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Description of key information

No data on toxicokinetics, metabolism and distribution are available for tert-dodecyl polysulphide (TPS). Based on its physicochemical properties, TPS is expected to be well absorbed by the respiratory and gastro-intestinal tracts; Limited absorption is expected through the skin.

The assessment of the toxicokinetics of TPS is based on the available toxicological data and the physicochemical properties of TPS as suggested by the REACH Guidance Chapter R.7c:

Molecular weight: 435 g/mole 

Vapour pressure: 0.000417 Pa @ 20°C

Water solubility: 2.6 10e-4 mg/L at 20°C 

Partition coefficient log Kow = > 12

ABSORPTION

Oral route

TPS is a highly lipophilic substances (log Kow >12 and very low water solubility), its absorption may be limited by its inability to dissolve into GI fluids and hence make contact with the mucosal surface. However, as any highly lipophilic and poorly soluble in water compounds, TPS may be taken up by micellular solubilisation.

Inhalation route

TPS is a substance with a low volatility, its vapour pressure is 4.17 10e-4 Pa at 20°C and its boiling point is 193.7°C at 100 kPa. As any highly lipophilic and poorly soluble in water compounds, TPS may be taken up by micellular solubilisation. This assumption of inhalation absorption is supported by the toxic effects observed in a repeated inhalation toxicity studied in rats.

Dermal absorption

The substance must be sufficiently soluble in water to partition from the stratum corneum into the epidermis. Therefore if the water solubility is below 1 mg/l, dermal uptake is likely to be low. Above a logP of 6, the rate of transfer between the stratum corneum and the epidermis will be slow and will limit absorption across the skin. Uptake into the stratum corneum itself may be slow.

The rate of absorption was estimated using the IH SkinPerm model using a Kp derived from the EPI Dermwin model. For a skin deposition of 1000 mg/h four 8 h, TPS is virtually not absorbed.

Therefore, according to the REACH Guidance, a default value of 10% skin absorption will be used for TPS.

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential
Absorption rate - oral (%):
100
Absorption rate - dermal (%):
10
Absorption rate - inhalation (%):
100

Additional information