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Stockholm Convention

The Stockholm Convention on Persistent Organic Pollutants aims to protect human health and the environment by banning the production and use of some of the most toxic chemicals known to humankind. The Convention became international law in May 2004, was ratified by New Zealand in September 2004, and entered into force for New Zealand on 23 December 2004. Persistent organic pollutants (POPs) are organic compounds that:

  • do not break down readily in the environment
  • are capable of long-range transport, bioaccumulate in human and animal tissue (and biomagnify in food chains)
  •  pose a risk of causing adverse effects to human health and the environment.

What chemicals are covered?

The 12 organochlorine (chlorine-containing) chemicals initially listed as POPs under the Convention in 2004 are:

  • pesticides (aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, mirex, hexachlorobenzene, and toxaphene)
  • industrial chemicals – PCBs (polychlorinated biphenyls), (hexachlorobenzene was also used as a pesticide)
  • unintentional by-products  – dioxins and furans (polychlorinated dibenzo-p-dioxins or PCDDs, and polychlorinated dibenzofurans or PCDFs).

An additional nine POP chemicals were listed in 2009. They are: 

  • lindane (insecticide with broad applications such as seed, soil and wood treatment, has toxic effects in laboratory animals and aquatic organisms; can be used as a human health pharmaceutical to treat head lice and scabies)
  • alpha hexachlorocyclohexane and beta hexachlorocyclohexane (insecticides, by-products of lindane manufacture, potentially carcinogenic to humans and adversely affects wildlife)
  • chlordecone (a pesticide, classified as a possible human carcinogen, is very toxic to aquatic organisms)
  • hexabromobiphenyl (industrial chemical, used as a flame retardant, classified as a possible human carcinogen)
  • tetrabromodiphenyl ether and pentabromodiphenyl ether (commercial pentabromo-diphenyl ether) (industrial chemical, used as an additive flame retardant, is toxic for wildlife)
  • hexabromodiphenyl ether and heptabromodiphenyl ether (commercial octabromodiphenyl ether) (industrial chemical, used as an additive flame retardant)
  • pentachlorobenzene (produced unintentionally and used as a chemical intermediate for the production of quintozene, and formerly in dyestuff carriers, as a fungicide and flame retardant, very toxic to aquatic organisms)
  • perfluorooctane sulfonic acid, its salts and perfluorooactane sulfonyl fluoride (an extremely persistent chemical, has several applications eg, electric and electronic parts, fire fighting foam, photo imaging, hydraulic fluids and textiles; binds to proteins in the blood and liver  – as opposed to other POPs which partition into fatty tissues).

National Implementation Plan

New Zealand's National Implementation Plan under the Stockholm Convention on Persistent Organic Pollutants (POPs) sets out how New Zealand proposes to meet convention obligations, such as reducing dioxin releases, completing the phase-out of PCBs, undertaking the environmentally sound management of POPs wastes such as obsolete chemicals and contaminated soils, and environmental monitoring. The scope of the Plan, originally prepared to address the first 12 POPs will require updating to include the nine ‘new POPs’.

Frequently asked questions about persistent organic pollutants

This section contains more detailed information about POPs in relation to New Zealand and the Stockholm Convention.

Why are POPs considered harmful?

Persistent organic pollutants (POPs) can persist for decades in the environment as they do not readily degrade through natural processes (chemical, biological and photolytic). On entering the food chain they become concentrated in the fatty tissues of birds, mammals and humans (bioaccumulation and biomagnification).There is clear evidence, particularly in the northern hemisphere, of POPs reaching regions of the globe (via the atmosphere, water and migratory species) where they have never been used or produced.


A significant feature of POP chemicals in humans and other mammals is that mothers transfer part of their own ‘body burden’ to infants in utero and via breast milk and it will take many generations for the presence of POPs to be minimised globally. This intergenerational aspect of POPs helps explain why the Stockholm Convention is committed to by over 170 countries.


POPs are a global issue for the environment and for human health. In wildlife, exposure to POPs are known to cause birth defects, various cancers, immune system dysfunction, and reproductive problems.


The weight of evidence concerning human impacts indicates that high levels of exposure to POPs over a long time may be associated with birth defects, fertility problems, greater susceptibility to disease, diminished intelligence, and some types of cancers. Emerging evidence indicates that many POPs may act as endocrine disruptors.

What was New Zealand's use of POP chemicals?

Organochlorine pesticides

From the mid-1940s until the 1970s some persistent organochlorine pesticides (including DDT, dieldrin) were used widely in New Zealand. The main areas of use were agriculture, horticulture, timber treatment and public health (see table below). Smaller amounts were also used for amenity purposes and in households.


The use of pesticides in New Zealand was not subject to compulsory regulatory control until the Agricultural Chemicals Act 1959 established the Agricultural Chemicals Board. The use of persistent organochlorine pesticides was then progressively restricted by a succession of legislative measures, so that, by the mid-1970s their use had effectively ceased in agriculture and horticulture. All Stockholm Convention POPs were formally deregistered by the Pesticides Board in 1989.


Below is a summary of the historical usage of persistent organochlorine pesticides in New Zealand:

Pesticide Application
DDT Used as a pasture insecticide to control grass grub (Costelytra zealandia) and porina (Wiseana sp.) caterpillars. Frequently mixed with fertiliser or lime and applied particularly to agriculture pastures, as well as lawns, market gardens and parks.
Aldrin and dieldrin Introduced in 1954 for use as stock remedies in sheep sprays or dips for controlling sheep ectoparasites. Aldrin was used to control horticultural pests such as wireworm, soldier fly and blackvine weevil, and in limited quantities to control household spiders. Dieldrin was used for controlling carrot rust fly, crickets and armyworm and was also used for timber preservation (mostly in plywood glues) and to mothproof carpets.
Chlordane Broad spectrum agricultural insecticide, also used in the timber industry as a treatment against termites and borer, and as an insecticide in glues used for the manufacture of plywood, finger jointed and laminated timber.
Hexachlorobenzene (HCB) Used experimentally between 1970 and 1972 as a seed-dressing fungicide for cereal grain.
Heptachlor, endrin and toxaphene Only small amounts of these pesticides were ever used in New Zealand.
Other organochlorines, Lindane (γ-HCH) Used as an insecticide in agriculture for the control of lice on cattle, ectoparasites (lice, keds and blowflies) in sheep and grass grub in pasture. Also used for insect control on vegetables and in orchards. Household use: flyspray, flea control and carpet moth.
PCP Approximately 5,500 tonnes of pentachlorophenol (PCP) is estimated to have been used in the New Zealand timber industry over a 35 to 40-year period as a timber preservative and as an antisapstain (fungicidal) treatment for freshly cut timber (mainly Pinus radiata). Its use in the timber industry ceased in 1988. PCP was also used to a relatively minor extent by the pulp and paper industry and the tanning industry, in mushroom culture in home gardens and on roofs to control moss and algae.

Polychlorinated biphenyls

Polychlorinated biphenyls (PCBs) were used widely in industry as electrical transformer fluids, heat transfer fluids, hydraulic fluids, solvent extenders, flame retardants, plasticisers, dielectric fluids, some paints and printing inks, immersion oils and sealants. The unusual industrial versatility of PCBs is directly related to their chemical and physical properties, which include resistance to acids and bases, compatibility with organic materials, resistance to oxidation and reduction, excellent electrical insulating properties, thermal stability, and non-flammability.


The widespread use of PCBs, coupled with industrial accidents and improper disposal has resulted in significant environmental contamination by these chemicals in many countries, particularly within the more industrialised northern hemisphere. Most New Zealand stocks of PCBs have already been shipped overseas and destroyed in a nationwide recall of PCBs used in the electrical supply industry. New Zealand is committed to complete the PCB replacement programme by 2016.

What is dioxin?

'Dioxin' is a generic term used to describe a family of chlorine-containing chemicals called dioxins and furans. These unwanted and highly toxic 'by-product' chemicals are formed in very small amounts when chlorine is present in some industrial processes, and during the burning (combustion, incineration) of organic materials.


For further information about dioxins, see Dioxins.

What is New Zealand doing to meet Stockholm Convention obligations?

Polychlorinated biphenyls

New Zealand will complete the phase out and destruction of Polychlorinated biphenyls PCBs) still in use in electrical transformers by 2016 (this timetable is in advance of the Convention deadline of 2025). PCBs discovered in old capacitors and fluorescent tube ballasts will be destroyed.

Stockpiles and wastes

The Ministry for the Environment, working with local government, is undertaking a national collection of agricultural chemicals in rural New Zealand. The programme has two stages, firstly to remove as much as possible the historical legacy of agrichemicals stored in rural sheds across the country. A key focus is the removal of persistent organic pollutants pesticides. The second stage is to put in place a longer-term industry led extended producer responsibility solution to manage and dispose of future unwanted chemicals to ensure that we do not recreate the same problem in the future.

Clean up of contaminated sites

The Government has established a Contaminated Sites Remediation Fund to help local government assess and clean up contaminated sites, including sites contaminated by persistent organic pollutants chemicals. The first major expenditure from the fund was used to clean up one of New Zealand's worst contaminated sites at Mapua (contaminated by DDT and dieldrin).


The Ministry for the Environment has published a series of guidelines for managing contaminated land.

Dioxin emissions reduction

Dioxins are released to the environment in very small amounts through a number of industrial and domestic activities, particularly the open burning of wastes. New Zealand is obligated under the convention to take measures to reduce, and where feasible ultimately eliminate, releases of dioxin. Although levels of dioxins in New Zealand foods (including our meats, dairy products and fish) are low and below the World Health Organisation guidelines, it is prudent to further minimise our exposure to dioxins where practicable.


As a first measure, the Ministry for the Environment has developed national environmental standards (NES) as regulations under the Resource Management Act 1991. The NES for Certain Air Pollutants, Dioxins and Other Toxics, bans certain activities that produce dioxins and other air toxins. The activities, banned from 8 October 2004, include:

  • lighting fires and burning waste at landfills
  • burning insulated copper wire, oil or tyres in the open
  • burning road seal
  • high-temperature incineration of hazardous waste (except for three facilities that had existing resource consents, two of which have now closed)
  • low-temperature waste incineration in schools and hospitals from October 2006 (unless the facility has a resource consent).

In 2000, the Ministry published an evaluation of dioxin releases (NZ Inventory of dioxin emissions to air, land and water, and reservoir sources).

In 2004, this work was followed up by an assessment of the NZ metallurgical industry (Dioxin and Furan Emissions to Air from Secondary Metallurgical Processes in New Zealand).

In 2011, the Ministry published a further evaluation of dioxin releases, which is an update of the 2000 Inventory report.

Further work on dioxin minimisation is set out in the Action Plan for Dioxins and other Annex C Chemicals, in New Zealand’s National Implementation Plan under the Stockholm Convention.

Recent New Zealand reports involving persistent organic pollutants

Investigation of brominated flame retardants present in articles being used, recycled and disposed of in New Zealand, Keet et al, September 2010, A technical report prepared for the Ministry for the Environment, Publication number: CR 95.


This study reports on the use, recycling and disposal to landfill in New Zealand of articles containing brominated diphenyl ether (BDE) flame retardants. Certain BDEs are listed as POPs under the Stockholm Convention on Persistent Organic Pollutants. The purpose of this study was to provide information on how BDEs were used in New Zealand, and to help the Ministry for the Environment assess waste disposal options for BDE-containing wastes.


Concentrations of persistent organic pollutants in the milk of New Zealand women
, Prepared by the Centre for Public Health Research, Massey University, as part of a Ministry of Health contract for scientific services, September 2010.


This survey is the third of three consecutive breast milk surveys, conducted in 1988, 1998 and 2008 and measured individual breast milk levels of persistent organic pollutants in New Zealand first time mothers aged 20 to 30. The survey was designed to provide time trend data for dioxins/furans, polychlorinated biphenyls and organochlorine pesticides and their metabolites, and provide baseline data for brominated flame retardants. The study followed the guidelines of the fourth World Health Organization Coordinated Survey of human milk for persistent organic pollutants.

Where can I get extra information?

The Ministry for the Environment has further information on its website:

Information is also available on the website for the Stockholm Convention.


The Ministry’s website contains extensive information on dioxins and organochlorines. All previous Ministry reports involving these chemicals can be accessed through this website.

 

Last updated: 9 February 2011