Phosphorous trichloride, reaction products with 1,1'-biphenyl and 2,4-bis(1,1-dimethylethyl)phenol

Endpoint summary

Description of key information

Expert statement: CAS 119345-01-6 has a minor potential for bioaccumulation. The relevant absorption rates can be estimated by expert judgement to 20% (oral), 10% (dermal) and 25% (inhalation).

Key value for chemical safety assessment

Bioaccumulation potential:

low bioaccumulation potential

Absorption rate - oral (%):

20

Absorption rate - dermal (%):

10

Absorption rate - inhalation (%):

25

Additional information

In order to assess the toxicokinetic behaviour of CAS 119345-01-6, the available toxicological and physico-chemical data as well as QSAR estimations were evaluated.

The substance, i.e. the unchanged parent compounds, is expected to be rather poorly absorbed via the oral route. With a molecular weight of > 500 g/mol, absorption in general can be considered as hindered. However, taking into account the Log Pow > 6, a hindered absorption e.g. by diffusion is indicated, and also, only water-soluble substances will readily dissolve into the gastrointestinal fluids and hence be available for absorption, which limits the absorption of the rather insoluble compound. The presence of absorption could also not be proven by any effects observed in animal studies. In consequence, only a minor absorption rate needs to be assumed, i.e. approx. 20%.

CAS 119345-01-6 has a very low vapour pressure and decomposes at 260-280°C before boiling, showing that the inhalative absorption as a gas does not have to be regarded, which is supported by the fact that it is solid at room temperature. However, the substance is commonly distributed in powder form. In case of accidental exposure the inhalation of particles so has to be regarded. Approx. 89% of the particles are <100 µm (inhalable fraction), ~ 40% are <10 µm (thoracic fraction), and ~19% are < 4µm (respirable fraction). Hence, a relevant proportion may reach the alveolar region, where no mechanical excretion mechanism as the ciliary movements is available. Due to the high logPow > 6, and its insolubility in water, immediate absorption by micellular solubilisation has to be assumed,butCAS 119345-01-6 does not fulfil the criteria of being perfectly absorbed via the lungs, hence,a precautionary absorption rate of up to 25% can be estimated, as its insolubility limits the further distribution via blood.

In case of CAS 119345-01-6, neither evaporation after skin contact nor very remarkable additional absorption-enhancing effects due to corrosivity need to be regarded. Taking into account the high molecular weight, high Log Pow and very low water solubility, a passage of the compound through all layers of the skin is unlikely. So, only a minor absorption rate of 10% needs to be taken into account.

Taking into account the molecular weight of > 500 g/mol (594.82 - 1035.44g/mol of the single constituents), the very lipophilic character and poor water solubility, the absolute systemic bioavailability is rather low and expected to be more extensive in fat tissues than in other tissues. As, after first pass metabolism if any, more hydrophilic metabolites are expected to occur, and a rather minor absorption of CAS 119345-01-6, no relevant peak exposure, AUC and prolonged bioavailability will occur.

Since CAS 119345-01-6 is not considered to be absorbed very well, extensive accumulation is not expected. After metabolism, the excretion of the metabolites, either as such or after Phase 2 metabolism, will occur faster than the parent compounds. The sites of metabolism of the all parent compounds were identified as the aromatic rings, aromatic hydroxylation is the most likely scenario for Phase-I-metabolism. It is most likely that the substance of interest will be subject to metabolism by cytochrome P450 enzymes and subsequent conjugation.

In conclusion, CAS 119345-01-6 has a minor potential for bioaccumulation in its non-metabolised form as absorption is hindered, and will be excreted accompanying / subsequent metabolism.

The present expert statement covers all relevant toxicokinetic parameters to assess the behaviour of CAS 119345-01-6 in the body, the available information is well-investigated and sufficient to enable one to perform a proper risk assessment. The tonnage-driven data requirement under REACH are fully met and hence, no further information needs to be gathered and further studies can be omitted due to animal welfare.