Chemical Protective Clothing: Could you be Sitting on a Health Time Bomb?
There are thousands of chemicals used globally with a wide range of associated hazards – acid burns, poison, toxicity and so on. Yet whilst some have short term effects that will be immediately apparent (it will hurt if you receive a splash of acid on your arm!), many have no immediate effects, but can cause irreversible damage to health – or even death – in the long term. Such chemicals are more difficult to deal with simply because contamination might not be noticed at all.
Chemicals also use different routes to enter the body; inhalation, ingestion, absorption through the skin and so on. Furthermore, the possible harmful effects of chemicals are all too commonly not well understood. Take a cursory glance through any collection of chemical safety data sheets and you will find many featuring sentences such as “suspected of causing cancer” or “may damage the unborn child”. In other words… we are not really sure. In a world in which chemicals are ubiquitous, who can predict what currently unknown harmful effects will emerge in the years and decades to come?
When protecting against chemicals therefor the mantra should be “do not take risks”. So if you use chemical protective clothing you might be surprised to learn that even when a permeation test indicates a “breakthrough” of >480 minutes, there could still be small amounts of a chemical permeating through the suit fabric and contaminating the wearers skin. And if a task is conducted regularly it could be happening repeatedly, the wearer and employer entirely unaware until months or years later when health problems – possibly devastating health problems – emerge.
There is an old (admittedly not very good) joke about a man that fell from the roof of a skyscraper. As he plummeted to the ground, people on each floor kept hearing him say “well, so far so good!” In the same way, when working with chemicals, assuming that, because there are no immediate problems apparent there are no problems, is dangerous. Just like the man in the joke who had no problem until he hit the ground, you will have no problems until they develop at some point in the future. By which time it is, of course far too late.
“How can a worker be contaminated? The test breakthrough for our suit is >480 minutes. We only use the suit for one hour maximum!”
This is the crux of the problem. Test “breakthrough” has been widely – in fact globally – misunderstood. Most users believe that “breakthrough” means the obvious. That it refers to when the chemical first “breaks through” the fabric. Thus the thinking goes:-
“The breakthrough for this suit against this chemical is >480 minutes, so no chemical has broken through in 480 minutes, therefor I am safe to wear this suit”.
It sounds reasonable… and yet it is entirely and completely wrong….
If “breakthrough” does not mean “breakthrough”, what does it mean?
The term “breakthrough” has actually become abbreviated from the term “Normalised Breakthrough”, which has a very specific definition. In fact it means this: “The time until the RATE of permeation reaches a predetermined speed”. In the case of CE standards that speed is generally 1.0µg /cm2/minute. (The standard also provides an option of 0.1µg /cm2/minute, and this latter rate is also used in the similar North American standard).
So if the “breakthrough” is measuring the time until a speed of permeation, then clearly the chemical must have started permeating at some point before that. The “first breakthrough” must by definition be before the “Normalised breakthrough”. In other words, at the point of “breakthrough” the chemical has already been permeating through the fabric and may have come into contact with the wearers’ skin. And because of the mistaken assumption about what “breakthrough” means, you might not even be aware of it. The possible effects of this misunderstanding are shown in the graphs below.
In this sense therefor – given the long term health effects of many chemicals and the fact that users could be being contaminated on a regular basis without anyone realising – you could be sitting on a health time bomb.
So what’s the solution?
The new 2018 version of EN 14325 (which defines all the classifications for protective clothing properties) recognises the problem with the original classification, stating:
“It can be dangerous to base considerations of safe wear time of given chemical protective clothing only on the value of normalised breakthrough time for a specific chemical”
To address the problem the new standard offers a second method of classifying chemical suit fabric. This takes into account:-
- The amount of chemical permeating over time
- The toxicity of the chemical – how much of it is required to cause harm
By comparing the two (i.e. that the time to reach a hazardous volume of chemical permeated is less than the exposure time) it offers a more realistic safe-use time. However, the permeation test and new classification cannot account for the effect of temperature. A higher temperature will result in faster permeation – in general terms a 10oC rise in temperature may result in a doubling of permeation rate. Yet all permeation tests are conducted at 23oC, so even if used for this new classification, test information is likely to be wrong if users are in environments at higher or lower temperatures.
The Permasure® Solution
Permasure® is a smart-phone app for use with selected Lakeland ChemMax chemical suits. It uses advanced molecular modelling to calculate permeation rates taking into account temperature and exposure time, thus providing an instant safe-use time for over 4000 chemicals in an instant.