chm.pops.intchm.pops.int/Portals/0/download.aspx?d=UNEP-POPS... · U N I T E D N A T I O N S E N V I RO N M E N T P R O G R A M M E Stockholm Convention on Persistent Organic Pollutants

U N I T E D N A T I O N S E N V I R O N M E N T P R O G R A M M E

Stockholm Convention on Persistent Organic Pollutants

关于持久性有机污染物的斯德哥尔摩公约 ▪ Convention de Stockholm sur les polluants organiques persistants ▪ اتفاقية استكهولم بشأن الملوثات العضوية الثابت Convenio de Estocolmo sobre Contaminantes Orgánicos Persistentes ▪ Стокгольмскaя конвенция о стойких органических загрязнителях

Expert meeting on Best Available Techniques and Best Environmental Practices and Toolkit for Identification and Quantification of Releases of Dioxins, Furans and Other Unintentional Persistent Organic Pollutants under the Stockholm Convention Bratislava, Slovakia, 29 September – 1 October 2015

UNEP/POPS/TOOLKIT/BATBEP/2015/2

Formation and release of unintentional POPs from production processes for pesticides and industrial

chemicals: Review of new information for reducing or preventing releases and related information gaps

Draft working document October 2015

Toolkit and BAT and BEP Expert Meeting, 29 September – 1 October 2015 page 2

Table of Contents List of abbreviations ........................................................................................................... 4

1 Background ........................................................................................................................ 5 1.1 Introduction and Scope ................................................................................................ 5 1.2 Classification of sources of chemicals containing unintentional POPs in the UNEP Toolkit and some further considerations ................................................................................ 6 1.3 Approaches to reduce or eliminate UPOPs formation and release during chemical production ............................................................................................................................... 7

1.3.1 Substitution of the chemicals associated with UPOPs formation and release ..... 8 1.3.2 Change of the synthesis route ............................................................................... 8 1.3.3 Optimize a synthesis route to reduce the potential for UPOPs formation and release (defining BAT/BEP and related emission levels (BATEL)) .................................. 8 1.3.4 Separation of unintentional POPs from the product or from intermediate........... 9

1.4 Basic considerations of PCDD/PCDF and other UPOPs formation in the production of chemicals ............................................................................................................................ 9

1.4.1 Formation of PCDD/PCDF due to precursor quality of the chemical ................. 9 1.4.2 Formation of unintentional POPs due to chlorination of polyaromatic hydrocarbons (PAHs) ....................................................................................................... 10 1.4.3 Condensation reaction of smaller organochlorines to unintentional POPs ........ 10 1.4.4 Formation of PCDD/PCDF and UPOPs from unintentionally formed precursors 11 1.4.5 Occurrence of UPOPs during chemical production due to the use of chemicals already contaminated with unintentional POPs ................................................................ 11 1.4.6 De novo formation in high temperature processes ............................................. 11

Unintentional POPs in the production of chlorinated aromatic compounds (pesticides and industrial chemicals) ................................................................................................................. 12

UPOPs releases from the production and use of pesticides and other industrial chemicals 12 1.5 Chlorobenzenes .......................................................................................................... 13

1.5.1 Further information needed for chlorobenzene production processes ............... 13 1.6 Chloranil .................................................................................................................... 14

1.6.1 Further information needed for chloranil production processes ........................ 14 1.7 Pentachlorophenol ..................................................................................................... 15

1.7.1 Further information needed for PCP production processes ................................ 17 1.8 2,4-D and derivatives ................................................................................................. 17

1.8.1 Further information needed for 2,4-D and derivative production processes ...... 18 1.9 DDT and PCDD/PCDF in Dicofol ............................................................................ 18

1.9.1 Further information needed for dicofol production processes ........................... 19 1.10 PCNB ..................................................................................................................... 20

1.10.1 Further information needed for dicofol production processes ........................... 20 1.10.2 Pesticides recently associated with PCDD/PCDF formation and releases or suspected to contain PCDD/PCDF ................................................................................... 20

2 Unintentional POPs in the production of aromatic pigments ........................................... 21 2.1 Phthalocyanine dyes and pigments ............................................................................ 23

2.1.1 Further information needed for phthalocyanine production processes .............. 25 2.2 Dioxazine dyes and pigments .................................................................................... 25

2.2.1 Further information needed for dioxazine dyes production processes ............... 26 2.3 Tetrachlorophthalic acid (TCPA) and related pigments ............................................ 26

2.3.1 Further information needed for TCPA production processes ............................ 27 2.3.2 Pigments produced from TCPA ......................................................................... 28 2.3.3 Further information needed for TCPA-related pigment production processes .. 28


Azo-colorants (dyes and pigments) ...................................................................................... 29 Further information needed azo-dyes production processes ............................................ 30

3 Unintentional POPs in the production of chlorinated aliphatic chemicals ....................... 30 3.1.1 Production of tetrachloromethane ...................................................................... 31 Production of tetrachloroetylene ...................................................................................... 31 Production of trichloroethylene (TCE) ............................................................................. 32 3.1.2 Further information needed for chlorinated methane and ethane productions ... 32

3.2 Polychlorinated paraffins ........................................................................................... 34 3.2.1 Further information needed for chlorinated paraffin production processes ....... 35

3.3 Chloroprene and Polychloroprene ............................................................................. 35 3.3.1 Further information needed for polychloropren production processes .............. 36

4 Unintentional POPs in the production of inorganic chemicals ........................................ 36 4.1 Hydrogen chloride (HCl) ........................................................................................... 37

4.1.1 Primary production of HCl ................................................................................. 37 4.1.2 Secondary HCl from chemical production ......................................................... 37 4.1.3 Secondary HCl from destruction of (highly) chlorinated wastes ....................... 38 4.1.4 Further information needed for processes were HCl is produced/generated ..... 38

4.2 Metal chlorides and other inorganic salts and oxides ................................................ 38 4.2.1 Magnesium chlorine ........................................................................................... 39 4.2.2 Calcium chlorine ................................................................................................ 39 4.2.3 Copper chlorides ................................................................................................. 40 4.2.4 Copper sulfate (CuSO4) ...................................................................................... 41 4.2.5 Ferric chloride .................................................................................................... 42 4.2.6 Titanium chloride and titanium oxide ................................................................ 43 4.2.7 Zinc chloride ....................................................................................................... 44 4.2.8 Zinc Oxide (ZnO) ............................................................................................... 45

4.3 Sodium hypochlorite (NaOCl) ................................................................................... 46 5 References ........................................................................................................................ 47 6 Annex ............................................................................................................................... 56


List of abbreviations

AlCl3 Aluminum chloride alpha-HCH Alpha-hexachlorcyclohexane beta-HCH Beta-hexachlorcyclohexane CaO Calcium oxide CaCl2 Calcium chloride CAS Chemical Abstracts Service CNP Chlornitrofen CuCl2 Cupric Chloride Cu2(OH)3Cl Dicopper chloride trihydroxide CuSO4 Cupric Sulphate dl-PCB Dioxin-like polychlorinated biphenyls dl-PCN Dioxin-like polychlorinated naphtalenes EDC Ethylendichloride EF Emission Factor FeCl2 Ferrous Chloride FeCl3 Ferric chloride Ha Hectare HCB Hexachlorobenzene HCl Hydrogen chloride 2,4-D 2,4-Dichlorophenoxyacetic acid 2,4-DB 4-(2,4-dichlorophenoxy)butyric acid Kg Kilogram MgCl2 Magnesium chloride NaOCl Sodium Hypochlorite ng Nanogram OCDD Octachlorodibenzodioxin PCDD Polychlorinated Dibenzo-p-dioxins PCDF Polychlorinated Dibenzofurans PCNB Pentachloronitrobenzene PCP Pentachlorophenol PCP-Na Pentachlorophenol sodium salt PeCBz Pentachlorobenzene POPs Persistent Organic Pollutants ppb Part Per Billion ppm Part Per Million PXBs Polychloro-bromobiphenyls PVC Polyvinyl chloride SES Spent Etching Solutions TBZC Tetra-basic zinc chloride TCE Trichloroetylene TCPA Tetrachlor phthalic acid TeCP Tetrachlorphenol TEQ Toxic Equivalent t tonne UNEP United Nation Environment Programme US EPA United States Environment Protection Agency UPOPs Unintentionally Produced Persistent Organic Pollutants VCM Vinyl Chloride Monomer WHO World Health Organization Zn Zinc ZnO Zinc Oxide µg Microgram


1 BACKGROUND 1.1 Introduction and Scope The “BAT/BEP Guidelines on best available techniques and provisional guidance on best environmental practice relevant to Article 5 and Annex C of the Stockholm Convention on Persistent Organic Pollutants” contains a chapter VI F on “Specific chemical production processes releasing chemicals listed in Annex C” (UNEP 2007). This chapter addresses some chemical production processes and rather general measures to reduce PCDD/PCDF from these processes. However the guidance did not attempt to define best available techniques and best environmental practices for each of these processes individually; rather, the processes were examined for what they have in common and how those common practices can be addressed to reduce the formation, and particularly the release, of chemicals listed in Annex C of the Stockholm Convention (UNEP 2007).

The current document can be seen as a first attempt to gather information on relevant individual processes of chemical production with respect to the formation of unintentional POPs. This can help to assess and improve these processes where BAT/BEP is not yet applied and can help in developing better inventories of these processes and chemicals.

Unintentional POPs (UPOPs) are formed in a wide range of chemical processes where some are listed with emission factors in chapter 7 and a range are listed in Annex 2 of the Toolkit where emission factors have not yet been established (UNEP 2013). As a consequence, this document begins the development of a compilation of information on relevant chemicals and the related production processes and also on further information needs for individual productions and synthesis routes.

In recent years PCDD/PCDF have been identified as contaminants in certain chemicals that can have a direct impact on food and feed and result in relatively immediate human exposure. PCDD/PCDF concentrations in some of these chemicals (see e.g. HCl, CuSO4; ZnO) have been shown to vary greatly depending on the production or recycling processes used. In the last 15 years several cases have highlighted the particular relevance of PCDD/PCDF in chemicals for livestock and human exposure (Fiedler 2000; Malisch et al. 2014; Weber 2014) including, e.g.:

- Inorganic feed additives such as ZnO, CuSO4, and CaO (Kim et al 2009; Malisch 2000, Torres et al. 2013, Wang et al. 2014);

- HCl (Hoogenboom et al 2007; Wang et al. 2014); - PCP treated wood (Brambilla et al 2009; Hoogenboom et al. 2004; Huwe et al. 2004;

Fries et al. 2002);

- Mining of landfills that contain wastes from organochlorine production (Torres et al. 2013);

- Waste fat from industrial processes (Weber & Watson 2011); - Waste oils contaminated by unintentional POPs (Fiedler et al. 2000).

In addition, the presence of unintentionally formed PCB in paints and pigments used in consumer goods with potential exposure risk has been increasingly documented and highlighted (Anezaki et al, 2014; Grossmann 2010; Hu & Hornbuckle 2010; METI 2013; Washington State Department of Ecology 2014).

Comments in the last BAT/BEP meeting in Geneva (11/2014) pointed to the need for thorough identification and descriptions of the raw materials and technologies used in


manufacturing processes, because these factors may greatly influence PCDD/PCDF formation and release. The origin of raw/recycled materials must also be considered. As raw material resources diminish, growing reliance on recycling processes and secondary, recycled materials will also likely rise, bringing greater potential risk for human exposure via impacted foods/feeds and consumer goods.

Exposure-based information was considered difficult to include in the Toolkit, but rather the work should be centred around describing processes and providing process/technology emission factors rather than only product emission factors (Secretariat of the Stockholm Convention).

Agreement was made to frame the work in view of finding more information on the processes which are used to produce the chemicals in view of developing practical guidance for parties to address these additional sources of concern (UNEP 2015). The current document contains the initial overview of available information on major chemical production and, at the same time, aims to serve as a basis to develop a draft guidance.

The document is for circulation for further comments and additional input and will be discussed in the upcoming BAT/BEP expert meeting in Bratislava (29. September – 2. October 2015).

1.2 Classification of sources of chemicals containing unintentional POPs in the UNEP Toolkit and some further considerations For Toolkit groups 7b through 7h for unintentional POPs in chemicals, classes were defined for indicating the quality of the processes and for selecting related emission factors. Three simplified levels have been defined for a rough categorization and are suggested to be applied (see box 1 below; UNEP 2013).

The description of each class contains one or more criteria for determining the quality of a facility or process to help countries to decide which listed emission factor to select. The criteria are, however, very broad and provide minimal support in determining the class and selecting an emission factor due to the scarcity of relevant information and data/measurements.

For reliably determining emission factors for a chemical process, more detailed information is needed on materials inputs (feedstocks, reactants, solvents, etc.), process outputs (products and gaseous, liquid and solid releases), process conditions and refining procedures. Best would be measurements of PCDD/PCDF and other unintentional POP in products as well as in gaseous, solid and liquid wastes during standard operation of synthesis routes and for the range of operation conditions applied or occurring in a facility.

Such data are however rare. In fact, as described in this document, detailed information on process conditions and associated PCDD/PCDF and other UPOPs levels in chemicals and process outputs are available for only a very few processes. This document begins the compilation of such information for certain chemicals and it describes relevant BAT and respective UPOPs contamination levels and the conditions associated with low UPOPs levels. For chemicals and processes where such information is not available, a paragraph is added which briefly describes further information needed for the respective chemical or process with the aim that such information is gathered to compile the necessary knowledge to categorize processes and to improve process conditions.

In addition there are general approaches for reducing PCDD/PCDF and UPOPs releases for a certain chemical or for a certain application (see paragraph 2.6).


Also there is basic information and knowledge on UPOPs formation processes to allow assessments of the potential for UPOPs formation in the respective processes and, in some cases, for reducing or preventing UPOPs formation and release by mechanistic considerations (see 2.7).

1.3 Approaches to reduce or eliminate UPOPs formation and release during chemical production There are four basic approaches for reducing unintentional POPs contamination in chemicals and unintentional POPs formation and release during chemical production:

• Substitution of problematic chemicals and pesticides associated with UPOPs formation and release;

• Use of an alternative synthesis route with a lower potential or no potential for formation of PCDD/PCDF and other unintentional POPs;

Box 1: Guidance for classification of sources of chemicals listed in source group 7b to 7h in the Toolkit (UNEP 2013)

Low-end technologies: No information available, or processes (reactions, purification steps and wastewater and waste treatment) are not controlled in respect to the formation of PCDD/PCDF or other unintentional POPs. Chemical feedstocks, air emissions, wastewater, residues and products are not monitored for PCDD/PCDF, other unintentional POPs or indicator substances.

Mid-range technologies: Processes (reactions and purifications steps including prevention by process- and production-integrated measures and wastewater and waste treatment) are controlled to some extent to limit releases. Parameters of these processes (e.g. feedstock; temperature; presence or use of chlorine in some form and, if, used, its concentration) are also controlled to reduce formation and release of unintentional POPs. Process inputs and emissions to air, wastewater, residues and products are monitored to some extent for PCDD/PCDF, other unintentional POPs or indicator substances.

High-end technologies: Processes (reactions and purifications steps including prevention by process- and production-integrated measures and wastewater and waste treatment) are optimized for low or no releases. Parameters of these processes (e.g. feedstock; temperature; presence or use of chlorine in some form and, if, used, its concentration) are optimized for minimum formation and release of unintentional POPs. Chemicals, products or by-products, emissions to air, wastewater and residues are monitored for PCDD/PCDF, other unintentional POPs or indicator substances. A refining step is used where appropriate to minimize unintentional POPs in the final chemical, product or by-product. Process residues should be handled in an environmentally sound manner, as described in the guidance on the BAT and BEP.


• Modify and optimize the synthesis route to reduce or eliminate unintentional POPs formation and release; and

• Remove unintentional POPs from the final product and use BAT to treat all associated wastes and other outputs, including those from the production process.

All four approaches have been used and/or are used to reduce the formation and release of unintentional POPs in the production of chemicals and pesticides. The approaches are briefly described below with selected examples and can be applied in different ways and to different degrees in the production of chemicals to reduce unintentionally produced POPs.

1.3.1

Chemicals known to contain high UPOPs levels can be substituted by alternative chemicals with low or no potential for UPOPs content or formation. Appropriate substitution of POPs or POPs containing products by safer alternatives - chemical and non-chemical - is the best and most effective way to eliminate POPs from articles, products and processes and to reduce and prevent use-related environmental contamination and human health problems (see publication of POPs-phase out publication

Substitution of the chemicals associated with UPOPs formation and release

http://map.bcrc.cn/). This has been done in the past with the prime example 2,4,5-T which has been substituted already mainly in the 1970s and 1980s by e.g. 2,4-D, dicamba or triclopyr. Also PCP – recently listed in the Stockholm Convention - has been substituted largely by alternatives. E.g. in wood treatment PCP has been replaced by copper salts and other chemicals. Also the substitution of UPOPs-containing pesticides by integrated pest management or the substitution of unintentional POPs-containing dyes by natural dyes are examples of such substitutions.

1.3.2 Often different synthesis routes are available for the production of a chemical. Synthesis routes which are known to generate high levels of UPOPs may be substituted by another synthesis route with lower formation potential. Examples are, e.g., the production of tetrachlorophthalic acid in which synthesis in the gas phase produces higher levels of HCB compared to synthesis in liquid phase (Government of Japan 2006; see section

Change of the synthesis route

3.3). For the production of chloranil, direct chlorination of phenol has been substituted by chlorination of hydroquinone with the aim of reducing PCDD/PCDF contamination in the chloranil products

1

2.3

(see section ) and related chemicals produced from chloranil (see section 3.2).

1.3.3

Also synthesis routes can be optimized with the aim of reducing the formation of unintentional POPs.

Optimize a synthesis route to reduce the potential for UPOPs formation and release (defining BAT/BEP and related emission levels (BATEL))

Optimizing a production process for this purpose can include, e.g.:

• The raw materials, including solvents, should be selected with respect to their potential for triggering or contributing to UPOPs formation. For example, solvents, such as chlorinated benzenes, that are associated with high PCB formation potential (e. g. in the production of phthalocyanines; see section 3.1) can be substituted by other solvents. Suppliers can be required to meet specific limits with respect to

1 It has been revealed that also the formation of chloranil via the hydroquinone route has resulted in highly contaminated

chloranil with a higher emission factor for low-end technology compared to the listed emission factor for the synthesis route via phenol (UNEP 2013).

http://map.bcrc.cn/�


concentrations of PCDD/PCDF or other UPOPs (e.g. when HCl is used for chlorides possibly used as feed additive; see section 5.2).

• Critical process parameters (e.g. temperature, pH, chlorine use volume) need to be controlled and optimized in respect to minimizing unintentional POPs considering also the overall performance of a production process.

• The PCDD/PCDF and unintentional POPs content should be monitored to optimize and control known problematic production processes or processes where the formation of PCDD/PCDF are suspected (see table A1 and A2 in the Annex).

After the production process for a synthesis route is optimized with respect to UPOPs formation, BAT-levels for PCDD/PCDF and other UPOPs may be defined.

1.3.4 Even though parameters have been optimized, some processes may still have high formation of PCDD/PCDF and other UPOPs. In such cases, these pollutants need to be separated by appropriate separation technologies.

Separation of unintentional POPs from the product or from intermediate

Often unintentionally POPs have lower boiling points compared to the product and can be separated from the product by distillation. Separation of unintentional POPs from the product is described in the BAT/BEP guidance, e.g., for the EDC/VCM process with resulting distillation residues “heavy ends” (UNEP 2007). Also UPOPs can be separated by distillation from monoaromatic compounds such as chlorobenzenes, chlorophenols and derivatives.

Distillation residues containing the unintentional POPs must be managed appropriately, e.g., by high temperature destruction. If HCl is recovered, care must be taken to ensure that this secondary HCl contains low or no PCDD/PCDF or other unintentional POPs (see e.g. section 6.1 and section 6.2.4). Therefore BAT hazardous waste incinerator operated according BEP are needed (see UNEP 2007 and European Commission 2006) and possibly a refining of the resulting HCl.

For high molecular products (e.g. dyes and pigments) distillation might not be possible. In this case other separation technologies such as crystallisation and re-crystallization normally reduce the unintentional POPs content. This is used, e.g., in reducing HCB contamination in tetrachlorophatalic acid (see e.g. section 4.3). Also in this case the resulting (solvent) waste must be managed in an environmentally sound manner and the separated UPOPs finally destroyed.

1.4 Basic considerations of PCDD/PCDF and other UPOPs formation in the production of chemicals There are a range of formation pathways of PCDD, PCDF and other unintentional POPs during the production of chemicals in addition to other ways to contaminate chemicals and products with unintentional POPs. These pathways need to be understood and considered in order to reduce and/or eliminate UPOPs in chemical production processes.

Therefore in this chapter basic considerations are compiled on the different pathways how chemicals or products can become contaminated with PCDD/PCDF and other unintentional POPs.

1.4.1 The most well-known examples of high PCDD/PCDF levels in chemicals are those where the products are precursors of PCDD/PCDF, such as 2,4,5-trichlorophenol, Pentachlorophenol

Formation of PCDD/PCDF due to precursor quality of the chemical


and PCBs. Production processes for these chemicals have a very high potential for the formation of PCDD/PCDF and the products are listed in the Toolkit.

1.4.2

In some production processes involving chlorination, the presence of PAHs leads to the formation of PCDFs, PCBs, and PCNs by chlorination. The most well-known processes are the formation of PCDFs and PCNs in chloralkali production using graphite electrodes (Otto et al. 2006; Rappe et al. 1991). However, this formation route is also relevant for other organochlorine chemicals, e.g., the contamination of commercial PCBs mixtures with unintentional PCNs (Huang et al. 2014b; Yamashita et al. 2000). Recently the first detailed assessment of unintentional POPs in chlorinated paraffins revealed that also chlorinated paraffins (including long chain chlorinated paraffins) can contain high levels of PCBs and PCNs as well as PCDFs (Takasuga et al, 2012a,b). The pattern of the PCBs and PCN indicated that biphenyl and naphthalene were present in the reaction mixture and PCB and PCN were then formed by chlorination. It was estimated that approximately 100 tonnes PCB might be formed per year from the production of the approximately 1 million tonnes of chlorinated paraffins (Takasuga et al. 2012b).

Formation of unintentional POPs due to chlorination of polyaromatic hydrocarbons (PAHs)

1.4.3 Unintentional POPs are formed in some processes when smaller organochlorine chemicals undergo condensation reactions and build-up of aromatic compounds including unintentional POPs. Perhaps the most well-known in this regard is the production of chlorinated solvents such as tetrachloroethylene, trichloroethylene and ethylene dichloride which were known to contain high levels of HCB (Jacoff et al. 1986; Weber et al. 2011) and HCBD (UNEP 2012; UNEP 2013b). A first total screening of unintentional POPs in the production of chlorinated methanes in China revealed the formation of high levels of PCN and PCB, leading to estimated total releases of 563 g TEQ/year from PCNs and 32 g/year from PCDD/PCDF for 2010 (Zhang et al. 2015). The simplified formation mechanism of unintentional POPs in the production of perchlorethylene or tetrachloromethane are shown in Figure 1.

Condensation reaction of smaller organochlorines to unintentional POPs

Figure 1: Formation of unintentionally POPs in the production of perchlorinated solvents (Weber et al. 2011; for unintentional product distribution in TCM production see Zhang et al 2015)


1.4.4

In some processes neither the products or intermediates are PCDD/PCDF precursors but nevertheless PCDD/PCDF are formed. The above mentioned formation of aromatic compounds due to condensation reactions of smaller molecules is one example of the formation of chlorinated aromatic precursors (e.g. chlorobenzenes) which, by further dimerization, can form unintentional PCB and PCDF (Figure 1; Weber et al. 2011; Zhang et al. 2015). Also the formation of PCDD/PCDF in phthalocyanines which are not direct precursors but, during their production, they can partly be degraded at elevated reaction temperatures to precursors that form PCDD/PCDF (see section

Formation of PCDD/PCDF and UPOPs from unintentionally formed precursors

3.1).

1.4.5

In some cases PCDD/PCDF and other UPOPs are not formed in the production of the contaminated final product/chemical but are introduced in other feedstock chemicals, reactants, or solvents. In such cases, there is no need to modify the production processes for the desired final product. Instead the synthesis of the feedstock chemicals, reactants, or solvents that contain UPOPs must be modified to prevent UPOPs formation. Or, if this is not possible, the feedstock chemicals, reactants, or solvents must be refined to reduce UPOPs levels before being introduced to the production process of the final product. Some examples are as follows:

Occurrence of UPOPs during chemical production due to the use of chemicals already contaminated with unintentional POPs

• When PCDD/PCDF-contaminated chloranil was used as a raw material for producing dioxazine dyes and pigments, the PCDD/PCDF became contaminants in the dyes and pigments (UNEP 2013; see section 2.2 and 3.2).

• When HCB-contaminated tetrachlorophthalic acid was used to produce pigments, the HCB became a contaminant in the resulting pigments. (Government of Japan 2006, 2007).

• PCDD/PCDF that were contaminants in HCl produced as a by-product during the manufacture of chlorinated organic chemicals eventually occurred as contaminants in CuSO4 used as an additive in animal feed: The contaminated HCl was used to make an acid etching solution used in printed circuit board production; 2) the spent acid etching solution was used as the raw material for producing industrial cupric sulfate; and 3) the industrial cupric sulfate was used as the raw material for producing food grade CuSO4 (Wang et al. 2014; see section 5.1.2).

• Solvents containing UPOPs can be a major reason for UPOPs contamination as reported when contaminated chlorinated aromatic solvents were used in producing phthalocyanine blue (Brychky & Wagner (1998) see also section 4.1).

• Contamination with PCB and brominated-chlorinated biphenyls of ferric chloride recycled from the etching process in the production of printed circuit boards was considered to originate from brominated flame retardants in the printed circuit boards and chlorination (Nakano et al. 2007).

1.4.6 A major formation pathway for PCDD/PCDF in thermal processes is the de novo formation pathway where PCDD/PCDF and other unintentional POPs are formed by the degradation of aromatic carbon species (e.g. soot, PAH) by oxychlorination (Addink & Olie 1995; Weber et al. 2001). While this is the major mechanism for the formation of PCDD/PCDF in

De novo formation in high temperature processes


incineration processes there are also some high temperature processes in chemical production where the de novo formation is relevant. This includes e.g. the incineration of highly chlorinated waste and the associated recovery of HCl or the production of titanium chloride by high temperature process (900 °C) using elemental chlorine and carbochlorination process with addition of a carbon source (UNEP 2007; USEPA 2001; see section 5.2.6) or the Waelz process for recovery of zinc and production of zinc oxide (Hung et al. 2012; see section 5.2.8).

UNINTENTIONAL POPS IN THE PRODUCTION OF CHLORINATED AROMATIC COMPOUNDS (PESTICIDES AND INDUSTRIAL CHEMICALS) UPOPs releases from the production and use of pesticides and other industrial chemicals Chlorinated aromatic compounds were a major source of PCDD/PCDF in the historic production of certain aromatic pesticides (Götz et al. 2013; UNEP 2013; Weber et al. 2008) and can still be present in current pesticide formulation (Holt et al. 2010; Huang et al. 2014; Liu et al. 2013). It has recently been highlighted that UPOPs from chemical production have e.g. been considerably underestimated in the former PCDD/PCDF inventory in China, and that chemical production is recently identified as a major source of PCDD/PCDF and other UPOPs that should be considered in the update of China’s National Implementation Plan (Nie et al. 2015).

Production technologies impact the level of UPOPs contamination and release. While most pesticides in source category 7d are listed with a single emission factor, different production and refining technologies might result in considerably different values (as can be seen for e.g. 2,4-D where a good set of measurements were available and emission factors for different technology levels have been included in the Toolkit see below section 2.5).

Further, residues have been shown as potentially significant vectors of release from the production of pesticides and other organochlorine chemicals. This is especially evident when distillation or other clean-up steps are included and related wastes were disposed (Götz et al. 2013; Weber and Varbelow 2013; Japan Government 2006, 2007; Lysychenko et al. 2015).

Large PCDD/PCDF reservoirs exist from the former application of pesticides (Camenzuli et al. 2015; Masunaga et al. 2004; Seike et al. 2007; Suriname Ministry of Labour, Technological Development and Environment 2011; Weber et al. 2008) or from other large scale historic releases from former production processes (Verta et al. 2009; Birch et al. 2007). It has been revealed in recent years that these reservoirs have high relevance for feed and food (livestock)

2 safety (Birch et al. 2007; Hoogenboom et al. 2015, Kamphues and Schulze 2006;

Kamphues et al. 2011; Lake et al. 2014; Malisch et al. 1996; Weber et al. 2014). These reservoirs are therefore important for the inventory development

3

Therefore not only the levels of unintentional POPs in pesticide production or other industrial chemical with high PCDD/PCDF formation potential need to be minimized or eliminated but also the residues of such productions need to be minimized and appropriately managed and destroyed (see e.g. BAT&BEP Guidelines, Section VI.F Specific Chemical Production Processes Releasing Chemicals Listed in Annex C; UNEP 2007).

.

2 Guidelines have been developed for the management of livestock on the flood plains of the Elbe river contaminated with

PCDD/PCDF and other pollutants (Landwirtschaftskammer Niedersachsen 2010, 2011). 3 Currently, only a limited number of country inventories address this PCDD/PCDF legacy source which is described in

Chapter 10 of the Toolkit without specifying emission factors.


In this section information on the production processes of some pesticides and other chlorinated aromatic chemicals is compiled. Also further information needs on the individual production processes are formulated.

For a range of pesticides only initial information on PCDD/PCDF or other unintentional POPs was available by 2013 and was not sufficient to derive emission factors for the UNEP Dioxin Toolkit (UNEP 2013). These were listed in Annex 2 of the UNEP Toolkit and are also listed in Annex in this report.

1.5 Chlorobenzenes Chlorobenzenes are produced commercially by reacting Cl2 with liquid benzene in the presence of a catalyst such as ferric chloride (FeCl3). The predominant products of this reaction are monochlorobenzene, HCl, 1,2-dichlorobenzene (o-dichlorobenzene) (CAS 95-50-1) and 1,4-dichlorobenzene (p-dichlorobenzene) (CAS 106-46-7). As this direct chlorination process is continued, 1,2,4-trichlorobenzene (CAS 120-82-1), other tri-, tetra-, and pentachlorobenzenes, and, finally, hexachlorobenzene are formed. Total global production of chlorobenzenes in 2003 was estimated at 640,000 tons (China Chemical Reporter 2004).

Only one studies assessed the PCDD/PCDF level in products and intermediates (Table 1; Liu et al. 2004) and a few studies (German Environmental Agency 1985; Hagenmaier 1987). The levels in the intermediates were relatively high (620 ng TEQ/kg) (Liu et al, 2004; Table 1). Table 1: PCDD/PCDF contaminants in intermediates and products from (Liu et al. 2004)

Sample PCDD/PCDF (ng TEQ/kg) Intermediate: mixture of 1,2- and 1,4-dichlorobenzene after distillation and separation from monochlorobenzene 620

Intermediate: mixture of di- and trichlorobenzenes 1850 Residue left from purification of 1,2,4-trichlorobenzene 3370 1,4-Dichlorobenzene: after distillation and crystallization (98.1%) 39

1,2-Dichlorobenzene: after distillation and crystallization ND Purified 1,2,4-trichlorobenzene ND

1.5.1 Currently only a few studies have investigated the occurrence of PCDD/PCDF in chlorobenzenes (Hagenmaier 1987; German Environmental Agency 1985), and only one study assessed intermediates in chlorobenzene production. None of these studies assessed PCDD/PCDF content in relationship to the reaction conditions in the production process. Therefore further information is needed to define BAT levels and conditions:

Further information needed for chlorobenzene production processes

• Other than the process described by Liu et al. (2004), what, if any, production processes are in use for commercial production of PCBz?

• How does UPOPs formation vary with each such process in comparison to that reported by Liu et al. (2004)? What factors are important in triggering differences in PCDD/PCDF and UPOP levels?

• Do all processes for manufacturing PCBz use the same clean-up steps (distillation and crystallisation) for refining to the final product as those described by Liu et al. (2004)?


1.6 Chloranil p-Chloranil (CAS 118-75-2) is used as an intermediate in the production of medicines, pesticides, and dioxazine dyes (Liu et al

For p-chloranil manufacture, the Toolkit lists several PCDD/PCDF emission factors. While initial data on other UPOPs (PCB, HCB and PeCBz) are mentioned, no emission factors have been derived yet (UNEP 2013).

. 2012). It is also used as a fungicide and for seed treatment, although such uses are prohibited in some countries (UNEP 2013).

Some portion of the PCDD/PCDF and other unintentional POPs that occur in chloranil are transferred to dyestuffs, pigments, inks, etc. and other products made from chloranil (see chloranil-derived pigments and dyes below). In turn, some portion of PCDD/PCDF and other UPOPs in chloranil-derived materials are transferred into the production processes of textiles, polymers/plastics, and packaging materials (paper, tin cans, etc.) and released in process outputs (see, for example, source category 7g – Textile Production). Therefore some of this contaminated materials may potentially result in direct human exposure.

The two main synthesis methods for p-chloranil are. 1. The process of direct chlorination of phenol using Cl2, which produces both o- and p-

chloranil was developed and used in Germany until 1990. This process might still be used by producers in other countries (UNEP 2013; Kirk-Othmer 1991)

2. Conversion of phenol to hydroquinone, followed by the reaction of hydroquinone with Cl2 or hydrogen peroxide and hydrochloric acid to form p-chloranil. (Kirk-Othmer 1991)

There are other processes which can be used to synthesize chloranil. However it is not reported if they are used in full scale production of chloranil:

1. Hydroxylation and chlorination/oxidation of trichlorophenol with chromic acid with hydrochloric acid and potassium chlorate (Spencer 1982; Ashfort 1994)

2. Reaction of cyclohexane and hydrogen chloride with oxygen over a oxidation catalyst 3. From phenol, p-chlorophenol, or p-phenylenediamine by treatment with potassium

chlorate and hydrochloric acid. (Lewis 1993)

4. From aniline when treated with chlorine gas, in an aqueous mixture of sulfulric acid and acetic acid (at 105-115 °C). (Kirk-Othmer 1991)

Refining of raw chloranil: PCDD/PCDF emission factors for the two production routes in greatest use are high (400,000 µg TEQ/t and 1,500,000 µg TEQ/t respectively). The large difference in the PCDD/PCDF concentration from the different chloranil producing industries was explained by the difference in the PCDD/PCDF removal efficiency of the purification process (Liu et al. 2012). Therefore the purification of chloranil plays a crucial role in controlling the releases of the unintentional POPs during the chloranil production process. Details on the purification process of chloranil were not described in the paper. Currently the lower emission factors based on purification is only listed for the hydroquinone route (table 2). However, purification can most probably be applied to both processes.

1.6.1 In the current studies on PCDD/PCDF and other unintentional POP in chloranil no specific BAT/BEP measure within the synthesis process was reported in the papers (Liu et al. 2012)

Further information needed for chloranil production processes


which could currently be recommended for reduction of PCDD/PCDF and other unintentional POPs. Only the information is given that purification lead to the reduction of PCDD/PCDF content (Liu et al. 2012). Since the purification processes were not described, the following information is needed:

• Can crude chloranil be produced via the two main production methods (synthesis from phenol and synthesis from hydroquinone) with PCDD/PCDF emission factors lower than those currently listed in the Toolkit (400,000 µg TEQ/t and 1,500,000 µg TEQ/t respectively).

• What emission factors can be achieved only by optimizing reaction conditions and what are these conditions?

• Are other synthesis routes mentioned above applied in technical scale? Do any of them have advantages in respect to UPOPs formation?

• What are the refining steps used to clean the crude chloranil, can they be applied to both major synthesis routes, and what is their removal efficiency respectively.

Table 2: PCDD/PCDF emission factors for source category 7d p-Chloranil Production (UNEP 2013)

7d p-Chloranil Production Emission Factors (µg TEQ/t product) Classification Air Water Land Product Residue

1 Direct chlorination of phenol ND ND ND 400,000 ND

2 Chlorination of hydroquinone with minimal purification ND ND ND 1,500,000 ND

3 Chlorination of hydroquinone with moderate purification ND ND ND 26,000 ND

4 Chlorination of hydroquinone with advanced purification ND ND ND 150 ND

1.7 Pentachlorophenol Pentachlorophenol (PCP; CAS 87-86-5) and PCP-Na (CAS 131-52-2) has recently been listed as POPs in the Stockholm Convention with the exemption of wood preservative for utility poles and cross arms (UNEP 2015). Therefore no further PCP production is taking place for this specific use.

PCP and PCP-Na were also used as pesticides and as preservatives for wood indoor, leather, textiles (including cotton or wool) and for killing snails in areas where schistosomiasis is epidemic (Zheng et al. 2011). These other uses are not listed as exemptions.

PCDD/PCDF in PCP resulted in contamination of livestock from PCP treated wood in stables (Fries et al. 2002; Huwe et al. 2004) or from recycling of wood in animal bedding (Brambilla et al. 2009). Also the use of PCP treated saw mill dust in feed additive caused food contamination (Hoogenboom et al. 2004) or from contamination of feed from drying with PCP treated wood (Schwind & Hecht 2004). PCP was also the source of PCDD/F in guargum, which is used globally as food starch (European Commission Community Reference Laboratory for Dioxins and PCBs in Feed and Food 2007a,b).

Single emission factors for PCP and PCP-Na are listed in the Toolkit without information on differentiation of production quality (e.g. high-end or low-end production process).

Production of PCP:


PCP is produced via the reaction of chlorine with liquid phenol, chlorophenol or a polychlorophenol to produce 2,4,6-trichlorophenol, which is then converted to PCP by further chlorination at progressively higher temperatures in the presence of catalysts (aluminum, antimony, their chlorides, or others) (Borysiewicz, 2008).

A patent was issued in 2010 on a method for improving PCP production by reducing PCDD/PCDF contamination (Savage and Yu, 2010). In this patent PCP is produced by the progressive chlorination of phenol. Because PCDD/PCDF formation occurs mainly in the late stage of the reaction, one conclusion was to stop the reaction at a certain degree of chlorination (Savage & Yu 2010).

PCP has also been produced from the thermolysis of hexachlorocyclohexane (HCH) as a recycling approach of waste isomers including a chlorination step and hydrolysis (Wu 1999).

Currently only one emission factor is listed in the Toolkit (634,000 μg TEQ t-1) without assigning particular described production conditions. It is well documented that PCP can have much higher (10,000,000 μg TEQ t-1) and lower (10,000 μg TEQ t-1) contamination levels. These known values of commercial PCP might tentatively be assigned for low-end, mid-range and high-end production processes.

Production of PCP-Na: The main production process for PCP-Na is the dissolution of PCP flakes in sodium hydroxide solution (Borysiewicz, 2008). PCP-Na has also been produced via alkaline hydrolysis of hexachlorobenzene (HCB) in methanol and dihydric alcohols, in water and mixtures of different solvents in an autoclave at 130 - 170°C (Borysiewicz 2008).

The Stockholm Convention Center China recently measured the PCDD/PCDF and PCB levels in PCP-Na from the last registered PCP production China in 2011

4

Another sample of a PCP-Na formulation (65% active ingredient) was taken in 2011 from the Chinese market (Huang et al. 2014). The PCDD/PCDF level in this sample was extremely high at a concentration of 1,815,000 μg TEQ t-1 (recalculated to PCP)

and a PCP formulation from the maket (Huang 2014). The PCDD/PCDF content of the PCP-Na was low (2100 µg WHO (2005) TEQ t-1). Also PCB levels of 76 µg WHO (2005) TEQ t-1 were measured in the PCP sample.

5

Table 3: Emission factors for PCP and PCP-Na for high-end, mid-range and low-end emission factors (Huang 2014; Masunaga et al. 2001; UNEP 2013)

. The PCDD/PCDF levels in this PCP-Na is more than an order of magnitude higher compared to the current emission factor in the Toolkit (12,500 μg TEQ t-1), while the levels in the PCP-Na from the Chinese production facility was a factor of 6 lower (2,100 μg TEQ t-1) compared to the current default emission factor. These relatively contemporary values can be used to improve the information on emission factors currently listed in the Toolkit (Table 3).

Chemical (Former) Use6 Information available supports to

development of EF for PCDD/PCDF

4 The last officially PCP production in China had a license for PCP production until 2011 and stopped production then.

Currently there is no PCP production in China. 5 The congener pattern of the PCP formulation had a different congener pattern compared to the raw pesticide of the only

registered Chinese PCP-Na producer. Therefore, it is concluded that this sample does not originate from the registered plant but that either the PCP-Na stem from import or from PCP of a non-registered PCP production.

6 Only the use of PCP in wood preservation has been exempted in the Stockholm Convention listing. However countries

having not ratified the convention or having not opted in for PCP might still produce and use PCP for other uses.


PCP Fungicide (Wood; leather, textile); pesticide

Low-end 10,000 μg TEQ t-1 Mid-range (Toolkit) 634,000 μg TEQ t-1 High-end 10,000.000 μg TEQ t-1

PCP-Na Fungicide (Wood; leather, textile); pesticide

Low-end 2,100 μg TEQ t-1 Mid-range (Toolkit) 12,500 μg TEQ t-1 High 1,815,000 μg TEQ t-1

1.7.1 In the current studies on PCDD/PCDF and other unintentional POPs in PCP only one patent described measures within the synthesis process to reduce PCDD/PCDF (Savage & Yu 2010).

Further information needed for PCP production processes

No information was described for the purification.

Therefore the following information is needed for better defining production and purification processes:

• What are the process conditions and PCDD/PCDF and other UPOPs levels in PCP and PCP-Na production that can be reached without refining steps?

• What are the refining steps for clean-up of PCP and PCP-Na and what levels of PCDD/PCDF and other UPOPs can be reached with the refining steps.

1.8 2,4-D and derivatives 2,4-Dichlorophenoxyacetic acid (2,4-D, CAS 94-75-7) and its derivatives (Table 4) are systemic herbicides used to control broadleaf weeds. 2,4-D is one of the world’s most widely used pesticides (Industry Task Force, 2012).

PCDD/PCDF emission factors currently listed in the Toolkit range from 0.1 μg WHO-TEQ t-1 (high-end technology) to 5,688 μg WHO-TEQ t-1 (low-end technology). Recent measurements in China were between 13.4 and 268 µg TEQ t-1, which are, on average, slightly lower than the emission factor of mid-range technologies (170 µg TEQ t-1).

Also other UPOPs have been detected in 2,4-D derivatives. Liu et al. (2013) analysed PCDD/PCDF, PCB, PeCBz and HxCB in 2,4-DB from three different Chinese producers and reported values in the range of 293 to 695 μg TEQ t-1. The WHO-TEQ values of the PCBs were relatively low and between 0.057 and 0.466 μg TEQ t-1. HCB levels ranged from ND to 2907 µg t-1 and PeCB concentration from 372 to 3084 µg t-1 Liu et al. (2013).

Production of 2,4-D and derivatives Manufacture of 2,4-D and derivatives involve two major production steps:

• Chlorination of phenol to form 2,4-dichlorphenol (2,4-DCP), and

• Synthesis of the 2,4-D or derivative from 2,4-DCP. From mechanistic considerations, the chlorination step has a high PCDD/PCDF formation potential. High levels in 2,4-DCP from an East European production (Grochowalski et al. 2012) confirm that most PCDD/PCDF formation occurs in the step of 2,4-DCP production.

However also the second step – synthesis of derivative from 2,4-DCP - has a certain PCDD/PCDF formation potential.


2,4-D is commonly prepared by the condensation of 2,4-dichlorophenol with monochloroacetic acid in a strongly alkaline medium at moderate temperatures. The alkali metal salts of 2,4-D are produced by the reaction of 2,4-D with the appropriate metal base. Amine salts are obtained by reacting amine and 2,4-D in a compatible solvent. Esters are formed by acid-catalysed esterification with azeotropic distillation of water or by direct synthesis in which the appropriate ester of monochloroacetic acid is reacted with dichlorophenol to form the 2,4-D ester (IPCS 1989).

Higher reaction temperatures and alkaline conditions during the manufacture of 2,4-D increase the formation of PCDD/PCDF. However, currently there is no study published to which degree the formation of newly formed PCDD/PCDF in the second production steps significantly contribute to the total PCDD/PCDF contamination compared to the PCDD/PCDF levels.

Alternative synthesis route:

2,4-D can also be produced by the chlorination of phenoxyacetic acid, but this method leads to a product with a high content of 2,4-dichlorophenol and other impurities. Table 4: 2,4-D and relevant derivatives

2,4-D and derivatives CAS numbers 2,4-D CAS 94-75-7 2,4-D sodium salt CAS 2702-72-9 2,4-D diethyl amine CAS 2008-39-1 2,4-D dimethylamine salt CAS 2008-39-1 2,4-D isopropyl ester CAS 94-11-1 2,4-D ethylhexyl ester CAS 1928-43-4 2,4-D butoxyethyl ester CAS 1929-73-3 2,4-DB (4-(2,4-dichlorophenoxy)butyric acid) CAS 94-82-6 2,4-D isooctyl ester CAS 25168-26-7

1.8.1 In the current studies on PCDD/PCDF and other unintentional POPs in 2,4-D or 2,4-D derivatives, no details on process parameters (e.g. temperature, pH or time) and related unintentional POPs formation and levels are described. Also no details on purification of 2,4-DCP and 2,4-D and derivatives have been published.

Further information needed for 2,4-D and derivative production processes

Therefore the following information is needed for better defining production and purification processes of 2,4-D and derivatives:

• What are the process conditions and the related levels of PCDD/PCDF and other unintentional POPs in the production of dichlorophenol (DCP).

• What are refining steps for dichlorophenol and achievable levels of PCDD/PCDF and UPOPs?

• Under which conditions are further PCDD/PCDF and other UPOPs formed in the production of 2,4-D and derivatives from 2,4-DCP.

• What are refining procedures of 2,4-D and other derivatives.

1.9 DDT and PCDD/PCDF in Dicofol a) DDT in dicofol


Dicofol is normally synthesized from technical DDT. During the process, DDT is first chlorinated to an intermediate, Cl- DDT, followed by hydrolysis to dicofol (Tang et al 1998). The resulting active ingredient is a mixture of approximately 80% p,p’-dicofol and 20% o,p’-dicofol (van de Plassche et al. 2004).

After the synthesis reaction, DDT and Cl-DDT remain in the dicofol product as impurities (Qiu et al. 2005). High amounts of DDT were detected in Chinese dicofol in 2005 at levels up to 34% with an average of approx. 13% DDT, 4.4% DDE and 6.9% Cl-DDT (Qiu et al. 2005)

7

Two chemical industry sector standards of the People’s Republic of China, HG3699-2002 and HG3700-2002, require DDT impurity to be no more than 0.5% of technical dicofol or below 0.1% of formulated dicofol containing 20% dicofol (Qiu et al. 2005). In several countries (e.g. Argentina, Brazil, Canada, EU, USA) the DDT level in dicofol is limited to less than 0.1% (van de Plassche et al. 2004).

. This DDT contamination in dicofol resulted in the release in China of 12,912 tonnes of DDT from dicofol use from 1984 to 2003 (Wang et al. 2010), while only approx. 2,400 tonnes DDT was used for malaria control during the same period. Therefore from the total of 15,312 tonnes of DDT released, approximately 84% was from DDT as an impurity in dicofol (Wang et al. 2010). Dicofol from an Indian production formerly contained 3.5% DDT (van de Plassche et al. 2004).

Therefore, with BAT production of dicofol, it is possible to achieve levels of less than 0.1% DDT in dicofol. However it is unclear if the 0.1% can be reached in the production process of dicofol or if purification is needed. It was reported that dicofol produced by Dow AgroSciences (KELTHANE®) is purified on-site to meet the 0.1% DDT limit (van de Plassche et al. 2004). This indicates that dicofol production requires a refining step. The DDT and related substance content of crude dicofol produced by Dow AgroSciences and employed as feedstock for purification is unknown (van de Plassche et al. 2004)

8

b) PCDD/PCDF in dicofol product

.

Li et al. (2014) reported that the emission factor of PCDD/PCDFs for dicofol product in the Chinese dicofol production was 86.3 μg TEQ t-1. Also releases to wastewater and waste acid have been measured and estimated to be 0.074 μg TEQ t-1, 0.023 μg TEQ t-1 of dicofol (Li et al. 2014). Therefore the release via these vectors seems relatively small. On the basis of the annual dicofol production (c. 2000 t a-1), the annual amount of PCDD/PCDFs in product was estimated to be 0.17 g I-TEQ a-1 (Li et al. 2014) indicating a minor relevance and improvement potential.

1.9.1 Following further information is needed in respect to Dicofol production

Further information needed for dicofol production processes

• Achievable DDT levels in the raw dicofol (to clarify if 0.1% of DDT can be reached in the production without purification. This would also be a relevant information for assessing dicofol productions and related DDT waste.

7 This DDT contamination in dicofol resulted in China in an emission of 12,912 tonnes of DDT from dicofol use from 1984

to 2003 (Wang et al. 2010), while only approx. 2400 tonnes DDT was used for malaria control during the same period. Therefore from the total of 15,312 tonnes of DDT released, approximately 84% was from DDT as an impurity in dicofol (Wang et al. 2010).

8 The manufacturing wastes - including those containing DDT and related substances - are destroyed through appropriate

techniques like high-temperature incineration.


• Purification method of raw dicofol and achievable DDT levels.

1.10 PCNB The PCNB dataset of Holt et al (2010) and Hung et al. (2012) was used for developing emission factors for PCNB in the Toolkit (UNEP 2013). Additionally PCB data have been provided by the study of Huang et al. (2014). Recently Huang et al. (2014) published the full dataset in a peer reviewed paper (Huang et al 2014). Here the PCDD/PCDF data and PCB data included in UNEP toolkit have been confirmed within the peer review process. In addition HCB and PeCBz were measured in the study. HCB levels ranged between 3,700 to 52,000 µg t-1 and PeCBz between 40 and 300 µg t-1 (Huang et al. 2014).

PCNB can be produced by either the chlorination of nitrobenzene/chloronitrobenzene or the nitration of chlorinated benzenes (EHC41 1984). Today the production via nitrobenzene or chloronitrobenzene seems preferred (Huang et al. 2014). Chlorosulfonic acid is used as solvent and nitrobenzene or monochloronitrobenzene is used as the raw material. Iodine is used as catalyst (typically 0.3 %). After heating to 60–100 °C, the chlorine gas is introduced while stirring the mixture. The hydrogen chloride (HCl) generated is pumped into the adsorption kettle by a water injector. After the chlorination is completed, the mixture is educed and filtered (Huang et al. 2014).

The PCDD/F levels in the formulation were higher compared to the raw PCNB purchased from the producers (Huang et al. 2014). It was not clarified if PCDD/F is formed during processes used for producing the formulation (e.g. milling). PCNB has a PCDD/F formation potential in sun light (Holt et al. 2012) and might also under other conditions (e.g. milling processes during formulation) form PCDD/F.

1.10.1 Following further information is needed in respect to PCNB production

Further information needed for dicofol production processes

• PCNB formation mechanism of PCDD/F and reduction measures.

• Refining processes used and removal efficiency.

• Potential of formation of PCDD/F in formulation processes (milling) and reduction measures.

1.10.2

For a range of pesticide only initial information on PCDD/PCDF or other unintentional POPs are available which were not sufficient to derive emission factors yet (UNEP 2013). These pesticides were listed in Annex 2 of the UNEP Toolkit and are also listed in Annex A1 in this report. Also the USEPA has developed a list of pesticides known or suspected to be accompanied by PCDD/PCDF formation during production (US EPA 2005; Bretthauer et al. 1991). These are listed in Annex A2 in this report. For most of these pesticides no or very limited data on are available.

Pesticides recently associated with PCDD/PCDF formation and releases or suspected to contain PCDD/PCDF

Also many chlorinated aromatic chemicals not included in the toolkit or in the list in Annex are currently used in industry, consumer goods or a pesticides. The current pesticides produced (>1300 different pesticides) might contain a range of such chlorinated aromatic compounds not yet been assessed on their contamination level with PCDD/PCDF and other unintentional POPs. Depending on their possible contamination level, the production volumes and mode of use, might have relevance to the overall releases of unintentional POPs and related human exposure.


For these production processes and products following information would be valuable to conclude on contamination levels and source of contamination in the respective processes:

• More data on PCDD/PCDF and other unintentional POPs levels of the chemicals and the formulation.

• Details of the production process which might help to further evaluate the potential of formation of unintentional POPs in these processes or the introduction of unintentional POPs via other chemicals as described in section 2.7.7.

• Assessment of total dioxin-like toxicity as indicator for other dioxin-like compounds (e.g. dl-PCBs; dl-PCNs). Here the assessment of the chemicals from organochlorine industry had sometimes considerable higher dioxin-like toxicity where the measured PCDD/PCDF could only explain 5% (van Hattum et al. 2004). Also for pesticides it has been shown that the dioxin-like toxicity can be far higher than the TEQ measured by instrumental analysis of PCDD/PCDF and dl-PCBs (Huwe et al. 2003)

9. A

screening with accredited bio-assays for dioxin-like toxicity as listed approach in the UNEP BAT/BEP guidelines might be a cheap

10 and feasible approach to screen

PCDD/PCDF and dioxin-like substances in pesticides and industrial chemicals (van Hattum et al. 2004). If, for instance, in addition to chlorine, other substituents are present in the aromatic moiety or heteroatoms are present in a chemical/ pesticide, depending on the structure, the chemical might have dioxin-like toxicity. Dioxin-like compounds such as the pyridine analogue of 2,3,7,8-TCDD (2,3,7,8-TCDD-pyridine) was recently described as thermal condensation product from chlorpyrifos

11

2 UNINTENTIONAL POPS IN THE PRODUCTION OF AROMATIC PIGMENTS

(Sakiyama et al. 2012; Behnisch et al. 2013). Due to the additional substituents or heteroatom these compounds are not detected in the normal PCDD/PCDF analysis (Sakiyama et al. 2012) but might still have dioxin-like toxicity (Behnisch et al. 2013).

Unintentional POPs have been reported by a wide range of pigments and some emission factors have been listed in the UNEP toolkit (UNEP 2013). For a few pigments of different pigment groups (phthalocyanines see 4.1; dioxazine dyes see 4.2) some emission factors for PCDD/PCDF are listed in the UNEP toolkit (UNEP 2013). For other pigment groups high levels of HCB have been found (in particular those based on tetrachlorophthalic acid (TCPA) see 4.3) and some emission factors are included in Annex 48 in the UNEP toolkit (UNEP 2013).

In recent years PCB have been detected in a range of pigments (Anezaki & Nakano 2014; Anezaki et al. 2014; Hu and Hornbuckle 2010). Some of these belonging to already listed pigment groups and some belong were from pigment groups not yet listed in the UNEP toolkit including pigment group of azo-dyes and pigments (see section 4.4) and Polyaromatic type pigments (see section 4.5).

9 With combined instrumental and biological measurements it has been revealed that today the largest share of dioxin-like

toxicity in e.g. house dust or sewage sludge does not stem from PCDD/PCDF or dl-PCB but that other dioxin-like compounds are responsible for the toxicity (Tue et al. 2013; Venkatesean and Halden 2014).

10 The chemical analysis of a larger set of dioxin-like compounds (PCDD, PCDF, dl-PCBs, dl-PCNs, PBDD/PBDF,

PCDD/PXDF) is very expensive for individual samples. Therefore a pre-screening with bio-assay can result in a pre-selection of samples.

11 Chlorpyrifos is a high volume pesticide


These pigments are used for consumer products such as paints, plastics, print/magazines or packaging (including food). The Washington State Department of Ecology has recently measured PCB in a range of consumer (packaging, paper products, paint and colorants, caulks and printer inks). In most of the samples unintentional PCB were detected. Concentrations were in the ppb level with the highest PCB contamination of 320,000 µg t-1 in a green paint (Washington State Department of Ecology 2014).

The Japanese Ministry of Economy, Trade and Industry (METI) is monitoring the PCB content of pigments imported and used in Japan and have compiled data for batches of a range of pigments exceeding the Basel Convention low POPs limit for PCBs of 50 ppm (Table 5). Several of these pigments had PCB levels up to 2000 ppm for a Pigment Yellow-83 (Table 5).

In the study of the Japanese Ministry of Economy and Trade (METI) and the individual research groups PCDD/PCDF levels in the pigments were not reported and probably not measured. Also from the pigments with high PCB levels of METI (table 2) no PCDD/PCDF

12

Table 5: Pigment batches monitored by the Japanese Ministry of Economy and Trade exceeding 50 ppm limit for import or use in Japan (METI 2013)

emission factors are listed in the UNEP toolkit. For one pigment (Violet 23) investigated by Anazaki et al. 2014 and Anazaki & Nakano (2014) a PCDD/PCDF emission factor is listed in the toolkit.

Name of Pigment Name of Product Amount of PCB (ppm) Pigment Red -2 (CAS: 6041-94-7)

ZA-855 Red 37～58 ppm PERMANENT RED G-87 52 ppm FAST RED F2R (PR-2) POWDER 61 ppm

Pigment Red -112 (CAS: 6535-46-2)

ZA-862 Red 16～121 ppm Permanent Red GY

Pigment Yellow -12 (CAS: 6358-85-6)

Pigment Yellow 1207 1,500 ppm Disazo Yellow G 178－4 110 ppm


DISAZO YELLOW 3GR-M 220 ppm DISAZO YELLOW 3GR-M-5


SUIMEI YELLOW GGNB 810 ppm


SUIMEI YELLOW 7G 700 ppm SUIMEI YELLOW 7GKT 1000 ppm


SUIMEI YELLOW DRO-10 1,500 ppm SYMULER Fast Yellow 4539


SUIMEI YELLOW F10G 79 ppm


SUMIKAPRINT FAST YELLOW HR-M 52～280 ppm SUMITONE FAST YELLOW HR-M-5 SUMIKAPRINT FAST YELLOW HR-T-2 SUMIKAPRINT FAST YELLOW HR PY-2GN SUIMEI YELLOW ERT 2,000 ppm SUIMEI YELLOW 5RT Permanent Yellow HR-1183-2 59 ppm

12

For one pigment (Violet 23) investigated by (Anazaki et al. 2014) and (Anazaki & Nakano 2014 a) PCDD/PCDF emission factor is listed in the toolkit.


Pigment Yellow -165 (C16H12Cl2N4O)

FAST YELLOW F5G 208 ppm

Pigment Orange -13 (CAS: 3520-72-7)

Orange BO-01 1,000 ppm

Pigment Orange -34 (CAS: 15793-73-4)

SUIMEI PYRAZOLONE ORANGE GR-N 190 ppm

2.1 Phthalocyanine dyes and pigments Phthalocyanine dyes and pigments are widely used in paints and plastic. The global production rate in 2011 was about 420,000 tons (Linak et al. 2011).

Phthalocyanine dyes con contain a range of unintentional POPs including PCDD/PCDF, PCB and HCB (Heindl & Hutzinger 1989; Ni et al. 2005; Anezaki & Nakano 2014). Two phthalocyanine dyes - Phthalocyanine copper (CAS 147-14-8) and Phthalocyanine green (CAS 1328-45-6) - are listed with PCDD/PCDF and HCB emission factors in the Toolkit (UNEP 2013).

Phthalocyanine dyes and pigments are prepared by variations of the following methods (UNEP 2013):

• Reaction of phthalonitrile with metal or metal salts;

• Reaction of phthalic anhydride, phthalic acid or phthalimide, tetrachlorophthalic anhydride with e.g. specific organics, urea, metal salt and catalyst;

• Reaction of metal-free phthalocyanine or replaceable metal phthalocyanine with another metal.

Copper phthalocyanine (Phthalocyanine Blue BN, also called Monastral blue, phthalo blue (CAS 147-14-8, EINECS 205-685-1)), is a blue pigment generally produced using the second method (Heindl & Hutzinger 1986). The phthalic anhydride/imide, a metal salt, urea and a catalyst are heated at 170-200C for about four hours in a solvent such as trichlorobenzene, nitrobenzene or chloronaphthalene.

The blue of copper phthalocyanine is shifted towards green by replacing hydrogen atoms on the aromatic rings with chlorine (e.g. pigment green 7) or chlorine and bromine (e.g. pigment green 36). This is accomplished through direct chlorination of copper phthalocyanine by passing chlorine into an AlCl3/NaCl mixture at 180-200°C (Jain 2011). PCDD/PCDF have been detected in samples of copper phthalocyanine and phthalocyanine green (Ni et al. 2005), as well as nickel phthalocyanine (Hutzinger and Fiedler 1991).

Source for PCDD/PCDF and other UPOPs formation and related reduction option 1) Use of chlorinated aromatic solvent and applied temperature One source of unintentional POPs (in particular PCB and PCDD/PCDF) in phthalocyanines including the non-chlorinated stem from the use of chlorinated solvents (Table 6). The PCB-content of phthalocyanines was due to the use of chlorinated aromatic solvents like dichlorobenzene and trichlorobenzene (Anliker 1981; Kerner & Maissen 1980; Heindl & Hutzinger 1986) and were often above regulation limit in the EU and Stockholm Convention (50 ppm) or limit in the United States (25 ppm) (Brychky & Wagner 1998). Also PCDD/PCDF levels in phthalocyanines were sometimes above German chemical regulation limits (Brychky & Wagner 1998). There are two options for the presence of PCB and PCDD/PCDF from chlorobenzene solvents:


• They are already present in the chlorobenzene solvent.

• They are newly formed in the production of Phthalocyanines Both pathways are found in practice. Chlorobenzene can contain PCB and PCDD/PCDF (Hagenmaier 1985; German Environmental Agency 1985; Liu et al. 200). PCBs can be formed by the condensation of chlorobenzenes during condition of phthalocyanine synthesis reaching temperature of approx. 210°C (Brychky & Wagner 1998). E.g. PCBs are formed when heating of 1,2,4-trichlorobenzene (used as solvent) at 200°C in the presence of copper chloride. These reaction condition also resulted in the formation of PCDD/PCDF in ppt/ppb-range (Heindl & Hutzinger 1989).

When decreasing the temperature, PCDD/PCDFs are still formed at 180°C, but were not detected at 160°C and below (Heindl & Hutzinger 1989). This study demonstrates the importance of detailed assessment on temperature effects and metal effects on PCDD/PCDF formation when using chlorinated aromatic solvents or reaction products.

These pathways can also contaminate phthalocyanine blue where no chlorination is involved.

Another solvent which have been used and is still be used is monochloronaphthalene. This solvent seems to be used today also for photovoltaic devices (Chen et al. 2008). The use of chlorine in processes using chloronaphtalene will form polychlorinated naphtalenes (PCNs) recently listed in the Stockholm Convention.

This formation pathway via chlorinated aromatic solvents can be stopped/reduced by either

• substituting chlorinated aromatic solvents with other solvents

• using clean chlorinated aromatic solvents and controlling temperature below 160°C. 2) Formation of unintentional POPs during chlorination of phthalocyanine solvents Unintentional POPs can also be formed during the chlorination of phthalocyanine to chlorinated phthalocyanine (e.g. pigment green 7). The chlorination of phalocyanine is exothermal reaction over 15 to 30 hours which can reach up to 1210°C (Brychky & Wagner 1998). At this temperature and conditions some Phthalocyanine molecules might degrade and become precursor for PCDD/PCDF (Brychky & Wagner 1998) and other unintentional POPs such as HCB.

3) Formation of PCDD/PCDF during formulation of the pigments The temperature during formulation is normally below 100°C. Therefore PCDD/PCDF are not formed due to thermal condensation (see above). However in the formulation also strong oxidizing agents such as chromate, peroxide or perborate are used (Brychky & Wagner 1998). If precursors are present PCDD/PCDF might be form under such advanced oxidation conditions (Weber 2007; Vallejo et al. 2015).

Therefore for a BAT/BEP production and formulation of phthalocyanines following guidance were described for a high-end production (BAT) with low PCDD/PCDF (Brychky & Wagner 1998):

• The raw materials should be selected including the solvents

• The process parameters (in particular the temperature) need to be strictly controlled

• The formulation process need to be controlled in respect to The PCDD/PCDF and unintentional POPs content need to be monitored to optimize and control the production process.


2.1.1 While the formation mechanism and the conditions in the process of phthalocyanine blue and phthalocyanine green (Pigment 7) is quite well described there are a range of further information needed for minimizing PCDD/PCDF formation and release and to define BAT:

Further information needed for phthalocyanine production processes

• More quantitative data on PCDD/PCDF and other unintentional POPs for the individual steps and the definition of high-end, middle-bound and low-end processes

• Currently only information/Emission Factor for phthalocyanine blue and phthalocyanine green are listed in the Toolkit (table 6) and from other phthalocyanines no data are available and need to be gathered.

• There are also phthalocyanine compounds which use a combination of chlorination and bromination (e.g. pigment 36). Here in addition to PCDD/PCDF also brominated-chlorinated PXDD/PCDF and other mixed halogenated unintentional POPs analogues might be formed.

• What solvents are currently used in the phthalocyanine production and their effect on the PCDD/PCDF formation?

Table 6: PCDD/PCDF emission factors for source category 7d Phthalocyanine Dyes and Pigments Production (UNEP 2013)

7d Phthalocyanine Dyes and Pigments Production Emission Factors (µg TEQ/t product)

Classification Air Water Land Product Residue 1 Phthalocyanine copper (CAS 147-14-8) ND ND ND 70 ND 2 Phthalocyanine green (CAS 1328-45-6) ND ND ND 1,400 ND

2.2 Dioxazine dyes and pigments Tests on some of these dyes and pigments in the early 1990s showed PCDD/PCDF concentrations in the range 1 to 60 mg TEQ/kg (USEPA 2006a, Krizanec and Le Marechal 2006). Currently three Dioxazine dyes are listed with single emission factors in the Toolkit (UNEP 2013).

Production of dioxazine dyes and Dioxazine dyes and pigments are produced through the reaction of p-chloranil with aromatic amines in the presence of a base. The presence of unintentional POPs is mainly attributed to the use of PCDD/PCDF-contaminated p-chloranil. Also unintentional PCB including dioxin-like PCBs have been detected in some dioxazine dyes (Anezaki & Nakano 2014).

In particular the p-chloranil produced by the chlorination of phenol was considered as highly contaminated with PCDD/PCDF (USEPA 2006a, Krizanec and Le Marechal 2006) with an assigned emission factor of 400,000 µg TEQ/t (see section 3.2). As one solution an alternate production process was developed for producing chloranil with lower PCDD/PCDF content through the reaction of hydroquinone with HCl (UNEP 2013). However recent studies have shown that also chloranil produced via this pathway can also have extreme high PCDD/PCDF levels (Liu et al. 2012) and the low-end process has even higher EF (1,500,000 µg TEQ/t) compared to the EF of the phenol pathway (UNEP 2013; see section 3.2). Therefore high level of PCDD/PCDF can result from the use of chloranil from both production processes.


Other additional potential sources for unintentional POPs are chlorinated solvents used in the production process (see section 2.6.1).

Reduction of unintentional POPs in dioxazine dyes Since chloranil is considered the major source of unintentional POPs in dioxazine dyes, the contamination level of chloranil (see section 3.2) is the main factor of reaching low PCDD/PCDF and other unintentional POPs levels in dioxazine dyes.

Since also other chemicals used in the production process (e.g. solvents) might contribute to unintentional POPs also these would be controlled.

Finally dioxazine dyes might also be refined to reduce unintentional POPs. Such refining have not been described for dioxazine dyes in literature.

2.2.1 Currently only single emission factors are assigned for the three listed dioxazin pigments in the Toolkit without indicating PCDD/PCDF emission factor for high-end dioxazine dyes production processes. The following information is needed in respect to dioxazine dyes production:

Further information needed for dioxazine dyes production processes

• What are the BAT levels for chloranil (currently indicated as 150 µg TEQ/t see section 3.2 and UNEP Toolkit) and what levels would result in the dioxazine dyes if such a chloranil would be used in their production?

• Are there other unintentional POPs source in dioxazine dyes production?

• What refining steps (e.g. crystallization or solvent washing) are or can be applied in dioxazine production and what effect in PCDD/PCDF and other unintentional POPs reduction can be reached respectively?

2.3 Tetrachlorophthalic acid (TCPA) and related pigments TCPA is the primary feedstock for the production of a range of pigments. While no PCDD/PCDF data are available for TCPA, unintentional HCB concentrations as high as 3,000 g/t have been detected (Government of Japan 2006, 2007).

The contamination of TCPA is a major source of the TCPA-derived pigments (Government of Japan 2006).

Manufacturing process of tetrachlorophatalic acid There are two manufacturing methods of TCPA (Government of Japan 2006):

a) Gas-phase process

In the gas-phase process TCPA is produced by reacting phthalic anhydride with elemental chlorine in the gas phase.

b) Liquid-phase process

In the process using liquid method TCPA is manufactured by reacting phthalic anhydride with chlorine gas in the liquid phase. As solvent fuming sulfuric acid or chlorosulfonic acid is used.

According to the Report of the Government of Japan (2006), the gas-phase process result in higher HCB levels. As main reason of the higher HCB levels the higher temperature applied in the gas-phase process are mentioned and the related decarboxylation of phthalic acid (Government of Japan 2006). The temperature ranges and problematic temperatures and associated HCB levels were not mentioned.


As second parameter triggering the HCB production, the amount of chlorine and the control of excess of chlorine are mentioned (Government of Japan 2006).

Also the range of HCB in TCPA in the liquid process and associated parameters was not mentioned in the study. It seems that several 100 ppm HCB also is generated in the liquid process and need to be further refined by crystallization.

Recrystallization Process According to the Japanese TCPA report, manufacturers can reach in the first recrystallization process using a certain organic solvent a reduction of unintentional HCB in TCPA to 200 ppm. In the second recrystallization 80 ppm can be achieved and a third recrystallization can reduce levels to 40 ppm HCB (Government of Japan 2006).

The reduction of HCB in the process depends on the solvents used. Up to more than 80% reduction might be reached with some solvents but costs might prohibit the use of some solvents (Government of Japan 2006).

According to the Japanese survey of manufacturers, a recrystallization step add approximately 25 to 40% cost to the TCPA price (Government of Japan 2006).

Suggested BAT levels The study concluded that BAT levels of less than 200 ppm (with one recrystallization) and below 50 ppm can be achieved by modification of the production processes and by appropriate recrystallization (Government of Japan 2006). These values are currently included in the UNEP toolkit (Table III.48.13; UNEP 2013).

2.3.1 In the current studies on unintentional POPs in TCPA, no details are described on process parameters (e.g. temperature, pH or time) and related unintentional POPs formation and levels.

Further information needed for TCPA production processes

Therefore the following information is needed for better defining production and purification processes of TCPA:

• What are the levels of HCB in TCPA from the gas-phase process and what are levels which can be reached in this process. Are there other parameters then the temperature which triggers HCB levels from the gas-phase process?

• What are the levels of HCB in TCPA from the liquid-phase process and what are levels which can be reached in this process. What are the parameters which triggers the HCB levels from the liquid-phase process.

• Details on the recrystallization process and solvents to reach BAT levels.

• Further assessment of BAT levels suggested by the Government of Japan (currently it is stated that 200 ppm might be considered as BAT-level and 50 ppm can be reached). Assessment of HCB in TCPA produced by manufacturers in different regions and processes currently applied in practice.

• What are the levels of other unintentional POPs in the production processes of TCPA and in TCPA product.


2.3.2 TCPA-derived pigments include e.g. Pigment Yellow 110 (CAS 5590-18-1), Pigment Yellow 138 (CAS 30125-47-4), Solvent Red 135 (CAS 20749-68-2) and Solvent Red 162 (CAS 71902-17-5).

Pigments produced from TCPA

HCB is transferred into TCPA-derived pigments by TCPA used (Government of Japan 2006, 2007). Emission factors for HCB concentrations in some pigments have been established and are included in Annex 48 of the Toolkit. Proposed BAT levels are 10 ppm considering the transfer from TCPA and associated BAT levels (Government of Japan 2006).

Example: Solvent Red 135 an related HCB levels Solvent Red 135 is an industrially uses pigment included e.g. in plastic parts such as car parts in taillight covers (Government of Japan 2006). Levels in solvent red were found between 0.1 ppm to 310 ppm in an assessment of 38 samples (Government of Japan 2006) showing the wide range of contamination and that relative low levels can be reached.

Since no chlorination takes place in the process, all HCB are considered to stem from TCPA used. Other unintentional POPs were not assessed in the study.

Solvent Red 135 manufacturing process Solvent Red 135 is manufactured by reacting TCPA with 1,8-naphthylenediamine in a reaction solvent. The reaction product turns to Solvent Red 135 through a process of cooling, rinsing and drying (Government of Japan 2006). The detail of the process (e.g. kind of reaction solvent, condition of the reaction and the way of rinsing) depends on the manufacturer. Also water can be used in this production process (Government of Japan 2006).

If organic solvents are used in Solvent Red 135 production process, a large amount of the product HCB is dissolved in the solvent. Therefore the manufacturing process using organic solvent is an effective measure to reduce HCB level in Solvent Red 135 (Government of Japan 2006). The Solvent Red 135 produced in water shows a relatively high concentration level o

Documents

chm.pops.intchm.pops.int/Portals/0/download.aspx?d=UNEP-POPS... · U N I T E D N A T I O N S E N V I RO N M E N T P R O G R A M M E Stockholm Convention on Persistent Organic Pollutants