Questions and Answers on HTIW

What is ECFIA?

ECFIA is a trade organisation representing the High Temperature Insulation Wool (HTIW) industry in matters relating to Health, Safety and the Environment in Europe. It was created in 1979 as the European Ceramic Fibre Industry Association and is based in Paris, France.

What does ECFIA do?

We promote and finance improved standards and practices for the use of HTIW based on scientific research, and workplace programmes designed to protect the health and safety of workers involved in the manufacture and use of HTIW. ECFIA also serves as an expert resource for regulatory and other bodies and encourages appropriate legislation.

Who are ECFIA’s members?

ECFIA members manufacture a range of HTIW products and other traditional refractories for various industrial applications. Our members are: SAFFIL Ltd, being part of Unifrax (Great Britain); Unifrax France SAS; Morgan Thermal Ceramics Ltd (Great Britain); Morgan Thermal Ceramics de France S.A.; and Rath GmbH (Germany). Our associate members are: Mitsubishi Plastics Inc. (Japan); ITM Co Ltd (Japan); Denki Kagaku Kogyo Kabushiki Kaisha (DENKA) (Japan); Nutec Procal, S.L. (Spain); Promat International NV (Belgium); and M.E.SCHUPP Industriekeramik GmbH & Co. KG (Germany).

What are HTIW

High Temperature Insulation Wools are synthetic mineral wools used in high-temperature industrial applications where heat containment is required, typically used in the temperature range 600°C to 1800°C. They include three different types of wool: Polycrystalline Wools (PCW), Alumino Silicate Wools (ASW/RCF) and Alkaline Earth Silicate (AES) Wools. HTIW account for only about 2% of the total synthetic mineral wool production in Europe.

Where are HTIW used?

HTIW are used in high-temperature industrial applications such as iron and steel and non-ferrous metal manufacture, chemical and petrochemical industries, ceramics and glass production, power generation, domestic appliances, and the automotive Industry. HTIW products are also used in fire protection applications and, very rarely, in the construction industry.

What is ASW/RCF?

ASW is Alumino-Silicate Wool, reflecting its principal constituents. It is also known as Refractory Ceramic Fibre (RCF). It is manufactured by melting aluminium oxide and silica sand and then spinning or blowing the melt to produce fibres and is typically used in the 800 - 1400°C temperature range.

What is AES wool?

AES stands for Alkaline Earth Silicate. AES wool is made from a mixture of silicon, calcium and magnesium oxides, plus aluminium, titanium and zirconium oxides in varying proportions. It is manufactured by melting the raw materials and then spinning or blowing the melt to produce fibres and is normally used in the 600 - 1200°C temperature range.

What is PCW?

PCW is Polycrystalline Wool, made predominantly of aluminum oxide (typically 72-99%), with the remainder consisting of silicon. It is manufactured using a sol-gel technology and high temperature firing to produce fibres of well-defined dimensions. PCW is produced in relatively small quantities for very specific applications, typically in the temperature range 600 - 1800°C.

What makes fibres dangerous?

Inhaled fibres can be dangerous because they may be breathed deep into the lung and resist or avoid the body’s attempts at removal. If they persist in the lungs for a sufficiently long time and in sufficient quantities, they can cause damage by irritation and inflammation and eventually scarring or even cancer. There are three important characteristics – the ‘three Ds’ – that determine the degree of hazard posed by a fibre:

  • Dose – the number of fibres breathed in and reaching the deep lung (alveolar region)
  • Dimension – fibre length and diameter
  • Durability (better referred to as biopersistence) – the property that determines the extent to which a fibre will withstand the lung’s natural removal processes

Long, thin and biopersistent fibres are the most hazardous.

Why is ASW/RCF classified as carcinogenic?

The classification of ASW/RCF as carcinogenic in European regulation is based on the results of studies performed in the 1980’s in which experimental animals were exposed to extremely high concentrations of airborne fibres. It is now widely believed that the cancers found in these rats were at least partly due to ‘overload’ - a phenomenon by which otherwise inert particles can cause lung cancer if doses are high enough. ASW/RCF has been in industrial use for more than 60 years. Results of human epidemiological studies to date indicate that ASW/RCF workers are at no increased risk of lung cancer or mesothelioma.

What are the differences between HTIW and asbestos? Is it true that ASW/RCF is as dangerous as asbestos?

It is a mistake to believe that HTIW and asbestos are similar in their potential to cause damage to human health. There are several important reasons for this:

  • Asbestos splits longitudinally, producing long very thin fibres, whereas HTIW breaks (snaps) transversely, producing shorter thick fibres that are more readily removed from the lung.
  • Asbestos fibres are much more likely to become airborne than thicker, heavier HTIW fibres.
  • Asbestos – especially amphibole asbestos – is considerably more biopersistent in the lung than HTIW.

Exposed asbestos workers are at high risk of pulmonary fibrosis (asbestosis), lung cancer and mesothelioma. ASW/RCF workers so far show no increased risk whatever for these conditions.

How important is fibre chemistry in determining the toxicity of HTIW fibres?

The chemical constitution of an HTIW fibre is largely irrelevant except insofar as it affects its solubility and biopersistence in the lung. The amount of chemical substances leached from HTIW fibres in the lung as they dissolve is toxicologically insignificant.

What are the recommended maximum fibre exposure levels?

ECFIA’s position has been that an occupational exposure limit of 0.5 f/ml is appropriate for all HTIW. However, for ASW/RCF some countries (e.g. France and Norway) have set OELs as low as 0.1 f/ml. In 2012, SCOEL – the EC committee on occupational exposure limits – recommended an OEL for ASW/RCF of 0.3 f/ml. This issue is a matter of ongoing discussion within Europe.

What sort of fibre concentrations are found in the workplace and in the environment?

A comprehensive product stewardship program has been instigated by the HTIW industry which includes an extensive monitoring programme. Results show that exposures vary by functional job category and the particular task within the job. Exposures are highest for removal of used ‘after-service’ insulation, perhaps because the HTIW is partly devitrified and so breaks more easy, producing more dust. Measured fibre concentrations have reduced over the years and now average between 0.2 and 0.3 f/ml, although there is substantial variability in fibre concentrations even within a specific job category. Environmental measurements of HTIW (e.g. at the ‘factory fence’) are extremely low - generally below detection limits.

Are there any human studies on the health effects of these fibres?

In addition to the ‘CARE’ programme, which involves industry-wide worker exposure monitoring, ECFIA has been sponsoring ongoing epidemiological investigations into the possible health effects of exposure to ASW/RCF. The results to date show no increase in the incidence of lung fibrosis or lung cancer or mesothelioma (cancer of the chest lining) in exposed workers, or any long-term changes in lung function, although an increase in pleural plaques has been detected. [Pleural plaques are focal thickenings of the chest wall lining that occur at low incidence in the general population and have no link to any adverse health effects or symptoms.]

Are ‘after-service’ fibres more dangerous than freshly manufactured fibres?

When any synthetic vitreous fibre is heated at prolonged high temperatures it can ‘devitrify’ to form cristobalite, a type of crystalline silica. Since crystalline silica is classified by IARC as carcinogenic, this has led to the speculation that ‘after-service’ (heated) HTIW may be dangerous, even if the material is safe in its original form. However, studies have demonstrated very clearly that such devitrified fibres are not more toxic, and that the cristobalite they contain appears inactive or not bioavailable. Exposure measurements undertaken during demolition works have shown no or very low levels of cristobalite in the workplace air. Note: These considerations are not relevant to PCW because it is not a vitreous fibre. Also, no HTIWs contain crystalline silica in their newly manufactured form.

What is the environmental impact of HTIW?

Less raw material and energy are used in the manufacture of HTIWs than is the case for traditional refractory products. Moreover, HTIW products contribute to more efficient use of energy in industrial installations through improved insulation. It has been estimated that HTIW enables energy savings of up to €2bn per year in Europe and carbon dioxide reductions of up to 12 million tons p.a. Also, being used in the manufacture of motor vehicle catalytic converters and particle filters, HTIW are an indispensable element of the environmental efforts of the automotive industry. There are no health or environmental concerns regarding environmental releases of HTIW fibres.

Is the general public exposed to HTIW?

No. HTIWs are used in industrial applications only, where there is no potential for exposure of the general public. Contrary to some other lower-temperature insulation wools, they are rarely used in the construction industry - only in some specific fire protection applications. Measurements indicate that there is no environmental exposure to the general public.

What is the PSP?

PSP stands for 'Product Stewardship Programme'. Established in the 1990’s, ECFIA’s PSP is designed to assist HTIW manufacturers and end-users in the evaluation, control and reduction of workplace exposures, and helps ensure the proper manufacture, storage, handling, use and disposal of HTIW products. The CARE programme (see below) is a key element of the PSP.

How can industry control or reduce worker exposure to HTIW?

Workplace exposure control is a key element of ECFIA’s PSP. As part of this, and based on an extensive ongoing exposure monitoring programme called CARE, ECFIA has developed a set of best-practice guidelines to help industrial users control and reduce worker exposure. These ‘CARE Guidance’ documents - as well as various leaflets, posters, etc. for use at the workplace level - are all available on the ECFIA website.

What is the CARE programme?

CARE stands for ‘Controlled And Reduced Exposure’ and is a cross-industry programme of exposure monitoring and risk assessment for all HTIWs, encompassing ongoing reporting, workplace measures and control recommendations at both user company and manufacturer levels. It is a key component of ECFIA’s PSP.