The bioaccumulation factor of N-isopropyl-N'-phenyl-p-phenylenediamine was estimated to be 31.24 L/kg using the BCFBAF model included in the EPI-Suite Programm concluding that the substance has a low potential to bioaccumulate in biota. Within the scope of the Persistency-Bioaccumulation-Toxicity (PBT)-Assessment, the substance does not fulfil the B-criterion.

The substance falls within the applicability domain described above and, therefore, the predicted value can be considered reliable.

Description of key information

Based on the measured log Kow of 2.77 a BCF of 31.2 is estimated using EPI Suite program.
The BCF of 4-hydroxydiphenylamine, the main hydrolysis product from N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD) was determined by the Chemicals Inspection & Testing Institute of Japan (MITI, 1994) using a Bioconcentrations test that corresponds to OECD Guideline 305 C. The bioconcentration factor ranges from 3.3 - 49. For the second hydrolysis product p-quinoneimine-N-phenyl, the measured BCF is in the range of 1.2 – 23.

Key value for chemical safety assessment

BCF (aquatic species):
31.2 dimensionless

Additional information

Although no experimental BCF for the substance IPPD is available, the calculated result indicates that the substance does not meet the B criterion as it is far below the trigger value of 2000.

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