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A world with silica vol. 3

About what we read on the 25kg bag of CUARSIL

When we take a 25kg bag of CUARSIL we read, apart from the name, the granulometry and the percentages of binder it contains. The whole bag contains quartzite. But NOT all the content of the bag is SCR.

Let us remember the concept of SCR: Crystalline Silica Respirable:
- SILICA (SiO2). Quartz is the second most abundant mineral in the crust.
- And it is the most common CRYSTALLINE form of silicon oxide (silica); it is present in many rocks in different proportions (granite, sandstone, shale, etc.).
- RESPIRABLE… that fraction of silica dust that is capable of reaching the alveoli of the lungs. It will depend on how crystalline silica is used, process, environment and prevention measures, etc.

On the reverse side of the bag, we can read the pictogram and the name STOT RE 2

What do the words "STOT RE 2" on the bags mean?

The so-called CLP (Classification, Labelling, Packaging) Regulation introduced the "STOT" hazard categorisation to relate toxicity to the specific organ that may be affected. The acronym STOT (Specific Target Organ Toxicity) could be translated as "Specific Target Organ Toxicity".

This organ toxicity classifies substances into two groups:
- SE for single exposure and
- RE for repeated exposure.

In the foundry industry, refractories, etc., the STOT RE concept applies, which in turn is divided into two categories
- STOT RE 1(H372), expressly referring to "hazard": causes damage after repeated exposure.
- STOT RE 2(H373), only as a "warning": may cause harm after repeated exposure.

The difference between the two is that in the first case there is evidence of toxicity to humans or in animal experiments, while in the second case there is a presumption of toxicity, without such a rigorous determination of toxicity; in both cases after repeated exposures.

In any case, these labelling signals are complementary to other regulations that may apply to the substances. In the case of SCR, this is the case of its inclusion in RD 665/1997, already mentioned in the first informative summary of this series.

What does this pictogram imply?

The pictogram makes it necessary to act on two crucial aspects: the PROCESS and the RPE (respiratory protection equipment). Thus, once the existence of a risk is known, action (process) must be taken to reduce exposure as much as possible, using RPE to ensure that exposure is really minimal, when it is not achieved by technical means. In short, the optimisation of technical prevention (process) and the use of RPEs will ensure safe work with RCS.

Both aspects will be discussed in the next chapter.

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