Decision tree

Basic Problem Screening Guidance


The countries that have ratified the Stockholm Convention are obliged to implement a number of actions.  For contaminated sites, parties are encouraged to develop appropriate strategies, to identify sites contaminated by POPs listed in Annexes A, B or C.  Moreover, should a country undertake remediation of those sites then this should be performed in an environmentally sound manner.

    In general contaminated sites could arise from products and articles containing POPs that enter waste streams as well as a range of combustion processes particularly for the UP-POPs.  Stockpiles of POPs chemicals that are no longer allowed to be used according to any specific exemption or acceptable purpose or allowed to be exported would be designated as hazardous waste and these storage areas could be deemed contaminated sites.  It is also likely that because of co-disposal (historically a relatively common practice in many countries) of hazardous and medical waste and incineration/combustion/thermal process residues with municipal solid waste, a number of landfills or sections of landfills could be designated as contaminated sites.

A decision support framework to assist governments and other stakeholders to assign relative priorities for contaminated sites would need to take full account of the fact that POPs chemicals are not only toxic and persistent but once released and/or emitted into the environment can be bioaccumulated in food chains.  

The principal aim of this document is to present the first stage development of an overall decision support framework called the Basic Problem Screening Guidance. This aims to provide basic guidance to enable the process of identifying and carrying out a preliminary evaluation of sites that are believed to be contaminated to be streamlined.  A risk screening approach is used, to assist in assigning relative priorities for further actions to be determined.


To narrow the scope of any subsequent risk assessment activity by focussing on the characteristics of the site that constitute credible potential risks.

  • To assist in identifying ongoing exposures or potential exposures that are causing severe and unacceptable human and ecological effects or likely to cause such effects in the immediate future.

  • To serve to identify data and information gaps.  

  • Help to identify those sites that will have a low priority for remediation or do not require remediation as well as those that may require further investigation because of insufficient data.

  • The guidance resembles the so-called preliminary risk assessment in a typical comprehensive risk assessment framework and is tailor made to address POPs specific queries where possible.

The structure of the guidance document is based on queries related to basic site information, e.g. site ownership, accessibility and source-pathway-receptor concept as follows:

  • Basic site characterization: queries 1, 2, 3

  • Data availability for the site: queries 4, 5, 6

  • Environmental media as sources of contamination: queries 7, 8

  • Manmade activities as sources of contamination: queries 9, 10, 11, 12

  • Defining receptors and possible exposure pathways: query 13

Related Documents

  • Decision tree

    Download the guidance document as table (PDF 44 KB),

  • Decision tree

    Download the guidance document as diagram (XLS 134 KB)


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