6,6'-di-tert-butyl-2,2'-thiodi-p-cresol

PBT assessment

PBT assessment: overall result

Reference

Name:

LOWINOX® TBP6

Type of composition:

legal entity composition of the substance

State / form:

solid: particulate/powder

Reference substance:

LOWINOX® TBP6

PBT status:

the substance is not PBT / vPvB

Justification:

It can be concluded that the substance potentially fulfils the P criterion. According to ECHA guidance R11 Version 2.0 – November 2014 Table R.11—4: Screening criteria for P, vP, B, vB and T, the absence of degradation (0 % (ThODNH4) in 28 days) in an Manometric Respirometry Test (OECD 201 F). However due to high water insolubility (8 μg/L), it is not possible to assess the potential for hydrolysis by testing. The substance is a stable organic molecule and is, therefore, considered to not potentially hydrolyse in the environment. Since the substance is produced as an anti-oxidant, it can be argued that it may abiotically degrade in the environment.

No information is available on the bioaccumulative potential of the test substance, however a definitive study on the structural "meta" isomers is available. It is considered appropriate to utilise read across to this structural isomer as a close structural analogue..

A bioaccumulation study was conducted in 1979 with the test substance in accordance with the method used in ‘Bioconcentration test of chemicals in fish and shellfish (Kanpogyo No. 5, Yakuhatsu No. 615, 49 Kikyoku No. 392’. A flow-through system was used and the fish tested were carp (mean body weight: 27.1 g and mean body length: 10.3 cm). Two concentrations of the substance were tested (30 and 300 ppb w/v) and a dispersant was used (hydrogenated castor oil). The condition of the test fish was considered to be normal throughout the study. At 30 ppb w/v, the BCF value ranged from 0.12 or below to 4.2. At 300 ppb w/v, the BCF value ranged from 1.3 to 11 . Based on these results, the test substance is not considered to be bioaccumulative.

The substance is not classified as either carcinogenic, mutagenic or toxic for reproduction nor is it considered to be cause chronic toxicity.

No chronic aquatic toxicity data are available.  However there is no toxicity to the substance at the limit of solubility in water in the ecotoxicological tests. , therefore based on the available information, the test substance is assumed not to meet the criterion for Toxic to aquatic organisms.

In conclusion the substance cannot be considered to fulfil all the criteria for Persistence, Toxicity or Bioaccumulation, as specified in REACH Annex XIII. As such, the substance cannot be considered a PBT or vPvB substance, based on the available data.