Zinc bis[O-(2-ethylhexyl)] bis[O-(isobutyl)] bis(dithiophosphate)

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Endpoint:

bioaccumulation: aquatic / sediment

Type of information:

other: Expert Statement

Adequacy of study:

key study

Study period:

2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Statement is based on valid study data.

Principles of method if other than guideline:

The physicochemical properties of the test substance, and extensive ecotoxicity studies provide strong support in determining the bioaccumulation potential for this substance, and therefore may substitute for the experimentation of in vivo effects.

GLP compliance:

no

Radiolabelling:

no

Type:

other: Weight of evidence demonstrating that bioaccumulation potential is low, specifically related to PBT criteria

Remarks on result:

other: Weight of evidence demonstrating that bioaccumulation potential is low, specifically related to PBT criteria

Summary of available information derived from the "master dossier" for zinc dialkyl dithiophosphates - CAS # 26566 -95 -0:

Screening data

 

Based on read across from a structurally similar ZDDP compound that was tested for bioconcentration in fish, this substance is expected to have a low potential for bioaccumulation (Japanese MITI database, Gazette reference number 2-22945, “Zinc dialkyl dithiophosphate”;www.safe.nite.go.jp). The bioconcentration test was conducted in carp for 6 weeks at two concentrations (0.1 mg/L and 1.0 mg/L) and the resulting BCF values were all less than 100 -- MITI classified ZDDP as “non or not highly bioaccumulative”.

No empirical test data for structurally similar substances were found using the OECD Toolbox and ToxMatch program. 

 

Based on read-across to soluble complexes of zinc, measured BCF data reported in the U.S. EPA’s Ecotox Database shows that BCF values in various species including fish are much less than the screening criteria in the Guidance of 2,000.

 

Measured data on structurally similar substances as identified by the CAESAR database shows BCF values less than 1,000 (CAESAR dataset molecules ID 405 and 303).

 

Read-across evidence on bioaccumulation potential for this UVCB substance can also be taken from Environment Canada’s screening assessment (January 2010) for the ZDDP EC#218-679-9 (CAS#2215-35-2), which determined that the “substance has a low potential to accumulate in the lipid tissues of organisms”. Based on Environment Canada’s analysis, modeled data in fish resulted in fish BCF values less than 100 using the OASIS Forecast 2005 and BCFWIN models. 

Based on their analysis of available evidence, Environment Canada concluded that the ZDDP studied “is expected to have low bioaccumulation potential due to its physical and chemical properties”, in agreement with conclusions of the U.S. EPA which considers this group of substances to have low bioaccumulation potential (US EPA 2008).

 

QSAR predicted data from structurally similar (>90% Tanimoto index) substances found in the OECD toolbox had BCF values significantly less than the screening criterion. The CAS number provided by the OECD Toolbox for this structurally similar substance was #7405-05-2.

 

The OECD Toolbox also predicts No binding to protein for this substance. Protein binding has been shown to contribute to the bioconcentration potential of substances in aquatic species (Fairbrother et al. 2007; Cowan-Ellsberry et al. 2008; Franke 1996; Legierse et al. 1998; Tremolada et al. 2009; Veltman et al. 2006). Metal substances may form complexes with proteins for distribution, sequestration, and excretion depending on the substance’s relative bioaccessibility and bioavailability.

 

Measured data

The measured log Kow (per OECD 117 guidelines) of the registered substance has a value of 3.9. This is below ECHA screening criteria (less than 4.5 is not bioaccumulative) and this substance is not expected to be bioaccumulative. Additionally, OECD QSAR Toolbox predicts significant biotransformation of the substance to more water soluble metabolites. Elimination is expected to increase significantly and therefore reduce bioconcentration.

Conclusions:

Based on the weight of evidence from read across to structurally similar ZDDP substances with BCF data in fish (from Japanese MITI data, US EPA database, CAESAR database), significant expected biotransformation to more water soluble metabolites, and QSAR predictions, this substance is expected to have low bioaccumulation potential. This substance does not meet the criteria of concern for bioaccumulation based on information available.

Key value for chemical safety assessment

BCF (aquatic species):

100 dimensionless

BMF in fish (dimensionless):

100