Screening Tool Risico's van Stoffen
Screening tool | Risico's van Stoffen

Model description

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The PBT and PMT screening tool is an online tool designed to predict the persistence (P), bioaccumulation (B), mobility (M) and human toxicity (T) of chemicals based on modelling results for the endpoints of interest. Emissions of chemicals that are persistent and bioaccumulative and hazardous to humans and/or ecosystems (PBT), or that are very persistent and very bioaccumulative (vPvB) can result in irreversible effects. Similarly, this applies to substances that are persistent and mobile in the environment and hazardous to humans and/or ecosystems (PMT), or that are very persistent and very mobile (vPvM). Screening approaches can be used to identify possible PBT/vPvB and PMT/vPvM chemicals as early as possible.

The basic approach is to score chemicals from 0 (no or very low PBT/PMT potential) to 1 (very high PBT/PMT potential). Apart from the overall PBT/vPvB and PMT/vPvM-scores, for the individual properties P, B, M, and T the scores are constructed to give:

  • a score of 0 to 0.33 to indicate low to moderate P, B, M and/or T potential;
  • a score of 0.33 to 0.5 indicates high P, B, M and/or T potential;
  • and a score of 0.5 to 1 indicates very high P (vP), B, (vB), M (vM) and/or T potential.

The P-score for PMT screening is different from the P-score for the PBT screening. This is because the PBT assessment aims at substances that accumulate in soil and sediment (strongly adsorbing hydrophobic substances). The PMT assessment aims primarily at substances that tend to stay in water (hydrophilic mobile substances).

In soil and sediment the half-life is longer than in surface water. Therefore, different criteria are used for soil and sediment compare to water. Because hydrophobic substances accumulate in soil and sediment, the overall persistence of this substances mainly depents on persistence in soil and sediment. Therefore, the overall persistence for PBT/vPvB estimation is based on criteria for soil and sediment. As a result for the same substance different P scores can occur in the screening for PBT and PMT properties. Because hydrophilic substances do not bind to soil and sediment comparing to the overall persistence with the criteria for soil and sediment is not relevant.

The overall PBT/vPvB and PMT/vPvM scores are constructed based on the scores of three the individual indicators.

The most recent paper describing the methodology in detail is available via this link. The methodology is based on earlier work by Rorije et al. (2011) and Hartmann et al. (2021). A more practical description of the methodology as well as its application domain and interpretation of its output can be found on the PBT/vPvB information page and the PMT/vPvM information page.

Input

A CAS number of a chemical structure needs to be provided as input. The user can either search a single substance using the tab ‘Search single substance’ or a list of substances (CAS numbers) using the tab ‘Search a batch of substances’. Not all CAS numbers are included.

Output

The output for a single substance search includes the CAS-number and (when available) the name of the input chemical as well as the overall combined PBT, vPvB, PMT and vPvB scores and the individual P, B, M and T scores for that substance. Furthermore, an explanation of the scores is provided, which includes the predicted indicators for P, B and M that are used for the calculation of the scores. A link to more detailed substance information is also given, if available.

The output for the batch search includes the same information as the single substance search, except for the explanation on the P, B and M scores. A link to get that information per substance is included.

It should be noted that a low or high score is only a first indication that the substance is of potential low or high concern (for having PBT/vPvB or PMT/vPvM properties). The screening approach should be seen as a first screening step, which can be followed by further investigation of these properties. When evaluating the presented output, it is advised to not only look at the smiley indicators but to pay attention to the underlying scores.

Finally, it should be noted that predictions of low PMT concern (or absence of any prediction) does not mean that a chemical has no PBT or PMT concern per definition. The other way around, the prediction of a high PBT or PMT concern does not per definition mean that the substance has a high concern. The predictions are base on a model approach.

Further more other effects or properties might not be excluded. Furthermore, substances might still be of potential concern for human health and/or the environment for instance because of Carcinogenic, Mutagenic and/or Reprotoxic (CMR) properties. For more information please read the PMT/vPvM information page, PBT/vPvB information page, CMR information page or ZZS information page (in Dutch).

Abbreviations

CMR
Carcinogenic, mutagenic or reprotoxic
M
Mobile
PBT
Persistent, bioaccumulative and toxic
PMT
Persistent, mobile and toxic
vPvB
Very persistent and very bioaccumulative
vPvM
Very persistent and very mobile
ZZS
Dutch Substances of Very High Concern (in Dutch: Zeer Zorgwekkende Stoffen)