United Nations Environment Programme

Regionally Based Assessment of Persistent Toxic Substances


Courtesy of United Nations Environment Programme

Untitled Document


In 1997 the United Nations Environment Programme (UNEP) Governing Council decided that immediate international action should be initiated to protect human health and the environment through measures which will reduce and/or eliminate the emissions and discharges of an initial set of twelve “persistent organic pollutants” (POPs). The present project was initiated in mid-1998 at a time when the negotiations for an international legally binding instrument for implementing international action on certain persistent organic pollutants had just started and while the outcome of the negotiations was still purely conjectural. It was initiated by GEF after discussions with UNEP to address a broader set of issues and substances than those which finally were agreed under the Stockholm Convention on POPs. This project therefore deals with “persistent toxic substances” or PTS and is deliberately looking at a wider group of chemicals than the twelve “POPs” under the Stockholm Convention.

The Regionally Based Assessment of Persistent Toxic Substances (RBA PTS) Project was designed to gather data and assess the sources, environmental concentrations, the transboundary movement and effects of a selected number of PTS. The objective of the project is to provide a measure of the threats and damage to the environment and human health posed by these substances. It is intended that the results of the project will guide the Global Environment Facility (GEF) and other funding agencies toward priorities for future action to mitigate the effects of these PTS.

The project was designed to be based in the regions and draw on the resources and expertise at the country level. Regional teams were set up to be responsible for delivering the data gathering and assessment and UNEP provided central project management and coordination functions. A steering group made up of representatives of interested international organisations, environmental and industrial non-governmental organisations and scientists provided assistance to the project manager in guiding and delivering the project. For this project the globe was partitioned into twelve regions. The regions were linked to important international waters in keeping with the focus of the project.

The twelve regions were:
I – Arctic
II - North America
III – Europe
IV – Mediterranean
V - Sub-Saharan Africa
VI - Indian Ocean
VII - Central and North East Asia
VIII - South East Asia and South Pacific
IX - Pacific Islands
X - Central America and the Caribbean
XI - Eastern and Western South America
XII - Antarctica


As this was a regionally based assessment, most of the work occurred in the various regions and effectively at the country level. A key feature of the data gathering part of the project was that an invitation was extended very widely for data. Information was sought from governments, research institutions, academics, non-governmental groups and industry. A Regional Coordinator and an accompanying team of four to five persons were selected. The process for the assessment is explained in the box below.

The regional teams were responsible for data gathering and assembly. One tool that was developed to assist in this data gathering was a standard data input form or questionnaire. It was clear that when dealing with complex and disparate data from a wide variety of sources, there is no simple and effective system which will easily and adequately handle the information.

Technical workshops were held with wide participation of experts within each region. Regional Priority Setting Meetings were organised in which participants agreed on the key priorities related to PTS amongst the stakeholders. A Global Team of six experts, along with the Project Manager, was composed to develop the global report mainly from the findings of the regional reports. A Global Priority Setting Meeting allowed feedback and further input via comments and submissions into the draft report.

Chemicals assessed

The term ‘PTS’ does not imply any particular level of risk but rather is a broad consideration for substances that persist in the environment, are found in areas far removed from sources and display some level of toxicity. Persistent toxic substances may be manufactured intentionally for use in various sectors of industry, one important sub-group being pesticides, while others may be formed as by-products during a variety of processes (industrial, non-industrial and natural) including combustion.

All regions considered the 12 designated “Stockholm POP” chemicals. They were also able to select additional chemicals that were of concern within the region. This project was primarily concerned with data gathering and not with assessing which chemicals are or could be considered PTS and the inclusion of a chemical for assessment does not imply that it meets any particular criteria of toxicity, persistence or effect. Additionally, the assessment of any given chemical in this project does not imply in any way that the chemical should be subject to inclusion in the list of Stockholm POPs.
The chemicals considered under the project are listed below. Not all the other chemicals were necessarily assessed by every region during the regional assessment.


Many PTS are a historical problem, i.e., their massive and worldwide use occurred during a time of ignorance of the environmental problems potentially caused by them. In addition, the extensive
commercialisation and industrialisation that was undertaken some fifty years ago, increased the demand and pace for the production of chemicals and the development of poor processes even in waste management.

The root causes discerned for the expression of PTS are outlined below:

  • Persistence
  • Low water solubility
  • High toxicity
  • Unsustainable production/consumption
  • Cost of chemicals
  • Perceived effectiveness
  • Ignorance

The capacity to monitor PTS differs widely across regions. While undertaking sophisticated monitoring programmes and having adequate legislative action to enforce environmental protection, the developed regions still require further financial resources and increased monitoring facilities. However, the gap is wide with regards to the needs of the developing regions. In Sub-Saharan Africa, Central America and the Caribbean, the Indian Ocean and parts of Asia, the monitoring of PTS is mainly ad hoc and relies on analyses from research and on accidents. There is need for practical technology transfer and an increase in available financial resources to provide sustainable development of control mechanisms. Regional partnerships between developed and developing countries and among the latter should be encouraged.

Barriers do exist that mitigate against the implementation to solutions and alternatives to PTS. These include the following:

  • Lack of comprehensive scientific data
  • Lack of monitoring and inventory capacity
  • Lack of suitable legislative framework
  • Ineffective enforcement of regulations
  • Illegal trade and use
  • Inappropriate use and abuse
  • Lack of awareness and information
  • Commercial pressures
  • Lack of clear responsibilities and limited coordination
  • Lack of financial resources
  • Lack of availability and acceptance of alternatives

While many alternatives to PTS have been researched, it is not necessarily easy to find suitable, workable systems to replace the desired qualities of these chemicals. The quality of persistence, low water solubility toxicity and the cost efficiency of processes that may release or emit PTS are difficult to replace. However, there are real examples that do exist where alternative measures have been instituted and have generated the desired result that was provided by the replaced PTS.Examples include:

For pesticides – Integrated Pest Management; Integrated Vector Management; Replacement of chlorinated pesticides; Organic farming.

For industrial chemicals and unintended by-products – Environmentally sustainable production; Best available technology; Destructive technology without unwanted emissions.

Priority Environmental Source Issues

A lack of data was a serious constraint with the compilation of many of the regional reports, especially from regions with developing countries and countries with economies in transition. Quantitative comparisons of production and releases by source type and chemical across regions was very difficult, as the lack of data, method of reporting, completeness, reported time trends in reductions and or increases, allowed mostly qualitative horizontal comparisons.

The general and comparative sensitivity of specific regions was not considered (i.e. would a small source of PAH in Region I be more important, than a relatively large source in a region just to the south?). Key observations, considerations, conclusions and suggestions that follow are outlined below:

  • Obsolete stocks and reservoirs of released PTS (such as contaminated sediments and soils, and stocks of obsolete pesticides) are located in a number of regions and are major current sources. This aspect has been identified as a serious concern in developing as well as developed regions, thereby sharing a common environmental issue. This presents a potential of collaboration on remediation and other technologies between developed and developing nations, including nations with economies in transition.
  • Even though much has been done to reduce emissions, industrial activity, (both in developed and developing regions as well as countries with economies in transition) must still be considered as a major source of PCDD/PCDF, and probably other related PTS. The characterisation and location of these activities on a global basis needs to be better understood, for a strategic application of interventions to be cost and time effective.
  • Open burning and biomass burning are probable, but largely unknown sources of PAH and PCDD/PCDF in developing regions, or regions with a mixed economy. Open burning and biomass burning in many areas exposes biota and human populations, due to their close proximity (land fills, domestic heating, close location to water etc), and needs to be much better understood. Large cities as such can also be considered as a concentration of both various PTS sources and exposure routes, specifically involving the human population. Large cities are normally also located close to fresh water, and often with coastal areas, two areas of major concern due to pollution potential and sensitivity of the ecosystems.
  • The developed regions can be considered as the major sources of intentionally produced industrial PTS (chlorinated paraffins, PBDE, PFOS and others). This is then transported via the environment, as well as through trade, to other regions. A better understanding is needed, as double counting (produced in one country, and used in another) could give the false impression about specific chemicals. The issue of secondary sources, such as e-waste, also needs to be better understood, as production, transport, primary use, and waste treatment (secondary use), will all be potential sources (to a greater or lesser extent).
  • Very little is still known about the sources of organometalics in all the regions, although mercury is being addressed by the Global Mercury Assessment. Not enough information was available to make any qualitative statements about this issue, but concern is still obvious from the various regional reports.
  • PCB remains a large problem in almost all the regions, although it should be recognised that PCB is one of the specific issues that will be addressed by the National Implementation Plans under the Stockholm Convention.
  • DDT and the lack of a clear and effective alternative continue to hamper development, as well affecting the health of millions of people in many regions. Combined and continued efforts (such as with the WHO) is needed to address this insidious issue, as well as to raise the understanding of the problems in other regions.
  • The source profile (Table 2.9) indicates that much more is known about most PTS sources in the developed regions, but in developing regions, major data gaps exist regarding the non-intentional and intentionally produced industrial PTS. Capacity and means to address the related issues remain a primary aspect that will need attention to assist developing regions in this regard.
  • It must be recognised that the source profile is likely to change with more information from various activities, including the NIPs. Part of the lack of information can be ascribed to little capacity within developing regions to address source aspects. It will therefore be very useful if the source profile could be regularly updated, providing a clear means to understand the global issues, as well as to provide guidance on interventions, research and prioritisation.
  • The source profile is also likely to change, as changes in sources within the various regions, through mitigation measures or through economic and social development are likely to occur.
  • Perhaps one of the most useful outcomes of the Global Source Characterisation was the beginning of the relative understanding of the contributions and problems faced by the various regions. If the enhancement of this understanding can be done through the maintenance and expansion of some of the momentum and networks that has been generated through this effort, much value will be derived on a number of levels, inter alia research, capacity building, intervention planning and public trust.

The majority of the issues identified above, are in most cases regional specific. This means that addressing these priorities within the identified regions, will contribute significantly towards reducing the releases on a global scale. Addressing the issues on a regional level, within the scope of a global strategy, will enable better application of resources on mitigation measures, sustainable development, environmental protection and, human health improvement. Future developments however, could change the pattern. Increased industrialisation of developing regions could alter the global source profile, if appropriate technologies are not instituted.

Priority environmental concentration issues

As expected, the situation is very different across the regions. There are regions with a tradition in gathering information on PTS since the 70’s, whereas in others there are important data gaps or even no information exists for some PTS. Therefore, priorities across regions may be based on facts (existing information and reported hot spots) or suspicions that environmental levels are high due to the existence of a variety of sources. From the regional reports the following picture of concerns can be obtained:

  • The levels of PTS pesticide chemicals that were widely used across the regions in the past are now declining because regulatory measures, such as banning, use restrictions, etc. This is the case of DDT, heptachlor and chlordane. The use of mirex and toxaphene, which has been limited to certain regions, follow the same trends. These are in general PTS of secondary concern, except in the Polar Regions where there is evidence of still increasing levels.
  • PTS pesticide chemicals that are still in use show detectable levels in practically all environmental compartments and, in some cases, are quite high. Even when they are banned in some regions there are also examples of elevated environmental levels in recent records, demonstrating illegal use or transport between regions. Examples include lindane and endosulphan.
  • Industrial PTS chemicals which have been banned or subject to control in some regions (and environmental levels shows a clear decline since regulatory measures were taken), may still continue to be used in developing countries, where levels are even increasing as is the case of PCBs. Effective assessment, control of use and remediation will be a priority.
  • Unintentionally produced PTS are of concern in the developed world, where levels reported are high, and obviously of great concern. Data are scarce in the developing world, representing a big data gap, although open burning may be of high concern. This is particularly the case with PCDD/PCDFs and PAHs.
  • New candidate chemicals for global concern are insufficiently covered to draw a complete picture, while there are clear evidences of ecotoxicological effects for some of them. Gathering information becomes a priority. This is the case of PCP, brominated compounds, alkylphenols, etc.

For a better assessment of the PTS levels and effects, two major gaps need to be adequately filled, and this becomes also a priority:

Data generation and gathering should be extended throughout the regions, particularly for some PTS and compartments, and more important, in a harmonised manner, to allow data to be compared over time and between studies, countries and regions.

Regionally adapted benchmarks, namely environmental quality guidelines and human tolerable daily intakes, should be defined and more widely used to compare measures of environmental levels with environmental or health effects.

Integration of information on environmental measurements of sources and pathways with physical and biological models is required to aid the design and implementation of monitoring, research, and management, including mitigation.


While many recommendations were made in reports at the regional level, an attempt has been made to extract considerations that can be translated to achieving a global strategy. It is expected that any future actions that would consider the data from these reports will ensure that only validated information is captured in the decision process. Some positive considerations which developed during the implementation of this project should be incorporated into any relevant post project exercise.

Network – The use of the network established should be incorporated into any relevant post project enterprise. A good relationship exists among all the regional coordinators and teams that will provide synergy for any future project.

Regional Direction - The use of a regional strategy to attain global results has proven successful for the implementation of this project. This pattern should be replicated for future initiatives.
Emerging Chemicals - It will be appropriate for UNEP to concentrate on work associated with the twelve selected PTS under the Stockholm Convention. However, certain other emerging chemicals are a cause for concern globally and these should be considered in future programmes.

The Stockholm Convention has legally binding obligations for the Parties. These obligations consider the activities required to address the reduction and control of the selected twelve chemicals under the Convention. This report recognises the ultimate responsibility of the Parties to the Stockholm Convention, and presents certain recommendations on the Stockholm POPs for possible consideration at the Conference of the Parties. These include:

  • Ratification of Environmental International Conventions – The three major International Conventions pertaining to chemical management (Stockholm, Rotterdam and Basel) present a unique opportunity for all countries to be involved regionally and internationally in chemical management exercises that can only enhance the reduction of the levels and effects of PTS in the environment. In particular, the ratification of the Stockholm that directly considers the reduction and ultimate elimination of twelve POPs should be considered with priority.
  • Global strategy for Implementation of NIPs – All countries that have signed the Stockholm Convention that are considered ‘GEF eligible’ have access to funds to create National Implementation Plans (NIPs) under the Stockholm Convention. These Plans are being administered by several Executing International Agencies. Even though there are disparities between countries, it is recommended that a global strategy be crafted to ensure efficiency, foster synergy between Agencies and to promote regional collaboration during the development of NIPs
  • A global assessment of the strategies to eliminate the use of DDT for malaria control - Many countries are now battling to reduce if not eliminate the use of DDT for malaria vector control. A global assessment would include a close collaboration with industry and the WHO should recommend the best alternatives that now exist. The assessment would be used to promote the development of alternatives and to pursue the use of other less caustic chemicals and non-chemical solutions.

Below are post project initiatives suggested for future action based on the results of the assessment. These initiatives involve, in the main, chemicals outside of the twelve selected Stockholm POPs.

  • Update of the Regionally Based Assessment of PTS. Many pieces of data and aggregated analyses were not captured under the current assessment. As such, it is considered prudent that the assessment be updated on a regular basis. This exercise could be carried out every 3-5 years resulting in a periodic assessment of the status of the selected chemicals with room for possible addition or subtraction.
  • Filling of data gaps. Consistently throughout the regional reports, it was established that major data gaps existed that prevented the scientific acknowledgement of intuitive concerns for certain chemicals. These gaps varied from region to region and from chemical to chemical. Unfortunately, it is difficult to prioritise the importance of these data gaps on a global scale given the differences between regions. However, an effort to glean information based on regional priorities should be considered with expediency.
  • Conduct of a global assessment of PCDD/PCDFs and PAHs emissions from open burning. It is being shown from the RBA PTS that open burning is a major concern in all habitable regions under the project. However, there is limited knowledge of the extent of the problem. The NIPs being developed by each signatory to the Stockholm Convention includes an assessment of the needs associated with the reduction of emissions of dioxins and furans. However, this could be aided by a global programme to ascertain measurements for various open burning sites. The intention is to establish with a fair degree of accuracy, estimated emissions from these various sources using models based on representative measurements taken from major, established open burning sites.
  • A resource centre for new PTS chemicals. In order to be at the cutting-edge of the emerging concerns from certain PTS, UNEP Chemicals will develop a resource centre for those chemicals for which limited information is available especially in the developing world. These substances will include all the emerging chemicals identified in this report outside of the Stockholm POPs. The centre would be interactive and developed as a network with a clearinghouse function. Such a centre would collate data from the developed and developing world, collaborate in ongoing work analysing these chemicals in terms of production, use and environmental concentrations and provide publications to share the emerging information in a wide circulation throughout all countries.
  • A global strategy for increasing public awareness on PTS issues. Consistently, the recurring message in the recommendations for all the regional reports is the need for broad public awareness programmes especially among civil society to increase the knowledge and sensitivity on the dangers of these chemicals. The increased awareness of what these chemicals are in the first instance and the danger involved from exposure will go a long way in ensuring reduced risk to public health and the environment. Working with SAICM (The Strategic Approach to International Chemicals Management) and the IOMC (The Inter-Organization Programme for the Sound Management of Chemicals), emphasis is placed on informing the public through audio-visual means and wherever possible, in the local language and using appropriate awareness strategies.
  • A global source profile. Currently, the Stockholm Convention obliges Parties to the Convention to carry out source profiles for those substances under that Convention. In order to keep track of what is happening, a global profile of selected priority chemicals would be undertaken on a timely basis to provide useful information on the production, emissions and releases of certain PTSs. Such a programme would rely on relevant, existing, global and regional data centres as well as the global monitoring network being established. It would make use of the wide network already developed through the RBA PTS Project as a means of collecting vital country and regional information for assessment. The SAICM should consider this recommendation as part of its portfolio.
  • A global strategy for technology transfer. In the past the transfer of technology has on occasion not been appropriate given the differences in geography, development of supporting institutions, culture and language. In order to ensure maximum benefit from the transfer of technology to reduce the release and emissions of PTS and subsequent effects to the environment, an agreed strategy would be developed that has the acceptance of all stakeholders. It is recommended that the SAICM consider in its work the importance of technology transfer and the need for it to reflect national requirements and situations, and to consider developing guidance on this matter.
  • Development of capacities and predictive capability of the LRT of PTS. For most of the regions of the globe no quantitative region-specific tools for transport assessment exist. The three major reasons for that are: Lack of region-specific process and understanding; lack of sufficient/and or sufficiently good data for model input and a lack of capacity for developing and using transport models within the regions. This knowledge gap not only prevents a quantitative treatment of PTS fate, but may often impede even a conceptual qualitative understanding of PTS transport behaviour in regions other than the Northern temperate environment. Therefore, there is need to gain a quantitative understanding and predictive capability of the transport and accumulation behaviour of various PTS under a variety of geographic and climatic circumstances, that reflect the diversity of the entire global environment. To achieve this, the following should be undertaken: a) Conduct studies aimed at a quantitative understanding of fate processes that are both unique and important for the transport behaviour of PTS under various regional circumstances. Specifically, identify PTS fate processes of importance in polar, arid and tropical ecosystems and investigate them with the aim to derive quantitative information suitable for inclusion into regional and global fate and transport models for PTS. Such fate processes may include phase partitioning, air-surface exchange, contaminant focussing and degradation processes; b) Ensure there are resources and capacity for monitoring PTS in remote environments. Models and a quantitative understanding of fate processes can not substitute for field data, but are dependent on them; c) Support the development, improvement, evaluation and use of regional and global PTS transport models of variable complexity; and d) Build capacity within the regions
    for studying and modelling PTS transport processes.

For more information and to download the full version of this report go to: http://www.unep.org/

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