To Örebro University

As part of the global monitoring plan on persistent organic pollutants (GMP) under the Stockholm Convention passive air samplers equipped with polyurethane foam disks (PUFs) were applied to monitor dioxin-like POPs. For sampling, toluene-pretreated PUFs were exposed for three months during two years. Chemical analysis was performed in one accredited expert laboratory using internationally accepted methods; for comparison, all results were normalized to one PUF and 3 month exposure. Total TEQs, using WHO2005-TEFs, were lowest in the Pacific Islands countries (PAC) and had similar mean values in Africa (16.8 pg TEQ/PUF), Asia (16.9 pg TEQ/PUF), and Latin American and Caribbean countries (GRULAC, 13.3 pg TEQ/PUF). Using median values, Asia (13.4 pg TEQ/PUF) and GRULAC (13.1 pg TEQ/PUF) had higher amounts than Africa (6.1 pg TEQ/PUF) and PAC (2.1 pg TEQ/PUF). The contribution of PCDD/PCDF to the total TEQ was 2-3-times higher than from the dl-PCB. Mono-ortho PCB did not play a role in any of the samples. The previous 40 samples during 2010/2011 and the present 195 samples from 2017/2018 did not show a statistical difference (p value = 0.3), only for GRULAC, a downward trend was identified. It is recommended combining 4 PUFs to ‘annual’ samples.

The first worldwide interlaboratory assesment on persistent organic pollutants (POPs) under the Stockholm Convention was organized in the Asian/Pacific, Latin American and African regions during 2009-11.

A relatively large number of laboratories reported data for the PCDDs/PCDFs and dioxin-like PCBs, especially in the Asian region. Within the Asian region, several participants used high-resolution GC/high-resolution MS systems optimized for dioxin analysis. The availibility of High-resolution mass spectrometer instrumentation is limited in the Latin America and African regions, although recently several new laboratories for dioxins have started in the Latin American region.

An expert panel was convened to provide insight and guidance on per- and polyfluoroalkyl substances (PFAS) grouping for the purposes of protecting human health from drinking water exposures, and how risks to PFAS mixtures should be assessed. These questions were addressed through multiple rounds of blind, independent responses to charge questions, and review and comments on co-panelists responses. The experts agreed that the lack of consistent interpretations of human health risk for well-studied PFAS and the lack of information for the vast majority of PFAS present significant challenges for any mixtures risk assessment approach. Most experts agreed that "all PFAS" should not be grouped together, persistence alone is not sufficient for grouping PFAS for the purposes of assessing human health risk, and that the definition of appropriate subgroups can only be defined on a case-by-case manner. Most panelists agreed that it is inappropriate to assume equal toxicity/potency across the diverse class of PFAS. A tiered approach combining multiple lines of evidence was presented as a possible viable means for addressing PFAS that lack analytical and/or toxicological studies. Most PFAS risk assessments will need to employ assumptions that are more likely to overestimate risk than to underestimate risk, given the choice of assumptions regarding dose-response model, uncertainty factors, and exposure information.

Incomplete combustion processes can emit organic pollutants, metals, and fine particles. Combustion by-products represent global human and environmental health challenges that are relevant not only in heavily industrialized nations, but also in developing nations where up to 90% of rural households rely on unprocessed biomass fuels for cooking, warmth, and light. These issues were addressed at the Seventh International Congress on Combustion BY-Products, which convened 4-6 June 2001 in Research Triangle Park, North Carolina. This congress included a diverse group of multidisciplinary researchers and practitioners who discussed recent developments and future goals in the control of combustion by-products and their effects of exposure on human and ecologic health. Participants recommended that interdisciplinary, coordinated research efforts should be focused to capitalize on the important potential synergisms between efforts to reduce the adverse human health effects linked to exposures to combustion by-products and broader efforts to reduce greenhouse gas emissions and save energy through efficiency. In this article we summarize the principal findings and recommendations for research focus and direction.

The Stockholm Convention on Persistent Organic Pollutants (POPs) has established a global monitoring plan (GMP) to generate comparable data on the presence of POPs listed in the Stockholm Convention to identify changes in POPs concentrations over time and in regions. Perfluoroalkyl substances (PFAS) have been listed into the annexes of the Stockholm Convention in 2009 and 2019, namely perfluorooctane sulfonic acid (PFOS), its salts and perfluorooctane sulfonyl fluoride and perfluorooctanoic acid (PFOA), its salts and PFOA-related compounds. Perfluorohexane sulfonic acid (PFHxS) is recommended for listing in 2021.

Surface water samples from 22 countries through the UNEP/Global Monitoring Plan 2 projects were collected from 2017 until 2019. 144 water samples from Africa (n=44), Asia-Pacific (n=60), and the Group of Latin America and Caribbean countries (GRULAC) (n=40) were analyzed using a ultra-performance liquid chromatograph coupled to a tandem mass spectrometer (UPLC-MS/MS). The three PFAS were quantified in the range of 0.03 ng L-1 to 6.23 ng L-1 for ΣPFOS, 0.05 ng L-1 to 4.02 ng L-1 for PFOA and 0.03 ng L-1 to 3.51 ng L-1 for PFHxS. Variation between or within regions, time points, countries' economy and population density was assessed. Statistically significant difference was found only for the PFOA concentration in the Asia Pacific region (11 countries) in comparison to Africa (seven countries) and GRULAC (five countries).

Using the standardized sampling protocol for surface waters, these data may serve as a baseline for future monitoring activities and the starting point for trend assessment. 

The Stockholm Convention on Persistent Organic Pollutants includes in its aims the minimisation of unintentional releases of polychlorinated dibenzo-dioxins and dibenzofurans (PCDD/PCDF) and dioxin like PCB (dl-PCB) to the environment Development and implementation of policies to achieve this aim require accurate national inventories of releases of PCDD/PCDF/dl-PCB. To support this objective, the Conference of Parties established a process to review and update the UNEP Standardized Toolkit for Identification and Quantification of Dioxin and Furan Releases. An assessment of all emission inventories was that for many countries open burning of biomass and waste was identified as the major source of PCDD/PCDF releases. However, the experimental data underpinning the release estimates used were limited in number and, consequently, confidence in the accuracy of the emissions predictions was low. There has been significant progress in measurement technology since the last edition of the Toolkit in 2005. In this paper we reassess published emission factors for release of PCDD/PCDF and dl-PCB to land and air.

In total, four types of biomass and 111 emission factors were assessed. It was found that there are no systematic differences in emission factors apparent between biomass types or fire classes. The data set is best described by a lognormal distribution. The geometric mean emission factors (EFs) for releases of PCDD/PCDF to air for the four biomass classes used in the Toolkit (sugarcane, cereal crops, forest and savannah/grass) are 1.6 mu g TEQ(t fuel)(-1), 0.49 mu g TEQ(t fuel)(-1), 1.0 mu g TEQ(t fuel)(-1) and 0.4 mu g TEQ(t fuel)(-1), respectively. Corresponding EFs for release of PCDD/PCDF to land are 3.0 ng TEQ (kg ash)(-1), 1.1 ng TEQ (kg ash)(-1), 1.1 ng TEQ (kg ash)(-1) and 0.67 ng TEQ (kg ash)(-1). There are now also sufficient published data available to evaluate EFs for dl-PCB release to air for sugarcane, forest and grass/savannah; these are 0.03 mu g TEQ (t fuel)(-1), 0.09 mu g TEQ (t fuel)(-1) and 0.01 mu g TEQ (t fuel)(-1), respectively. The average EF for dl-PCB release to land is 0.19 ng TEQ (kg ash)(-1). Application of these EFs to national emissions of PCDD/PCDF for global estimates from open burning will lower previous estimates of PCDD/PCDF releases to air and to land by 85% and 90%, respectively. For some countries, the ranking of their major sources will be changed and open burning of biomass will become less significant than previously concluded.

Release of PCDD and PCDF from biomass combustion such as forest and agricultural crop fires has been nominated as an important source for these chemicals despite minimal characterisation. Available emission factors that have been experimentally determined in laboratory and field experiments vary by several orders of magnitude from <0.51 mu g TEQ(t fuel consumed)(-1) to >1001 mu g TEQ(t fuel consumed)(-1). The aim of this study was to evaluate the effect of experimental methods on the emission factor.

A portable field sampler was used to measure PCDD/PCDF emissions from forest fires and the same fuel when burnt over a brick hearth to eliminate potential soil effects. A laboratory burn facility was used to sample emissions from the same fuels. There was very good agreement in emission factors to air (EF(Air)) for forest fuel (Duke Forest, NC) of 0.52 (range: 0.40-0.79), 0.59 (range: 0.18-1.2) and 0.75 (range: 0.27-1.2) mu g TEQ(WHO2005) (t fuel consumed)(-1) for the in-field, over a brick hearth, and burn facility experiments, respectively. Similarly, experiments with sugarcane showed very good agreement with EFAir of 1.1 (range: 0.40-2.2), 1.5 (range: 0.84-2.2) and 1.7 (range: 0.34-4.4) mu g TEQ (t fuel consumed)(-1) for in-field, over a brick hearth, open field and burn facility experiments respectively. Field sampling and laboratory simulations were in good agreement, and no significant changes in emissions of PCDD/PCDF could be attributed to fuel storage and transport to laboratory test facilities.

This article provides an overview of concentrations of persistent organic pollutants (POPs) in ambient air on a global scale, including recent measurements and an extensive compilation of literature data. In this study, passive air samplers (PASs) were successfully employed to assess concentrations of POPs in ambient air from Africa, Latin America, the Caribbean, and the Pacific Islands. The project aimed to extend the knowledge on environmental contamination by POPs in these regions, where the currently available data are still limited to a few monitoring studies.

The ambient air concentrations of PCB in Africa were relatively high when compared to other regions. Waste, in particular electronic waste, exported to Africa from industrialized countries may be a possible source of PCB in Africa, where PCB have never been extensively used or produced. For DDTs, the wide range of concentrations and particularly high levels in some countries of Africa and the Pacific Islands reflect the use of DDT for malaria control in these regions. For PCDD/PCDF, concentrations in Africa and Latin America are similar to or even higher than in Europe, probably due to unfavorable combustion practices of chlorine-containing materials.

The data support the needs for further monitoring in developing countries and countries with economies in transition, and action to reduce environmental contamination by, and human exposure to, hazardous chemicals.

During the last decade, a number of studies have been devoted to the sources and emissions of Persistent Organic Pollutants (POPs) at regional and global scales. While significant improvements in knowledge have been achieved for some pesticides, the quantitative understanding of the emission processes and emission patterns for "non-pesticide" POPs are still considered limited. The key issues remaining for the non-pesticide POPs are in part determined by their general source classification. For industrial chemicals, such as the polychlorinated biphenyls (PCBs), there is considerable uncertainty with respect to the relative importance of atmospheric emissions from various source categories. For PCBs, temperature is discussed as a potential key factor influencing atmospheric emission levels and patterns. When it comes to the unintentional by-products of combustion and industrial processes (PCDD/Fs), there is still a large uncertainty with respect to the relative contribution of emissions from unregulated sources such as backyard barrel burning that requires further consideration and characterisation. For hexachlorobenzene (HCB), the relative importance of primary and secondary atmospheric emissions in controlling current atmospheric concentrations remains one of the key uncertainties. While these and other issues may remain unresolved, knowledge concerning the emissions of POPs is a prerequisite for any attempt to understand and predict the distribution and fate of these chemicals on a regional and global scale as well as to efficiently minimise future environmental burdens.

Dioxin and PCB monitoring programs for food and feeding stuff in most countries of the world, including many European Countries are currently inadequate. Better control of food production lines and food processing procedures is needed to minimize entry of dioxin to the food chain and will help to avoid dioxin contamination accidents. This would also improve the ability to trace back a possible contamination to its source. European guidelines for monitoring programs should be established to ensure comparable and meaningful results. These guidelines should define the minimum requirements for the design of monitoring programs, analytical methods, and quality assurance.

Though data from Northern Europe shows that the general population exposure to dioxin and PCB has decreased during the last ten years these compounds continue to be a risk of accidental contamination of the food chain. The most prominent recent example is the Belgian dioxin contamination of feeding stuff in 1999. The Belgian dioxin contamination was not detected due to dioxin monitoring programs but by their direct biological effects seen in animals. Four other cases of dioxin contamination have been detected in Europe since 1997 due to local monitoring programs. One of them (citrus pulp pellets 1998) was in a much larger scale than the Belgian dioxin contamination.

The general population's exposure to dioxins and PCBs is still in the same range (1-4 pg WHO-TEQ/kg body weight and day) as the recently revised WHO tolerable daily intake (TDI). There is concern that short-term high level exposure to dioxins, furans, and PCB may cause biological effects on the human fetal development and further research is required.

Further actions to control sources building on considerable advances already made in many countries may need to be supplemented by measures to prevent direct contamination of feeding stuff or food to reduce general population exposure further.

The annual releases of polychlorinated dibenzo-para-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) from 68 countries/regions were investigated by correlating quantitative emissions with economic status of the nations. The national dioxin/furan inventories were developed using the PCDD/PCDF Standardized Toolldt, which presents the quantitative releases from ten major source groups to five release vectors. The correlation between intensity of PCDDIPCDF release and economic status was discussed and the influence of economic status on composition of five release vectors and ten source groups was studied. As PCDD/PCDF are mainly released from human activities to environmental matrices, release per person (RpP) and release per unit area (RpA) are defined to reflect release burden (Donor) and contamination burden (Receptor), respectively. Based on these two concepts, International PCDD/PCDF Reduction Burden is characterized by burden quotient (BQ) and a calculation model is established. The numbers of countries/regions with high, moderate and low International PCDD/PCDF Reduction Burden were 19,31 and 18, respectively. The information in this paper can be used for politicians to develop legislations to improve International PCDD/PCDF Reduction.

For researches on toxic chemicals in settled indoor dust, selection of dust fraction is a critical influencing factor to the accuracy of human exposure risk assessment results. However, analysis of the selection of dust fraction in recent studies revealed that there is no consensus. This study classified and presented researches on distribution of toxic chemicals according to dust particle size and on relationship between dust particle size and human exposure possibility. According to the literature, beyond the fact that there were no consistent conclusions on particle size distribution of adherent fraction, dust with particle size less than 100 mu m should be paid more attention and that larger than 250 mu m is neither adherent nor proper for human exposure risk assessment. Calculation results based on literature data show that with different selections of dust fractions, analytical results of toxic chemicals would vary up to 10-fold, which means that selecting dust fractions arbitrarily will lead to large errors in risk assessment of human exposure to toxic chemicals in settled dust. Taking into account the influence of dust particle size on risk assessment of human exposure to toxic chemicals, a new methodology for risk assessment of human exposure to toxic chemicals in settled indoor dust is proposed and human exposure parameter systems to settled indoor dust are advised to be established at national and regional scales all over the world.

This research presents release inventories of unintentionally generated dioxin-like polychlorinated biphenyls (dl-PCB) and hexachlorobenzene (HCB), which so far have not been developed or assessed. For the inventory development, the amended Toolkit methodology as developed for reporting under the Stockholm Convention on Persistent Organic Pollutants, has been applied. Based on the activity rate (AR) obtained from various statistical yearbooks, reports, or scientific literature, and the emission factors (EFs) suited to each technology level, we estimated the preliminary release inventories of unintentionally produced dl-PCB and HCB from 36 source categories in China for the reference year 2015. The result showed that in 2015, 656 g TEQ of unintentionally produced dl-PCB and 2,145,504 g (or 2146 kg) of unintentionally generated HCB were released in China from these 36 source categories. Most of dl-PCB and HCB was released to air, 71% or 60%, respectively. For comparison and for the sources which could be estimated for all three unintentional POPs the total releases of PCDD/PCDF were 5695 g TEQ per year. Of these, 78% were released to air. For dl-PCB and HCB, the vast majority of the releases from the source group 7 Production and use of consumer goods - is found in the products and not in air. With respect to source attribution and releases to air, the source groups SG3 - Heat and power generation and SG2 - Ferrous and non-ferrous metal production dominate the air emission inventory. Due to the lack of EFs, the calculated releases to the water and land were not well covered, which overall results in an underestimation of the total releases for all unintentional POPs.

For comparison, the release inventories from Japan and from several other countries that were developed using methodologies other than the UNEP Toolkit are presented as well.

Within the framework of a United Nations Environment Programme (UNEP) Capacity Building Project for training of laboratory staff in developing countries on persistent organic pollutant (POP) analysis, an interlaboratory study was organised following an initial evaluation of the performance of laboratories (reality check) and a series of training sessions. The target compounds were polychlorinated biphenyls (PCB) and organochlorine pesticides (OCP). Seven laboratories from five countries (Ecuador, Uruguay, Kenya, Moldova, and Fiji) participated. Most of the laboratories had no experience in determining PCBs. Although chromatograms improved considerably after the training and installation of new gas chromatographic (GC) columns at participating laboratories, the level of performance in the interlaboratory study was essentially on par with the moderate performance level achieved by European POP laboratories in the 1980s. Only some individual results were within +/-20% of the target values. The relative standard deviations (R.S.D.s) in POP concentrations determined by laboratories in a sediment sample were >200% in a number of cases. The results for a certified herring sample were better with at least some R.S.D. values below 50% and most below 100%. Clean up was as one of the main sources of error. After inspection it was ascertained that training of laboratory staff and investments in simple consumables such as glassware and GC columns would help to improve the quality of the analysis more than major investments in expensive instrumentation. Creating an effective network of POP laboratories at different continents together with a series of interlaboratory studies and workshops is suggested to improve the measurements of POPs in these countries.

In support of the United Nations Environment Programme (UNEP) global monitoring plan under the Stockholm Convention contributing laboratories were offered to take part in a series of interlaboratory assessments on persistent organic pollutants (POPs). The results of two rounds of these assessments are reported. The target compounds were polychlorinated biphenyls, organochlorine pesticides, polybrominated diphenylethers, one polybrominated biphenyl and hexabromocyclododecane diastereomers. The matrices distributed were a test solution, fish, sediment, human milk, and air extracts. The number of participants in each round was well over 100, showing the interest of laboratories worldwide. The results showed that many laboratories still struggle to obtain acceptable standard deviations of around 25% for their determinations. In particular for organochlorine pesticides serious improvement in quality is required. Acceptable results were obtained for the air extracts and for the determination of polybrominated diphenylethers in various matrices.

This study presents four years ambient monitoring data of seventeen 2,3,7,8-chlorine substituted poly-chlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), twelve dioxin-like poly-chlorinated biphenyls (dl-PCBs) and sixteen polycyclic aromatic hydrocarbons (PAHs) designed by the US EPA at a background site in central Europe during 2011-2014. The concentrations expressed as toxic equivalents (TEQs) using the WHO2005-scheme for PCDD/Fs (0.2 fg m(-3)-61.1 fg m(-3)) were higher than for dl-PCBs (0.01 fg m(-3)-2.9 fg m(-3)), while the opposite was found in terms of mass concentrations. Sigma PAHs ranged from 0.20 ng m(-3) to 134 ng(-3). The mass concentration profile of PCDD/Fs, dl-PCBs and PAHs was similar throughout the four years. PCDD/Fs and PAHs concentrations were dominated by primary sources peaking in winter, while those of dl-PCBs were controlled by secondary sources characterized by a spring-summer peak. During 2011-2014, no significant decrease in the atmospheric levels of Sigma PCDD/Fs was observed. On the other hand, the concentrations of Sigma dl-PCBs and Sigma PAHs were decreasing, with halving times of 5.7 and 2.7 years, respectively. We estimated that 422 pg m(-2) year pg m(-2) year TEQ PCDD/Fs and 3.48 pg m(-2) year(-1)-15.8 pg m(-2) year(-1) TEQ dl-PCBs were transferred from the air to the ground surfaces via dry particulate deposition during 2011-2014.

This study focused on emissions of polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) from incineration and power generation processes. Increased concern over human exposure to both classes of compounds has meant that environmental regulators need to assess the contribution made by emissions from regulated processes to human exposure. In the first part of an assessment in the UK we reviewed literature data on emissions of PCB, focusing on the dioxin-like PCB assigned toxic equivalency factors by the World Health Organization, and PAR The literature study was supplemented by a series of plant tests to gather initial real plant data. Literature data were limited and the lack of standard protocols for measurement and reporting of both PCB and PAH meant that few data sets were comparable. Levels of dioxin-like PCB reported in the literature and measured in UK plant tests showed that well-controlled modern combustion plants with comprehensive pollution controls gave low emissions, typically about 5-10% of the toxic equivalent of the emissions of polychlorinated dibenzodioxins and dibenzofurans at the same plants and below the widely used standard of 0.1 ng TEQ/N m(3).

Occupational exposure of chloralkali workers to highly concentrated mercury (Hg) vapour has been linked to an increased risk of renal dysfunction and behavioural changes. It is generally believed that these workers are exposed to elemental Hg, which is used in abundance during the production process however, the lack in analytical techniques that would allow for identification of gaseous Hg species poses a challenge, which needs to be addressed in order to reach a consensus. Here, we present the results from simulated exposure studies, which provide sound evidence of higher adsorption rate of HgCl2 than Hg-0 and its irreversible bonding on the surface of hair. We found that chloralkali workers were exposed to HgCl2, which accumulated in extremely high concentrations on the hair surface, more than 1,000 times higher than expected from unexposed subjects and was positively correlated with Hg levels in the finger- and toenails.

The Global Monitoring Plan (GMP) according to article 16 of the Stockholm Convention on Persistent Organic Pollutants (POPs) requires that POP laboratories must be capable – at any time – to analyse samples for POPs within a variation of ±25%. Based on this target error of 25%, a statistical model using z-scores was applied to assess the performance of analytical laboratories for POPs and a number of matrices. Since the second round of these ‘Bi-ennial Global Interlaboratory Assessment on Persistent Organic Pollutants (POPs)’, carried out in 2012/2013, perfluoroalkyl substances (PFASs) have been included into the proficiency tests. The third round was carried out in 2016/2017. The test materials included test solutions of PFASs analytical standards, the abiotic matrices sediment, air (extract) and water and the biotic matrices fish, human milk and human plasma. The number of laboratories submitting results for PFASs remained quite stable (IL2 = 27 laboratories; IL3 = 29), but there was broader geographic distribution observed in IL3: in addition to the laboratories from Asia and the Western Europe/other groups, two laboratories from Africa participated, two from Central-Eastern Europe and one from the Latin American/Caribbean region.

Considering that PFASs were introduced for the first time in round 2, the results were good to reasonable compared to those of a number of other POPs included in the same study. However, it shall also be mentioned that for some matrices and PFASs, the number of laboratories submitting results was too small and the results too scattered to derive a consensus value. This was especially true for the PFOS precursor compounds and the air matrix. Also, laboratories struggle with the analysis of the branched PFOS isomers.

These interlaboratory assessments on PFASs gave promising results and demonstrated the importance of proficiency tests in an international environment to generate trust in laboratory results. The need to participate regularly in such intercomparison assessments is highlighted. The results show the current level of PFAS analysis, which varies by laboratory and by matrix rather than per geographic region.

Presently, there are less than 20 inventories to estimate releases of dioxins and furans. According to a recent survey, 12,900 g TEQ of these unwanted byproducts are emitted into the atmosphere by 16 countries. Highest emissions are from the densely populated industrialized countries of the Northern hemisphere - Japan and the United States of America. Whereas the metal producing and recycling industry is the sector with the highest dioxin emissions in Europe, waste incineration is considered to be the major source in many other countries. Measures to reduce dioxin emissions have resulted in strong downward trends, as shown e.g. in Germany and Japan; however, potentials for further reduction have been identified.

So far, countries have utilized own methods to calculate their dioxin emissions and the majority has addressed releases to air only. The future Stockholm Convention on POPs will require to continuously reduce dioxin emissions. In order to assist countries in inventory making, UNEP has produced the Toolkit, a methodology to establish comparable dioxin inventories that address releases to air, water and land, with products and in residues.

The present report provides a quality-assured database for the technosphere compartment as part of the further development of content and technology of the congeners profile POP dioxin database into a knowledge-based system.Based on the scientific know-how of a technical expert, sound proposals for the development of a flexible evaluation instrument were developed for a total of 278 samples from the technosphere (sources: research projects, EURL-Freiburg, evaluation of original scientific literature).The evaluation focused on the inventory and classification of these samples in terms of primary and secondary sources and their classification into further subgroups taking into account chemical and physical characteristics, the collection of new data and the raising the data quality of the already acquired data. The classification scheme developed here also allows the classification of future samples.For the recognition of typical patterns in the data, R programs for cluster analysis of the groups of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCCD/PCDF), dioxin-like polychlorinated biphenyls (dl-PCB) and non-dioxin-like polychlorinated biphenyls (ndl-PCB) were developed and successfully used. These programs can also be used to compare profiles of contaminated samples with existing profiles in the database.They are thus an important tool for investigating and solving dioxin and PCB problems.

This paper presents information in relation to production or generation of POPs compiled in inventories at national or global level, concentrations in the environment using ambient air data and information on body burden using human milk data. The pathway source inventory-environmental concentration-body burden is evaluated for “typical classes of POPs”.

For unintentionally generated persistent organic pollutants such as polychlorinated dibenzo-para-dioxins and polychlorinated dibenzofurans (PCDD/PCDF), the development and maintenance of national release inventories is an obligation for parties to the Stockholm Convention on Persistent Organic Pollutants. About 20 years after the first dioxin inventories have been published, a systematic approach has been developed and now is applied worldwide to establish complete, comparable inventories that are consistent in format and content. The basis for such inventories is the “Toolkit,” a collection of emission factors and description of activities and processes that form and release PCDD/PCDF. The Toolkit uses a five-vector approach, i.e., not only releases to air but also to other compartments such as water, land, product, and residue are included. The assessment of the quantitative data for releases from ten source groups to five release vectors provides interesting insight in the country’s geographic, economic, and development status. After the first round of reporting PCDD/PCDF inventories, 86 inventories have been assessed, and it can be seen that the total releases of PCDD/PCDF from the ten source categories have a positive correlation with the size of the population and a negative correlation with economic status.

Chlorinated paraffins (CPs) are a group of synthetic organic chemicals consisting of n-alkanes with varying degrees of chlorination, usually between 40 and 70% by weight. There are no known natural sources of CPs. CPs are produced by chlorination of n-alkane feedstocks. CPs typically are viscous oils with low vapor pressures; they are practically insoluble in water but are soluble in chlorinated solvents or mineral oils. They are toxic to wildlife, long-lasting in the environment and build up in the tissues of organisms. Long-chain CPs are believed to be much less toxic to aquatic life than the related short- or medium-chain CPs. CPs consist of extremely complex mixtures allowing many possible positions for the chlorine atoms. Depending on the degree of chlorination, they are grouped into low (<50%) and high (>50%) chlorine containing. Depending on the chain length, the products are often subdivided into short-chain (C10–C13), medium-chain (C14–C17) and long-chain (C18–C30) CPs. CPs, including short-chain chlorinated paraffins (SCCPs), are used worldwide in a wide range of applications such as plasticisers in plastics, extreme pressure additives in metalworking fluids, flame retardants and additives in paints. Their wide industrial applications probably provide the major source of environmental contamination. CPs may be released into the environment from improperly disposed metalworking fluids containing CPs or from polymers containing CPs. Loss of CPs by leaching from paints and coatings may also contribute to environmental contamination. The potential for loss during production and transport is expected to be less than that during product use and disposal. Despite many efforts, a global picture as to the definition of CPs, present production, uses and occurrences is still not yet obtained. Since about 20 years, SCCPs have become subject to regulation at national and international level due to their physical–chemical properties and adverse effects. Action has been initiated for severely restricting or banning production and use of certain CPs. The latest activities include the listing of SCCPs under the Persistent Organic Pollutants (POPs) Protocol of the United Nations Economic Commission for Europe (UNECE) Longe-Range Transboundary Air Pollution Convention and ongoing discussions on including SCCPs to the Stockholm Convention on POPs.

PCDD/PCDF can be formed in a variety of industrial and thermal processes. Especially the combustion sources contribute to the ambient air levels. In addition to the well-investigated emissions from municipal waste incinerators dioxins were measured in the flue gases of other thermal emitters. It was found that some recycling plants can emit high concentrations of PCDD/PCDF. Ambient air concentrations monitored over several years have shown a clear seasonal trend with higher PCDD/PCDF levels in winter and lower concentrations during summer. Thus, results from short-term measurements cannot be used to calculate annual means for ambient air concentations or deposition rates. Dioxins, once concentrated in sewage sludge and compost can re-enter the environment when these ''reservoirs'' are applied onto agricultural and horticultural soils.

The Stockholm Convention on Persistent Organic Pollutants requires Parties to implement certain measures to protect human health and the environment from persistent organic pollutants by eliminating or reducing production, use, and releases of these chemicals. The global treaty involves politics and economics, but also science and technology to resolve global environmental problems. It is a living treaty and will evolve with time. First results to tackle a global problem jointly by developed and developing countries can already be seen. The Stockholm Convention also calls for cooperation between intergovernmental organizations.

Since polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF) were quantified in the emissions from the Amsterdam municipal solid waste incinerator (MSWI) in 1977, more than 20 years of intensive research gave many answers on how PCDD and PCDF can form in thermal processes. As a result, it can be concluded that PCDD/PCDF can be formed in all combustion processes where organic carbon, oxygen, and chlorine are present. Although there are still open questions, findings can be summarized as follows:

• PCDD/PCDF can be formed in the gas phase as well as in the heterogeneous phase.
• Geometry of the combustion chamber, time, temperature, feeding rate, input (chlorine), and so forth may have an influence on the formation of PCDD/PCDF.
• There may be different processes dominating to form PCDD or PCDF.
• The amount of PCDD and PCDF formed differs between types of thermal processes.
• Within the same process categories, e.g., MSWIs, hazardous waste incinerators, steel mills, etc., the PCDD/PCDF pattern is very similar.
• Formation of PCDD/PCDF can be prevented by addition of "inhibitors" such as sulfur- or nitrogen-containing agents.
• Results from field investigations, i.e., waste wood combustion and a new technology for thermal treatment of municipal solid waste, support these basic findings.

The Stockholm Convention on Persistent Organic Pollutants (POPs) established an effectiveness evaluation to assess the efficiency of measures taken by Parties under the Convention. Among these measures, a Global Monitoring Plan requires countries to analyze core matrices for POPs. To assist countries in setting up networks for these core matrices and to generate high-quality, comparable results, the United Nations Environment Program has implemented projects in 32 developing countries. The results demonstrate the worldwide presence of POPs in air and in humans, although at different scales.

In two series of ambient air measurement campaigns to support the implementation of the global monitoring plan (GMP) component of the Stockholm Convention on Persistent Organic Pollutants (POPs), passive air samplers (PAS) using polyurethane foams were implemented by the United Nations Environment Programme (UNEP). With the same laboratories responsible for the chemical analyses of the different groups of POPs, a total of 423 PUFs were analyzed for organochlorine pesticides (OCPs) including hexachlorobenzene (HCB) and polychlorinated biphenyls (PCB); 242 for dioxin-like POPs. For trend analysis, to compare amounts of POPs in the PUFs during the first phase in 2010/2011 and the second phase from 2017 to 2019, only results were assessed that were generated in the same country and for the same POP in both campaigns. Finally, there were 194 PUFs available for OCPs (GMP1 = 67 and GMP2 = 127), 297 for PCB (GMP1 = 103, GMP2 = 194), 158 for polychlorinated dibenzodioxins and polychlorinated dibenzofurans (PCDD, PCDF) (GMP1 = 39, GMP2 = 119), and 153 for dl-PCB (GMP1 = 34, GMP2 = 119). Indicator PCB and dioxin-like POP were quantified in all countries at all times; decreases of about 30% based on median values were determined. A 50% increase was found for HCB. By scale, DDT remained with the highest values, although more than 60% decrease was found; mainly due to smaller values in the Pacific Islands. Our assessment showed that on relative scale - per PUF - trend analysis was achieved and that such approach should be undertaken at regular intervals, not necessarily on an annual basis.

Four samples of Chinese tea (two green teas, and two brick teas) were analyzed for their concentrations of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF), chlorinated pesticides and PAH. The infusions prepared from these teas were also analyzed for PCDD/PCDF. The levels of DDT and its metabolites in tea leaves were within the safety limit of 0.2 mg/kg. Rather high levels of total PAH were obtained in brick tea (1048-1162 mg/kg), when compared with green tea (497-517 mg/kg). In terms of PCDD/PCDF, the concentrations of green tea and brick tea differed by a factor of 16, while the concentrations of all infusions were within a factor of 2. The dioxin concentrations in green tea leaves can be explained through uptake of atmospheric PCDD/PCDF. The higher concentrations in the brick tea leaves are due the longer exposure time, and to certain extent, the use of old leaves, branches and roots when making the tea, and additional components such as soil particulates through contamination. Certain Chinese populations drinking a large amount of brick tea (>31 per day) indicated that individuals of these populations consume more tea than Europeans or North Americans result in a comparably higher intake of PCDD/PCDF. Tea consumption can attribute to up to 10% of the TDI recommended by WHO (only PCDD/PCDF considered, no PCB analyzed).

Nine catfish fillets, three catfish nuggets, two feed samples, and one pond sediment were analyzed for PCDD, PCDF, and-PCB. Farm-raised catfish from Mississippi, Alabama, and Arkansas contained significant levels of 2,3,7,8-substituted PCDD and PCDF. In addition, a large number of non-2,3,7,8-substituted congeners were present in all samples. The catfish fillets and catfish nuggets also contained high concentrations of dioxin-like PCB, as well as a number of non-dioxin-like PCB. The TEQ based on PCDD and PCDF ranged from 9.5 to 43.0 pg/g lipid and the TEQ based on PCB ranged from 0.45 to 4.9 pg/g lipid for all catfish samples. The dioxin-like PCB contributed 4-16% to the total TEQ (PCDD/PCDF/PCB) for the catfish samples. The major source for the PCDD, PCDF, and PCB appears to be from feed and not from pond sediment. Immunoreactive CYP1A protein was elevated 2.5 fold in the pond-raised catfish compared to the aquarium-raised one. The results of this study suggest that the PCDD/PCDF are more important than the PCB in the CYP1A induction.

n 1994, we analyzed 43 foodstuff samples from local supermarkets in southern Mississippi, USA, for PCDD/PCDF. 2,3,7,8-Cl4DD could be quantified in 31 of these samples. On a lipid basis, levels in meat (0.53-1.10 pg I-TEQ/g) and dairy products (0.42-1.10 pg I-TEQ/g) were slightly lower than those reported from other industrialized countries. While levels in dairy samples from the United States and Europe are comparable, there is a difference in the contribution of individual congeners to the I-TEQ: for example, in milk samples from Germany approximately 40% of the I-TEQ is due to the presence of 2,3,4,7,8-Cl5DF while in the Mississippi samples this congener only contributes 16%. The highest concentrations of PCDD/PCDF in our study were detected in the farm-raised catfish (10.2-27.8 pg I-TEQ/g). A unique finding was that in addition to the 2,3,7,8-substituted PCDD/PCDF the catfish samples contained many non-2,3,7,8-substituted congeners. This is unusual because vertebrate animals selectively eliminate or metabolize the non-2,3,7,8-substituted congeners.

For the global monitoring plan (GMP) established under the Stockholm Convention on Persistent Organic Pollutants (POPs), passive air samplers (PAS) equipped with polyurethane foam disks (PUFs) were recommended for generating comparative results on the presence of POPs in countries. One representative sampling location was designed in each of the 42 countries and the PAS/PUFs exposed for three months to collect POPs during 2017–2019. The PUFs were analyzed in three laboratories according to their chemical nature and concentrations reported per PUF and 90 ± 3 days of exposure. In total, 381 PUFs were analyzed for organochlorine pesticides (OCPs), industrial chlorinated POPs, dioxin-like POPs (dl-POPs), brominated flame retardants (BFRs), and perfluoroalkane substances (PFAS). Concentrations typically varied by a factor of up to three for a POP and often within the same geographic region or other denominator such as similar latitudes or altitudes. Maximum values were found for DDT (895 ng/PUF) in Africa, but the highest medium value was in the Latin American countries. Also, polychlorinated biphenyls (PCB) and hexachlorobenzene (HCB) were most abundant across all parameters assessed. Noteworthy were high values in single countries, such as DDT in the Solomon Islands, toxaphene in Mexico, β-HCH and lindane in Tanzania, hexachlorobutadiene and hexabromocyclododecone in Mongolia, deca-BDE and PFOS in Zambia. Although we had two sampling locations at very high altitudes, >2000 m, we could determine increasing POPs concentrations with increasing altitudes only for HCB but not for other POPs. A general dependency on latitudes with higher concentrations towards the north and south pole could not be found, although the most northern station in Mongolia had two of the maxima and elevated values for some legacy POPs.

Neuraminic acid derivatives were separated easily by liquid chromatography on amino phases and using acetonitrile/15 mM phosphate buffer, pH 5.2 as mobile phase. Detection at 200 nm allowed determination of substances in the nanomole range. All solvent systems were used isocratically at room temperature. The separation did not depend on ion-exchange but on a partition mechanism, the solutes being separated according to their polarity. Thus, it was possible to optimize the resolution by varying the stationary phase and the composition of the eluent.

On the basis of physico‐chemical data, such as water solubility and vapour pressure as well as acute toxicity tests we developed an ecotoxicological model for preliminary hazard assessment. By use of the reciprocal product from log H and LC₅₀ we developed a suitable ranking system that allows us to predict potential damage to aquatic organisms through pesticides

Combustion processes are known to produce dioxins and especially municipal waste incineration is thought to have the highest contribution to the general background. On the other hand the general acceptance of non-thermal waste treatment methods such as composting is much higher than incineration. The results of an estimation on the input of PCDD/PCDF to Germany show that besides the thermal processes so-called sinks for pollutants, such as sewage sludge, compost, and foliage represent a reservoir to release dioxins by use in agriculture.

Many chemicals are in common commercial use for which no information on the environmental fate or toxicity exists. Recent legislation requires that many substances be assessed for their toxicity to aquatic organisms within a very short time and determine which of these chemicals need to be studied in greater detail. It would be impossible to measure the acute and chronic effects of all of these compounds on a single organism, let alone a battery of different types of organisms, communities or ecosystems. Initially, the chemicals on the European Inventory of Existing Commercial Chemical Substances (EINECS) need to be screened and relative hazard to the environment determined. In response to OECD directives, there has been a great deal of activity by government and industry scientists. At the International Workshop on Advances in Environmental Hazard and Risk Assessment it was concluded that quantitative structure activity relationships (QSAR) could and should be used in the hazard assessment process. Papers published in that volume outline the advantages, disadvantages, limitations, advances and research requirements.

The QSAR, structure‐activity based chemical modeling and information system, which was developed by the US‐Environmental Protection Agency was used to predict the acute toxicity of 113 substances from the “Old Substances”; list of the German government to the four commonly used aquatic toxicity test organisms: Daphnia magna (DM), fathead minnow (FHM), rainbow trout (RBT), and blue‐gill sunfish (BG).

Of these compounds the QSAR system predicted the acute toxicity of 87 substances towards fathead minnow. For the other three species examined the QSAR system could be used to predict toxicity for 78 compounds.

The predicted toxicities were compared to observed toxicities of compounds which have been evaluated and stored in the “Aquire”; data base. Observed toxicity values were available for at least one species for 38 compounds. The toxicities of some compounds are well predicted while those of other compounds were not well predicted. Overall, the QSAR system accurately classified the acute toxicity ranges of 50%, 64%, 56% and 56% of the compounds investigated for DM, FHM, RBT and BG, respectively. Of the compounds studied 10 were very poorly predicted, of these the QSAR system overpredicted the toxicity of three, while underpredicting the toxicity of seven. Of these seven compounds, five contained amino groups.

Polychlorinated dibenzo‐p‐dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) represent a class of tricylic, almost planar, aromatic ethers with 1 to 8 chlorine atoms. Congeners with substituents in the positions 2, 3, 7, and 8 are of special concern due to their toxicity, stability, and persistence. These compounds have been identified in almost all environmental compartments and humans.

Dioxins are a potent carcinogen for animals and—at the moment—considered a probable carcinogen for humans. Actual toxicological risk assessment for humans are based on 2,3,7,8‐Cl4DD carcinogenicity studies on rodents. Tumorigenic effects were found for 2 strains of rats and 2 strains of mice. All dioxins and furans elicit common toxic and biological responses, starting with a specific binding to a protein receptor, but existing epidemiologic data do not provide definitive data on human health effects.

Toxicity equivalency factors (TEFs) have been developed by several agencies as a provisional method of risk assessment for complex mixtures of PCDD/PCDF.

Dioxins have never been produced intentionally and have never served any useful purpose. They are formed in trace amounts as by‐products in industrial processes; for instance within the chemical industry, of the pulp and paper industry, metallurgical processes, processes for reactivation of granular carbon, dry cleaning, and the manufacture of flame‐retarded plastics.

The main pathway for dioxins to enter the environment is via combustion processes. Incineration is of special importance since PCDD/PCDF are directly released to the atmosphere from either stationary sources, such as municipal, hazardous and hospital waste incinerators, the combustion of sewage sludge, and scrap metal recycling, or diffuse sources, e.g. automobile exhausts, private home heating with fossil fuels, forest fires, and cigarette smoking. Furthermore, fires with PCB and PVC have additionally contributed to the total dioxin load. The emission gases can undergo long‐range transport, so that dioxins have been found even in remote areas.

Besides the two primary sources (industrial processes and combustion processes) the release of dioxins from contaminated areas and waste dumps via the leachate and the application of sewage sludge for fertilization represents a third source of PCDD/PCDF.

After more than 10 years of dioxin research the most important sources of PCDD/PCDF have been identified and analytical methods have been developed for their quantification in trace levels and in complex matrices.

Various efforts have been undertaken to reduce the emission of dioxins: for example, optimization of combustion processes for municipal waste incineration, use of unleaded gasoline, ban of chemicals, such as polychlorinated biphenyls (PCBs) and pentachlorophenol (PCP). More detail is provided in the pulp and paper section where changes have been initiated to significantly reduce the sources of PCDD/PCDF.

However, relatively little is known about transport and transformation processes, so only rough estimates can be made. Photodegradation has been found to be the primary process for 2,3,7,8‐Cl4DD breakdown. A half‐life of 3–4 days has been estimated for photochemical degradation under oxidative conditions. Field studies on the fate of 2,3,7,8‐Cl4DD in soil gave a half‐life of 9.1 (Seveso) and 12 years (under special conditions: sand, erosion), respectively. Biodegradation seems to be negligible. Transfer factors soil‐plants for PCDD/PCDF have been determined—with a high degree of uncertainty—to be less than 0.1.

Human exposure primarily occurs via ingestion whereas inhalation is a minor pathway. Dermal absorption can be neglected although skin contact to polluted surfaces may occur. Due to the lipophilicity of PCDD/PCDF and their potential for accumulation, foods such as meat and especially dairy products contribute most to the dioxin body burden of humans.

Both national agencies and international organizations have recognized the significance of this problem and as a result have initiated regulations, recommendations and research programmes (1) to understand where and how PCDD/PCDF are formed, (2) to reduce their impact on the environment and to humans, and (3) to start remedial action on contaminated areas.

Copper slag, containing high levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF) was used as covering material of a community sports field. This led to a contamination up to 40 000 fold in comparison to background concentrations in soils. Levels and patterns of dioxins found in sediments of a nearby river proved a translocation of contaminated copper slag, while slightly elevated dioxin levels found in soil from nearby house gardens could not be attributed to the sports field as the source of dioxins.

The annual flux of dioxins and furans to the environment was estimated using worst-case assumptions and the potential exposure of humans was deduced. Calculations of possible PCDD/PCDF-fluxes to the environment showed that only one major process - wind erosion - may have contributed to more than 90% of the total dioxin flux from the contaminated site to the surroundings, Based on PCDD/PCDF-exposure pathways for humans it was concluded that the PCDD/PCDF-content of the copper slag of the sports field did not pose a health hazard to athletes nor to the residents living in the neighbourhood.