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The Organochlorines Programme

A major research programme conducted between 1996 and 2001 has shown that in New Zealand we have very low levels of contamination by dioxins and other toxic organochlorine chemicals in our bodies and our environment. Even better news is that dioxin residues in our food are among the lowest recorded in the world. We want to make sure it stays that way.

The Ministry for the Environment’s Organochlorines Programme, which began in 1995, set out to:

  • research levels of organochlorines in our bodies, in our food and in our environment
  • reduce industrial emissions of dioxin to air, land and water
  • clean up land contaminated with organochlorine residues, and
  • manage the safe disposal of waste stocks of organochlorine chemicals.

Organochlorines are chemicals that contain carbon and chlorine atoms joined together. Harmful organochlorines are those which do not break down easily and which stay in the environment and in our bodies for a long time. These include:

  • dioxin (which is very toxic).
  • industrial chemicals which are toxic in their own right AND contain dioxin, such as polychlorinated biphenyls (PCBs) and pentachlorophenol (PCP)
  • chlorinated pesticides that are toxic (such as dieldrin and DDT).

Organochlorines are stable and vapour forming and can be carried by air currents for long distances. Eventually they condense and are deposited on land and water, particularly in cold climatic regions.

Build-up in food chain

If they contaminate the food supply of animals, organochlorines become more concentrated as they move up through the food chain, so the highest levels of organochlorines are found in species at the top of the food chain – human beings, fish-eating birds and marine mammals. Organochlorines build up in the fatty tissue and stay in the body for a long time because they are only slowly metabolised and excreted.

Persistent organochlorine residues have been detected in air, water, soil, sediment, fish and birds throughout the industrialised world. They have also been found in remote areas, such as open oceans and polar regions. In remote areas, where there are no significant local sources, any contamination must come from other parts of the globe.

Scientific studies

Scientific studies since the 1950s have shown that a high body burden of organochlorines pesticides, such as DDT, in animals can cause ecological damage. For example, abnormalities in the reproduction and development of fish-eating birds are well known.

There is currently international concern that the levels of organochlorines, such as dioxins and PCBs, found in some marine mammals, may be damaging their health. Effects seen include a range of illnesses affecting fertility, reproduction, the immune system and growth.

Organochlorines in New Zealand

The Ministry has completed a series of investigations into levels of organochlorines in New Zealand. These include measuring the levels of organochlorines in:

An inventory of dioxin emissions has also been undertaken.

The information collected in these reports has been assessed by world authorities on the toxicology and ecotoxicology of these chemicals. A report on the health risk to the New Zealand population was published in 2001.

With the advent of the Stockholm Convention on Persistent Organic Pollutants, the Ministry’s ongoing work on organochlorines is now guided by the New Zealand's National Implementation Plan under the Stockholm Convention on Persistent Organic Pollutants (POPs).

Dioxin

An key priority of the Organochlorines Programme has been addressing issues of dioxin. This is because of its potential to cause adverse health effects even at very low levels of exposure. Whilst levels of dioxin in New Zealander’s bodies are low, the Ministry believes that it is necessary to further reduce emissions so that the levels continue to fall over time. Actions to reduce dioxin emissions to the environment have been proposed.

Tests of dioxin in residential soils at Paritutu in New Plymouth

A study to measure dioxin in soils at residential properties in the New Plymouth suburb of Paritutu has been completed. For more information refer to Dioxin Soil Investigations in New Plymouth.

Information

The Ministry has released a number of Organochlorine Bulletins that report on the work undertaken in the Organochlorines Programme.

Stockholm Convention

A United Nations environmental treaty on these toxic chemicals has recently been negotiated. The objective of the treaty is to protect human health and the environment from persistent organic pollutants (POPs). For more information on the treaty, see the Ministry's Stockholm Convention information, or visit the Stockholm Convention website.

Other websites on organochlorines

Other useful information on organochlorines and persistent organic pollutants (POPs) is available from these websites:

Last updated: 17 September 2007