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Hazardous substances

Helicopter aerial spraying

Hazardous substances are used throughout the region for many purposes.

 For example, more than 90,000 tonnes of corrosive substances are used in the dairy and mining industries and for paper processing. The timber treatment industry also uses large volumes of toxic and corrosive preservatives. Many hazardous substances can also be found around the home.

It’s important that we recognise what substances may be hazardous, and use and dispose of them correctly.

What hazardous substances are used for


The Martha Mine in Waihi uses explosives and toxic materials, such as sodium cyanide. Explosives are also used at most coal mines and many quarries. The mining industry also uses other hazardous material such as water treatment chemicals and fuels (as do a range of other industries).

Agriculture and horticulture

Agricultural and horticultural activities use large amounts of pesticides. From June 1997 to June 1998 approximately:

  • 336 tonnes of herbicides
  • 284 tonnes of fungicides, and
  • 25 tonnes of insecticides, were used in the Waikato1.

Between 1999 and 2003, pesticide imports into New Zealand increased by 12 per cent.  The greatest increase in use has been in herbicides2

As we learn more about the pesticides we use, we have reduced or eliminated our use of those that have significant toxicological effects, and those that persist in the environment.  Most modern pesticides degrade fairly quickly in the environment. The main risk with using modern pesticides happens at the time of application.

Continued storage or inappropriate disposal of historic pesticides can pose risks to human and stock health, soil quality and water quality of streams and groundwater.  Farmers and growers need to be careful about safe storage of all pesticides, and to ensure the safe disposal of any pesticides that they no longer want.

Timber treatment sites

In the Waikato region there are:

  • 30 operating timber treatment sites
  • 74 abandoned sites
  • at least 14 timber waste disposal sites.

A range of hazardous timber preservatives, including copper, chromium, arsenic and boron are, or have been, used or left at these sites. In the past, large volumes of pentachlorophenol (a very hazardous organochlorine chemical) were used. Poor management of these hazardous substances has the potential to threaten the health of workers and contaminate air, soil and water.

Around the home

You may be surprised to learn that many everyday products we use around the home can be hazardous to our families, ourselves, and the environment. These products include:

  • solvents - for example, mineral turpentine
  • cleaning fluids - for example, oven and drain cleaners
  • garden chemicals - for example, herbicides, fungicides and insecticides
  • paints - for example, enamel based paints
  • dyes - for example, textile and hair dyes
  • adhesives - for example, those containing solvents
  • stored fuels - for example, petrol and oil
  • old car batteries.

Safe handling and use

Some industries have developed codes of practice to guide the handling and use of hazardous substances in a safe, environmentally responsible fashion.

Industries with codes of practice include:

  • oil industry - for example, procedures for dealing leaks in underground storage tanks.
  • agricultural industry - for example, procedures for the correct use, storage, labelling and disposal of pesticides.
  • timber industry - for example, procedures for safe storage and use of timber treatment chemicals. In 1993 the Code of Practice for the Safe Use of Timber Preservatives and Antisapstain Chemicals was established to minimise the risk to workers in the timber industry and the environment.
Rules for use and storage 
Do Don't
Read all labels and accompanying information and ensure labels don’t get damaged. Use volatile, flammable or explosive substances around open flames or sparks.

Use with adequate ventilation.

Use with inadequate ventilation.
Store in an appropriate, labelled container. Pour down the drain or dump in a landfill.
Store in a secure location, away from children, pets, livestock and wildlife.


Wear gloves and/or protective clothing.  
Keep the container closed and secure when not in use.  


Hazardous substances must be disposed of in a safe and thoughtful manner. Read more about:

What Waikato Regional Council is doing

Waikato Regional Council works with other agencies such as the fire service, police and the city and district councils to respond to emergency issues involving hazardous substances. We also prepare emergency response plans, such as the Regional Marine Oil Spill Contingency Plan.

The use of agrichemicals is allowed in our Waikato Regional Plan, provided that the risk of spray drift onto neighbouring properties is managed.

We advocate and aim to increase public awareness about the safe use, transport and disposal of hazardous substances.

Further information

Find out more about contaminated sites in the Waikato region.


Environmental Protection Authority logo

Find out about how hazardous substances are managed and regulated nationally by Environmental Protection Authority (EPA).

Find out about the Hazardous Substances Toolbox - a multi-media package from the EPA to help employers who own or manage small industrial businesses work safely with hazardous substances.

Check out the WorkSafe New Zealand website for important workplace safety and health information, laws and regulations.

The USA’s Agency for Toxic Substances and Disease Registry has lots of information on various hazardous substances and their health effects.


  1. Holland, P.T., Rahman, A. 1999: Review of trends in Agricultural Pesticide Use in New Zealand. MAF Policy Technical Paper 99/11.
  2. Manktelow, D. et al., (2005): Trends in Pesticide Use in New Zealand: 2004. Report to the Ministry for the Environment, Project SMF4193. 78pp.