New Zealand

Investigating Persistent Organochlorines in New Zealand

Organochlorines are chemicals in which carbon and chlorine are combined. Some organochlorines are found in nature and some are byproducts of combustion and industrial processes, but the vast majority many have been specifically manufactured for a wide range of uses, including pharmaceuticals, pesticides, plastics, and solvents.

Most of these chemicals break down and become dispersed into the environment. However, a small number are chemically very stable. That means they break down only very slowlyare very stable substances and can remain in the environment for a long time.

Of the many thousands of organochlorines that exist, a number are also known to be toxic to humans and animal life.

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

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

The organochlorine chemicals which arehave all four properties of persistentce, toxic, vapour-forming, and concentrateing up the food chain, are among the chemicals now referred to internationally as persistent organic pollutants (POPs). These chemicals are a focus of international concern.

Organochlorines have entered the environment through accidents (e.g. fires and spillages), industrial discharges, the manufacture and use of organochlorine pesticides in agriculture and industry, combustion processes (e.g. motor vehicles, incineration units), and disposal of organochlorine wastes.

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.

A number of organochlorine chemicals (including several identified as POPs) are being studied under the Organochlorines Programme of the Ministry for the Environment:

Dioxins are produced as unwanted by-products from a number of industrial discharges (e.g. from pulp and paper millsunits where chlorine is used in the bleaching process) and from combustion processes (e.g. incineration of wastes, the burning of fuels such as coal and wood, and vehicle emissions). Dioxins are also found as contaminants in a range of organochlorine chemicals, including pentachlorophenol (PCP). Dioxins are distributed throughout the global environment. Because they have the potential to cause very high toxic ityeffects and and cancer,-causing properties, particularly in laboratory animal studies, the presence of low levels of dioxins in the environment has been the subject of controversy and concern for several decades.

PCBs (polychlorinated biphenyls) were used in the electrical supply industry from the 1930s, mainly in transformers and capacitors. The use of PCBs has been illegal in New Zealand since 1994, and most stocks have now been shipped overseas for destruction. In the past, PCBs were also used as heat exchange fluids, as paint additives, in carbonless copy paper, and in plastics.

Chlorinated pesticides. The following organochlorine pesticides are no longer used in New Zealand:

PCP, a fungicide, was used extensively by sawmills in New Zealand in the treatment of freshly cut timber (mainly Pinus radiata). One concern is the presence of dioxins in PCP wastes. PCP was also used to a relatively minor extent in New Zealand by the pulp and paper industry, in mushroom culture, and in home gardens to control moss and algae. The use of PCP in the timber industry ceased in 1988, and it was withdrawn from sale deregistered in 1991.

DDT is an insecticide that has been used world-wide in horticulture and agriculture. It is still used in some tropical countries for the control of malarial insects that transmit malaria. In New Zealand, tThe use of DDT was prohibited on New Zealand farmland in 1970, and its sale for all other purposes (e.g. borer bombs) was banned was deregistered in 1989.

Dieldrin was used as an agricultural insecticide and, along with chlordane, was used in the timber processing industry. The sale of dieldrin as an agricultural insecticide was banned was deregistered in New Zealand in 196889, and its sale for all other purposes (e.g. spider control) was also banned in 1989.

Lindane Lindane was used as an insecticide in agriculture for the control of lice on cattle and grass grub in pasture, and for insect control on vegetables and in orchards. As with DDT, the use of lindane was progressively restricted under a permit system and its sale for use was banned in 1989.

The other organochlorine pesticides being studied in the Organochlorines Programme are aldrin, hexachlorobenzene and heptachlor. These pesticides were used to only a limited extent in New Zealand agriculture.

Studies in Europe and North America show that the general population are exposed to organochlorines mainly through consuming the fatty component of foods such as dairy products, meat and fish.

Organochlorine residues have been detected in the fatty tissue of people all over the world. Two previous studies have indicated that levels of dioxins in the general population of New Zealanders are in the low to medium range relative to more industrialised countries.

In some countries there is evidence of a decrease in the level of dioxins in people over the past one to two decades. This is probably because cleaner production methods are now being used by industry and because of tighter regulations governing industrial emissions of dioxins.

Most of what is known about the human health effects of organochlorines comes either from studies on workers using or involved in the manufacture of organochlorine substances, or from accidental poisonings. High exposure to dioxins can cause a servere skin rash, condition known as chloracne. High exposure to PCBs may also cause chloracne, as well as liver damage and respiratory problems.

The possible effects on humans from long-term exposure to dioxins and PCBs are not well understoodknown. However, the most toxic dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin) is classified by the United States Environmental Protection Agency, and the International Agency for Research on Cancer as a cancer-causing substance.

Dioxins have been shown in laboratory animal studies to be capable of causing e and promote and promoting cancer, disrupting endocrine and immune systems, and adversely aeffecting reproduction, development and behaviour. To what extent dioxins and PCBs may are causecontribute to or cause thesesame eeffects in humans is uncertain. Epidemiological studies have are not clearly demonstrated such eeffects cut. Even when dioxin and PCB exposure has been very high as the result of industrial accidents and poisonings, increased incidences of cancer have been difficult to show.

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

Dioxins and PCBs are cancer-causing substances in animals. A range of other illnesses, including those affecting fertility, reproduction and growth, may also result from living in an environment contaminated by dioxins or PCBs. 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.

In order to determine the situation in New Zealand a number of aspects are being investigated:

• What levels of dioxins, PCBs and organochlorine pesticides are present in the New Zealand environment?
• For these contaminants, how "clean" or "polluted" is New Zealand relative to other countries?
• Are organochlorines found in New Zealand at levels likely to pose a threat to the environmental ecology or to human health?
• What are the reservoirs and current significant hazards and emission sources of dioxins and PCBs in New Zealand, and what should be done to manage the hazards identified any risks associated with them?
• What emission standards are applied through regulation in other countries to protect human health and the environment, and what standards should be adopted in New Zealand?
• Can contaminated soils and organochlorine wastes be treated safely,
  and what clean-up standards should apply?

The Government has set up the Organochlorines Programme in the Ministry for the Environment to research what levels of organochlorines are present in the New Zealand environment, what levels occur in our diet, and what levels are present in our bodies.

Information on reservoirs and present day hazards and emissions of dioxins and PCBs will be collected and evaluated. This research is being carried out to establish whether human health or the environment is being placed at risk from these contaminants.

The Ministry will then develop a management strategy to address any problems found. This will include developing national environmental standards to control limitcontrol future emissions of dioxins.

Clean-up levels will be established for sites contaminated by the organochlorines being studied in the Organochlorines Programme. Technologies capable of undertaking site clean up and destroying organochlorine-containings wastes will also be identified.

The work of the Organochlorines Programme is being carried out in three phases:

Phase 1. Research

The Ministry expects to complete its research in late 1998. The results of the research Information based on the scientific reports will be made public.

The Ministry will develop a draft management strategy, and highlight the key decisions needed. A formal process of public consultation will begin towards the end of 1998.

Public comments will be taken into account in the final preparation of the standards and guideline documents. The programme is expected to make recommendations to the Government in June 1999.

The Organochlorines Programme is one of a number of related Ministry initiatives to further encourage achieve the safe use of chemicals and disposal of waste. These include:

• The Hazardous Substances and New Organisms Act and regulations, to be administered by the newly established Environmental Risk Management Authority.
• National environmental standards for the management of hazardous waste.
• Guidelines for assessment and management of contaminated sites.
• Future work will focus on the Government's intent to phase out persistent organochlorine chemicals.

If you have concerns, questions, or just want to be kept informed about the Organochlorines Programme, please contact the Ministry for the Environment.

Howard Ellis or Dr Simon Buckland
Ministry for the Environment
PO Box 10 362
Wellington
Fax: (04) 917 7437