tris (4-nonylphenol, branch) phosphorous acid ester

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Limitations in the existing biodegradation data for TNPP mean that persistence (P) cannot be ruled out for TNPP. However, the potential for bioaccumulation (B) is very low. The toxicity (T) endpoint evaluation is somewhat unresolved as the registrants have conclude that the TNPP database does not meet the toxicity criteria; however, the recent harmonised classification for TNPP indicates that it is hazardous to the environment. Overall, it is concluded that TNPP is not a PBT substance.

Persistence (P, vP)

TNPP is not readily biodegradable; however, due to its very low water solubility the amount of material entering the aquatic ecosystem will be very low. Further, the very low water solubility likely impacted the biodegradation results by the high potential for TNPP sorption in the test system. The potential for abiotic degradation has been considered, but wasconcluded that hydrolysis of TNPP in the aquatic environment will not be considered as an important phenomenon (EU RAR; France 2008). This is based on the expected very low water solubility of the substance that would not enable hydrolysis to occur in large amount. Furthermore, the high hydrophobicity of TNPP (high log Kow) will contribute to a large adsorption of the substance on sediment when entering the aquatic compartment thus reducing its availability for hydrolysis."  However, it should be noted that para-nonylphenol (PNP), a constituent of TNPP and possible hydrolysis product is not persistent. Bas

sed on this information, TNPP may meet the criteria for persistence.

Bioaccumulation (B, vB)

TNPP's large molecular weight and very high Kow suggest that it will not bioaccumulate to any significant extent. Bioaccumulation occurs with Log Kow values >3 but <8 as at values over 8 the amount of material available is so small that the metabolism and excretion rates exceed those of uptake. Measured data on bioaccumulation of TNPP are not available. A calculated BCF has been obtained using EpiWin: 3.162 L/kg. This value is well below the B criterion of 2000 L/kg; indicating that TNPP is not a PBT substance.

Toxicity (T)

TNPP has a low order to toxicity for both environmental and mammalian species, including recent chronic daphia. Aquatic toxicity has not been observed at concentrations at or below TNPP’s water solubility limit. There are multiple acute, subchronic and chronic mammalian studies that support the conclusion that TNPP does not pose a significant hazard to human health. As such, the registrants concluded that TNPP does nto meet the toxicity criteria. Separately, the ECHA Risk Assessment Committee concluded that TNPP should be classified as hazardous to the environment. As such, the harmonised classification suggest that that TNPP is (T) toxic.