Asbestos is a naturally occurring mineral. Traditionally used in a wide variety of applications it is mined in much the same way as iron, lead and copper. Asbestos is composed of silicon, oxygen, hydrogen, and various metal cations (positively charged ions). However, unlike most minerals, which turn into dust particles when crushed, asbestos breaks up into tiny fibres invisible to the human eye. The main producers are the former USSR, Canada and South Africa. Most of the asbestos previously imported into the UK came from South Africa.

Asbestos is hazardous to health and the first recorded death from an asbestos-related illness (asbestosis) was in 1915. In 1935, researchers in the UK and USA were beginning to suspect a link between asbestos exposure and lung cancer and by 1955 this link was confirmed (International Federation of Chemical, Energy, Mine and General Workers' Unions, 2000). Three diseases are commonly linked to asbestos exposure:

• asbestosis, a fibrosis or scarring of the lungs (through massive over-exposure)
• lung cancer
• mesothelioma, a cancer of the inner lining of the chest or abdominal wall (through lower level exposure).

Disease development has a latent period of between 10-30 years and no safe exposure level has been identified at present. These diseases result from the inhalation of asbestos fibres. Their shape and size enables them to penetrate deep into the lungs. Crocidolite and amosite are thought to be the most dangerous types since their tiny fibres are easily inhaled.

The perception of risk from asbestos is far in excess of actual risk. Since it is not possible to calculate a 'safe' level, there is a general perception that any contamination is harmful. This is not the case. For example, there is no risk attached to touching or even eating asbestos; ingested fibres simply pass through the body. Asbestos is only hazardous if inhaled. This will usually occur only after the material is damaged, thereby liberating airborne fibres. Paradoxically, if you can see asbestos, it is not dangerous as the fibres will be too big to pass the natural filter mechanisms of the respiratory tract.

The risk is highest for those whose work brings them into contact with asbestos. For example:

• workers who renovate old buildings who may experience 'occupational exposure'
• family members of workers in contact with asbestos-containing material may inhale asbestos fibres attached to clothing
• people who live or work near asbestos-related operations may inhale airborne asbestos fibres. This is known as 'neighbourhood exposure'.

The amount of asbestos a worker is exposed to will vary according to:

• the concentration of fibres in the air
• duration of exposure
• breathing rate (workers doing manual labour breathe faster)
• weather conditions
• the effectiveness of protective devices worn.

The risk of asbestosis is minimal for those who do not work with asbestos, or are not affected by 'neighbourhood exposure'. Studies show that the risk of dying from lung cancer for those working with asbestos is five times greater than those who do not. This is smaller than the risk from smoking: smokers are 11 times more likely to contract lung cancer than non-smokers. However, smoking and working with asbestos leads to a far higher risk of dying from lung cancer - 55 times greater than those who neither smoke nor have been exposed to asbestos (Willey 1997).

Mesothelioma is a rare form of cancer which most often occurs in the thin membrane lining of the lungs, chest, abdomen, and (rarely) heart. Virtually all cases of mesothelioma are linked with asbestos exposure. Approximately 2% of all miners and textile workers who work with asbestos, and 10% of all workers involved in the manufacture of asbestos-containing gas masks go on to contract mesothelioma.

Workers who manufacture and install asbestos insulation have an increased risk of mesothelioma. There is also increased risk for those living with asbestos workers or those in close proximity to the above sites which may be responsible for creating large quantities of airborne asbestos fibres.

The younger people are when they inhale asbestos, the more likely they are to develop mesothelioma. Enormous efforts are thus being made to prevent school children from being exposed to asbestos fibres, particularly from asbestos which may have been used in the construction of school buildings.

There are three main types of asbestos:

• chrysotile ('white' asbestos) - the first to be commercially mined in Quebec, Canada, 1870s;
• crocidolite ('blue' asbestos) - first mined in South Africa during the 1890s; and
• amosite ('brown' asbestos) - also from South Africa, first mined in 1916

Other varieties include anthophyllite and actinolite-tremolite, details of which are summarized in Table 1.

Table 1 Types of asbestos and their usage

TYPE	PERCENTAGE OF TOTAL	GENERAL USES
Chrysotile (white asbestos)	95	asbestos-cement building products asbestos-cement pipes fire-resistant insulation products friction materials, e.g. car brake linings textiles products floor tiles moulded plastics and battery boxes many others (prohibited for new products since November 1999)
Crocidolite (blue asbestos)	3	shipbuilding mixed with chrysotile for asbestos pressure pipes and sheeting (prohibited for new products since 1986)
Amosite (brown asbestos)	1-2	bonds well with plastics and used in floor tiles, fireproof boards in ships and insulation sprays (prohibited for new use since 1986)
Anthophyllite		industrial talc, paper processing, plastic products, asbestos cement pipes and friction materials
Actinolite - tremolite		found primarily as natural contaminates in other materials such as talc

SOURCE: INTERNATIONAL FEDERATION OF CHEMICAL, ENERGY, MINE AND GENERAL WORKERS' UNIONS 2000

Asbestos was introduced to the UK in 1895 (Willey 1997). It appealed to the manufacturing sector and building trade by offering the following properties:

• not flammable
• a good insulator against heat, electricity, noise and vibration
• The low cost of labour in South Africa made asbestos cheap to produce and up until 1978, the UK had imported over one million tonnes of asbestos (Willey 1997). The use of crocidolite declined in UK manufacturing during the 1960s and has not been used at all since 1970 (Environment Agency 1999). Amosite and chrysolite use also declined in the 1960s.

However, it was not until 1986 that amosite and crocidolite were banned in the UK. Chrysolite, the most commonly used asbestos, was only recently banned in new products in 1999, with a few rare exceptions (see Legislation). The legislation banning chrysolite was in advance of a European Commission Directive on the Marketing and Use of Certain Dangerous Substances and Preparations (Asbestos) 1999/77/EC, which requires a total ban by 2005.

The colour of asbestos cannot usually be determined by sight, as it is often incorporated with other materials which disguise it. Laboratory analysis is needed for identification.

Asbestos has a wide range of uses. It may still be found in wall cladding, ceiling tiles, fire doors, behind radiators, inside night storage heaters, in linings to gas central heating cupboards and in ducts of central heating systems. One study has estimated that 3,000 different types of commercial product contain asbestos (EPA 1999).

In industrial countries, asbestos products surround us. Walking around any big city inevitably means breathing in some asbestos fibres. Research has shown that over 60% of people will have asbestos fibres in their lungs when they die, yet it will not have played a role in their demise (International Federation of Chemical, Energy, Mine and General Workers' Unions 2000).

The use and management of asbestos is highly regulated in the UK. Regulations tightly constrain asbestos management, transportation and disposal. The classification of asbestos as special waste, under the Special Waste Regulations 1996, requires that a specialist asbestos contractor must be used, except in strictly defined circumstances. The regulations also stipulate that asbestos waste can only be transported by carriers licensed to transport special waste and disposal must take place at designated sites. The main legislation that covers the usage and disposal of asbestos is outlined below:

Asbestos (Prohibitions) (Amendment) Regulations 1999 (SI 1999/2373) prohibits the importation, supply and use of chrysotile, effective from November 1999.

Asbestos (Licensing) (Amendment) Regulations 1998 (SI 1998/3233) defines the type of work with asbestos that must be licensed and notified to the enforcing authority. The regulations now include removal, repair and disturbance within its definition.

As defined in the Special Waste Regulations 1996 (SI 1996/972), any asbestos material containing more than 0.1% of asbestos is classified as special waste, regardless of chemical form (i.e. chrysotile, crocidolite, etc) or source (household, commercial, industrial). Uniquely, asbestos is the only household waste material that is classed as special waste.

The objective of the Chemicals (Hazard Information and Packaging for Supply) Regulations 1994 (SI 1994/3274), otherwise known as CHIP Regulations, is to protect people and the environment from the adverse effects of hazardous chemicals. Chemicals are classified by their hazardous qualities and the associated risks they present. All forms of asbestos are listed as Category I carcinogens in the Approved Supply List; they are also classed as toxic.

Containers must be labelled in accordance with prescribed requirements.

Control of Asbestos in Air Regulations 1990 (SI 1990/No number identified) sets limits for the discharge of asbestos into the air from processes using asbestos.

As amended by the Control of Asbestos at Work (Amendment) Regulations (SI 1992/3068) and the Control of Asbestos at Work (Amendment) Regulations 1998 (SI 1998/3235). These specify control limits and action levels which have to be complied with when working with asbestos. The regulations stipulate that asbestos waste must be stored and transported in sealed, properly labelled containers according to CHIP and CDG.

Asbestos (Licensing) Regulations 1983 (SI 1983/1649) defines the licensing requirements.

The demolition or redevelopment of older buildings and equipment accounts for the generation of the majority of asbestos waste in the UK. The hazardous qualities of asbestos limits the management options.

The use of asbestos in new products and as insulation is prohibited. However, where building renovation or the replacement of asbestos is concerned, waste cannot be avoided. The problems associated with dealing with asbestos waste will reduce over time.

If materials such as asbestos sheeting are sound and there is no sign of flaking there is no reason why they cannot be reused, provided safe working practices are followed.

Asbestos waste is not suitable for recycling under any circumstances.

The decision to remove asbestos can be difficult. In many instances it is better to leave the material in-situ provided the material is intact, as removal can disturb the fibres. Removal and disposal of asbestos usually has to involve specialist contractors. Householders should seek advice from their local authority if they suspect that they have asbestos in their home (see Case Study: Nottinghamshire County Council).

Asbestos waste is categorised as special waste and is therefore subject to strict consignment note requirements for generation and transport. Before removal from site, the waste will normally be double bagged and labelled to show the origin of the waste before being consigned for final disposal to a licensed asbestos site.

Asbestos from industrial premises will normally be dealt with by a specialist contractor who will take responsibility for the correct handling and disposal of the waste.

The same cannot be said of asbestos in homes. The most common problem occurs when householders want to demolish an old garage with asbestos roofing. They will usually contact their local authority for advice. Difficulties are often encountered as they expect an asbestos waste collection free of charge. However, not all local authorities make provision for asbestos disposal from households, since it is not a controlled waste. Asbestos is classified as special waste (no matter from whom it is generated), and there is considerable confusion and misinformation about how it should be dealt with by the public. Local authorities will often recommend contacting a specialist contractor to remove the waste, but this can be expensive.

In Nottinghamshire, households have two options for dealing with asbestos waste. They can have the asbestos collected by their district council as part of a monthly 'milk round' collection. Alternatively, the householder can deliver the asbestos to a licensed landfill site. Collected waste is placed directly into the bucket of a mechanical digger, deposited at the base of the landfill face and covered with the day's waste.

SOURCE: NHHWF 1998

Since the November 1999 ban on the importation, supply and usage of chrysotile, all asbestos is effectively banned from new products and processes in the UK. Efforts will now focus on dealing with the very considerable quantities of asbestos that are still in use. As explained in the waste management options above, where asbestos is intact it is best left in situ, particularly where it is not in a sensitive area. However, eventually this ageing material will begin to decay and anyone owning a building that contains asbestos will face the considerable cost of removal.

Increasingly, local authorities are reluctant to offer asbestos disposal as a free service to households. The costs of landfill disposal may cause more authorities to review the facilities that they offer.

The impact of the recently adopted Landfill Directive (1999/31/EC) on the management of hazardous waste is still unclear. The banning of co-disposal, currently practiced in the UK (where municipal waste is mixed with hazardous waste) will result in the concentration of waste in hazardous 'coffins'. Once licensed, the landfill operator will not be able to divest themselves of the license and will be responsible for the site in perpetuity. One likely result may be to cause landfill operators to reconsider their ownership and management of the licensed hazardous waste sites that currently accept asbestos waste. The cost of asbestos disposal may well increase if the number of sites accepting the waste decline and landfill taxes continue to rise.