Appendix 5: Reproduction of Annex C, Stockholm Convention

Unintentional production

Part I: Persistent organic pollutants subject to the requirements of Article 5

• chemical
• polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF)
• hexachlorobenzene (HCB) (CAS No. 118-74-1)
• polychlorinated biphenyls (PCB).

Part II: Source categories

Polychlorinated dibenzo-p-dioxins and dibenzofurans, hexachlorobenzene and polychlorinated biphenyls are unintentionally formed and released from thermal processes involving organic matter and chlorine as a result of incomplete combustion or chemical reactions.  The following industrial source categories have the potential for comparatively high formation and release of these chemicals to the environment:

(a) waste incinerators, including co-incinerators of municipal, hazardous or medical waste or of sewage sludge

(b) cement kilns firing hazardous waste

(c) production of pulp using elemental chlorine or chemicals generating elemental chlorine for bleaching

(d) the following thermal processes in the metallurgical industry:

(i) secondary copper production

(ii) sinter plants in the iron and steel industry

(iii) secondary aluminium production

(iv) secondary zinc production.

Part III: Source categories

Polychlorinated dibenzo-p-dioxins and dibenzofurans, hexachlorobenzene and polychlorinated biphenyls may also be unintentionally formed and released from the following source categories, including:

(a) open burning of waste, including burning of landfill sites

(b) thermal processes in the metallurgical industry not mentioned in Part II

(c) residential combustion sources

(d) fossil fuel-fired utility and industrial boilers

(e) firing installations for wood and other biomass fuels

(f) specific chemical production processes releasing unintentionally formed persistent organic pollutants, especially production of chlorophenols and chloranil

(g) crematoria

(h) motor vehicles, particularly those burning leaded gasoline

(i) destruction of animal carcasses

(j) textile and leather dyeing (with chloranil) and finishing (with alkaline extraction)

(k) shredder plants for the treatment of end of life vehicles

(l) smouldering of copper cables

(m) waste oil refineries.

Part IV: Definitions

1 For the purposes of this Annex:

(a) “polychlorinated biphenyls” means aromatic compounds formed in such a manner that the hydrogen atoms on the biphenyl molecule (two benzene rings bonded together by a single carbon-carbon bond) may be replaced by up to 10 chlorine atoms; and

(b) “polychlorinated dibenzo-p-dioxins” and “polychlorinated dibenzofurans” are tricyclic, aromatic compounds formed by two benzene rings connected by two oxygen atoms in polychlorinated dibenzo-p-dioxins and by one oxygen atom and one carbon-carbon bond in polychlorinated dibenzofurans and the hydrogen atoms of which may be replaced by up to eight chlorine atoms.

2 In this annex, the toxicity of polychlorinated dibenzo-p-dioxins and dibenzofurans is expressed using the concept of toxic equivalency which measures the relative dioxin-like toxic activity of different congeners of polychlorinated dibenzo-p-dioxins and dibenzofurans and coplanar polychlorinated biphenyls in comparison to 2,3,7,8-tetrachlorodibenzo-p-dioxin.  The toxic equivalent factor values to be used for the purposes of this Convention shall be consistent with accepted international standards, commencing with the World Health Organization 1998 mammalian toxic equivalent factor values for polychlorinated dibenzo-p-dioxins and dibenzofurans and coplanar polychlorinated biphenyls.  Concentrations are expressed in toxic equivalents.

Part V: General guidance on best available techniques and best environmental practices

This Part provides general guidance to parties on preventing or reducing releases of the chemicals listed in Part I.

A General prevention measures relating to both best available techniques and best environmental practices

Priority should be given to the consideration of approaches to prevent the formation and release of the chemicals listed in Part I.  Useful measures could include:

(a) the use of low-waste technology

(b) the use of less hazardous substances

(c) the promotion of the recovery and recycling of waste and of substances generated and used in a process

(d) replacement of feed materials which are persistent organic pollutants or where there is a direct link between the materials and releases of persistent organic pollutants from the source

(e) good housekeeping and preventive maintenance programmes

(f) improvements in waste management with the aim of the cessation of open and other uncontrolled burning of wastes, including the burning of landfill sites.  When considering proposals to construct new waste disposal facilities, consideration should be given to alternatives such as activities to minimize the generation of municipal and medical waste, including resource recovery, reuse, recycling, waste separation and promoting products that generate less waste.  Under this approach, public health concerns should be carefully considered

(g) minimisation of these chemicals as contaminants in products

(h) avoiding elemental chlorine or chemicals generating elemental chlorine for bleaching.

B Best available techniques

The concept of best available techniques is not aimed at the prescription of any specific technique or technology, but at taking into account the technical characteristics of the installation concerned, its geographical location and the local environmental conditions.  Appropriate control techniques to reduce releases of the chemicals listed in Part I are in general the same.  In determining best available techniques, special consideration should be given, generally or in specific cases, to the following factors, bearing in mind the likely costs and benefits of a measure and consideration of precaution and prevention:

(a) General considerations:

(i) The nature, effects and mass of the releases concerned: techniques may vary depending on source size.

(ii) The commissioning dates for new or existing installations.

(iii) The time needed to introduce the best available technique.

(iv) The consumption and nature of raw materials used in the process and its energy efficiency.

(v) The need to prevent or reduce to a minimum the overall impact of the releases to the environment and the risks to it.

(vi) The need to prevent accidents and to minimise their consequences for the environment.

(vii) The need to ensure occupational health and safety at workplaces.

(viii) Comparable processes, facilities or methods of operation which have been tried with success on an industrial scale.

(ix) Technological advances and changes in scientific knowledge and understanding.

(b) General release reduction measures: When considering proposals to construct new facilities or significantly modify existing facilities using processes that release chemicals listed in this annex, priority consideration should be given to alternative processes, techniques or practices that have similar usefulness but which avoid the formation and release of such chemicals.  In cases where such facilities will be constructed or significantly modified, in addition to the prevention measures outlined in section A of Part V the following reduction measures could also be considered in determining best available techniques:

(i) Use of improved methods for flue-gas cleaning such as thermal or catalytic oxidation, dust precipitation, or adsorption.

(ii) Treatment of residuals, wastewater, wastes and sewage sludge by, for example, thermal treatment or rendering them inert or chemical processes that detoxify them.

(iii) Process changes that lead to the reduction or elimination of releases, such as moving to closed systems.

(iv) Modification of process designs to improve combustion and prevent formation of the chemicals listed in this Annex, through the control of parameters such as incineration temperature or residence time.

C Best environmental practices

The Conference of the Parties may develop guidance with regard to best environmental practices.