- Print Friendly - Help

Dioxins in New Zealand's food supply

Dioxin monitoring over recent years has confirmed that dioxin levels and dietary exposure levels in New Zealand are lower than intake levels recommended by the World Health Organization.

What dioxins are and how they are produced

Dioxins are a family of chemical compounds that share several common characteristics. They are not produced intentionally and, unlike pesticides, are not applied to plants or farmland for beneficial purposes. They are produced as unwanted by-products in some industrial and thermal processes.

Both natural and manmade dioxins are colourless, odourless, organic compounds containing carbon, hydrogen, oxygen and chlorine.

Dioxins are produced from:

• volcanoes and forest fires

• man-made processes such as manufacturing, incineration, paper and pulp bleaching, and exhaust emissions

• burning municipal waste, household trash and fuels like coal, wood or oil

How dioxins get into our food supply

Dioxins can enter the food supply through a number of different routes. In fish, the primary route of exposure is through water. Plants and animals are exposed to dioxins primarily through particles in the air. Airborne dioxin particles settle on forage or feed, which is then eaten by animals. Dioxins can concentrate in the fatty tissues of beef and dairy cattle, poultry, pork or seafood. Dioxin particles that settle on fruits and vegetables as a result of airborne exposure are removed by washing.

Compared to most chemicals, dioxins acute toxicity is very high. For example, the most toxic dioxin has a lethal dose for guinea pigs at 0.5 micrograms per kilogram. The least toxic dioxin is about 500 micrograms per kilogram. Most other chemicals are much less acutely toxic.

Despite dioxins acute toxicity, the only reported effect in humans is chloracne and porphyria. Chloracne is a skin disorder. Porphyria is a blood disorder that leaves a person sensitive to sunlight, amongst other things. These two human effects occurred under dirty industrial conditions. Outside of dirty industrial conditions, human exposures are low.

Dioxin intake levels and exposure

Dioxins are bound up in body fat and so they take a very long time to get out of the body if exposure ceases, and there is a constant background of very low-level exposure.

Their long term effects are somewhat uncertain. Many scientists believe them to be possibly carcinogenic. Other scientists think they are tumour promoters and only advance the growth of existing tumorous cells. Their high acute toxicity means it is very difficult to carry out a good long-term study because doses have to be so low that any effects are likely to be lost in background incidences of effects.

Studies have shown a decrease in the concentrations of dioxin contaminants in New Zealand over the last few years in breast milk, the environment and food. This is consistent with declining levels in other countries where similar testing has been carried out.

Dioxins and the role of other government agencies in New Zealand

The Ministry of Health has a whole-of-government co-ordinating role for dioxins in New Zealand. They are also focused on the health effects of dioxins and ensuring adequate treatment is available for those who may be suffering from the effects of dioxin exposure.

Ministry of Health dioxin information and links [Ministry of Health]

The Ministry for the Environment has proposed a Dioxin Action Plan. As part of this plan, they proposed a national environmental standard under the Resource Management Act, to regulate dioxin emissions from industrial facilities.

The Ministry for the Environment provide more detailed information about dioxins, how they are managed and research reports on dioxin levels.

Ministry for the Environment dioxin information and links [Ministry for the Environment]

Research by Food Standards Australia New Zealand

Food Standards Australia New Zealand (FSANZ) released a report of its analytical survey of dioxins in a range of food sampled in Australia in May 2004. The purpose of the survey was to assess the risk to human health associated with the dietary exposure of the Australian population to dioxins.

The overall conclusion of the report based on available data, was that the public health and safety risk for Australians from exposure to dioxins is very low.

The situation in New Zealand reflects these findings. All work to date indicates that the risk to public health through exposure to dioxins in food and in the environment is at least as low as in Australia.