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Executive Summary
1 Introduction
Dioxin belongs to a class of environmental pollutants known as organochlorines. Persistent organochlorines are toxic, do not readily break down in the environment, and accumulate in human and animal tissue. The Government's goal is to protect human health and the environment from risks posed by dioxin. Work being done on dioxin by the Ministry for the Environment is focused on four areas: discharges to air, deposition on to land and into landfills, soil concentrations appropriate for different land uses, and direct entry into food manufacturing processes.
The current proposal is an action plan for reducing dioxin discharges to air. There are good reasons for choosing discharges to air as the first priority, not the least of which is that this is probably the most important pathway of human exposure for the general population. Further action plans aimed at reducing people's exposure to other sources will be developed and reported on separately.
2 Taking action on dioxin
Action has been taken by many developed countries to reduce releases of, and exposure to, dioxin. The United Nations has developed a global convention (the Stockholm Convention) on persistent organic pollutants, including dioxin. New Zealand is a signatory, and the development of a dioxin action plan is required under the convention. The current document will address some, but not all, of New Zealand's obligations under the Stockholm Convention, and other work will be forthcoming.
This action plan for air discharges should be designed at a national level, but must be implemented at a regional level because of the requirements of the Resource Management Act 1991. Much of what is proposed is consistent with regional council air plans.
Because the sources of dioxin discharges to air are so diverse, the action plan is likely to include different kinds of policy instruments. The components of the dioxin action plan must be both effective and efficient.
3 Why we should take action on dioxin
Animal studies show that dioxin is extremely toxic. Although less is known about its impact on human health, it is widely assumed that dioxin has the potential to cause neurobehavioural, developmental, reproductive and immunotoxic effects, and cancer.
Although the current dioxin intake of New Zealanders is relatively low compared with other industrialised countries, and is falling, it is close to the World Health Organization's tolerable daily intake. A major portion of the dioxin that enters the body of the typical New Zealander originates as a discharge to air and is eventually ingested in meat and dairy products.
New Zealand should take action to safeguard the quality of its foods, both to protect the health of its people and avoid any potential for damage to the economy. Increasingly our clean green image is used for promoting New Zealand and biologically based products in export markets.
4 Sources of discharges of dioxin to air
There are many different sources of dioxin discharges to air, but four categories can be distinguished: waste combustion, fuel combustion, metallurgical production and processing, and other sources such as accidental fires. Recommended actions to reduce dioxin emissions to air have been made on a source-by-source basis by applying a set of decision criteria.
5 Actions for waste disposal sources
Waste disposal sources of dioxin discharges are clearly the highest priority for action. Table 1 contains a summary of the recommended actions.
The single largest source of dioxin discharges to air is landfill fires. If this source is not minimised, the case for controlling any other source is weak. A ban on dioxin discharges to air from landfill fires through a national environmental standard (NES) is recommended. If the recommended ban can reduce the incidence of landfill fires - both intentional and accidental - by 90%, then total current discharges of dioxin to air would fall by about 35%.
The second largest source is the burning of waste in '44-gallon drums' or in backyard fires. An NES that bans the discharges of dioxin to air from the domestic burning of waste (excluding vegetation, untreated wood, paper and cardboard) is recommended, although its effectiveness would be less than the landfill fire ban. If the amount of dioxin-creating waste burned in this uncontrolled manner were halved, then total current discharges of dioxin to air would fall by at least 5%. The ban should extend to waste burned on farms, including agrichemical wastes.
An NES setting an upper limit on discharges of dioxin to air is recommended for waste incineration. The proposed upper limit on the concentration of dioxin in exhaust gases is 0.1 ng TEQ/Sm3, and is the same as the European Commission directive on waste incineration.(See footnote 1)
Although there are as yet no municipal waste incinerators in New Zealand, there is potential for this technology to become established. Just one large poorly performing municipal incinerator could double the total amount of dioxin currently discharged to air from all existing sources. Establishing a limit on dioxin discharges now is seen as taking a preventive and precautionary approach. The existence of an NES governing dioxin discharges would also assist the resource consent process, and will save costs to developers and regional councils required to process such a consent.
The NES would also apply to the co-incineration of municipal waste, as well as to the incineration of medical waste, hazardous waste and sewage sludge. If applied to all existing incinerators that burn waste, it will virtually eliminate dioxin discharges from these sources. Total current discharges of dioxin to air would fall by at least 6%. A draft of the proposed NES is given in this action plan.
6 Actions for sources other than waste disposal
Options for reducing dioxin discharges from sources not involving the combustion of waste are more limited. In some instances, changes taking place for other reasons are reducing dioxin discharges as a side-benefit.
The two largest non-waste disposal sources are fuel combustion in industry and in homes. Because the concentration of dioxin in exhaust gases from burning fuel is generally low, control technology is much less cost-effective than it is when waste is burned. The trend from open fires to enclosed solid fuel burners should increasingly reduce dioxin from domestic fuel combustion.
The focus for action should be on industrial burning of 'contaminated' wood. There is some evidence that dioxin discharges from the combustion of contaminated wood are much greater than dioxin discharges from the combustion of virgin wood and virgin wood waste.
Recommendations for dioxin sources other than waste disposal are as follows.
- Relatively little national data exists about the extent of the practice of burning contaminated wood in industry, and action to gather information should be undertaken.
- No action is required for discharges from vehicle fuel combustion. Technological change and initiatives in the Vehicle Fleet Emissions Control Strategy will result in this source continuing to decline.
- Dioxin discharges from iron and steel manufacture are already well controlled, and no national action is required.
- Monitoring is recommended for non-ferrous foundries, with one exception. The practice of burning insulated copper wire in order to reclaim the copper is unacceptable, and an NES that bans the discharge of dioxin to air from this practice is recommended.
- Crematoria account for less than 1% of all dioxin discharges to air, and this is likely to decline as modern crematoria replace the existing older-style units. Educational initiatives are appropriate for this source.
- Accidental fires are a significant source of dioxin discharges, which can be reduced if chlorinated materials are not used in buildings. The monitoring of international initiatives in this area is recommended. Fire prevention programmes can also help to reduce dioxin discharges in the future.
- No national action is required for minor miscellaneous sources such as cigarette smoking.
7 Application of actions
Implementation and enforcement costs of an NES will fall primarily with regional councils. For some sources, for example outdoor burning, the cost will vary with the level of enforcement chosen by local authorities. In cases where actions within this plan are complementary to activities set out in regional air plans, there will be no additional costs to councils. Educational material will be required for some of the actions, which will be prepared by the Ministry for the Environment in liaison with local authorities and the industry sectors.
Compliance costs to industry will include technology costs if plant upgrades or process modifications are required, initial costs of dealing with new regulations, and the annual cost of monitoring discharges.
For discharges that are prohibited by the NES or for new sources required to meet an upper discharge limit, these sources must comply with the NES from the date the standard comes into force. The NES will not apply retrospectively to existing resource consents, but regional councils may review consents when the NES comes into force. In such cases, transitional provisions will be determined on a case-by-case basis. An NES will override regional air plans.
Two industrial sources of dioxin are particularly uncertain, and require the collection of additional information. This data could be either volunteered by the industry or industry could be required to report it.
Footnote:
1 ng TEQ/Sm3 = nanograms of dioxin toxic equivalents per
reference-standardised cubic metre of gas.
