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PBT assessment

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PBT assessment: overall result

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Tetraphosphorus trisulphide
Type of composition:
legal entity composition of the substance
State / form:
solid: particulate/powder
Related composition:
Composition 0
Reference substance:
Composition 1
Tetraphosphorus trisulphide
Type of composition:
boundary composition of the substance
State / form:
solid: particulate/powder
Reference substance:
Composition 1
PBT status:
the substance is not PBT / vPvB

According to Annex XIII of the REACH Regulation (EC n. 1907/2006), a substance is PBT if it fulfills all three of the following criteria.

1) Persistence

A substance fulfills the persistence criterion (P) when:

– the half-life in marine water is higher than 60 days, or

– the half-life in fresh- or estuarine water is higher than 40 days, or

– the half-life in marine sediment is higher than 180 days, or

– the half-life in fresh or estuarine water sediment is higher than 120 days, or

– the half-life in soil is higher than 120 days.

The assessment of the persistency in the environment shall be based on available half-life data collected under the adequate conditions, which shall be described by the registrant.

2) Bioaccumulation

A substance fulfills the bioaccumulation criterion (B) when:

– the bioconcentration factor (BCF) is higher than 2000.

The assessment of bioaccumulation shall be based on measured data on bioconcentration in aquatic species. Data from freshwater as well as marine water species can be used.

3) Toxicity

A substance fulfills the toxicity criterion (T) when:

– the long-term no-observed effect concentration (NOEC) for marine or freshwater organisms is less than 0.01 mg/l, or

– the substance is classified as carcinogenic (category 1 or 2), mutagenic (category 1 or 2), or toxic for reproduction (category 1, 2, or 3), or

– there is other evidence of chronic toxicity, as identified by the classifications.


According to the REACH Regulation (EC n. 1907/2006), Annex VII, Column 2, the biodegradation study does not need to be conducted if the substance is inorganic. Tetraphosphorus trisulphide contains no carbon atom and it is fully inorganic. The substance is stable to hydrolysis. The substance meets the screening criteria for being possibly considered as Persistent or very Persistent. However the substance contains no halogenated substituent and very persistent property is unlikely.

Tetraphosphorus trisulphide has an estimated value of log Kow = - 0.23 calculated by EPI Suite v.4.11 even though inorganic salts are out of the applicability domain (SMILES notation used as input for prediction: S1P2P3P2SP1S3). The estimated log Kow = -0.23 is lower than the threshold value for potential bioaccumulation (log Kow ≥4.5). The inorganic nature of Tetraphosphorus trisulphide raises no concern regarding potential bioaccumulation of the substance because a low affinity for biological organic tissues is expected.

Tetraphosphorus trisulphide is toxic according to annex VI of the CLP Regulation (EC n.1272/2008). Based on short-term aquatic toxicity experimental data, Tetraphosphorus trisulphide is not expected to be harmful/toxic to the aquatic life even though it is classified H400 (Aquatic Acute tox. cat.1) according to Annex VI of the CLP Regulation (EC n.1272/2008). The substance is not Carcinogenic, mutagenic or toxic for reproduction. However, the substance is classified for repeated oral toxicity (H373 STOT Rep. Exp. 2) according to the CLP Regulation (EC n.1272/2008).

Anyway the substance does not fulfill the criteria to be PBT.