Should I be concerned about exposure to asbestos

Asbestos risk when doing home improvement

Explore the earth with brains and a hammer

The realization that asbestos can make you sick was at least rudimentary at the end of the 19th century. Nevertheless, the nationwide asbestos ban (with one exception) did not take place until around 1993 (in the EU, as far as I know, it was not even banned until 2003). This means that asbestos-containing building materials were used for a period of over 100 years. And so there is also an asbestos risk for everyone who works with these building materials.


Asbestos use

A total of around 5.7 million tons of asbestos were imported into Germany (Federal Republic and GDR). Most of this asbestos (depending on the source 70-73% or 3.99 / 4.3 million tons) was used in the production of asbestos cement, which is 39.9 million tons with an average asbestos content of 10% by weight Asbestos cement. Chemical construction products containing asbestos also accounted for a significant proportion of asbestos uses. This somewhat bulky term includes asbestos-containing plasters, fillers and tile adhesives, which have recently come more and more into focus.

These products are not only characterized by a very inhomogeneous and often very low asbestos content (in some cases it was even mixed by hand). Thin-bed adhesives for wall tiles can sometimes contain asbestos as little as 0.04% by mass. Often it can be significantly more. Of course, this means very high demands on laboratory analysis in order to be able to detect these low levels.

To do this, the problem would have to be known first. Because in contrast to other classic asbestos products such as fiber cement or cushion vinyl and Floorflex floor coverings, hardly any do-it-yourselfer is likely to be aware that a danger can lurk here. This is because the processing of these products can lead to increased exposure to asbestos in the indoor air in the rooms concerned.

It is estimated that these so-called concealed asbestos products are found in a good 25% of all buildings. Buildings that were built or renovated in the 1960s and 1970s are particularly suspicious. In principle, however, all new buildings or conversions up to 1995 are suspect.

Asbestos and home improvement

So if someone is renovating such an apartment on their own, it can also happen that he inadvertently and unknowingly works on material contaminated with asbestos. When drilling, milling and other mechanical activities such as chipping off wall tiles, asbestos fibers can then be released very easily. But how big is the risk? I have often asked myself the question (and often I had to try to answer it to others).

Some time ago I came across a short paper by Helmut Sagunski who tried to answer exactly this question (and which I am largely following here).
A one-off event is assumed. For example, the renovation of individual rooms in an inhabited house. The exposure lasts for days or possibly even a few weeks and clearly exceeds the background exposure that normally prevails in Germany.

If asbestos fibers get into the lungs over long periods of time and in large quantities, they can lead to various diseases including lung cancer. Their dimensions (thickness and length) and their chemistry determine how they behave in the lungs. The individual types of asbestos show differences in their carcinogenic potential.

How exactly asbestos causes cancer is not yet fully understood. This is also due to the long period of time that can elapse between exposure to asbestos and the onset of an illness. That can be an average of 30 years, but also more. The length of the period may indicate a multi-step process. The asbestos fibers in the alveoli presumably set off an inflammatory cascade that can lead to lung cancer.

Malignant mesothelioma is particularly feared. The US Environmental Protection Agency (EPA) published an exposure-cancer risk relationship study that found the additional risk of developing lung cancer or mesothelioma after lifetime exposure to 1,000,000 fibers per cubic meter of air is 1: 4 (0.23). In this case, lifelong exposure means that the person in question was exposed to asbestos 24 hours a day, 365 days a year for over 70 years at a respiratory rate of 20 m³ per day. There was no distinction between serpentine asbestos (chrysotile) and amphibole asbestos.


Fiber years and fiber days

In Germany, an exposure of 8 hours per day on 240 days per year over 40 years at a breathing rate of 10 m³ is assumed for the working life. This means that the additional risk after a working life exposure to 1,000,000 fibers of asbestos per m³ of breathing air is around 1:23 (0.043).

In order to simplify the information on cumulative exposure, the Committee on Hazardous Substances has introduced the term "fiber year". Around 2.4 billion asbestos fibers are inhaled during a fiber year. One fiber year is linked to a cancer risk of 1: 1000. It takes around 25 fiber years to recognize an asbestos-related occupational disease.

In 2008, the Committee for Hazardous Substances set a so-called tolerance risk of 1: 250 (corresponding to 4 fiber years) and an acceptance risk of 1: 2,500 (corresponding to 0.4 fiber years). It is also being considered whether the acceptance risk will be reduced to 1:25 000 (corresponding to 0.04 fiber years) from 2018 onwards.

In relation to a working life, the tolerance risk is 100,000 fibers and the acceptance risk is a concentration of 10,000 asbestos fibers per m³ of breathable air and should possibly be reduced to 1,000 fibers in 2018.

According to the Committee on Hazardous Substances, this means that normally no risk-reducing measures need to be taken in the event of loads of up to 100,000 fibers per m³ of breathable air. However, these are mandatory for loads.


Asbestos risk

For do-it-yourselfers, there have been no detailed studies to date with regard to the fiber concentrations that occur. Nevertheless, the hidden asbestos deposits in particular represent a risk that should not be underestimated.

In order to keep the risk assessment reasonably clear, the fiber day was introduced instead of the usual term of the fiber year. A fiber year corresponds to 240 fiber days. One fiber day corresponds to the intake of 10,000,000 asbestos fibers (at a breathing rate of 10m³ and an exposure of 1,000,000 asbestos fibers).

At present, 100,000 jobs per day are accepted for an entire working life in Germany. Over 40 years around 1 billion fibers are inhaled, which means the risk of developing cancer of 1: 2,500 or 4 * 10-4.

Chopping the tiles off the wall, drilling in plaster containing plaster or sanding, on the other hand, only represents a relatively small increase in the risk, even if this can lead to short-term strong inhalation of many asbestos fibers. Let's look at three different typical home improvement scenarios.

When drilling holes in an asbestos-plastered wall, for example, around 10,000 asbestos fibers per m³ can get into the room air. In the assumed scenario, it is assumed that the load lasts only one hour and was then stopped by ventilation. This corresponds to around 0.001 (in fiber years this is 0.000004 fiber years)) fiber days and an additional risk of 4 * 10-9 for cancer.

If tiles are knocked off a wall with tile adhesives containing asbestos, around 100,000 fibers per m³ can get into the room air. In addition, such an activity takes much longer than simple drilling. In the estimated scenario, the activity is approx. 8 hours (and means around 10 m³ of breathing air consumption). The air pollution is then ended by thorough ventilation of the room. The exposure here corresponds to 0.1 fiber day (or 0.0004 fiber years). The additional cancer risk is 4 * 10-7.

Even more fibers are released when sanding a wall with plaster containing asbestos. In the assumed scenario, around 1,000,000 fibers per m³ of room air are assumed, even if the working time may only last 1 hour. Subsequent ventilation can only reduce the load by around 90%. Further reductions of another 90% are made in the following days by ventilation. The total number of fibers inhaled in this scenario is estimated at 2,000,000. This corresponds to around 0.2 fiber days (or 0.0008 fiber years) with an additional cancer risk of 8 * 10-7.

The risk of a single increased exposure is therefore measurable and present. An accumulated asbestos dose is presumably responsible for the development of asbestos-related lung diseases.

What is to be done when the case has occurred? Above all, reduce further exposure. For this purpose, the materials to be processed, such as plaster, fillers and tile adhesive, should be analyzed before processing.

Smokers should give up smoking. The risk of asbestos-related illness increases by several orders of magnitude for smokers. Of course, you should possibly consult a specialist.

Gunnar Ries studied mineralogy in Hamburg and did his doctorate there at the Geological-Paleontological Institute and Museum on the weathering behavior of East African carbonatites. He works at CRB Analyze Service GmbH in Hardegsen. The opinions expressed here are my own