Executive Summary
This Mercury Inventory has been compiled as part of the information needed to inform the potential development of a product stewardship programme for lighting in New Zealand. In particular it is intended to assess the relative environmental impact of mercury-containing lamps, including the increased use of compact fluorescent lamps (CFL), compared to the impact of mercury from other natural and anthropogenic sources. The report has been prepared by Pattle Delamore Partners Limited on behalf of the Ministry for the Environment.
Mercury is a toxic, naturally occurring heavy metal. It occurs in three forms, elemental mercury (as a liquid or vapour), inorganic mercury compounds and organic mercury compounds. The most toxic form is the organic compound methylmercury.
Elemental mercury and inorganic and organic mercury compounds can be transformed in the environment from one form to another in a series of complex processes. In general, however, elemental mercury exists mostly in the atmosphere, while inorganic and organic mercury compounds exist mostly in land and water environments.
Sources of mercury in New Zealand fall broadly into two categories:
- Natural sources in land, soils, air and water and, notably in New Zealand, from volcanic and geothermal activity; and
- Anthropogenic sources from various industrial, chemical, medical and dental, electrical and domestic applications, including mercury-containing lighting equipment and lamps.
The total annual mercury emissions for New Zealand in 2008 have been estimated using the 2005 draft of the UNEP Mercury Toolkit to be 3,000 kg Hg/year, with roughly equal contributions from natural and anthropogenic sources. A lack of data means that some of the UNEP categories could not be estimated. Emissions from these sources are thought to be small. In addition, some industries considered major sources in the UNEP toolkit either do not exist in New Zealand, or are small.
The most significant natural sources of mercury were volcanic emissions, comprising 54% of natural emissions and 28% of total emissions. The most significant anthropogenic sources were combustion of fossil fuels (440 kg Hg/year) and geothermal power generation (350 kg Hg/year), representing 29% and 23% of the anthropogenic emissions, respectively. Other significant anthropogenic mercury sources included wastewater biosolids (180 kg Hg/year) and mercury-containing batteries (170 kg Hg/year).
Mercury-containing lamps are currently a small potential source of emissions, contributing approximately 50 kg/year which is only 3% of total anthropogenic emissions and less than 2% of overall mercury emissions from New Zealand. Compact fluorescent lamps currently make up about a third of potential emissions from mercury-containing lamps.
On a per capita basis, the total anthropogenic mercury inventories compiled for New Zealand, Ireland, Canada, the United States and the United Kingdom are comparable (of the order of 10-4 kg/person/year), whereas that of Denmark and Australia are an order of magnitude greater (10-3 kg/person/year). Excluding Australia’s mercury releases from roads (which no other country has estimated), Australia’s reported emissions are about twice those of New Zealand, the major difference being primary metal production.
Ten-year projections of the mercury emission have been calculated and the change in relative contribution of mercury from mercury-containing lamps has been assessed. This calculation has assumed emissions from New Zealand’s natural mercury sources will remain the same.
There are considerable uncertainties with forecasting future anthropogenic emissions, related to such things as economic performance, the price of competing sources of energy and changes in policies with respect to mercury both in New Zealand and overseas. The predictions, being relative to current emissions, also have the same uncertainties as the current emission calculations.
Overall the anthropogenic mercury loads in 2018 are predicted to be 2,100 kg Hg/year an increase of 600 kg Hg/year or 40%, over 2008. Emissions from geothermal power generation (an increase of 190% to 1,020 kg Hg/year) are expected to be the largest contributor to anthropogenic mercury loads in 2018, followed by wastewater treatment (200 kg Hg/year) and dry cell batteries (170 kg Hg/yr). The geothermal power generation prediction is uncertain, however, being sensitive to the price and availability of competing sources of energy and relies on various power generators constructing power stations that they have indicated are, or may be, in the pipeline.
The contribution from mercury-containing lamps is estimated to remain about the same in absolute terms, assuming a high-use scenario for CFLs, and the mercury content of CFLs staying constant. In relative terms, this results in a halving of the contribution from mercury-containing lamps relative to the total mercury emissions. Compact fluorescent lamps will contribute only about half of the mercury from mercury-containing lamps.
With respect to the effects of mercury on the environment, most concern has been expressed globally over the accumulation of anthropogenic mercury from diffuse sources in aquatic ecosystems. Bioaccumulation and biomagnification of mercury may result in adverse effects on the aquatic animals and associated wildlife, but can also cause increased dietary intakes of mercury in the human population due to higher concentrations of methylmercury in fish.
There is limited evidence that mercury exposure is of concern in New Zealand, however. Apart from occupational exposure for a relatively small number of people (e.g. dental workers), dietary exposure through eating long-lived predatory marine species of fish, or fresh water fish caught in geothermal regions, is the most likely route for exposure. Dietary exposure to mercury may account for up to 54% of a person’s total exposure to mercury and nearly all their exposure to methylmercury compounds. However, a number of studies have demonstrated that the benefits of eating a modest amount of fish outweigh the risks of exposure to methylmercury.
Mercury emitted from geothermal and industrial sources, the latter mainly from the combustion of coal and generation of geothermal power, is unlikely to pose any direct toxicity threats to humans. However, studies have shown that small increases in atmospheric loadings lead to a direct increase in the concentration of mercury in fish.
Exposure to mercury from broken CFLs will result in short-term exposure to mercury. However, exposure to broken lamps is of short duration and expected to be infrequent. It is thought that mercury exposure from broken CFLs poses minor or no direct threat to human health if prompt and proper clean up is carried out. Calculations using an extreme scenario of frequent breakages with improper clean-up techniques, suggests that an adult may be exposed to up to 4% of the World Health Organization’s Provisional Tolerable Weekly Intake (PTWI), and an infant up to 8% of the WHO PTWI, but actual exposure is likely to be considerably less.
There is a variety of legislation and regulation controlling the use, storage and discharge of hazardous substances and safety within the workplace. However, apart from mercury and mercury-containing compounds having to be approved under the Hazardous Substances and New Organisms Act 1992, there are virtually no specific nationwide controls on mercury. The few specific regulatory controls are for work place exposure via approved codes of practice under the Health and Safety in Employment Act 1992 and controls on trade waste discharges to sewers under some local bylaws. New Zealand otherwise relies on various guidelines for air, water, landfills and biosolids.
Various overseas jurisdictions have specific statutory controls on mercury and, in general, it can be concluded that Europe and the United States are more advanced than New Zealand in imposing specific controls on mercury.
