Tetrakis(phenylmethyl)thioperoxydi(carbothioamide)

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics

Type of information:

other: summary document

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

other: Assessment based on other endpoint studies

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test material

Test material information

Constituent 1

Reference substance name:

Tetrakis(phenylmethyl)thioperoxydi(carbothioamide)

EC Number:

404-310-0

EC Name:

Tetrakis(phenylmethyl)thioperoxydi(carbothioamide)

Cas Number:

10591-85-2

Molecular formula:

C30H28N2S4

IUPAC Name:

N,N-dibenzyl[(dibenzylcarbamothioyl)disulfanyl]carbothioamide

Results and discussion

Any other information on results incl. tables

Results from other studies which were used to perform this toxicokinetic assessment.

Physical chemistry:

Melting temperature: 130 - 132°C (RCC NOTOX NO.0808/C613)

Boiling temperature: 147-149°C (at 101.3 kPa) (RCC NOTOX NO.0808/C614)

Relative density: 1.124 kg/m3 (26°C) (RCC NOTOX NO.0808/C615)

Vapour pressure: 0.86 +1- 0.04 kPa at 25°C (RCC NOTOX No. 0808/C616)

Surface tension: Approx. 71.4 mN/m at 21°C (RCC NOTOX NO.0808/C617)

Water solubility: 0.001 - 0.01 mg/l at 20.5°C (RCC NOTOX No. 0808/C518)

Fat solubility: 1.9 g/kg at 37°C (RCC NOTOX No. 08081C519)

Partition coefficient: Log Pow: 3.4 - 3.7 at 20°C (RCC NOTCiX No. 0808/C 20)

Dissociation constant: TBzTD is not a substance that can dissociate: No basic or acidic functionalities. (Personal communication)

Hydrolysis: Indication of hydrolysis from partition coefficient study (by means of HPLC as TBzTD is not stable in water). The chromatogram showed 2 peaks, one derived from the test substance and one from decomposition product(s). (RCC NOTOX No. 0808/C620)

Particle size (MMAD): No data

Toxicological properties:

Acute oral toxicity: LDso > 5000 mg/kg (rat); no macroscopic findings that could be associated with the test substance (RCC NOTOX No. 0808/1035)

Acute inhalation toxicity: > 5 mg/l (4 hours, rat) (RCC No. 209902)

Skin irritation: Not irritant (RCC NOTOX No. 0808/1036)

Eye irritation: Not irritant (RCC NOTOX No. 0808/1037)

Sensitisation: Not sensitizing (guinea pig) (RCC NOTOX No. 0808/1080)

28 days subacute toxicity: NOAEL > 1000 mg/kg/day (RCC NOTOX 0808/1474)

Ames test: not mutagenic (TNO v87.225/270064)

In vitro cytogenetic test in human lymphocytes: not mutagenic (RCC NOTOC No. 0808/ECH 152)

Micronucleus test in mice: a borderline increase in the number of micronuclei was observed (RCC NOTOX No. 0808/MN1240)

One-Generation reproduction toxicity: NOAEL parental > 1000 mg/kg bw, NOAEL reproductive > 1000 mg/kg bw, NOAEL developmental > 1000 mg/kg bw (NOTOX project. 488595)

Applicant's summary and conclusion

Conclusions:

Interpretation of results: low bioaccumulation potential based on study results.
Based on its high molecular weight, low water solubility and other physico-chemical parameters the bioavailability of TBzTD is expected to be low. Absorption via the oral, inhaltory and dermal route is estimated to be about 10% each.

Executive summary:

Oral

The octanol/water partition coefficient of TBzTD, being 3.4-3.7, is favourable for absorption. However, the water solubility of TBzTD is very low (below 0.01 mg/L at 20°C). In general, a compound needs to be dissolved before it can be taken up from the gastro-intestinal tract after oral administration (1). The absorption will furthermore be lowered by the relatively large molecular weight of the compound (MW>500), limiting the passage through biological membranes. Overall, it is expected that TBzTD will be absorbed to a limited extend in the gastro-intestinal tract. For risk assessment purposes the oral absorption of TBzTD is set at 10%. The results of the toxicity studies do not provide reason to deviate from this proposed oral absorption. After absorption of TBzTD from the gastro-intestinal tract, metabolism may occur in the liver (3). Excretion of TBzTD will mainly occur via faeces, due to the low water solubility and relative high molecular weight of the substance. As a consequence of the relative high molecular weight of TBzTD, excretion in bile is considered not relevant.

Inhalation

The relatively low vapour pressure / high boiling point indicate that the substance will not be available for inhalation as a vapour. In the absence of data on particle size distribution, absorption resulting from exposure via inhalation cannot be excluded, and is therefore assumed to take place. Particles with a size <100 μm have the potential to be inhaled. Particles with a diameter >5 μm will deposit in the nasopharyngeal region and subsequently be coughed or sneezed out of the body or swallowed. Particles below 5 μm might reach the tracheobronchial or pulmonary regions. TBzTD, being a lipophilic substance (log Pow 3.4-3.7) has the potential to be absorbed directly. However, based on its low water solubility (below 0.01 mg/L at 20°C) TBzTD will not dissolve into the mucus lining of the respiratory tract. For risk assessment purposes, the inhalation absorption for TBzTD is set at 10%, based on the low water solubility of TBzTD. Dermal TBzTD being a solid with a relative high molecular weight has no real potential for dermal absorption. Furthermore, its low water solubility does not facilitate dermal absorption. However, the criteria for 10% dermal absorption as given in the TGD (2) (IV1W>500 and log Pow >4) are not met, and therefore 100% dermal absorption of TBzTD should be considered for risk assessment purposes. It is, however, generally accepted that dermal absorption is lower compared to oral absorption. The 100% dermal absorption derived from physical/chemical properties of the substance should therefore be considered as a non-realistic assumption, and for risk assessment purposes a lower dermal absorption of e.g. 10% might be considered more appropriate. Based on the present available data, no additional conclusions can be drawn on the distribution, metabolism and excretion of TBzTD after dermal absorption.