The future is Silica-free

17 February, 2021
Breton continues expanding its range of products and technologies made available to its clientele, putting health and safety first.
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Oxygen and silicon are the two elements that predominate in the composition of the Earth's crust, the former accounting for 60% and the latter for 20%. When these two elements combine, they give rise to the most common compound in the Earth's crust: Silicon Dioxide or Silica, with the chemical formula SiO2, which is present in many of the stones we know, as well as in glass and ceramics.

Silica can be found in various forms, which can be divided into two macro-families:
1.        Amorphous silica
2.        Crystalline silica
In Amorphous Silica, the arrangement of SiO2 units does not respect a precise spatial order. In nature, they consist mainly of silicas of volcanic origin, such as pumices, and silicas of biological origin, such as diatomaceous earth. There are also synthetic amorphous silicas, which are present in glass or fused silica.
Amorphous silica is not considered hazardous to health, even in the form of fine, inhalable dust.

In Crystalline Silica, on the other hand, the SiO2 units are arranged in space according to precise rules.
The forms of crystalline silica are made of:
  • Quartz
  • Cristobalite
  • Tridymite
In nature, the most common is quartz.Cristobalite and tridymite are rare and are commonly formed in the firing/use of refractory bricks.
Quartz is found in granites and porphyries, quartzites, coastal sands, ceramics and porcelain, bricks, quartz-resin slabs.
Cristobalite has a high degree of whiteness and is therefore also produced artificially from quartz for use as mineral filler in various industrial products including quartz-resin slabs.
Crystalline forms of silica are the most common in nature. Minerals and siliceous stones, as well as finished products made from them, which we walk on and handle every day, pose absolutely no health problems. However, they can be dangerous if they are reduced to a fine powder which, if constantly inhaled over time, can damage the lung tissue and cause serious damage to health.

Fine crystalline silica dust can be generated by dry processing of silica stones, such as grinding and crushing, cutting, calibrating, polishing and suchlike.

The most common disease caused by prolonged inhalation of these silica dusts is silicosis, which in a severe form may cause irreparable damage to the pulmonary system. In more serious situations, lung cancer may also occur.
In 2012, the IARC - International Agency for Research on Cancer - recognised crystalline silica in its respirable fraction as a carcinogen.
The people most at risk of contracting these diseases are those working in the production and processing of materials containing crystalline silica - workers in mines and quarries, steelworks, foundries, cement factories and those who manufacture and process stones containing quartz or cristobalite.

The amount of dust inhaled and the duration of exposure to it, together with the size of the inhaled particles, are the determining factors in the development of silicosis and lung cancer.
Depending on the duration of exposure to silica dust and the amount inhaled, silicosis manifests itself in mild or severe forms, ranging from chronic (the most common form occurring after exposure of 15-20 years to low levels of silica) to acute (occurring after inhalation of high levels of silica dust, even for only a few years).
The fractions of silica dust identified as most dangerous are those smaller than 10 microns, as they are considered inhalable and can even reach and deposit in the pulmonary alveoli, causing lungs irritation.

However, it is important to consider the fact that the end-users of materials containing crystalline silica do not run any risk at all, as the disease results from inhaling the dust during processing.
The problem of occupational diseases related to exposure to silica is very much felt at all levels, so that several organisations, both at national and international level, deal with it.

In Italy, since 2003, there has been the NIS - Network Italiano Silice (Italian Silica Network), which deals with the dissemination of technical documents to manage the risk of occupational exposure, also in collaboration with the local health authorities.

In Europe, the main organisation is NEPSI - European Network for Silica, formed by the European sectoral associations of employees and employers who, on 25 April 2006, signed the Social Dialogue "Agreement on Workers' Health Protection through the Correct Handling and Use of Crystalline Silica and Products Containing it".
The Network has published several studies and documents, the most relevant one being the "Guide to Good Practice for Workers' Health Protection", a vademecum that helps to assess the risk of exposure and procedures for its prevention.
The regulatory framework inherent to crystalline silica dust exposure limits has undergone multiple changes and updates in recent years, both in the EU and worldwide. Among the latest changes, "work involving exposure to respirable crystalline silica dust generated by a manufacturing process" has been included among those classified as carcinogenic, as stipuleted in the EU Directive 2017/2398 and transposed by Legislative Decree of 1st June 2020 no. 44 with entry into force last 24th June 2020.

According to the European Directive, mentioned above, the occupational exposure limit for crystalline free silica (CAS 14808-60-7) is 0.1 mg/m³ respirable fraction in an 8-hour reference period.
This threshold is further reduced depending on the country and its legislation or reference values set by different organisations:
  • In America, the ACGIH - American Conference of Governmental Industrial Hygienists, has set a limit of 0.025 mg/m³.
  • In Canada, the limit given by the Canada Labour Code ranges from 0.025 to 0.1 mg/m³ (depending on the Canadian province).
  • The SCOELScientific Committee on Occupational Exposure Limits sets it at 0,050 mg/m³
  • The NOHSCNational Occupational Health & Safety Commission at 0,1 mg/m³.
The standard EN 689 defines a strategy for conducting exposure measurements to demonstrate compliance with occupational exposure limits.
If a 'not insignificant health' risk is detected, specific prevention and protection measures must be implemented, including health surveillance; with the obligation to repeat measurements more frequently to monitor that limits are not exceeded over time.

In Italy, as silica is considered a carcinogenic agent, the obligations are defined in Article 237 - Technical, organisational, procedural measures of the Consolidated Act on health and safety at work D. Lgs. 9th April 2008, n. 81. Legislative Decree no. 81 of 9th April 2008 and the relevant sanctions involve "imprisonment from three to six months or a fine from €2,740.00 to €7,014.40" for the employer/manager who does not apply the above-mentioned prevention measures.
 The stone industry processes different types of stone, whose content in quartz/cristobalite can be extremely variable. Commonly processed materials in the stone industry with a significant quartz content include: granite (20-60% quartz), quartzites and sandstones (95% quartz), quartz-based engineered stone (75% quartz), and ceramics (10-15% quartz).

Technological operations (sawing, calibrating, smoothing/polishing, shaping, etc.) are normally carried out in the industries with dedicated machinery using water, which helps to drastically reduce the dispersion of dust in the environment and, therefore, the degree of workers exposure to crystalline silica dust.

It is estimated that, with an adequate water flow, at least 99% of the dust generated by the tools is removed and evacuated with the water used for machining. The remaining part, normally less than 1%, is nebulized into the air through small water droplets (aerosols) generated by rotating tools, which in poorly ventilated environments can then deposit on the surrounding surfaces and subsequently dry out. To avoid the risk that the small percentage of dust deposited on the surfaces after the drying of the aerosol is lifted by air currents, it is necessary to wash the surfaces of the working environment frequently.

In certain working conditions, particularly those outside industrial environments, unfortunately not all machining operations are carried out using water and, as a result, a considerable amount of dust, potentially containing crystalline silica, is dispersed into the environment. If it is not removed with extraction equipment, the dust remains suspended in the air and settles on the surrounding surfaces, only to rise again with any air currents.
As a result, operators are at serious risk of inhaling large quantities of dust if they are not provided with adequate personal safety equipment.
Breton has always been committed to perfecting technologies and production processes in the natural stone and composite stone industry, respecting the environment and the health and safety of people.

All Breton equipment and machines work with adequate water flows, complying with the most stringent limits imposed by regulations. Furthermore, machine users are provided with appropriate operating instructions regarding the cleaning of the workplace and the possible use of PPE to avoid exposure to dust potentially containing crystalline silica.

But Breton, aware of the fact that in certain work situations where there is little concern for environmental health there is a risk of dispersed fine dust, has gone even further. It has therefore developed technologies and products with exceptional physical and mechanical properties but silica-free.

It has developed Lapitec®, a sintered stone composed of pure natural minerals with superior aesthetic and physical characteristics that does not contain quartz.
It has also recently developed Bioquarzo®, an industrial quartz free of crystalline silica that can be used as an alternative raw material to natural quartz for the manufacture of Bretonstone® (quartz-based engineered stone).



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