ILA - International Lead Association

1. Introduction

Lead is one of man's most valuable commodities. Occurring naturally in the environment, the metal is mined and processed in some 60 countries. The usage continues to increase and has risen from 4 million tonnes per year worldwide in the 1960s to 6 million tonnes in the 1990s. Of this, nearly 2 million tonnes per year is produced in Europe. Secondary production or recycling is now widely practised and currently accounts for some 70 per cent of usage worldwide.

Lead has some important properties, in particular malleability (i.e. it can be hammered into shape), ease of production, ease of melting and joining, and good corrosion resistance in most common environments. As a result, it has been used for purposes such as roofing, window cames, piping, kitchen/tableware and ornamental uses for many centuries. Its high density has proved effective for weights and anchors for fishing lines, boats, and later for munitions. This property is now utilised in lead radiation screening and soundproofing. The electrochemical properties of lead enable it to be used in storage batteries in all motor vehicles, and for some back-up power supplies. Certain compounds of lead, particularly brightly coloured lead oxides, and leaded glasses and leaded glazes on ceramics, have been used for millennia. The use of most leaded paints has recently been phased out, but lead is still an important addition to some glasses and glazes.

However, it has been known since ancient times that exposure to lead can have serious consequences for health. Accounts of symptoms consistent with chronic lead (and other metal) poisoning dating from the Roman period have been found, and there is evidence that many, in particular the nobility at the time, suffered from high exposure to lead. Up until recent decades, many workers suffered lead poisoning from exposure in the workplace.

Today, it is known that exposure to lead can cause adverse effects on many parts of the body. The organs potentially most affected are the brain and nervous system, kidneys, blood, and the reproductive system of both sexes. Lead in certain forms is also considered a possible carcinogen. Of particular concern is that relatively low levels can affect the developing foetus and young children, impairing their mental development and causing a small but measurable decrease in IQ. However, clinical symptoms are only found in very highly exposed individuals (who are usually exposed at work) and this is now extremely rare in the Western World.

Although mining, processing, manufacturing and the use of lead-containing products, together with recycling and waste disposal will continue to give rise to small emissions and losses to the environment, responsible action by industry coupled with the development and implementation of appropriate environmental regulations, designed to protect both human health and the ecosystem, keep these losses to a minimum. In a world driven by high technology, the continuing uses of lead which now avoid significant sources of human exposure, present little or no risk.

Nevertheless, the very word lead has, since the 1970s, evoked an emotive reaction in many of the general population and to a degree in the minds of politicians and regulators. They are not necessarily aware of the full scientific facts but are easily swayed by the more biased and articulate lobbyists, some of whom hold extremist views.

This book aims to:

• explain what lead is and to describe its properties
• detail the present applications, and compare its suitability with other alternative materials and substances (this includes lead metal, alloys containing lead, compounds of lead, and other substances containing lead);
• describe the EU (and, in less detail, worldwide) lead industry as it is today, including the amount of production, consumption, re-use and recycling, and market trends;
• describe the risks of exposure to lead - to the health of the general public, to occupationally exposed workers, and to ecosystems - arising from manufacture, use and disposal of lead and lead-containing substances (and also from natural sources of lead);
• describe the lead emissions from industries which produce and use lead, and detail measures undertaken by the industries to minimise emissions;
• present trends in the use / production of lead, and in levels of exposure to humans;
• critically assess:
  • whether lead is a suitable material for its current uses;
  • whether these products or their manufacture present significant cause for concern;
  • and in the light of these points, whether lead is likely to remain in use in the future.

In summary, this book presents an unbiased account of the present day activities of the lead industry, the production, uses and disposal of lead - and the potential risks to human health and the ecosystem that still remain. It is prepared on the basis of factual evidence, incorporating the use of state-of-the-art science, using the specialist advice of a team of experts from Imperial College of Science, Technology and Medicine, London. It has been written independently of the lead industry. It aims to provide a source of factual information for policy makers, regulators and scientific advisers in local and national government, the European Community and international organisations, together with non-governmental organisations and industry. In short, its primary objective is to set the record straight and pave the way for the future of lead as a sustainable and safe commodity.

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2. Properties of Lead

Lead has the advantages of low melting temperature and extreme malleability, which allow easy casting, shaping and joining of lead articles.  Besides this lead is slow to corrode and there are many examples of lead articles which have lasted for centuries.  Lead is relatively abundant. Lead concentrates can be easily extracted from the ore and winning the metal from the concentrate does not need much energy.  This reflects also in a fairly low price compared with other non-ferrous metals. Lead can be recycled as a secondary raw material from lead-acid batteries, from metallic scrap and from several composite consumer products in conjunction with existing recycling loops, for example for steel, zinc and copper, at moderate costs.

However, compared with other metals, lead has extremely low strength, exacerbated by its creep and fatigue behaviour.  Thus it is unsuitable for applications that require even moderate strength.  (Some of its mechanical properties are closer to those of higher strength plastics than most metals.)

Lead is rarely used in its pure form, as small alloying additions considerably increase its strength.  For applications requiring higher strengths, composites such as lead clad steel can be used.

The very high density of lead lends itself to some quite different applications, such as shielding against sound, vibrations and radiation, for example as protection for users of computer and TV screens.  For these purposes lead is used in metallic form or as lead compounds in lead glasses.

Some compounds of lead have their own useful properties, particularly in relation to colour and glass-forming ability.

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3. Applications of Lead

Examples of lead use have been known for thousands of years. The Romans used lead on a large-scale for plumbing, tank lining and domestic articles such as cooking pots and tableware, and also in glasses and glazes on pottery. Lead use has continued to grow and, in recent times, has risen from 4 million tonnes per annum in the 1960s to 6 million tonnes in the 1990s, due primarily to an increase in demand for lead-acid batteries. Present uses of lead and lead compounds are:

LEAD METAL

Lead-acid storage batteries
The major use worldwide, primarily as a starter battery in motor vehicles, but also as traction batteries for zero-emission electric vehicles and to provide emergency backup power supply, mostly for computer and telecommunication systems. Good rates of recycling are already achieved for starter batteries, though they could be improved upon in some countries; very high recycling rates are achieved for traction and backup batteries. Alternatives are under development for some applications, though at present these could not replace lead at comparable cost, or for technical reasons.

Constructional uses: pipe and sheet
Lead piping is now a minor application, as it is no longer used for domestic water supplies because of concerns that lead slowly dissolves in soft water and may pose a risk to health, and because of improvements in alternative materials. However, much lead piping remains in place. New lead pipes are used in the chemical industry.

Lead sheet is widely used on roofs for flashings and weatherproofings, and is often used for complete roofs on both historic and modern buildings.

Cable sheathing
Lead sheaths are used to protect underwater and some underground power cables. This is now a minor application of lead.

Radiation screening
Lead is the most effective of the commonly available materials for screening from X-rays and some other types of radiation. It is widely used in hospitals as part of X-ray equipment, and also in nuclear power stations.

Miscellaneous products
Lead is widely used in shot and other munitions. Some alternatives are available, and are used in situations where lead poses a particular risk to wildlife, especially to birds, as a result of ingestion. Lead is also used extensively in weighting applications.

Lead alloys
Lead-tin solder is widely used, particularly by the electronics industry. Very minor applications are in bearings and ornamental ware (pewter) - though alternative materials are now generally used. Small additions of lead are made to some steels, brasses and bronzes to improve machinability.

COMPOUNDS OF LEAD

Batteries
This is a major use of lead oxide. Lead dioxide is pasted on to the battery grids, and is the active material in the electrochemical reaction.

Pigments and other paint additives
Lead compounds were widely used until a few decades ago. They have been replaced in certain applications following concerns about potential impacts to human health. Leaded paints are still used in specialised outdoor applications as coatings for commercial vehicles and other industrial applications because of excellent rust-proofing properties. Lead dryers are still used in alkyd-based air-drying paints as very efficient and cost effective through-dryers.

Glasses and glazes
Lead additions improve the appearance and cutting properties of crystal glass. Small additions are also made to optical and electrical glass. The major application of leaded glass is in television screens and computer monitors, to protect viewers from the harmful X-rays generated by these appliances. Lead-containing glazes are used for some pottery, tiles and tableware.

Functional ceramics
Lead titanates/zirconates are used in the electronics industry in various functions.

Additions to PVC
Small additions of organic lead compounds to some grades of PVC improve durability and heat resistance, both in manufacture and in service. This is a significant market for lead compounds.

Leaded petrol
Lead compounds were universally added to petrol to improve its efficiency at low cost. This has been the major source of lead emissions to the environment. It is now being phased out almost universally because of concerns about health impacts.

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4. Lead Industry Profile

LEAD PRODUCTION

About 60% of lead produced world-wide is derived from ore. Lead ore is mined in many countries around the world, though three quarters of world output comes from only six countries: China, Australia, USA, Peru, Canada and Mexico. Small amounts are mined in several countries in Europe, with the biggest producer being Sweden. Total production has been at a similar level since the 1970s; new mines open or are expanded to replace old mines (Note: all these mines contain at least two metals (also zinc, sometimes silver, gold and copper) so lead extraction is not the only reason for the mining.)

The production of refined metallic lead from minerals dug out of the ground involves a number of steps which are outlined below.

Mineral extraction – mining and separation of the lead-rich mineral (ore) from the other extracted materials to produce a lead concentrate.

Primary production – production of metallic lead from lead ore concentrates involves the following process steps:

Smelting – reacting the lead rich mineral with other ingredients, to yield impure metallic lead. This is traditionally done in two stages:

l roasting in air, turning the lead concentrate (usually lead sulphide) into lead oxide;

l heating the lead oxide in a blast furnace with coke to yield metallic lead.

Alternative single stage methods offer many potential advantages in terms of overall efficiency, energy consumption and lower emissions (e.g. QSL, Kivcet, Isasmelt, TBRC).

Refining – the removal of impurities and other metals from the crude lead (S, Cu, Ni, As, Sb, Bi, Ag, Au, etc.). The refining process is applied in several steps in kettles with addition of specific agents, or alternatively, smaller quantities are processed by electrolytic refining.

Total production of refined lead (from all sources) has a different pattern, with the highest production rates being in the more industrialised countries. North America and Western Europe produce over half the world’s refined lead, and the trend is for slowly rising production. Production in China and some countries are now major producers. The world-wide trend is for a slow increase in production, though there have been short-term falls in production in the 1970s and 1980s, as a result of oil crises and economic recession.

Alloying – of refined lead with other metals to give the desired composition.

Secondary production – the production of refined metal by processing lead scrap. It is often possible to simply re-melt scrap lead, with very little extra processing. However, compounds of lead (such as battery pastes) require smelting. Refining is often needed to remove any unwanted contamination and alloying additions in the feed material. The procedures are similar to those outlined for primary processing, but in general, fewer operations are required.

The proportion of lead produced from secondary sources (i.e. scrap metal), which represents about 60% of total world-wide production, is also higher in the more industrialised countries. North America produces 70% of its lead from secondary sources, and Western Europe 60%. In contrast, Chinese production is almost entirely from ore.

In Western Europe the lead producing industry consists of:

Primary production - eight smelters in five countries with a total capacity of 600,000 tonnes and a labour force of 2,000.

Secondary production - 30 smelters in 12 countries with a total capacity of 750,000 tonnes and a labour force of approximately 3,000. Secondary production requires much less energy (less than half) than producing lead from ore. (Primary production 7,000-20,000 MJ/t lead, secondary production 5,000-10,000 MJ/t lead).

TRADE IN LEAD

Lead is bought and sold by many countries on the world market, in the forms of ore, impure metal and refined metal, as well as final products. The USA, South East Asia, and Western Europe are the largest importers of lead in its various forms, though many of these countries also export refined metal. The main exporters of lead are the countries which mine large amounts of lead ore.

CONSUMPTION OF LEAD

Lead is used by all industrialised nations. The USA is by far the biggest consumer, with some countries in Asia (China, Japan, Korea) and Europe (UK, Germany, France and Italy) also using large amounts. Most of the lead is used for batteries, an application which has grown enormously in importance. The use of lead pipe has declined, as it is no longer used for potable water supplies, though lead sheet is used in roofing and other applications, particularly in the UK. The use of lead in chemicals remains at about 10% of European consumption; much of this is used in glass for TV screens and stabilisers in PVC. Lead cable sheathing, shot and alloys are minor uses of lead. The addition of lead compounds to petrol was at one time a significant market, but this has already been phased out in the USA and most of Europe, and is declining in many other countries. It now represents a minor market segment with less than 1 percent of total consumption worldwide.*

ECONOMIC VALUE OF LEAD

It is impossible to calculate this accurately. The battery market is chosen as an example as the major lead-based product sold world-wide. Data for 1999 suggest that the automotive battery market had a turnover of $6-10 billion, and batteries for back up power supplies $2.85 billion, with the latter expected to expand rapidly.

Employment in lead and related industries
Though there are no precise figures, estimates by the lead industry suggest that between 70,000 and 90,000 people are employed in lead mining, smelting and refining, and over 2,000 more in lead oxide manufacture. Battery manufacture is estimated to employ about 60-70,000 people. Many more work in industries which use small amounts of lead in their products.

* In countries which are members of the ILZSG, including: Australia, Austria, Belgium, Canada, Finland, France, Germany, India, Italy, Japan, Republic of Korea, Mexico, Netherlands, New Zealand, Scandinavia, South Africa, South East Asia, Spain, Switzerland, United Kingdom, United States.

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5. Recycling of Lead

Lead is a material which is very easy to recycle. It can be re-melted any number of times, and provided enough processes to remove impurities are performed, the final product (termed secondary lead) is indistinguishable from primary lead produced from ore.

The amount of lead recycled as a proportion of total production is already fairly high worldwide. Over 50% of lead consumed is derived from recycled or re-used material; the figure is higher in Western Europe (60%) and the USA (70%). Secondary production rates compare favourably with other metals.

The long lifetimes associated with some applications of lead coupled with steadily increasing production mean that secondary production as a proportion of total production is not a good indicator of the actual recycling rate for lead (defined as lead recycled as a proportion of end-of-life material).

Recycling rates of lead and other metals are estimated to be much higher than for other materials such as paper, plastics and glass. Disincentives to recycle these materials include: low costs of raw materials to make virgin products, relatively high collection and transportation costs for a low value product and, particularly for plastic and paper, problems with inferior product quality.

Factors influencing high collection rates of lead are:

• the biggest consumer of lead is the battery industry which has a very high rate of collection and return of scrap batteries in most EU Member States;
• many other products used in much smaller amounts are suitable for recycling, and may be returned via scrap merchants;
• in conjunction with the iron and steel industries, zinc, copper and lead are recovered within the recycling processes of these industries;
• some applications which result in its unrecoverable dispersal into the environment, in particular as petrol additives and some paint uses, are being drastically reduced.

Recycling is performed where the industry finds it economic to do so. Recovering scrap metal has the advantages that it is easier and much less energy intensive than producing primary lead from ore (the production of recycled lead requires 35-40% of the energy needed to produce lead from ore.) Recycling also reduces dispersal of lead in the environment and conserves mineral resources for the future.

It is estimated that at least 85% of lead consumed could potentially be recycled. However, in practice the amount that is recovered is lower.

Some lead products are not recycled, either because it is not economic to do so at present, or simply because it is not practical to do so. However, recycling rates are generally increasing. Legislative and economic factors are two key incentives for this increase.

Any figures for recycling rates of lead must be treated with caution. Figures for recycling rates of lead batteries are available in a few countries, such as Italy, where collection systems involve recording this information. However, for lead recycling in general, quoted recycling rates are usually based upon estimates from lead consumption and secondary production. These figures can be distorted by:

• international trade in both scrap and refined lead;
• long time lags as a result of the long service life of some products;
• changes in lead consumption, which is generally rising world-wide, so that even a total recovery of lead would not be sufficient to meet demand for new lead products.

Improved waste management systems, such as incentives for battery recovery, guidelines for handling old building materials, old vehicles, electronic scrap, stricter quality demands for dumping materials and also progress in production techniques tend to generate higher recycling rates.

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6. Sources, Levels and Movements of Lead in the Environment

NATURAL OCCURENCE

Lead occurs naturally in low concentrations in all rocks, soils and dusts, usually ranging from 2 to 200 parts per million. The total amount of lead in the earth’s crust is estimated to be 3.1 x 10¹⁴ tonnes. Some soils have relatively high concentrations of lead, where the underlying parent rock has significant lead content. Lead contents of waters are generally low, but significant amounts of lead-rich dusts and vapours are carried in the air, from windblown material and volcanoes. However, these natural emissions are small in comparison with those resulting from human activity.

ANTHROPOGENIC SOURCES OF LEAD

Production of lead – Mining, smelting and refining of lead and other metals have in former times caused large emissions. Most of this is solid waste material, but sizeable emissions have also occurred to the atmosphere and to water. Modern techniques have minimized emissions to meet statutory requirements, including employment of best available technology.

Use of lead – Mobile sources (i.e. vehicles running on leaded petrol) continue to be a major contributor of lead to atmosphere in some countries, and this gives rise to elevated lead levels in soils, dusts and surface waters. Emissions are declining in many countries with the phasing out of leaded petrol, but lead deposited from petrol in the past remains in the environment. Residues from leaded paints, though now not used except for a few specialised outdoor applications, still continue to present a significant source of lead in house dusts and garden soils. Emissions from direct use of lead in other forms are small, resulting from abrasion and corrosion of lead or its compounds in some applications. Much of this material ends up in the sewage system, and contributes to levels of lead in discharged water and sewage sludge.

End-of-life of lead products – Most of the lead used at present is in products, such as batteries and lead sheet, which are largely recycled. Emissions can occur from collecting and processing operations, but these are small in modern well-run installations; legislation in all EU countries limits permissible industrial emissions. Recycling is certainly the preferred end-of-life option. For items which are not recycled, releases to the environment are much greater at the end of their lives than during use. For example, lead shot from hunting and firing ranges can locally result in high levels of lead in the soil, and lost lead weights add to the burden of lead in aquatic systems. These applications together can be the prime sources of lead inputs to waters and soils, in countries where there are no significant emissions from industry or leaded petrol. However, in general these inputs are relatively small and local.

Lead in the waste stream: landfill, incineration and compost – Many lead-containing products (such as leaded solder, glass, PVC, and small lead items) are disposed of as waste. Lead in most forms is fairly inert, and if buried in a modern well-maintained landfill, any releases should be very small. However, in the long term, some small losses of lead and other metals can be expected in leachate.

Disposal by incineration can result in emissions. However, EU legislation requires that exhaust gases are thoroughly cleaned, and the lead-rich dusts and vapours are trapped and must be disposed of, usually to landfill. Several countries in Europe use incineration (sometimes with energy recovery) as a preferred disposal method for municipal solid waste; it is also the recommended route for the non-metallic fraction from end-of-life vehicles, even though this fraction contains up to about 0.5kg of lead per vehicle. Lead in incinerator ash is usually subject to final disposal in controlled landfills to prevent releases to the environment.

Some countries in Europe compost significant amounts of biodegradable waste. In a few cases, lead items in the waste stream can enter this fraction if not separated fully; if resulting composts have levels of lead or other metals above agreed standards, this cannot be used for agriculture or gardens.

OTHER SOURCES OF LEAD

Coal and oil combustion results in the emission of small amounts of lead, along with many other metals. Sewage sludge often contains lead and other metals, from various sources, though inputs to farmland are strictly controlled by EU legislation. Application of sludge to land continues to be a source of lead input at low levels to agricultural soils.

CHEMICAL SPECIES OF LEAD

The behaviour of lead in the environment depends upon the chemical form it is in. Natural weathering processes usually turn metallic lead and its compounds into compounds which are relatively stable and insoluble. However, under acid conditions soluble compounds can also result in increasing mobility and potential bioavailability.

TRANSPORT OF LEAD IN THE ENVIRONMENT

Small lead particles emitted to air can remain in the atmosphere for over three weeks and in that time they may travel many hundreds of kilometers, though larger particles, which may constitute up to 95% of the emission, settle out within very short distances of the source. Deposition from atmosphere is a major contributor to lead inputs to water and to land but this continues to fall as the use of leaded gasoline is phased out. Lead can be carried in water, either dissolved or as waterborne particles. However, few compounds of lead dissolve readily in water, though most of this lead is then precipitated as a solid and becomes incorporated in the sediments at the base of the watercourse or ocean. In most cases lead in soil is relatively insoluble and has a low mobility. Thus, soils contaminated with lead retain high lead contents for many hundreds, even thousands, of years. Lead compounds are more mobile under acidic conditions, which can occur in mine wastes or from landfill leachate.

BIOAVAILABILITY OF LEAD

Knowledge of the total lead content of a surface soil is not very helpful in assessing the potential risk to humans or other organisms, because the degree of exposure to lead depends very much on the chemical and mineral form in which the lead occurs. The majority of lead compounds are relatively insoluble, though the small amounts of lead passing into the soil solution are easily taken up by biota. Some very insoluble lead compounds have little or no effect on living organisms. However, there is no single test for bioavailability: a compound which is unavailable to plants because it does not dissolve in soil water, may dissolve in the acidic stomach of an animal which ingests it. The development of simple cost-effective tests for bioavailability remains an urgent research requirement.

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7. Lead Exposure to Humans ands Other Oragnisms

Lead can reach the biosphere, including humans, by a number of routes. The main exposure routes to humans are:

• Food – This is a major source of lead intake for the adult population. Produce can be contaminated from airborne deposition and lead-rich soil, though this can be reduced with careful washing. Previously, leaded solders in cans and wine bottle capsules contributed to lead intake in the general population, but these have been phased out. In the home, the use of lead crystal or ceramic tableware glazed with leaded glazes can cause a small contribution, but such articles manufactured in the Western World are tested to ensure that leaching is acceptably low.
• Water – Old lead pipes, which are still in place in many dwellings, can slowly dissolve in some soft and acidic waters. Improved water treatment to reduce plumbosolvency, reduces the lead content of water to acceptable levels in the majority of dwellings. However, the problem is not eliminated without replacement of lead pipes within the home, which incurs expense to the homeowner. A WHO guideline of 10mg/l for drinking water is complied with in most cases.
• Air – Direct absorption by inhalation is a minor exposure route for most people, though it can be significant to individuals occupationally exposed. Airborne lead-containing particles fall to earth, most within a short distance of source, and add to lead contents of dusts, soils and food. A weak link between levels of lead in air and exposed populations has been established. The WHO recommended an air quality standard in 1987 of 0.5-1.0mg/m3. The EU lead in air standard is currently 0.5 mg/m3 and the UK has set an air quality target of 0.25 mg/m3. Air lead levels are falling in Western Europe, as leaded petrol is being phased out. Elevated levels can be found in some industrial areas.
• Soil and dust – Ingestion of soil and house dust is a major pathway for the exposure of young children to lead, due to “hand-to-mouth” activity. The major source of lead in house dust in older properties is leaded paint (now phased out, but still in situ in many dwellings). This is the major source of lead exposure to children living in older dwellings in the USA. Other contributions to dust are from airborne emissions, particularly in countries where leaded petrol is still used. Lead contents in house dusts in urban areas of the UK are declining. Lead contents of soils cannot be expected to decline for many years, as lead has a low mobility in soil.

Lead exposure levels in the general population have markedly declined over the past 30 or so years and by the 1990’s average national levels for blood lead in the EU were mostly well below 10 mg/dl.

TRENDS IN LEVELS OF LEAD EXPOSURE IN HUMANS

Levels of lead exposure in the general population have fallen in the USA and Western Europe, with average national values for blood lead in the EU in the 1990s mostly well below 10 µg/dl. Decreased exposure from several sources has brought this about, though it is believed that the reduction of leaded petrol is a major contributory factor. Other measures have included: improved water treatments reducing plumbosolvency; phasing out of leaded solders in food cans; and phasing out of the use of leaded paints. Improved industrial practices have resulted in lower emissions. A small proportion of individuals continue to receive doses of lead which are deemed unhealthy, particularly in the developing World and in Eastern Europe. The most highly exposed individuals tend to be the more deprived members of society. Occupational exposure has also decreased dramatically in the western world with improved technology, hygiene and management practices.

EFFECTS OF LEAD EXPOSURE ON HUMAN HEALTH

A small number of adults occupationally exposed to lead have in the past shown increased risk of kidney damage, nerve damage, infertility and, possibly, a small increase in blood pressure and the risk of contracting certain cancers at high levels of exposure. However, today such effects are rarely observed. The greatest concern for the general population is that lower levels of lead exposure, which some of the general population may receive, appear to cause a small decrease in the intellectual development of young children. Children are more vulnerable because their nervous system is developing; they absorb more lead than adults because of behavioural and physiological differences. There is no accepted threshold level, but the body of evidence to date does not find any effect below 10mg/dl blood lead. Individuals whose diet is lacking in iron or calcium absorb more lead than those who are well nourished.

ECOTOXICITY

Lead can have adverse effects on living organisms. High doses can interfere with some biochemical processes required for normal functioning. Most lead compounds have low solubilities in water and are not readily absorbed by most living organisms. Soluble compounds of lead can readily be taken in, and have been studied most widely (particularly for aquatic organisms). However, some organisms (such as molluscs) can absorb solid lead compounds from sediments, and there is little data available on the toxicity of this. Tetraethyl lead is much more toxic than inorganic lead compounds, but it breaks down quickly in the environment. Some aquatic species bioaccumulate lead, but there is no evidence for biomagnification at higher levels in food chains. Lead in soil generally does not have great effects on plants or earthworms except at highly elevated concentrations; its potency varies with soil type. In general, the bioavailability and toxicity of lead compounds are greater in acidic conditions, and less in alkaline or saline conditions.

The major impact of lead on wildlife, particularly waterfowl, results from the ingestion of lead shot (from ammunition or fishing weights). This can cause acute lead poisoning, sometimes fatal. For this reason, the use of lead shot for small fishing weights, and in some cases, in ammunition, is restricted in an increasing number of countries.

POLICY APPROACHES

A strategy based on risk assessment is generally used to predict the potential harm to target populations and to assist the regulatory process. This requires knowledge of the nature of the hazard (i.e. the lead compound), the exposure pathways to the target population, and the dose-response relationship. Sources of uncertainty in these predictions should be clearly stated. The precautionary principle can be used when there is lack of data on risk, and the potential for harm exists.

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8. Industrial Emissions and Controls

Emissions of lead, together with other harmful or potentially hazardous substances, can occur at all stages of production, from mining of ore, during smelting and refining, and also, potentially, during the manufacture of the finished products. Lead emissions also occur from non-related industries, such as other metal works, incinerators and in, small amounts, from power stations. The quantities of emissions are declining in the Western World as environmental legislation reduces permitted releases, increasingly effective pollution abatement technologies are used, and industry moves gradually towards inherently cleaner, more efficient technologies. However, some emissions are inevitable, especially from older plants which process many thousands of tonnes of material per year. However, the requirement to use Best Available Techniques under forthcoming IPPC legislation will further reduce emissions from older plants.

The bulk of emissions are in the form of solid wastes; a much smaller amount is emitted to air, and less still to water. The form of the emissions determines their likely mobility, bioavailability and potential to reach and affect a target ecosystem or human population. Other important factors are whether the emissions are part of controlled, measured releases, uncontrolled fugitive emissions, or resulting from a plant incident.

Despite the recognition of historical environmental damage and health effects in the work force connected with the lead industry over many centuries, it is only in the past hundred or so years that effective control measures began to be implemented, both to protect the health of workers and to reduce pollution. Good plant design, with reduction of the potential for the emission of contaminating substances, is of paramount importance, and the newer smelting processes are inherently much cleaner than traditional blast furnaces. Pollution abatement technologies, including the treatment of exhaust gases and liquid effluents to remove a proportion of the metal content, have also significantly reduced emissions. Other general measures to improve the cleanliness of sites are implemented to varying degrees. These measures, taken together, have considerably reduced emissions.

Throughout the Western World, factories are legally required to operate within the limits on discharges set by their regulatory authority, although not all emissions are continuously monitored. In this respect, many plants in the EU have some form of perimeter monitoring. There are inherent problems in measuring fugitive emissions, such as windblown dusts, can be addressed by monitoring air quality within and at the perimeter of the site and modelling the results. In general it is difficult to estimate the percentage of the emission arising from fugitive sources. In certain countries allowable discharges are set individually for each plant.

There are legal limits and recommended guidelines for concentrations of lead in air outside plants, and monitoring is usually practised. Sites with the highest concentrations of lead in air are in the vicinity of industrial locations. Compliance with the former EU standard of 2mg/m³ is now virtually universal, though there are still a few sites which exceed the new standard and the WHO guideline value of 0.5mg/m³.

Those mostly exposed to releases within the plant are the workforce. Before industrial controls were introduced around the turn of the century, lead poisoning was common in foundry workers, and was also found in other trades which used lead. The implementation of controls such as maintaining minimum standards of air quality within the works, medical surveillance of employees, use of protective equipment, and provision of conditions of good hygiene in general, have made excessive occupational lead exposure a rare occurrence.

Outside the Western World, control measures are not always enforced to the same degree and there are still undoubtedly many cases of high occupational exposure to lead and environmental damage resulting from industrial emissions in the developing world.

In short, while it is important to recognize the huge improvements made by industry in recent decades, there are considerable variations between standards in the developed and the developing world. Emissions from some plants outside the EU continue to contribute towards elevated exposure of local residents, and high lead levels in soils leave a legacy for centuries. It is therefore important to continue to work toward implementation of best practice, and to aim for a level of emission that is globally sustainable.

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9. Is Lead a Sustainable Commodity?

• The use of lead in many products, particularly those of major importance, gives little cause for concern, and offers considerable economic and practical advantages.
• Levels of lead exposure in the general population have fallen over the past two decades in many countries, particularly the EU and USA. The vast majority of the population now receives doses well below levels of concern.
• Some of the minor applications of lead have impacts, or the potential for impacts, either in use or disposal, and the use of suitable risk management measures should be pursued. The most damaging applications of lead have been phased out in the West, although some old products such as paint and pipes continue to cause elevated exposure to a minority of the population. Some of these products are still used outside Western countries.
• As the use of lead in dispersive applications declines, emissions from manufacturing industry and from refuse disposal by incineration and landfill, are becoming proportionally more significant sources of lead in the environment.
• Good practice in the production of lead can reduce, though never eliminate, emissions, and corresponding risks to workers, local residents, and the environment. Standards vary even between different plants in the EU, and much more so world-wide. Though great improvements have been made, industrial emissions remain a matter for close attention.
• Changing patterns of lead use are likely to help reduce impacts during manufacture, use and disposal of products, as dispersive applications are phased out, and higher proportions are recycled.
• Historical practices have resulted in contamination which remains in soils for centuries. Present practice has significantly reduced emissions, and impacts on the environment have decreased markedly. The long term fate of lead, particularly in refuse, is likely to be an important focus of attention in the future.
• It may be concluded that lead is a sustainable commodity when produced, used and recycled in a responsible manner. Efforts to restrict or even ban its use are not backed up by sound scientific evidence, but rather based on emotive comment and misguided public perception.
• compare the impacts of lead with those of alternative products.

The pattern of lead usage and production has changed dramatically during recent decades, and thus so have the impacts. It is helpful to consider the current situation.

CURRENT STATUS OF LEAD CONSUMPTION

• total world-wide consumption is slowly rising (currently 6 million tonnes per year 1995-1998 (ILZSG, 1999);
• batteries (for vehicles and for emergency power supply) account for the majority of lead use, and are of growing importance;
• other significant uses of metallic lead are in building, alloying, cable sheathing, and shot and weights;
• the major use of lead compounds is in glass for television and computer monitor screens. Other important uses include PVC, lead crystal and some ceramics glazes. Small quantities are used in some paints for special applications;
• uses which have been or are in the process of being phased out in the EU include white lead paints, petrol and pipes.

CURRENT STATUS OF LEAD MANUFACTURE

• total production is slowly rising to keep pace with demand, particularly in some parts of the developing world;
• world-wide, around 50% of lead is produced from scrap batteries and other products. The proportion is higher in many industrialised countries. Recycling rates of lead compare very favourably with other materials;
• the proportion of secondary production is increasing as dispersive applications of lead (petrol and paint) are phased out in many countries. As a result more of the lead used is suitable for recycling;
• in many recycling processes (steel, copper, brass, etc.), lead is concentrated via flue dust and recovered in the recycling chain for zinc, tin and other metals;
• some losses to the environment are inevitable from the production of lead (as with all manufacturing processes);
• secondary production of lead from scrap results in less solid wastes, uses less energy and reduces the consumption of mineral resources, compared to the production of lead from ore;
• control measures implemented in the EU have greatly reduced the emissions from factories in recent decades. However, the situation is less certain in parts of the developing world.

CURRENT STATUS OF HUMAN EXPOSURE

• the level of lead exposure in the general population in the EU and other Western countries has fallen dramatically in the last 2 decades;
• this is partly attributable to the phasing out of lead in petrol. Other contributions have been from reduced use of leaded pipes, paints, solder in food cans, plumbing solders and reductions in industrial emissions;
• the majority of the general population in the West has very low levels of lead exposure which give no cause for concern;
• a small minority of the population in some Western countries continues to receive elevated exposure. This is mainly from old lead products which remain in service (pipes in the water distribution system and paint). Proximity to industry contributes to some cases;
• exposure to lead in the workplace has fallen dramatically as a result of various control measures. However, there continue to be very small numbers of cases causing concern.

The questions to be addresses here include:

• does the continued use of lead and lead containing products present significant risks to human health or the environment?
• do the advantages of using lead for certain applications justify its use, when considering potential risks to health or the environment?

It must be recognised that:

1. In the past, widespread use of lead in dispersive applications (particularly petrol and paint) has caused considerable environmental contamination, with consequences for human health and the environment which can sometimes still be observed today. The elevated environmental levels will remain for centuries in soils, although mostly in a non-bioavailable form. Similarly, lead water pipes continue to contribute to elevated levels of lead intake to a proportion of the population in areas of soft water. The risks arising from these uses have been reduced as a result of controls and legislation.
2. In the Western World, exposure of humans to lead has fallen considerably in the last two decades. The phasing out of leaded petrol is considered the most significant single factor in this. Other contributing factors are: phasing out of leaded paints; phasing out of leaded solders in food cans; phasing out of leaded water pipes and improved treatments of waters to reduce plumbosolvency; improved industrial controls. As a result, the majority of the population has lead intakes which are well within accepted limits, and not believed to be detrimental to health. However, certain minority groups have levels of exposure which could be detrimental, particularly to children. These are generally related to industrial sources, high lead content in water, some hobbies which involve lead or lead compounds; or, most importantly for young children, exposure to old leaded paint and lead-rich soil and indoor dust.
3. Major modern uses of lead (particularly in batteries, television glass, radiation shielding) offer considerable advantages over alternatives and present no recognisable hazard to humans or ecosystems.
4. Some minor applications can have impacts and alternatives are available, or could be in the future, though they may be more expensive. Lead shot and fishing weights can poison waterfowl and add to lead levels in soils and sediments; their use is restricted or banned in wetland areas in some EU Member States. Lead incorporated into glass or glazed tableware has the potential to leach into food or beverages (particularly acidic fruit or beverages) which are stored in them; such items are required to pass standard tests to ensure that leaching rates are low. These potential impacts are recognised, and some measures are taken in the EU and elsewhere to avoid problems.
5. Many of the minor and dispersive applications of lead end up in the ground or in waste streams. There is thus the possibility of migration into soils and waters, and uptake by living organisms in the future. The fate of lead in waste streams is likely to be the subject of increasing attention in the future.
6. The long term fate of lead in the environment depends upon the chemical form in which it occurs, since this affects its ability to migrate and enter food chains. Many forms of lead have low mobility and little effect on living species; the chemical forms of lead can change over time, particularly if the water table moves, or if the acidity of the environment changes.
7. Production of lead invariably results in some releases and can, in certain cases, cause adverse effects on health. Significant improvements in industrial practice have been made, which have lowered the impacts of the manufacture of lead and its products in many countries. However, this still remains an important issue.
8. Most of the lead used at present is for products suitable for recycling, and recycling rates of lead are far better than those of most other materials. However, efforts should be made to improve recycling rates still further in order to avoid lead losses in the waste stream and to reduce the potential impacts of lead production on ecosystems and on human exposure.

CONCLUSIONS

• The use of lead in many products, particularly those of major importance, gives little cause for concern, and offers considerable economic and practical advantages.
• Levels of lead exposure in the general population have fallen over the past 2 decades in many countries, particularly the EU and USA. The vast majority of the population now receives doses well below levels of concern.
• Some of the minor applications of lead have impacts, or the potential for impacts, either in use or disposal, and the use of suitable risk management measures should be pursued. The most damaging applications of lead have been phased out in the West, although some old products such as paint and pipes continue to cause elevated exposure to a minority of the population. Some of these products are still used outside Western countries.
• As the use of lead in dispersive applications declines, emissions from manufacturing industry and from refuse disposal by incineration and landfill, are becoming proportionally more significant sources of lead in the environment.
• Good practice in the production of lead can reduce, though never eliminate, emissions, and corresponding risks to workers, local residents, and the environment. Standards vary even between different plants in the EU, and much more so world-wide. Though great improvements have been made, industrial emissions remain a matter for close attention.
• Changing patterns of lead use are likely to help reduce impacts during manufacture, use and disposal of products, as dispersive applications are phased out, and higher proportions are recycled.
• Historical practices have resulted in contamination which remains in soils for centuries. Present practice has significantly reduced emissions, and impacts on the environment have decreased markedly. The long term fate of lead, particularly in refuse, is likely to be an important focus of attention in the future.
• It may be concluded that lead is a sustainable commodity when produced, used and recycled in a responsible manner. Efforts to restrict or even ban its use are not backed up by sound scientific evidence, but rather based on emotive comment and misguided public perception.

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References

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Annex

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