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Dioxins and other organochlorines

This page explains what organochlorines are, why they can be harmful and what we are doing to reduce the negative impacts of these chemicals in New Zealand.

What are organochlorines?

Organochlorines are chemicals that contain carbon and chlorine atoms joined together. 

They include:

  • dioxins
  • industrial chemicals which are toxic in their own right and contain dioxins
  • chlorinated pesticides that are toxic, such as dieldrin and DDT.

Organochlorines are stable and vapour-forming. They can be carried by air currents for long distances. Eventually they condense and deposit on land and water, particularly in colder regions.

Some organochlorines are known to be harmful. There has been insufficient research to conclude definitively that all organochlorines are harmful.

Why organochlorines can be harmful

If organochlorines contaminate the food supply of animals, they will become more concentrated as they move up through the food chain. The highest levels of organochlorines are therefore found in human beings, fish-eating birds and marine mammals.

Organochlorines can be harmful as they do not break down very easily.  They build up in the fatty tissue and stay in the body for a long time. There are 12 organochlorines listed as persistent organic pollutants (POPs) under the Stockholm Convention. A POP is a hazardous organic chemical compound that is resistant to biodegradation.

The Stockholm Convention on Persistent Organic Pollutants commits governments to take measures to protect human health and the environment from POPs.

The Government consulted on its proposal to add additional persistent organic pollutants to those banned or restricted under New Zealand legislation. This is to comply with our obligations under the Stockholm Convention on Persistent Organic Pollutants. 

 Find out more about the consultation (the consultation has closed)


Dioxins, which are highly toxic, are created by any kind of burning process. This burning includes some industrial processes, burning of waste, and fires at landfills, backyards and in forests.  The burning of coal and wood and to a lesser extent the combustion of petrol and diesel in motor vehicles are also a source of dioxins.

Dioxins are also made during the bleaching of pulp and paper and when people manufacture or use chemicals such as:

  • polychlorinated biphenyls (PCBs), which are used in transformers and capacitors in the electrical industry
  • 2,4,5-T, a herbicide used to control gorse and other woody weeds
  • pentachlorophenol (PCP), a fungicide used to treat timber
  • PCBs, 2,4,5-T and PCPs are no longer used in New Zealand.

For further information including health effects and guidance see Dioxins [Ministry of Health website].