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Reference
Endpoint:
basic toxicokinetics in vitro / ex vivo
Adequacy of study:
supporting study
Reliability:
other: Expert statement is attached.
Rationale for reliability incl. deficiencies:
other: No studies are available on the toxicokinetics, metabolism and distribution of dihexadecyl peroxodicarbonate. Predictions were made based on physical-chemical properties and information from tox. studies.
Executive summary:

Basic Toxicokinetics for 1,1,3,3-tetramethylbutyl peroxyneodecanoate (CAS# 51240-95-0)

 

In order to fulfill the requirements for submission of a REACH dossier according to Annex IX of REACH Regulation (EC) No.1907/2006 (for substances >100 tones/year) and in absence of data on the toxicokinetics and dermal absorption, an assessment of toxicological behaviour is required.No studies are available on the toxicokinetics, metabolism and distribution of 1,1,3,3-tetramethylbutyl peroxyneodecanoate.

 

1,1,3,3-tetramethylbutyl peroxyneodecanoate is unstable with a hydrolysis half lifeless than 24 hours at 15°C (OECD111).The pure peroxide is not commercially available and always used in closed systems. Due to its instability, a phlegmatizer is added. Therefore the commercial product is always a mixture of peroxide and phlegmatizer.  

Multiple breakdown products were identified (Datta, 2012). The breakdown products were not quantified. 1,1,3,3-tetramethylbutyl peroxyneodecanoate is converted to TMBH hydroperoxide (CAS#5809-08-5) which is broken down to neopentyl alcohol (CAS#75-84-3).Other breakdown products are 2,2,4-trimethylpentanol-2 (CAS# 123-44-4) and acetone (CAS# 67-64-1). 

 

Below are some physical chemical properties of 1,1,3,3-tetramethylbutyl peroxyneodecanoate and a common phlegmatizer, isododecane (CAS# 93685-81-5)

 

Endpoint

1,1,3,3-tetramethylbutyl peroxyneodecanoate

Isododecane

Mixture

MW

300.48

170.34

 -

WS

33.6 µg/L 

Insoluble (Supplier SDS); 4.86 ug/L (Disseminated Dossier); 43.57 ug/L (EPIWEB)

-

Log Pow

>6.5 (6.9 extrapolated)

6.96 (QSAR cal from disseminated dossier); 6.01 (EPIWEB)

 -

VP

 0.0001 -0.01Pa 25°C(calculated)

180 Pa (measured)

<0.24 Pa at 25°C(measured)

Skin irritation

Cannot assess the irritation potential of the peroxide alone due to stability issues.  

Repeated exposure can defat skin and lead to irritation (supplier SDS)

 

Irritant Cat 2

 

NOTE: All measurements are based on experimental work with a phlegmatizer/peroxide mixture and/or calculation. The pure peroxide is highly unstable and will completely decompose. 1,1,3,3-Tetramethyl- butyl peroxyneodecanoates 70% in isododecane is classified as a peroxidetype D. Flammability is an intrinsic hazard in this class.

The Self-Accelerating Decomposition Temperature (SADT) of the substances is 15°C (reference SADT: CLP regulations 2.15.2.3 and UN Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria, 5th revised edition, sub-sections 28.1, 28.2, 28.3 and Table 28.3.)

 

The available physico-chemical and toxicological information of the substance has been evaluated and used to assess the toxicological behaviour. The results of this analysis will address the question on how the chemical will react in the body.

The ECHA “Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance May 2008” document provides guidance, which physico-chemical properties commonly determine oral, inhalatory and dermal absorption, distribution, metabolism and elimination of substances(Link:http://echa.europa.eu/documents/10162/13632/information_requirements_r7c_en.pdf)

 

Dermal Absorption

Based on the log Pow of 6.9, the peroxide is expected to stay partitioned in the phlegmatizer. Based on the log Pow of 6.96, vapor pressure and water solubility, the phlegmatizer is not expected to penetrate the skin to a significant degree. Therefore, the peroxide would not be expected to be significantly absorbed either. The substance is mildly irritating to skin and increased absorption due to damaged skin is therefore not very likely. 

 

If absorbed however, the peroxide would quickly undergo thermal decomposition at body temperature to multiple breakdown products.

Inhalation Absorption

The measured vapor pressure of the peroxide isododecane mixture was<0.24 Pa at 25°Cand of the peroxide 0.0001 -0.01Pa°C. Based on the low vapor pressure and pattern of use, inhalation is not expected to be a major route of exposure. If inhalation of the peroxide does occur, as stated above it will rapidly decompose to multiple breakdown products.

 

Oral Absorption

A 28-day oral gavage study, of the peroxide (70%) in phlegmatizer, in rats, resulted in effects on the kidneys of males (alpha 2μglobulin), livers of males and females (increase liver weights, diffuse hepatocellular hypertrophy) and thyroid follicular hypertrophy and minimally-slightly increased extramedullary hemopoiesis at 30 mg/kg/day. The liver effects were considered adaptive and the alpha 2μglobulin is specific to the male rat. The effects on the thyroid are a secondary effect due to increased metabolism of T3/T4 and the observations in the spleen are caused by an increased demand.

 

In a 90-day oral gavage study reported in the REACH disseminated dossier, the phlegmatizer was administered to rats at 500, 2500 and 5000 mg/kg/day. The same liver effects were reported at 2500 and 5000 mg/kg/day. The same kidney effects were reported in all dose groups. 

 

While it is not possible to establish the causative agent of the effects noted in the 28-day study with the product, (i.e. the solvent or peroxide), the peroxide is expected to quickly decompose at body temperature to multiple breakdown products.

 

Conclusion

While toxicokinetic data is not available on 1,1,3,3-tetramethylbutyl peroxyneodecanoate, if absorbed, it is expected to be rapidly converted to multiple breakdown products. 1,1,3,3-tetramethylbutyl peroxyneodecanoate is not expected to bioaccumulate.

 

Description of key information

While toxicokinetic data is not available on 1,1,3,3-tetramethylbutyl peroxyneodecanoate, if absorbed, it is expected to be rapidly converted to multiple breakdown products. 1,1,3,3-tetramethylbutyl peroxyneodecanoate is not expected to bioaccumulate. 

Key value for chemical safety assessment

Bioaccumulation potential:
low bioaccumulation potential
Absorption rate - oral (%):
100
Absorption rate - dermal (%):
10
Absorption rate - inhalation (%):
100

Additional information

Basic Toxicokinetics for 1,1,3,3-tetramethylbutyl peroxyneodecanoate (CAS# 51240-95-0)

 

In order to fulfill the requirements for submission of a REACH dossier according to Annex IX of REACH Regulation (EC) No.1907/2006 (for substances >100 tones/year) and in absence of data on the toxicokinetics and dermal absorption, an assessment of toxicological behaviour is required.No studies are available on the toxicokinetics, metabolism and distribution of 1,1,3,3-tetramethylbutyl peroxyneodecanoate.

  

1,1,3,3-tetramethylbutyl peroxyneodecanoate is unstable with a hydrolysis half lifeless than 24 hours at 15°C (OECD111).The pure peroxide is not commercially available and always used in closed systems. Due to its instability, a phlegmatizer is added. Therefore the commercial product is always a mixture of peroxide and phlegmatizer.  

Multiple breakdown products were identified (Datta, 2012). The breakdown products were not quantified. 1,1,3,3-tetramethylbutyl peroxyneodecanoate is converted to TMBH hydroperoxide (CAS#5809-08-5) which is broken down to neopentyl alcohol (CAS#75-84-3).Other breakdown products are 2,2,4-trimethylpentanol-2 (CAS# 123-44-4) and acetone (CAS# 67-64-1). 

 

Below are some physical chemical properties of 1,1,3,3-tetramethylbutyl peroxyneodecanoate and a common phlegmatizer, isododecane (CAS# 93685-81-5)

 

Endpoint

1,1,3,3-tetramethylbutyl peroxyneodecanoate

Phlegmatizer

Mixture

MW

300.48

170.34

 -

WS

33.6 µg/L 

Insoluble (Supplier SDS); 4.86 ug/L (Disseminated Dossier); 43.57 ug/L (EPIWEB)

-

Log Pow

>6.5 (6.9 extrapolated)

6.96 (QSAR cal from disseminated dossier); 6.01 (EPIWEB)

 -

VP

 0.0001 -0.01Pa 25°C(calculated)

180 Pa (measured)

<0.24 Pa at 25°C(measured)

Skin irritation

Cannot assess the irritation potential of the peroxide alone due to stability issues.  

Repeated exposure can defat skin and lead to irritation (supplier SDS)

 

Irritant Cat 2

 

NOTE: All measurements are based on experimental work with a phlegmatizer/peroxide mixture and/or calculation. The pure peroxide is highly unstable and will completely decompose. 1,1,3,3-Tetramethyl- butyl peroxyneodecanoates 70% in isododecane is classified as a peroxidetype D. Flammability is an intrinsic hazard in this class.

The Self-Accelerating Decomposition Temperature (SADT) of the substances is 15°C (reference SADT: CLP regulations 2.15.2.3 and UN Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria, 5th revised edition, sub-sections 28.1, 28.2, 28.3 and Table 28.3.)

 

The available physico-chemical and toxicological information of the substance has been evaluated and used to assess the toxicological behaviour. The results of this analysis will address the question on how the chemical will react in the body.

The ECHA “Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance May 2008” document provides guidance, which physico-chemical properties commonly determine oral, inhalatory and dermal absorption, distribution, metabolism and elimination of substances(Link:http://echa.europa.eu/documents/10162/13632/information_requirements_r7c_en.pdf)

 

Dermal Absorption

Based on the log Pow of 6.9, the peroxide is expected to stay partitioned in the phlegmatizer. Based on the log Pow of 6.96, vapor pressure and water solubility, the phlegmatizer

is not expected to penetrate the skin to a significant degree. Therefore, the peroxide would not be expected to be significantly absorbed either. The substance is mildly irritating to skin and increased absorption due to damaged skin is therefore not very likely. 

 

If absorbed however, the peroxide would quickly undergo thermal decomposition at body temperature to multiple breakdown products.

Inhalation Absorption

The measured vapor pressure of the peroxide phlegmatizer

mixture was<0.24 Pa at 25°Cand of the peroxide 0.0001 -0.01Pa°C. Based on the low vapor pressure and pattern of use, inhalation is not expected to be a major route of exposure. If inhalation of the peroxide does occur, as stated above it will rapidly decompose to multiple breakdown products.

 

Oral Absorption

A 28-day oral gavage study, of the peroxide (70%) in phlegmatizer

in rats, resulted in effects on the kidneys of males (alpha 2μglobulin), livers of males and females (increase liver weights, diffuse hepatocellular hypertrophy) and thyroid follicular hypertrophy and minimally-slightly increased extramedullary hemopoiesis at 30 mg/kg/day. The liver effects were considered adaptive and the alpha 2μglobulin is specific to the male rat. The effects on the thyroid are a secondary effect due to increased metabolism of T3/T4 and the observations in the spleen are caused by an increased demand.

 

In a 90-day oral gavage study reported in the REACH disseminated dossier, the phlegmatizer

was administered to rats at 500, 2500 and 5000 mg/kg/day. The same liver effects were reported at 2500 and 5000 mg/kg/day. The same kidney effects were reported in all dose groups. 

 

While it is not possible to establish the causative agent of the effects noted in the 28-day study with the product, (i.e. the solvent or peroxide), the peroxide is expected to quickly decompose at body temperature to multiple breakdown products.

 

Conclusion

While toxicokinetic data is not available on 1,1,3,3-tetramethylbutyl peroxyneodecanoate, if absorbed, it is expected to be rapidly converted to multiple breakdown products. 1,1,3,3-tetramethylbutyl peroxyneodecanoate is not expected to bioaccumulate.