4-(4-nitrophenylazo)-2,6-di-sec-butyl-phenol

PBT assessment

PBT assessment: overall result

Reference

Name:

Boundary Composition: 4-(4-nitrophenylazo)-2,6-di-sec-butyl-phenol

Type of composition:

boundary composition of the substance

State / form:

liquid

Reference substance:

Boundary Composition: 4-(4-nitrophenylazo)-2,6-di-sec-butyl-phenol

PBT status:

the substance is not PBT / vPvB

Justification:

The available evidence on degradation, bioaccumulation potential, and toxicity for Mortrace SB Conc (and impurities) indicates that the screening criteria for persistence (P) is met, the criteria for bioaccumulation potential (B) is not met, and the criteria for toxicity (T) is met. Based on the information described below, the substance can be considered P and T, but not B. Thus, Mortrace SB Conc is not PBT and is not vP/vB.

Persistence assessment:The test substance is not readily biodegradable. Mortrace SB Conc was tested for its ready biodegradability in the modified Sturm test (OECD 301B) at nominal concentrations of 10 and 20 mg/L. The relative degradation values calculated from the measurements performed during the test period revealed 21% degradation at the low concentration and 13% at the high concentration. Since 60% biodegradation was not reached, the criteria for ready biodegradability were not met. Since the known impurities of Mortrace SB Conc. are isomers of the main component, these impurities. (≤ 4% of the composition) are predicted to also not be readily biodegradable using a read across approach to the main component. Based on screening level criteria, the test substance is considered persistent (P).

Bioaccumulation assessment:The bioaccumulation potential of Mortrace SB Conc. was assessed in a dietary bioaccumulation study. For substances with log Kow values >6, a dietary study is used as a replacement to estimate the bioconcentration factor. Juvenile rainbow trout were administered Mortrace SB Conc in the diet (2 μg/L) for 14 days followed by a 21 -day depuration phase. Theestimated BCF from this dietary bioaccumulation study was 842 - 1070. The lipid normalized biomagnification factor from this study was 0.0174. Both of these data points indicated that Mortrace SB does not meet the criteria for bioaccumulative (B). Since the impurities present in Mortrace SB Conc are very similar in structure to the major component, a read across approach seems justified. Thus, based on the definitive dietary bioaccumulation study with Mortrace SB Conc, the test substance and associated impurities are not expected to be bioaccumulative (B).

Toxicity assessment:The screening assessment for environmental toxicity is based on acute aquatic toxicity testing. An acute toxicity study with the carp,Cyprinus carpio, reported a 96 -hour LC50 value of 10 μg/L. An acute toxicity test withDaphnia magnareported a 48 -hour EC50 of 10 μg/L. A growth inhibition study with the green algae,Scenedesmus subspicatus, reported an estimated 72 -hour ErC50 of 6.7 μg/L (based on growth rate), and a NOEC of 0.28 μg/L. Based on a read across approach with the main component of Mortrace SB Conc., the estimated acute toxicity values for the impurities in Mortrace SB Conc. (≤ 4%) were below the screening level criteria of 0.1 mg/L.  Since the experimental and estimated acute toxicity values for the major component and impurities in Mortrace SB Conc all fall below the screening level criteria of 0.1 mg/L and the more definitive acute toxicity criteria of 0.01 mg/L, Mortrace SB Conc is considered toxic (T) to the environment. Additionally,Mortrace SB Conc meets the criteria for T due to evidence of specific target organ toxicity after repeated exposure (STOT RE category 2 according to the CLP Regulation) and reproductive toxicity (category 2 according to CLP).

Constituent		P/vP		B/vB		T
Mortrace SB Conc. CAS name:4-(4-nitrophenylazo)-2,6-di-sec-butyl-phenol) CAS #: 111850-24-9 EC #: 410-610-2 ~ 98.2% (w/w) (≥ 96% and < 100% w/w)		Biodegradation rates of 13 – 21% according to the OECD 301B. Thus, not readily biodegradable. P based on screening criteria.		The estimated BCF from a dietary bioaccumulation study was 842 – 1070 and the lipid normalized BMF = 0.0174. Not B based on REACH Annex XIII.		NOECAlgae= 0.28 μg/L 72-hr ErC50Algae= 6.7 μg/L 48-hr EC50Daphnia= 10 μg/L 96-hr LC50fish= 10 μg/L Mortrace SB is not classified as a mutagen, or reproductive toxicant, but itdoes meet the criteria for T due to evidence of specific target organ toxicity after repeated exposure (STOT RE category 2 according to the CLP Regulation).   T based on REACH Annex XIII.
Impurities		P/vP		B/vB		T
Isomers of 4-(4-nitrophenylazo)-2,6-di-sec-butyl-phenol ~0.5 % (w/w) (≥ 0% and < 1% w/w)		Not readily biodegradable based on read across to4-(4-nitrophenylazo)-2,6-di-sec-butyl-phenol) P based on screening criteria.		Read across to Mortrace SB Conc:The estimated BCF from a dietary bioaccumulation study was 842 – 1070 and the lipid normalized BMF = 0.0174. Not B based on REACH Annex XIII		Read across to Mortrace SB Conc: NOECAlgae= 0.28 μg/L 72-hr ErC50Algae= 6.7 μg/L 48-hr EC50Daphnia= 10 μg/L 96-hr LC50fish= 10 μg/L Mortrace SB is not classified as a mutagen, or reproductive toxicant, but itdoes meet the criteria for T due to evidence of specific target organ toxicity after repeated exposure (STOT RE category 2 according to the CLP Regulation). T based on REACH Annex XIII.
Unspecified impurities each below 1% w/w ~1.3% w/w (≥ 0% and ≤3% w/w)		Unknown		Unknown		Unknown

Likely routes of exposure:

The substance is not a PBT/vPvB substance, therefore the emission characterisation does not need to be conducted.